4022e3 3. ASSESSMENT OF RISKS TO HUMAN HEALTH DOWNSTREAM OF THE FORMER DELORO MINE SITE

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3. ASSESSMENT OF RISKS TO HUMAN HEALTH DOWNSTREAM OF THE FORMER DELORO MINE SITE

3.1 Introduction

The second component of the Phase II Moira River Study was to conduct a Preliminary Quantitative Risk Assessment (PQRA) of the Moira River system downstream of the Deloro Mine Site (see Figure 3.1-1). The objective of this PQRA was to determine whether there are potential current and future human health risks associated with substances released to the Moira River system from the Deloro Mine Site. The study is intended to guide future risk management strategies and remedial options. The study is not designed to examine potential health risks associated with historical exposures. The results of the PQRA were used to identify metals and exposure pathways that warranted additional study and/or risk management. This section presents the rationale, methodology and results of the PQRA.

In the PQRA, the Moira River system (or river system) includes the Moira River, Moira Lake and Stoco Lake.

As noted above, this is a screening assessment. In such an assessment, it is important to ensure that all relevant exposure scenarios are evaluated and that scenarios of concern are properly identified for further study. To ensure that these goals are met, the present assessment uses conservative data and assumptions with respect to chemical concentrations (highest and average concentrations are considered), exposure scenarios (use of the river for potable water, and recreational use of the river on a regular and frequent basis) and receptors (those most likely to have the highest exposure for the scenarios considered). Because of the use of this conservative approach, exposure estimates should be considered "worst case" estimates which are likely to overestimate true exposure levels and associated risks.

The worst case estimates produced by the PQRA added layers of safety to the assessment. Elimination of concern about particular metals or pathways of exposure was possible and defensible because of these layers of safety. Thus, if exposures were less than benchmark values (representing safe and acceptable exposures), it could be concluded with confidence that there was no risk to human health. Layers of safety are discussed further in Section 3.4.3.7.

PRELIMINARY QUALITATIVE RISK ASSESSMENT (PQRA) STUDY AREAS

REFERENCE
BASE MAP PROVIDED BY GIS GOLDER MISSISSAUGA

SCHEMATIC ONLY NOT TO SCALE

The primary objective of the PQRA is to determine the potential future health impacts associated with substances present in the river system and which are related to releases from the Deloro Mine Site.

3.1.1 Scope of Work

This PQRA was developed according to the risk assessment frameworks and methodologies

detailed in the following documents:

"Guideline for Use at Contaminated Sites in Ontario, Revised February, 1997 (MOE 1996);
"Guidance on Site Specific Risk Assessment (SSRA) for Use at Contaminated Sites in Ontario, May, 1996" (MOE 1996b); and
Deloro Village Environmental Health Risk Study (CanTox 1999).

As stated in the Terms of Reference for this study, the Preliminary Quantitative Risk Assessment (PQRA) was completed in a manner consistent with the environmental health risk assessment conducted for the Village of Deloro.

To support the completion of this screening level PQRA, a survey was conducted specifically to assess if residents were ingesting water from the Moira River system. This survey consisted of a questionnaire addressing:

Location in the watershed;
The use of the Moira River system as a source of drinking water;
Year round or seasonal residency; and
Other uses of water from the Moira River system (washing/bathing/gardening/ swimming/cooking).

The questionnaire did not address consumption patterns or number of occupants nor other issues relevant to a detailed exposure assessment. In July 1999, a total of 624 questionnaires were hand delivered by the Moira Lake Property Owners' Association or mailed to potential survey participants by the Ministry of the Environment to residents as far downstream as the outlet of Stoco Lake.

A total of 231 households responded and of these, eight households indicated that they use water from the river system for drinking purposes. Three of these respondents were located on Moira Lake, four were located downstream and an eighth respondent did not provide a location. Followup telephone contacts by the MOE revealed that one of the three respondents on Moira Lake stated that he had completed the questionnaire in error and was in fact consuming water from a drilled well. One respondent from Stoco Lake indicated that they were using a distillation system to treat the water prior to consumption. Nevertheless, the results of this survey indicate that some people may be using the Moira River system for drinking water purposes. The residents located downstream of the former Deloro Mine Site to the outlet of Moira Lake were subsequently reminded by a joint letter from the Hastings and Prince Edward Counties Health Unit and the Ministry of the Environment stating that the Ontario Drinking Water Objective for arsenic had been exceeded in the water of Moira Lake and that an alternative supply or treatment to remove arsenic should be considered (Appendix IX).

Although some residents may be using the river system as a source of drinking water, this water use pattern is clearly not indicative of the general water use pattern by most residents. Inclusion of this exposure pathway into the risk assessment will overestimate the potential health impacts to the vast majority of area residents that do not use the river system as a source of drinking water. Therefore, the PQRA considered both water use scenarios (i.e., water from the river system is used/not used as a source of drinking water) so as to provide a more reliable assessment of potential health impacts for residents of the study area.

3.1.2 Study Area Selection

The following four areas of the Moira River system downstream of the Deloro Mine Site were selected for the PQRA (Figure 3.1-1):

Moira River from Deloro to Moira Lake (designated as Area "A");
Moira Lake (designated as Area "B");
Stoco Lake (designated as Area "C"); and
Moira River downstream of Stoco Lake (designated as Area "D").

These areas were selected because they represent discrete sections of the river system that are likely to exhibit different environmental conditions based on their different physical characteristics, relative recreational use and proximity to the Deloro Mine Site. In addition to the four study areas, several reference locations were selected to provide data on the background concentrations of metals in areas not impacted by the Deloro Mine Site or other known point sources of metals (see Section 1.0). Some of the reference locations are part of the Moira River system upstream of the study areas and, as such, may contribute to the overall loading of metals into the system. Water and sediment samples were collected at all reference locations and analyzed for the same parameters as samples from the four study areas. Comparison of the concentrations detected in the reference locations to the study areas provides an indication of the impacts associated with the release of metals from the Deloro Mine Site.

3.1.3 Report Organization

Section 3.2 provides an overview of the approach that was employed for the PQRA. The problem formulation, which describes how humans may be exposed to chemicals in the river system, is described in Section 3.3. Section 3.4 describes the methodology, modelling results and the risk characterization. The conclusions and recommendations are given in Section 3.5.

3.2 Study Approach

This section describes the approach used for the PQRA to evaluate the potential impacts associated with the Moira River system. The PQRA is comprised of the following three steps:

Step 1) Data Compilation and Analysis

Chemical analysis data from this study and other studies of the Moira River system are discussed in Sections 2.1 and 2.2 with detailed data presentation in Appendices I and II. Fish tissue data were provided by the Ontario Sport Fish Contaminant Monitoring Program. The water, sediment and fish tissue chemistry data provided the input for the exposure analysis required for the PQRA.

Step 2) Problem Formulation

The problem formulation stage integrates basic information about potential risks into a conceptual model that describes how humans may be exposed to chemicals that represent a health risk. There are three prerequisites for a risk to exist (Figure 3.2-1):

A chemical must be present at concentrations that may cause a deleterious health effect;
A human receptor must be present; and
An exposure pathway by which the human receptor can come into contact with the chemical must exist.

Figure 3.2-1 Environmental Risk Components

However, the presence of all three components does not automatically indicate that an unacceptable risk or exposure is present, but only that it could exist.

Information about these three risk components is used to develop the problem formulation. The problem formulation focuses the risk assessment by eliminating chemicals, receptors and pathways that are not applicable or of little or no concern. This is done by examining chemicalspecific parameters, characteristics of the study area (e.g., land use and geology) and the likely presence and activities of receptors (e.g., children and adult receptors). This information is used to develop a conceptual site model (CSM) which depicts the combinations of chemicals, receptors and connecting pathways that require further examination in the PQRA.

Step 3) Preliminary Quantitative Risk Assessment

The PQRA uses equations to estimate receptor exposure to substances of potential concern via the various pathways and exposure routes (inhalation, dermal absorption, and ingestion) identified in the CSM.

For non-carcinogenic substances, estimated exposures are compared to benchmark values that are expected to pose no risk, even among sensitive people exposed every day over a lifetime. For substances that are known to cause or probably cause cancer in people, an estimate of incremental lifetime cancer risk is developed.

3.3 Problem Formulation

3.3.1 Chemical Screening

The chemical screening process involves comparing the concentrations of chemicals measured in the water, sediment and fish to screening criteria. Screening criteria include guidelines or objectives set by regulatory agencies. These guidelines or objectives represent concentrations in water, sediments or fish that are protective of human health under all plausible exposure scenarios. When guidelines or objectives were not available, chemical concentrations in the study areas were compared to the corresponding concentration in water, sediment or fish samples from the reference locations. Chemicals detected at concentrations greater than the screening criteria or at concentrations greater than the reference locations were examined further in the PQRA. Chemicals detected at concentrations below or equal to the screening criteria are unlikely to represent a health risk and were not examined further.

3.3.1.1 Surface Water

Annual average and the ten-year average of the annual maximum metal concentrations in surface water (lakes and river) were compared to screening criteria. This approach involved comparing metal concentrations to the appropriate Ontario Drinking Water Objective (ODWO) (MOE 1999_a). If an ODWO was not available, criteria from Table A (potable groundwater) of the MOE Cleanup Guideline were used (MOE 1999b). Both the ODWO_s and Table A criteria are protective of human health, and consider exposure scenarios such as using the river water as potable drinking water and accidental ingestion during swimming. If exceedances of screening criteria only occurred at reference sites, the metal was not considered further. If exceedances occurred at both reference and Moira River system sites,but concentrations were higher at reference sites, the metal was not considered further. Substances that were detected at concentrations greater than the screening criteria were compared to the concentrations detected at the reference locations to determine if they are related to the Deloro Mine Site or if they are representative of normal background concentrations. Substances present in the river system at levels greater than the screening criteria and deemed to be related to releases from the Deloro Mine Site were evaluated further in the PQRA.

Water quality in the Moira River system fluctuates by season (i.e., water concentrations of metals are generally higher in late summer and early fall) (discussed in Section 2.1). Therefore, both annual mean and the ten-year average of the annual maximum detected concentrations were used to evaluate water quality in the chemical screening process. Use of the annual mean concentration provided a good indicator of overall water quality in the river system, whereas the ten-year average of the annual maximum concentration represented a reasonable "worst case" scenario.

Water quality data from 1990 to present was evaluated in this assessment. Data collected prior to 1990 were not evaluated since they were unlikely to be representative of existing environmental conditions.

Within the study areas and reference locations, concentrations of aluminum, iron and manganese occasionally exceeded the ODWOs. The screening criteria (ODWOs) for aluminum, iron and manganese are based on aesthetics or operational guidelines for water treatment facilities and are not health-based. Comparison of the concentrations detected in water to concentrations found in the reference locations and in surface waters throughout the Canadian Shield indicated that the levels of these metals detected in Study Area A did not appear elevated (CCME 1995). At the concentrations detected, these chemicals were not anticipated to represent a health risk. Therefore, these metals were not evaluated further in this assessment.

Cadmium, chromium and lead were also detected in a few study area samples at concentrations greater than the screening criteria. Comparison of the concentrations detected in the study areas to the reference locations reveals that the study area concentrations were not elevated relative to the reference sites. There are no data to indicate that these substances are associated with historical releases from the Deloro Mine Site. For instance, historical levels of lead have exceeded the PWQO at reference locations with greater magnitude than those found in the Moira River system and there have been only a few minor exceedances of the ODWO for this substance over the past ten years. These results indicate that the background geology in the area is likely the predominant source of lead to the Moira River system and not the Deloro Mine Site. The concentrations of lead, cadmium and chromium in the study area do not appear to be related to the Deloro Mine Site. Therefore, these substances in water were not considered further in this assessment.

There were also some study area samples with elevated concentrations of various metals that did not appear to be related to background. The concentrations detected were orders of magnitude higher than all other data points for these metals. These spurious results likely represent reporting or data transcription errors in the original data set and were considered outliers.

Since no radioactive substances (including uranium) were detected in water at concentrations greater than the screening criteria, the potential health risks associated with these substances were considered negligible. Therefore, these substances were not addressed further in this assessment.

Moira River from Deloro to Moira Lake (Study Area A)

Comparison of the annual mean and the ten year average of the annual maximum concentrations in water to the appropriate screening criteria revealed that the concentrations of arsenic, cobalt and nickel exceeded the screening criteria (see Tables 3.3-1 and 3.3-2). Therefore, the potential health risks associated with these substances in water were evaluated further in the PQRA (see Section 3.4). No other substances were detected at concentrations greater than the screening criteria.

Moira Lake (Study Area B)

Comparison of the annual mean and the ten year average of the annual maximum concentrations in water to the appropriate screening criteria revealed that arsenic concentrations exceeded the screening criteria (see Tables 3.3-3 and 3.3-4). Therefore, arsenic was evaluated further in the PQRA. No other substances were detected at concentrations greater than the screening criteria. Stoco Lake (Study Area C) Comparison of the annual mean and the ten year average of the annual maximum concentrations in water to the appropriate screening criteria revealed that maximum arsenic concentrations exceeded the screening criteria (see Tables 3.3-5 and 3.3-6). Therefore, the potential health risks associated with maximum arsenic concentrations in water in Study Area C were investigated further in the PQRA.

Moira River Downstream of Stoco Lake (Study Area D)

Comparison of the annual mean and the ten year average of the annual maximum concentrations in water to the appropriate screening criteria revealed that no substances were detected atconcentrations greater than the screening criteria (see Tables 3.3-7 and 3.3-8). Therefore, the potential health risks associated with substances in water in Study Area D were not evaluated further in the PQRA.

Table 3.3-1

Area A Exceedances for Yearly Maximum Concentrations

Parameter	Year	ODWO¹mg/L	Basis	Table A²mg/L	Reference	Site
Parameter	Year	ODWO¹mg/L	Basis	Table A²mg/L	Malone	D/S Deloro	Moira HWY-7	Young's Creek	Moira D/S Young's Creek
					W1	W2	DM7	DM1	DM8
ALUMINIUM,UNFILTERED TOTAL	1990	0.1	OG	NA	0.19	0.11
ALUMINIUM,UNFILTERED TOTAL	1991	0.1	OG	NA	0.06	0.125
ALUMINIUM, UNFILTERED TOTAL	1992	0.1	OG	NA	0.052	0.044
ALUMINIUM, UNFILTERED TOTAL	1993	0.1	OG	NA	0.06	0.1
ALUMINIUM, UNFILTERED TOTAL	1994	0.1	OG	NA	0.047	0.1
ALUMINIUM, UNFILTERED TOTAL	1995	0.1	OG	NA	0.061	0.049
ALUMINIUM, UNFILTERED TOTAL	1996	0.1	OG	NA	0.05	0.08
ALUMINIUM, UNFILTERED TOTAL	1997	0.1	OG	NA		0.0392
ALUMINIUM, UNFILTERED TOTAL	1998	0.1	OG	NA		0.0318
ALUMINIUM, UNFILTERED TOTAL	1999	0.1	OG	NA
ARSENIC, UNFILTERED TOTAL	1990	0.025	IMAC	0.025	0.015	0.13
ARSENIC, UNFILTERED TOTAL	1991	0.025	IMAC	0.025	0.002	0.39
ARSENIC, UNFILTERED TOTAL	1992	0.025	IMAC	0.025	0.004	0.18
ARSENIC, UNFILTERED TOTAL	1993	0.025	IMAC	0.025	0.001	0.092	0.113	0.523	0.121
ARSENIC, UNFILTERED TOTAL	1994	0.025	IMAC	0.025	0.0016	0.16	0.151	0.513	0.187
ARSENIC, UNFILTERED TOTAL	1995	0.025	IMAC	0.025	0.001	0.023	0.197	0.299	0.221
ARSENIC, UNFILTERED TOTAL	1996	0.025	IMAC	0.025			0.059	0.528	0.061
ARSENIC, UNFILTERED TOTAL	1997	0.025	IMAC	0.025			0.177	0.171	0.193
ARSENIC, UNFILTERED TOTAL	1999	0.025	IMAC	0.025	0.0005	0.27
COBALT, UNFILTERED TOTAL	1990	NA		0.1	0.0088	0.015
COBALT, UNFILTERED TOTAL	1991	NA		0.1	0.0023	0.0185
COBALT, UNFILTERED TOTAL	1992	NA		0.1	0.0006	0.0064
COBALT, UNFILTERED TOTAL	1993	NA		0.1	0.0005	0.0041	0.018	0.057	0.005
COBALT, UNFILTERED TOTAL	1994	NA		0.1	0.0002	0.0028	0.017	0.53	0.043
COBALT, UNFILTERED TOTAL	1995	NA		0.1	0.0006	0.0024	0.005	0.009	0.01
COBALT, UNFILTERED TOTAL	1996	NA		0.1	0.0002	0.0016	0.004	0.26	0.021
COBALT, UNFILTERED TOTAL	1997	NA		0.1		0.00121	0.1	0.33	0.34
COBALT, UNFILTERED TOTAL	1998	NA		0.1		0.00407
COBALT, UNFILTERED TOTAL	1999	NA		0.1	0.000397	0.00255
IRON, FILTERED TOTAL	1996	0.3	AO	NA	0.22
IRON, UNFILTERED TOTAL	1990	0.3	AO	NA	0.32	0.33
IRON, UNFILTERED TOTAL	1991	0.3	AO	NA	0.58	0.42
IRON, UNFILTERED TOTAL	1992	0.3	AO	NA	0.32	0.32
IRON, UNFILTERED TOTAL	1993	0.3	AO	NA	0.33	0.5
IRON, UNFILTERED TOTAL	1994	0.3	AO	NA	0.19	0.43
IRON, UNFILTERED TOTAL	1995	0.3	AO	NA	0.38	0.38
IRON, UNFILTERED TOTAL	1996	0.3	AO	NA	0.24	0.28
IRON, UNFILTERED TOTAL	1997	0.3	AO	NA		0.135
IRON, UNFILTERED TOTAL	1998	0.3	AO	NA		0.16
IRON, UNFILTERED TOTAL	1999	0.3	AO	NA
LEAD, UNFILTERED TOTAL	1990	0.01	MAC	0.01	0.005	0.005
LEAD, UNFILTERED TOTAL	1991	0.01	MAC	0.01	0.005	0.005
LEAD, UNFILTERED TOTAL	1992	0.01	MAC	0.01	0.005	0.005
LEAD, UNFILTERED TOTAL	1993	0.01	MAC	0.01	0.005	0.005	0.015	0.511	0.017
LEAD, UNFILTERED TOTAL	1994	0.01	MAC	0.01	0.005	0.005	0.023	0.016	0.022
LEAD, UNFILTERED TOTAL	1995	0.01	MAC	0.01	0.005	0.005	0.007	0.006	0.007
LEAD, UNFILTERED TOTAL	1996	0.01	MAC	0.01	0.005	0.005	0.001	0.002	0.001
LEAD, UNFILTERED TOTAL	1997	0.01	MAC	0.01		0.00418	0.007	0.006	0.007
LEAD, UNFILTERED TOTAL	1998	0.01	MAC	0.01		0.0071
LEAD, UNFILTERED TOTAL	1999	0.01	MAC	0.01	0.00323	0.00499
MANGANESE, FILTERED TOTAL	1996	0.05	AO	NA	0.039
MANGANESE, FILTERED TOTAL	1997	0.05	AO	NA
MANGANESE, FILTERED TOTAL	1998	0.05	AO	NA		0.0375
MANGANESE, UNFILTERED TOTAL	1994	0.05	AO	NA	0.026	0.022
MANGANESE, UNFILTERED TOTAL	1995	0.05	AO	NA	0.048	0.073
MANGANESE, UNFILTERED TOTAL	1996	0.05	AO	NA	0.039	0.04
MANGANESE, UNFILTERED TOTAL	1997	0.05	AO	NA		0.0187
MANGANESE, UNFILTERED TOTAL	1998	0.05	AO	NA		0.129
MANGANESE, UNFILTERED TOTAL	1999	0.05	AO	NA
NICKEL, UNFILTERED TOTAL	1990	NA		0.1	0.004	0.008
NICKEL, UNFILTERED TOTAL	1991	NA		0.1	0.013	0.065
NICKEL, UNFILTERED TOTAL	1992	NA		0.1	0.005	0.008
NICKEL, UNFILTERED TOTAL	1993	NA		0.1	0.002	0.004	0.015	0.051	0.017
NICKEL, UNFILTERED TOTAL	1994	NA		0.1	0.0011	0.0027	0.021	0.042	0.018
NICKEL, UNFILTERED TOTAL	1995	NA		0.1	0.0009	0.0015	0.033	0.036	0.008
NICKEL, UNFILTERED TOTAL	1996	NA		0.1	0.0005	0.0015	0.012	0.088	0.01
NICKEL, UNFILTERED TOTAL	1997	NA		0.1		0.00072	0.04	0.133	0.13
NICKEL, UNFILTERED TOTAL	1998	NA		0.1		0.00351
NICKEL, UNFILTERED TOTAL	1999	NA		0.1	0.00087	0.00773

- Ontario Drinking Water Objectives, Ministry of Environment, 1994.
- Table A: Surface soil and groundwater remediation criteria for three land uses in a potable groundwater situation, Guideline for Use at Contaminated Sites in Ontario, Ministry of Environment and Energy, 1997.

AO - Aesthetic objective.
IMAC - Interim maximum acceptable concentration.
MAC - Maximum acceptable concentration.
NA - No value available.
OG - Operational Guideline.
BOLD - Exceeds ODWO. Where no ODWO is available, concentration exceeds Table A.

Table 3.3-2
Area A Exceedances for Average Concentrations

Parameter	Year	ODWO¹	Basis	Table A²	Reference	Site A
		mg/L		mg/L	Malone	D/S Deloro	Moira HWY-7	Young's Creek	Moira D/S Young's Creek
					W1	W2	DM7	DM1	DM8
ARSENIC, UNFILTERED TOTAL	1990	0.025	IMAC	0.025	0.002	0.033
ARSENIC, UNFILTERED TOTAL	1991	0.025	IMAC	0.025	0.001	0.084
ARSENIC, UNFILTERED TOTAL	1992	0.025	IMAC	0.025	0.002	0.042
ARSENIC, UNFILTERED TOTAL	1993	0.025	IMAC	0.025	0.001	0.023	0.036	0.201	0.047
ARSENIC, UNFILTERED TOTAL	1994	0.025	IMAC	0.025	0.001	0.036	0.034	0.195	0.047
ARSENIC, UNFILTERED TOTAL	1995	0.025	IMAC	0.025	0.001	0.019	0.062	0.156	0.071
ARSENIC, UNFILTERED TOTAL	1996	0.025	IMAC	0.025			0.024	0.195	0.030
ARSENIC, UNFILTERED TOTAL	1997	0.025	IMAC	0.025			0.034	0.096	0.063
ARSENIC, UNFILTERED TOTAL	1999	0.025	IMAC	0.025	0.001	0.083

COBALT, UNFILTERED TOTAL	1990	NA		0.1	0.002	0.004
COBALT, UNFILTERED TOTAL	1991	NA		0.1	0.001	0.006
COBALT, UNFILTERED TOTAL	1992	NA		0.1	0.001	0.002
COBALT, UNFILTERED TOTAL	1993	NA		0.1	0.001	0.002	0.018	0.044	0.004
COBALT, UNFILTERED TOTAL	1994	NA		0.1	0.000	0.001	0.010	0.183	0.024
COBALT, UNFILTERED TOTAL	1995	NA		0.1	0.000	0.001	0.003	0.007	0.004
COBALT, UNFILTERED TOTAL	1996	NA		0.1	0.000	0.002	0.003	0.103	0.011
COBALT, UNFILTERED TOTAL	1997	NA		0.1		0.001	0.028	0.139	0.092
COBALT, UNFILTERED TOTAL	1998	NA		0.1		0.002
COBALT, UNFILTERED TOTAL	1999	NA		0.1	0.000	0.002

LEAD, UNFILTERED TOTAL	1990	0.01	MAC	0.01	0.005	0.005
LEAD, UNFILTERED TOTAL	1991	0.01	MAC	0.01	0.005	0.005
LEAD, UNFILTERED TOTAL	1992	0.01	MAC	0.01	0.005	0.005
LEAD, UNFILTERED TOTAL	1993	0.01	MAC	0.01	0.005	0.005	0.007	0.051	0.005
LEAD, UNFILTERED TOTAL	1994	0.01	MAC	0.01	0.005	0.005	0.012	0.007	0.010
LEAD, UNFILTERED TOTAL	1995	0.01	MAC	0.01	0.005	0.005	0.003	0.004	0.003
LEAD, UNFILTERED TOTAL	1996	0.01	MAC	0.01	0.005	0.005	0.001	0.002	0.001
LEAD, UNFILTERED TOTAL	1997	0.01	MAC	0.01		0.004	0.005	0.003	0.004
LEAD, UNFILTERED TOTAL	1998	0.01	MAC	0.01		0.002
LEAD, UNFILTERED TOTAL	1999	0.01	MAC	0.01	0.003	0.003

MANGANESE, UNFILTERED TOTAL	1994	0.05	AO	NA	0.014	0.011
MANGANESE, UNFILTERED TOTAL	1995	0.05	AO	NA	0.041	0.040
MANGANESE, UNFILTERED TOTAL	1996	0.05	AO	NA	0.038	0.040
MANGANESE, UNFILTERED TOTAL	1997	0.05	AO	NA		0.019
MANGANESE, UNFILTERED TOTAL	1998	0.05	AO	NA		0.058
MANGANESE, UNFILTERED TOTAL	1999	0.05	AO	NA

- Ontario Drinking Water Objectives, Ministry of Environment, 1994
- Table A: Surface soil and groundwater remediation criteria for three land uses in a potable groundwater situation, Guideline for Use at Contaminated Sites in Ontario,Ministry of Environment and Energy, 1997

AO - Aesthetic objective
IMAC - Interim maximum acceptable concentration
MAC - Maximum acceptable concentration
NA - No value available
BOLD - Exceeds ODWO. Where no ODWO is available, concentration exceeds Table A.

Table 3.3-3
Area B Exceedances for Yearly Maximum Concentrations

Parameter	Year	ODWO¹	Basis	Table A²	Reference	Site
		mg/L		mg/L	Deer Cr	HWY 62 Bridge	Moira Lk Narrows	Moira Lk Outlet
					W4	W6	W7	W8
ALUMINIUM, UNFILTERED TOTAL	1990	0.1	OG	NA		0.062
ALUMINIUM, UNFILTERED TOTAL	1991	0.1	OG	NA		0.03
ALUMINIUM, UNFILTERED TOTAL	1992	0.1	OG	NA		0.099
ALUMINIUM, UNFILTERED TOTAL	1993	0.1	OG	NA		0.034
ALUMINIUM, UNFILTERED TOTAL	1994	0.1	OG	NA	0.15	0.031
ALUMINIUM, UNFILTERED TOTAL	1995	0.1	OG	NA	0.14	0.041
ALUMINIUM, UNFILTERED TOTAL	1996	0.1	OG	NA	0.05	0.04	0.04
ALUMINIUM, UNFILTERED TOTAL	1997	0.1	OG	NA	0.0338		0.0436
ALUMINIUM, UNFILTERED TOTAL	1998	0.1	OG	NA	0.0226		0.0188
ALUMINIUM, UNFILTERED TOTAL	1999	0.1	OG	NA

ARSENIC, UNFILTERED TOTAL	1990	0.025	IMAC	0.025	0.021	0.085
ARSENIC, UNFILTERED TOTAL	1991	0.025	IMAC	0.025	0.016	0.165
ARSENIC, UNFILTERED TOTAL	1992	0.025	IMAC	0.025	0.003	0.097
ARSENIC, UNFILTERED TOTAL	1993	0.025	IMAC	0.025	0.002	0.077
ARSENIC, UNFILTERED TOTAL	1994	0.025	IMAC	0.025	0.002	0.079
ARSENIC, UNFILTERED TOTAL	1995	0.025	IMAC	0.025	0.001	0.015
ARSENIC, UNFILTERED TOTAL	1996	0.025	IMAC	0.025
ARSENIC, UNFILTERED TOTAL	1997	0.025	IMAC	0.025
ARSENIC, UNFILTERED TOTAL	1999	0.025	IMAC	0.025	0.0015	0.047	0.076	0.024

CHROMIUM, UNFILTERED TOTAL	1990	0.05	MAC	0.05		0.0006
CHROMIUM, UNFILTERED TOTAL	1991	0.05	MAC	0.05		0.001
CHROMIUM, UNFILTERED TOTAL	1992	0.05	MAC	0.05	0.001	0.001
CHROMIUM, UNFILTERED TOTAL	1993	0.05	MAC	0.05	0.0009	0.0014
CHROMIUM, UNFILTERED TOTAL	1994	0.05	MAC	0.05	0.001	0.0005
CHROMIUM, UNFILTERED TOTAL	1995	0.05	MAC	0.05	0.0011	0.0012
CHROMIUM, UNFILTERED TOTAL	1996	0.05	MAC	0.05	0.0012	0.0008	0.0008
CHROMIUM, UNFILTERED TOTAL	1997	0.05	MAC	0.05	6.71E-06		0.000678
CHROMIUM, UNFILTERED TOTAL	1998	0.05	MAC	0.05	0.259 ³		0.000928
CHROMIUM, UNFILTERED TOTAL	1999	0.05	MAC	0.05

IRON, FILTERED TOTAL	1996	0.3	AO	NA	0.1		0.16
IRON, UNFILTERED TOTAL	1990	0.3	AO	NA		0.2
IRON, UNFILTERED TOTAL	1991	0.3	AO	NA		0.2
IRON, UNFILTERED TOTAL	1992	0.3	AO	NA	0.29	0.19
IRON, UNFILTERED TOTAL	1993	0.3	AO	NA	0.27	0.3
IRON, UNFILTERED TOTAL	1994	0.3	AO	NA	1	0.25
IRON, UNFILTERED TOTAL	1995	0.3	AO	NA	0.22	0.19
IRON, UNFILTERED TOTAL	1996	0.3	AO	NA	0.12	0.22
IRON, UNFILTERED TOTAL	1997	0.3	AO	NA	0.233		0.13
IRON, UNFILTERED TOTAL	1998	0.3	AO	NA	0.185		0.128
IRON, UNFILTERED TOTAL	1999	0.3	AO	NA

MANGANESE, FILTERED TOTAL	1996	0.05	AO	NA	0.014		0.028
MANGANESE, FILTERED TOTAL	1997	0.05	AO	NA
MANGANESE, FILTERED TOTAL	1998	0.05	AO	NA
MANGANESE, UNFILTERED TOTAL	1994	0.05	AO	NA	0.029	0.011
MANGANESE, UNFILTERED TOTAL	1995	0.05	AO	NA	0.042	0.053
MANGANESE, UNFILTERED TOTAL	1996	0.05	AO	NA	0.018	0.038
MANGANESE, UNFILTERED TOTAL	1997	0.05	AO	NA	0.0693		0.018
MANGANESE, UNFILTERED TOTAL	1998	0.05	AO	NA	0.0661		0.061
MANGANESE, UNFILTERED TOTAL	1999	0.05	AO	NA

- Ontario Drinking Water Objectives, Ministry of Environment, 1994
- Table A: Surface soil and groundwater remediation criteria for three land uses in a potable groundwater situation, Guideline for Use at Contaminated Sites inOntario, Ministry of Environment and Energy, 1997
- Exceedance in reference area only; therefore not a contaminant of concern.

AO - Aesthetic objective
IMAC - Interim maximum acceptable concentration
MAC - Maximum acceptable concentration
NA - No value available
OG - Operational Guideline
BOLD - Exceeds ODWO. Where no ODWO is available, concentration exceeds Table A.

Table 3.3-4
Area B Exceedances for Average Concentrations

Parameter	Year	ODWO¹	Basis	Table A²	Reference	Site B
		mg/L		mg/L	Deer Cr	HWY 62 Bridge	Moira Lk Narrows	Moira Lk Outlet
					W4	W6	W7	W8
ARSENIC, UNFILTERED TOTAL	1990	0.025	IMAC	0.025	0.001	0.027
ARSENIC, UNFILTERED TOTAL	1991	0.025	IMAC	0.025	0.001	0.036
ARSENIC, UNFILTERED TOTAL	1992	0.025	IMAC	0.025	0.001	0.031
ARSENIC, UNFILTERED TOTAL	1993	0.025	IMAC	0.025	0.001	0.025
ARSENIC, UNFILTERED TOTAL	1994	0.025	IMAC	0.025	0.001	0.031
ARSENIC, UNFILTERED TOTAL	1995	0.025	IMAC	0.025	0.001	0.014
ARSENIC, UNFILTERED TOTAL	1996	0.025	IMAC	0.025
ARSENIC, UNFILTERED TOTAL	1997	0.025	IMAC	0.025
ARSENIC, UNFILTERED TOTAL	1999	0.025	IMAC	0.025	0.001	0.025	0.028	0.016

CHROMIUM, UNFILTERED TOTAL	1990	0.05	MAC	0.05		0.001
CHROMIUM, UNFILTERED TOTAL	1991	0.05	MAC	0.05		0.001
CHROMIUM, UNFILTERED TOTAL	1992	0.05	MAC	0.05	0.001	0.001
CHROMIUM, UNFILTERED TOTAL	1993	0.05	MAC	0.05	0.001	0.001
CHROMIUM, UNFILTERED TOTAL	1994	0.05	MAC	0.05	0.001	0.000
CHROMIUM, UNFILTERED TOTAL	1995	0.05	MAC	0.05	0.000	0.001
CHROMIUM, UNFILTERED TOTAL	1996	0.05	MAC	0.05	0.001	0.001	0.001
CHROMIUM, UNFILTERED TOTAL	1997	0.05	MAC	0.05	0.000		0.001
CHROMIUM, UNFILTERED TOTAL	1998	0.05	MAC	0.05	0.052 ³		0.001
CHROMIUM, UNFILTERED TOTAL	1999	0.05	MAC	0.05

MANGANESE, UNFILTERED TOTAL	1994	0.05	AO	NA	0.0225	0.01045
MANGANESE, UNFILTERED TOTAL	1995	0.05	AO	NA	0.0308	0.0366
MANGANESE, UNFILTERED TOTAL	1996	0.05	AO	NA	0.016	0.033
MANGANESE, UNFILTERED TOTAL	1997	0.05	AO	NA	0.0693		0.01735
MANGANESE, UNFILTERED TOTAL	1998	0.05	AO	NA	0.025858		0.037475
MANGANESE, UNFILTERED TOTAL	1999	0.05	AO	NA

- Ontario Drinking Water Objectives, Ministry of Environment, 1994
- Table A: Surface soil and groundwater remediation criteria for three land uses in a potable groundwater situation, Guideline for Use at Contaminated Sites in Ontario, Ministry of Environment and Energy, 1997
- Exceedance in reference area only; therefore, not a substance of concern.

AO - Aesthetic objective IMAC - Interim maximum acceptable concentration MAC - Maximum acceptable concentration NA - No value available BOLD - Exceeds ODWO. Where no ODWO is available, concentration exceeds Table A.

Table 3.3-5
Area C Exceedances for Yearly Maximum Concentrations

Parameter	Year	ODWO¹	Basis	TableA²	Reference				Site
		mg/L		mg/L	Black R	Skootamatta R	Sulphide Cr	Clare R	Stoco Lk Inlet	Stoco Lk Outlet	Stoco BRG
					W9	W10	W12	W13	W11	W15	W17
ALUMINIUM, UNFILTERED TOTAL	1990	0.1	OG	NA
ALUMINIUM, UNFILTERED TOTAL	1991	0.1	OG	NA
ALUMINIUM, UNFILTERED TOTAL	1992	0.1	OG	NA
ALUMINIUM, UNFILTERED TOTAL	1993	0.1	OG	NA
ALUMINIUM, UNFILTERED TOTAL	1994	0.1	OG	NA	0.045	0.053	0.079	0.066	0.04	0.037	0.029
ALUMINIUM, UNFILTERED TOTAL	1995	0.1	OG	NA	0.087	0.095	0.13	0.081	0.097	0.069	0.06
ALUMINIUM, UNFILTERED TOTAL	1996	0.1	OG	NA	0.1	0.16	0.11	0.06	0.1	0.08	0.07
ALUMINIUM, UNFILTERED TOTAL	1997	0.1	OG	NA	0.0619	0.0682	0.12	0.0439	0.0493	0.0467	0.0548
ALUMINIUM, UNFILTERED TOTAL	1998	0.1	OG	NA	0.0513	0.0546	0.0852	0.0368	0.0424	0.0466	0.0349
ALUMINIUM, UNFILTERED TOTAL	1999	0.1	OG	NA						0.0337

ARSENIC, UNFILTERED TOTAL	1990	0.025	IMAC	0.025	0.001	0.001	0.002	0.002	0.008	0.019	0.016
ARSENIC, UNFILTERED TOTAL	1991	0.025	IMAC	0.025	0.001	0.002	0.007	0.003	0.011	0.018	0.016
ARSENIC, UNFILTERED TOTAL	1992	0.025	IMAC	0.025	0.001	0.001	0.009	0.002	0.024	0.026	0.027
ARSENIC, UNFILTERED TOTAL	1993	0.025	IMAC	0.025	0.001	0.001	0.001	0.005	0.009	0.026	0.028
ARSENIC, UNFILTERED TOTAL	1994	0.025	IMAC	0.025	0.001	0.001	0.001	0.002	0.009	0.012	0.012
ARSENIC, UNFILTERED TOTAL	1995	0.025	IMAC	0.025	0.001	0.001	0.001	0.001	0.0052	0.0042	0.0039
ARSENIC, UNFILTERED TOTAL	1996	0.025	IMAC	0.025
ARSENIC, UNFILTERED TOTAL	1997	0.025	IMAC	0.025
ARSENIC, UNFILTERED TOTAL	1999	0.025	IMAC	0.025	0.0005	0.0005		0.001	0.018	0.018	0.018

CADMIUM, UNFILTERED TOTAL	1990	0.005	MAC	0.005				0.0002
CADMIUM, UNFILTERED TOTAL	1991	0.005	MAC	0.005				0.0012
CADMIUM, UNFILTERED TOTAL	1992	0.005	MAC	0.005	0.0002	0.0002	0.0002	0.0002	0.0002	0.0002	0.0002
CADMIUM, UNFILTERED TOTAL	1993	0.005	MAC	0.005	0.0003	0.0003	0.0003	0.0003	0.0003	0.0002	0.0002
CADMIUM, UNFILTERED TOTAL	1994	0.005	MAC	0.005	0.0002	0.0003	0.0003	0.0004	0.0003	0.0003	0.0003
CADMIUM, UNFILTERED TOTAL	1995	0.005	MAC	0.005	0.0002	0.0001	0.0015	0.0001	0.0003	0.0002	0.0001
CADMIUM, UNFILTERED TOTAL	1996	0.005	MAC	0.005	0.0001	0.0002	0.0001	0.0002	0.0001	0.0001	0.0001
CADMIUM, UNFILTERED TOTAL	1997	0.005	MAC	0.005	0.000392	0.000239	0.000166	0.000392	0.0000376	0.000261	0.000365
CADMIUM, UNFILTERED TOTAL	1998	0.005	MAC	0.005	0.000414	0.00031	0.368³	0.00025	0.000229	0.246³	0.00017
CADMIUM, UNFILTERED TOTAL	1999	0.005	MAC	0.005						0.0000616

IRON, FILTERED TOTAL	1996	0.3	AO	NA	0.36	0.46	0.38	0.2	0.3	0.3	0.3
IRON, UNFILTERED TOTAL	1990	0.3	AO	NA				0.25
IRON, UNFILTERED TOTAL	1991	0.3	AO	NA				0.54
IRON, UNFILTERED TOTAL	1992	0.3	AO	NA	0.76	0.8	0.8	0.34	0.55	0.56	0.43
IRON, UNFILTERED TOTAL	1993	0.3	AO	NA	0.76	0.84	0.88	0.5	0.63	0.55	0.51
IRON, UNFILTERED TOTAL	1994	0.3	AO	NA	0.79	0.84	1.3	0.41	0.54	0.54	0.46
IRON, UNFILTERED TOTAL	1995	0.3	AO	NA	0.68	0.57	1.5	0.29	0.43	0.35	0.31
IRON, UNFILTERED TOTAL	1996	0.3	AO	NA	0.4	0.48	0.38	0.28	0.54	0.36	0.34
IRON, UNFILTERED TOTAL	1997	0.3	AO	NA	0.356	0.351	0.831	0.188	0.245	0.196	0.201
IRON, UNFILTERED TOTAL	1998	0.3	AO	NA	0.361	0.304	0.838	0.216	0.258	0.26	0.222
IRON, UNFILTERED TOTAL	1999	0.3	AO	NA

MANGANESE, FILTERED TOTAL	1996	0.05	AO	NA	0.048	0.046	0.044	0.029	0.046	0.048	0.05
MANGANESE, FILTERED TOTAL	1997	0.05	AO	NA						0.0269
MANGANESE, FILTERED TOTAL	1998	0.05	AO	NA			0.258	0.0563			0.124
MANGANESE, UNFILTERED TOTAL	1994	0.05	AO	NA	0.023	0.024	0.05	0.023	0.024	0.024	0.03
MANGANESE, UNFILTERED TOTAL	1995	0.05	AO	NA	0.073	0.064	0.48	0.085	0.069	0.12	0.039
MANGANESE, UNFILTERED TOTAL	1996	0.05	AO	NA	0.038	0.046	0.044	0.036	0.046	0.057	0.068
MANGANESE, UNFILTERED TOTAL	1997	0.05	AO	NA	0.063	0.0597	0.2	0.0566	0.0542	0.0429	0.0404
MANGANESE, UNFILTERED TOTAL	1998	0.05	AO	NA	0.0611	0.0525	0.527	0.0775	0.0577	0.16	0.169
MANGANESE, UNFILTERED TOTAL	1999	0.05	AO	NA

- Ontario Drinking Water Objectives, Ministry of Environment, 1994
- Table A: Surface soil and groundwater remediation criteria for three land uses in a potable groundwater situation, Guideline for Use at Contaminated Sites in Ontario, Ministry of Environment and Energy, 1997
- Exceedance at both reference and downstream Moira site, and downstream Moira site concentration is less than reference; therefore, not a substance of concern.

AO - Aesthetic objective
IMAC - Interim maximum acceptable concentration
MAC - Maximum acceptable concentration
NA - No value available OG - Operational Guideline
BOLD - Exceeds ODWO. Where no ODWO is available, concentration exceeds Table A.

Table 3.3-6
Area C Exceedances for Average Concentrations

Parameter	Year	ODWO¹	Basis	Table A²	Reference				Site C
		mg/L		mg/L	Black R	Skootamatta R	Sulphide Cr	Clare R	Stoco Lk Inlet	Stoco Lk Outlet	Stoco BRG
					W9	W10	W12	W13	W11	W15	W17
ALUMINIUM, UNFILTERED TOTAL	1990	0.1	OG	NA
ALUMINIUM, UNFILTERED TOTAL	1991	0.1	OG	NA
ALUMINIUM, UNFILTERED TOTAL	1992	0.1	OG	NA
ALUMINIUM, UNFILTERED TOTAL	1993	0.1	OG	NA
ALUMINIUM, UNFILTERED TOTAL	1994	0.1	OG	NA	0.038	0.046	0.040	0.033	0.032	0.019	0.015
ALUMINIUM, UNFILTERED TOTAL	1995	0.1	OG	NA	0.064	0.080	0.099	0.056	0.063	0.047	0.042
ALUMINIUM, UNFILTERED TOTAL	1996	0.1	OG	NA	0.090	0.140	0.100	0.060	0.087	0.073	0.070
ALUMINIUM, UNFILTERED TOTAL	1997	0.1	OG	NA	0.040	0.053	0.092	0.034	0.039	0.035	0.039
ALUMINIUM, UNFILTERED TOTAL	1998	0.1	OG	NA	0.023	0.025	0.045	0.027	0.024	0.023	0.016
ALUMINIUM, UNFILTERED TOTAL	1999	0.1	OG	NA						0.034

CADMIUM, UNFILTERED TOTAL	1990	0.005	MAC	0.005				0.000
CADMIUM, UNFILTERED TOTAL	1991	0.005	MAC	0.005				0.000
CADMIUM, UNFILTERED TOTAL	1992	0.005	MAC	0.005	0.000	0.000	0.000	0.000	0.000	0.000	0.000
CADMIUM, UNFILTERED TOTAL	1993	0.005	MAC	0.005	0.000	0.000	0.000	0.000	0.000	0.000	0.000
CADMIUM, UNFILTERED TOTAL	1994	0.005	MAC	0.005	0.000	0.000	0.000	0.000	0.000	0.000	0.000
CADMIUM, UNFILTERED TOTAL	1995	0.005	MAC	0.005	0.000	0.000	0.000	0.000	0.000	0.000	0.000
CADMIUM, UNFILTERED TOTAL	1996	0.005	MAC	0.005	0.000	0.000	0.000	0.000	0.000	0.000	0.000
CADMIUM, UNFILTERED TOTAL	1997	0.005	MAC	0.005	0.000	0.000	0.000	0.000	0.000	0.000	0.000
CADMIUM, UNFILTERED TOTAL	1998	0.005	MAC	0.005	0.000	0.000	0.061³	0.000	0.000	0.049³	0.000
CADMIUM, UNFILTERED TOTAL	1999	0.005	MAC	0.005						0.000

IRON, UNFILTERED TOTAL	1990	0.3	AO	NA				0.175
IRON, UNFILTERED TOTAL	1991	0.3	AO	NA				0.213
IRON, UNFILTERED TOTAL	1992	0.3	AO	NA	0.363	0.405	0.577	0.172	0.262	0.222	0.194
IRON, UNFILTERED TOTAL	1993	0.3	AO	NA	0.423	0.386	0.567	0.228	0.296	0.192	0.182
IRON, UNFILTERED TOTAL	1994	0.3	AO	NA
IRON, UNFILTERED TOTAL	1994	0.3	AO	NA	0.456	0.482	0.779	0.212	0.322	0.250	0.219
IRON, UNFILTERED TOTAL	1995	0.3	AO	NA	0.492	0.438	0.968	0.196	0.360	0.270	0.236
IRON, UNFILTERED TOTAL	1996	0.3	AO	NA	0.400	0.470	0.360	0.240	0.420	0.330	0.320
IRON, UNFILTERED TOTAL	1997	0.3	AO	NA	0.291	0.271	0.654	0.174	0.217	0.191	0.189
IRON, UNFILTERED TOTAL	1998	0.3	AO	NA	0.217	0.261	0.577	0.161	0.174	0.126	0.128
IRON, UNFILTERED TOTAL	1999	0.3	AO	NA

MANGANESE, UNFILTERED TOTAL	1994	0.05	AO	NA	0.023	0.023	0.027	0.012	0.023	0.012	0.016
MANGANESE, UNFILTERED TOTAL	1995	0.05	AO	NA	0.038	0.049	0.177	0.055	0.048	0.048	0.026
MANGANESE, UNFILTERED TOTAL	1996	0.05	AO	NA	0.038	0.046	0.044	0.033	0.043	0.053	0.059
MANGANESE, UNFILTERED TOTAL	1997	0.05	AO	NA	0.046	0.037	0.140	0.036	0.041	0.043	0.034
MANGANESE, UNFILTERED TOTAL	1998	0.05	AO	NA	0.051	0.038	0.188	0.034	0.035	0.074	0.092
MANGANESE, UNFILTERED TOTAL	1999	0.05	AO	NA

- Ontario Drinking Water Objectives, Ministry of Environment, 1994
- Table A: Surface soil and groundwater remediation criteria for three land uses in a potable groundwater situation, Guideline for Use at Contaminated Sites in Ontario, Ministry of Environment and Energy, 1997
- Exceedance at both reference and downstream Moira site, and downstream Moira site concentration is less than references; therefore, not a substance of concern.

Table 3.3-7
Area D Exceedances for Yearly Maximum Concentrations

Parameter	Year	ODWO¹	Basis	Table A²	Reference		Site
		mg/L		mg/L	Palliser Cr Quinte	Palliser Cr Foxborough	Cannifton	Belleville HWY-2	Belleville Victoria St
					W18	W19	W20	W23	W24
ALUMINIUM,UNFILTERED TOTAL	1990	0.1	OG	NA
ALUMINIUM,UNFILTERED TOTAL	1991	0.1	OG	NA
ALUMINIUM,UNFILTERED TOTAL	1992	0.1	OG	NA
ALUMINIUM,UNFILTERED TOTAL	1993	0.1	OG	NA					0.032
ALUMINIUM, UNFILTERED TOTAL	1994	0.1	OG	NA			0.029	0.06	0.11
ALUMINIUM, UNFILTERED TOTAL	1995	0.1	OG	NA			0.22	0.082	0.042
ALUMINIUM, UNFILTERED TOTAL	1996	0.1	OG	NA			0.08	0.1
ALUMINIUM, UNFILTERED TOTAL	1997	0.1	OG	NA			0.0449	0.0452	0.0361
ALUMINIUM, UNFILTERED TOTAL	1998	0.1	OG	NA	0.0194	0.113	0.0332	0.0314	0.0335
ALUMINIUM, UNFILTERED TOTAL	1999	0.1	OG	NA	0.0146	0.0787

CHROMIUM, UNFILTERED TOTAL	1990	0.05	MAC	0.05			0.0017	0.0015
CHROMIUM, UNFILTERED TOTAL	1991	0.05	MAC	0.05			0.001	0.009
CHROMIUM, UNFILTERED TOTAL	1992	0.05	MAC	0.05			0.001	0.0005
CHROMIUM, UNFILTERED TOTAL	1993	0.05	MAC	0.05			0.0007	12 ³	0.0005
CHROMIUM, UNFILTERED TOTAL	1994	0.05	MAC	0.05			0.0009	0.0011	0.0006
CHROMIUM, UNFILTERED TOTAL	1995	0.05	MAC	0.05			0.0012	0.001	0.001
CHROMIUM, UNFILTERED TOTAL	1996	0.05	MAC	0.05			0.0006	0.0004
CHROMIUM, UNFILTERED TOTAL	1997	0.05	MAC	0.05			0.000071	0.000582	0.00263
CHROMIUM, UNFILTERED TOTAL	1998	0.05	MAC	0.05	0.00478	0.000275	0.163³	0.00075	0.000729
CHROMIUM, UNFILTERED TOTAL	1999	0.05	MAC	0.05	0.000783	0.000616

IRON, FILTERED TOTAL	1996	0.3	AO	NA			0.32	0.32
IRON, UNFILTERED TOTAL	1990	0.3	AO	NA			0.31	0.32
IRON, UNFILTERED TOTAL	1991	0.3	AO	NA			0.3	0.31
IRON, UNFILTERED TOTAL	1992	0.3	AO	NA			0.33	0.28
IRON, UNFILTERED TOTAL	1993	0.3	AO	NA			0.092	0.37	0.16
IRON, UNFILTERED TOTAL	1994	0.3	AO	NA			0.96	1.6	0.4
IRON, UNFILTERED TOTAL	1995	0.3	AO	NA			0.67	0.28	0.31
IRON, UNFILTERED TOTAL	1996	0.3	AO	NA			0.36	0.42
IRON, UNFILTERED TOTAL	1997	0.3	AO	NA			0.17	0.168	0.23
IRON, UNFILTERED TOTAL	1998	0.3	AO	NA	0.0283	0.263	0.195	0.183	0.199
IRON, UNFILTERED TOTAL	1999	0.3	AO	NA	0.0248	0.323

LEAD, UNFILTERED TOTAL	1990	0.01	MAC	0.01			0.005	0.005
LEAD, UNFILTERED TOTAL	1991	0.01	MAC	0.01			0.005	0.005
LEAD, UNFILTERED TOTAL	1992	0.01	MAC	0.01			0.005	0.005
LEAD, UNFILTERED TOTAL	1993	0.01	MAC	0.01			0.005	0.005	0.005
LEAD, UNFILTERED TOTAL	1994	0.01	MAC	0.01			0.006	0.006	0.005
LEAD, UNFILTERED TOTAL	1995	0.01	MAC	0.01			0.0058	0.005	0.005
LEAD, UNFILTERED TOTAL	1996	0.01	MAC	0.01			0.005	0.005
LEAD, UNFILTERED TOTAL	1997	0.01	MAC	0.01			0.00445	0.00787	0.0138
LEAD, UNFILTERED TOTAL	1998	0.01	MAC	0.01	0.00534	0.000416	0.00413	0.00654	0.00899
LEAD, UNFILTERED TOTAL	1999	0.01	MAC	0.01	0.00909	0.0035	0.00399	0.00399	0.00512

MANGANESE, FILTERED TOTAL	1996	0.05	AO	NA			0.051	0.052
MANGANESE, FILTERED TOTAL	1997	0.05	AO	NA
MANGANESE, FILTERED TOTAL	1998	0.05	AO	NA				0.0527
MANGANESE, UNFILTERED TOTAL	1994	0.05	AO	NA			0.031	0.032	0.026
MANGANESE, UNFILTERED TOTAL	1995	0.05	AO	NA			0.23	0.056	0.088
MANGANESE, UNFILTERED TOTAL	1996	0.05	AO	NA			0.065	0.08
MANGANESE, UNFILTERED TOTAL	1997	0.05	AO	NA			0.0539	0.0528	0.0654
MANGANESE, UNFILTERED TOTAL	1998	0.05	AO	NA	0.0116	0.0741	0.0495	0.0404	0.342
MANGANESE, UNFILTERED TOTAL	1999	0.05	AO	NA	0.0158	0.0892

- Ontario Drinking Water Objectives, Ministry of Environment, 1994
- Table A: Surface soil and groundwater remediation criteria for three land uses in a potable groundwater situation, Guideline for Use at Contaminated Sites in Ontario, Ministry of Environment and Energy, 1997
- Outlier; data entry or laboratory error

AO - Aesthetic objective
IMAC - Interim maximum acceptable concentration
MAC - Maximum acceptable concentration

NA - No value available
OG - Operational Guideline
BOLD - Exceeds ODWO. Where no ODWO is available, concentration exceeds Table A.

Table 3.3-8
Area D Exceedances for Average Concentrations

Parameter	Year	ODWO¹	Basis	Table A²	Reference		Site D
		mg/L		mg/L	Palliser Cr Quinte	Palliser Cr Foxborough	Cannifton	Belleville -2 HWY	Belleville Victoria St
					W18	W19	W20	W23	W24
ALUMINIUM, UNFILTERED TOTAL	1990	0.1	OG	NA
ALUMINIUM, UNFILTERED TOTAL	1991	0.1	OG	NA
ALUMINIUM, UNFILTERED TOTAL	1992	0.1	OG	NA
ALUMINIUM, UNFILTERED TOTAL	1993	0.1	OG	NA					0.021
ALUMINIUM, UNFILTERED TOTAL	1994	0.1	OG	NA			0.029	0.031	0.039
ALUMINIUM, UNFILTERED TOTAL	1995	0.1	OG	NA			0.102	0.046	0.040
ALUMINIUM, UNFILTERED TOTAL	1996	0.1	OG	NA			0.080	0.087
ALUMINIUM, UNFILTERED TOTAL	1997	0.1	OG	NA			0.036	0.035	0.025
ALUMINIUM, UNFILTERED TOTAL	1998	0.1	NA	OG	0.015	0.101	0.015	0.013	0.019
ALUMINIUM, UNFILTERED TOTAL	1999	0.1	OG	NA	0.013	0.069

CHROMIUM, UNFILTERED TOTAL	1990	0.05	MAC	0.05			0.001	0.001
CHROMIUM, UNFILTERED TOTAL	1991	0.05	MAC	0.05			0.001	0.001
CHROMIUM, UNFILTERED TOTAL	1992	0.05	MAC	0.05			0.001	0.001
CHROMIUM, UNFILTERED TOTAL	1993	0.05	MAC	0.05			0.001	1.091³	0.001
CHROMIUM, UNFILTERED TOTAL	1994	0.05	MAC	0.05			0.000	0.001	0.000
CHROMIUM, UNFILTERED TOTAL	1995	0.05	MAC	0.05			0.001	0.001	0.001
CHROMIUM, UNFILTERED TOTAL	1996	0.05	MAC	0.05			0.000	0.000
CHROMIUM, UNFILTERED TOTAL	1997	0.05	MAC	0.05			0.000	0.000	0.001
CHROMIUM, UNFILTERED TOTAL	1998	0.05	MAC	0.05	0.003	0.000	0.027	0.000	0.001
CHROMIUM, UNFILTERED TOTAL	1999	0.05	MAC	0.05	0.000	0.000

IRON, UNFILTERED TOTAL	1990	0.3	AO	NA			0.137	0.140
IRON, UNFILTERED TOTAL	1991	0.3	AO	NA			0.160	0.105
IRON, UNFILTERED TOTAL	1992	0.3	AO	NA			0.228	0.157
IRON, UNFILTERED TOTAL	1993	0.3	AO	NA			0.068	0.129	0.120
IRON, UNFILTERED TOTAL	1994	0.3	AO	NA			0.087	0.001
IRON, UNFILTERED TOTAL	1994	0.3	AO	NA			0.503	0.407	0.266
IRON, UNFILTERED TOTAL	1995	0.3	AO	NA			0.398	0.208	0.300
IRON, UNFILTERED TOTAL	1996	0.3	AO	NA			0.340	0.370
IRON, UNFILTERED TOTAL	1997	0.3	AO	NA			0.156	0.152	0.137
IRON, UNFILTERED TOTAL	1998	0.3	AO	NA	0.023	0.222	0.074	0.069	0.162
IRON, UNFILTERED TOTAL	1999	0.3	AO	NA	0.023	0.230

MANGANESE, UNFILTERED TOTAL	1994	0.05	AO	NA			0.031	0.020	0.025
MANGANESE, UNFILTERED TOTAL	1995	0.05	AO	NA			0.106	0.032	0.065
MANGANESE, UNFILTERED TOTAL	1996	0.05	AO	NA			0.058	0.066
MANGANESE, UNFILTERED TOTAL	1997	0.05	AO	NA			0.036	0.036	0.033
MANGANESE, UNFILTERED TOTAL	1998	0.05	AO	NA			0.034	0.027	0.095
MANGANESE, UNFILTERED TOTAL	1999	0.05	AO	NA	0.013	0.064

- Ontario Drinking Water Objectives, Ministry of Environment, 1994
- Table A: Surface soil and groundwater remediation criteria for three land uses in a potable groundwater situation, Guideline for Use at Contaminated Sites in Ontario, Ministry of Environment and Energy, 1997
- Outlier; data entry or laboratory error

Summary of Substances of Potential Concern in Surface Water

The results of the chemical screening process indicated that arsenic, cobalt and nickel concentrations were present in water at concentrations greater than human health-based screening criteria, and required further evaluation in the PQRA, as summarized in Table 3.3-9.

Table 3.3-9
Substances in Water Which Require Further Assessment in the PQRA

Substance	Area A	Area B	Area C
Arsenic	/	/	/*
Cobalt	/
Nickel	/*

/substance requires further evaluation in the PQRA.
/* maximum concentrations only.

3.3.1.2 Sediment

It is possible that area residents may come into contact with sediments from the Moira River system during recreational activities such as swimming. However, there are no sediment criteria that consider the potential human health impacts associated with exposure to substances in sediments. In the absence of appropriate health-based screening criteria, sediment concentrations of arsenic, cadmium, cobalt, lead, nickel, and chromium from each study area were compared to concentrations in the reference locations. Any substances with statistically significant (p < 0.05) elevated concentrations relative to the reference locations were identified and evaluated further in the preliminary quantitative risk assessment (PQRA). For the statistical analysis, deep water and near shore (i.e., shallow water) sediment samples from each study area and reference areas were used. However, the exposure models considered only the near shore (i.e., sediment samples taken from a water depth of 1 meter or less) sediment samples since a child aged 5 - 11 is unlikely to come into contact with sediments present at greater depths. Data from the reference locationsare provided in Table 3.3-10.

Table 3.3-10
Reference Sediment Samples (µg/g dry weight), Sampled April 1, 1999

Parameter	MR-1	MR-2	MR-3	BR-1	CL-1	CL-2	CL-3	CL-4	CL-5	CL-6	CL-7	CL-8
Arsenic	1.4	2.9	14	4.7	0.8	1.7	1.7	0.9	0.6	0.6	0.6	3.8
Cadmium	0.3	0.2	0.7	0.4	0.2	0.5	0.2	0.2	0.2	0.2	0.2	0.8
Chromium	18	27	24	18	1	8	7	3	1	4	4	15
Cobalt	5.6	7.5	9	7.1	0.5	2.9	2.2	1	1.2	0.8	0.7	6.3
Lead	3	5	8	4	4	23	11	6	2	2	2	49
Nickel	9.2	15	13	8.5	1.3	5.9	3.3	1.7	0.9	1.6	1.4	11

Parameter	RL-1	RL-2	RL-3	RL-4	RL-5	RL-6	RL-7	SKR-1	SR-1	SR-2	SR-3	Average
Arsenic	5.7	4.3	5.5	1	1	0.8	2.8	2.3	2.4	2.1	2.1	2.81
Cadmium	1.9	2.3	0.7	0.3	0.3	0.2	0.5	0.3	0.6	0.6	0.6	0.34
Chromium	18	31	32	8	9	11	15	18	26	32	38	10.83
Cobalt	12	14	15	3.7	3.4	3.5	4.9	6.3	8.5	8	9	3.73
Lead	71	140	20	6	8	15	47	6	30	39	32	9.92
Nickel	15	24	21	4.8	4.8	5.1	7.9	9.3	15	17	19	6.07

Moira River from Deloro to Moira Lake (Study Area A)

Arsenic, cadmium, cobalt, chromium, lead, and nickel concentrations in sediments were found to be significantly higher in Study Area A (p < 0.05) than at reference sites. Therefore, these substances in sediment were evaluated further in the PQRA. Data from Study Area A are provided in Table 3.3-11.

Table 3.3-11
Study Area A Sediment Samples (mg/g dry), Sampled April 1, 1999

Parameter	MR-4	MR-5	MR-6	MR-7	MR-8	YC-1	MR-9	MR-10	MR-11
Parameter	0.4 m	1.5m	<1m	<1m	<1 m	3.0 m	<1 m	3.5 m	>1
Arsenic	140	170	280	500	1300	3000	260	260	660
Cadmium	0.3	0.6	0.4	0.5	0.5	1.9	1.2	1.5	2.6
Chromium	25	140	240	450	440	1600	540	740	1100
Lead	11	25	25	22	20	56	24	28	66
Nickel	33	77	250	550	520	1000	440	470	680

Moira Lake (Study Area B)

Arsenic, cobalt and nickel were found to have significantly higher concentrations in Study Area B sediments (p < 0.05) than at reference sites. Therefore, these substances were evaluated further in the PQRA. Data from Study Area B are provided in Table 3.3-12.

Stoco Lake (Study Area C)

The concentrations of arsenic, cobalt and nickel were found to be significantly higher concentrations in Study Area C sediments (p < 0.05) than at reference sites. These substances in sediments were evaluated further in the PQRA. Data from Study Area C are provided in Table 3.3-13.

Table 3.3-12
Study Area B Sediment Samples (µg/g dry), Sampled April 1, 1999

Parameter	ML-1	ML-2	ML-3	ML-4	ML-5	ML-6	ML-7	ML-8	ML-9	ML-10	ML-11	ML-12	ML-13	ML-14
Parameter	> 4 m	> 4 m	> 4 m	> 4 m	> 4 m	1 m	> 1 m	> 1 m	> 1 m	> 1 m	> 1 m	> 1 m	> 1 m	> 1 m
Arsenic	310	290	600	150	150	110	210	15	57	8.8	17	100	170	31
Cadmium	3	2.6	2.3	0.8	1	1.2	0.5	0.2	0.5	0.2	0.2	0.5	0.9	0.4
Chromium	29	38	27	19	10	13	5	10	27	13	11	11	7	7
Cobalt	770	760	760	420	420	250	190	39	83	26	47	140	350	68
Lead	81	92	140	40	27	27	30	5	16	6	7	18	18	7
Nickel	590	640	460	320	260	240	100	33	72	22	36	83	270	36

Table 3.3-13
Study Area C Sediment Samples (µg/g dry), Sampled April 1, 1999

Parameter	MR-12	SL-1	SL-2	SL-3	SL-4	SL-5	SL-6	SL-7	SL-8	SL-9	SL-10	SL-11	SL-12	SL-13	SL-14	SL-15
Parameter	3.5 m	4 m	5 m	4 m	9 m	7 m	1 m	> 1 m	> 1 m	> 1 m	> 1 m	> 1 m	> 1 m	> 1 m	> 1 m	> 1 m
Arsenic	17	42	99	96	130	54	6.3	12	16	36	6.2	7.5	4.6	2.9	2.6	3.9
Cadmium	0.6	0.8	2.3	0.4	2.2	2.7	0.2	0.4	0.4	0.7	0.2	0.2	0.2	0.2	0.2	0.3
Chromium	18	29	50	18	48	43	18	25	19	27	9	7	12	6	9	8
Cobalt	45	68	200	77	140	76	4.6	12	12	20	5.2	6.2	3	3.7	3.9	6.4
Lead	11	29	84	14	78	71	15	30	9	16	3	3	3	2	2	4
Nickel	24	41	130	37	92	63	11	16	18	31	6.2	5.8	4.6	4.9	4.6	5.8

Moira River Downstream of Stoco Lake (Study Area D)

Arsenic and cadmium had significantly higher concentrations in sediments from Study Area D (p < 0.05) than at reference sites. However, cadmium concentrations in sediments from Study Areas B and C were not elevated relative to the control sites. If the Deloro Mine Site is the source of cadmium to the river system, it is expected that cadmium would also be detected in Study Areas B and C at elevated concentrations relative to the reference sites. Since this is not the case, it was concluded that the elevated concentration of cadmium in Study Area D is not due to the Deloro Mine Site, but rather is likely due to a local source of cadmium to the Moira River. Therefore, cadmium in sediments in Study Area D was not evaluated further in the PQRA. Data from Study Area D are provided in Table 3.3-14.

Table 3.3-14
Study Area D Sediment Samples, Sampled April 1, 1999

Parameter	MR-13	MR-14	MR-15	MR-16
Parameter	1.5 m	1.0 m	1.3 m	0.3 m
Arsenic	50	21	11	29
Cadmium	2.5	0.8	0.3	0.9
Chromium	35	21	10	22
Cobalt	150	55	33	38
Lead	51	26	9	69
Nickel	73	34	14	26

Summary of Substances of Potential Concern in Sediments:

The results of the chemical screening process indicated that arsenic, cadmium, cobalt, chromium,lead, and nickel were present in sediments in the study areas at concentrations greater than the reference locations, as summarized in Table 3.3-15.

Table 3.3-15
Substances in Sediment Which Require Further Assessment in the PQRA

Priority Substance	Area A	Area B	Area C	Area D
Arsenic	/	/	/	/
Cadmium	/
Chromium	/
Cobalt	/	/	/
Lead	/
Nickel	/	/	/

Since the concentrations of these metals in sediments downstream of the Deloro Mine Site were elevated relative to the reference locations, these substances were evaluated further in the PQRA (Section 3.4).

3.3.1.3 Fish

Substances of potential concern identified in sediment in each of the four study areas were also considered with respect to exposures from consumption of fish. Concentrations of metals in sport fish fillets are provided in Table 3.3-16. These data were obtained from the MOE Sport Fish Contaminant Monitoring Program.

The MOE data indicated that metals including lead, nickel, cadmium, chromium and arsenic were found in fish tissue, but not at levels which would suggest a need for consumption restrictions (MOE, 1999). As discussed in the environmental health risk assessment conducted for the Village of Deloro, background concentrations of arsenic in fish from Ontario and other parts of Canada range from 0.1 to 0.4 µg/g (wet weight) (CanTox, 1999). This is consistent with the levels of arsenic present in fish in the all of the study areas except for northern pike, rock bass and smallmouth bass in Study Area A. Nevertheless, exposure to these metals due to the consumption of fish from the Moira River system were evaluated further in the PQRA.

3.3.2 Exposure Characterization

The river system from Moira Lake downstream is used recreationally for swimming and fishing, and the surrounding areas are either wooded or used for agriculture. There are numerous residences and cottages located adjacent to the lakes within the study area. Upstream from Moira Lake there are few cottages and limited opportunities for in-water recreation because of the rocky nature of the river substrate. As discussed previously (see Section 3.1.1), the majority of residents in the study area do not drink water from the river system, but there are a few individuals that indicated in the water use survey that they use water from the system as potable water. These individuals received a reminder letter to avoid drinking untreated surface water (Appendix IX).

Table 3.3-16
Average Metal Concentration (and Standard Deviation) in Sport Fish Fillets
per Location (µg/g wet weight)

Location	Species	Metals				Samples (n)
Location	Species	Arsenic	Cadmium	Lead	Nickel	Samples (n)
STUDY AREA A: MOIRA RIVER	Largemouth Bass	0.267±0.02	0.029±0.02	0.020±0.00	0.020±0.00	3
	Northern Pike	0.768±0.50	0.050±0.00	0.083±0.13	0.020±0.00	4
	Pumpkinseed	0.413±0.11	0.054±0.01	0.020±0.00	0.020±0.00	4
	Rock Bass	0.675±0.22	0.047±0.00	0.020±0.00	0.020±0.00	4
	Smallmouth Bass	1.113±0.33	0.026±0.02	0.020±0.00	0.020±0.00	8
	Yellow Perch	0.140	0.042	0.020	0.020	1
Average		0.719±0.43	0.039±0.02	0.030±0.05	0.030±0.05	24
STUDY AREA B: MOIRA LAKE	Largemouth Bass	0.27	0.04	0.6	0.4	1
	Northern Pike	0.13	0.04	0.6	0.4	1
	Smallmouth Bass	0.218±0.10	0.139±0.49	0.47±0.15	0.427±0.36	20
	Walleye	0.052±0.03	0.055±0.10	0.511±0.27	0.664±0.78	44
Average		0.107±0.10	0.080±0.28	0.501±0.24	0.584±0.67	66
STUDY AREA C: STOCO LAKE	Brown Bullhead	0.168±0.07	0.005±0.00	0.046±0.06	0.020±0.00	10
	Largemouth Bass	0.084±0.02	0.025±0.02	0.020±0.00	0.047±0.04	10
	Northern Pike	0.065±0.04	0.005±0.00	0.124±0.13	0.020±0.00	8
	Pumpkinseed	0.133±0.05	0.005±0.00	0.118±0.20	0.020±0.00	4
	Rock Bass	0.131±0.05	0.010±0.01	0.132±0.13	0.062±0.08	9
	Smallmouth Bass	0.166±0.15	0.166±0.15	0.241±0.12	0.091±0.08	10
	Walleye	0.045±0.06	0.017±0.01	0.175±0.14	0.103±0.07	14
	Yellow Perch	0.056±0.01	0.005±0.00	0.092±0.12	0.020±0.00	5
Average		0.091±0.09	0.013±0.01	0.136±0.14	0.064±0.07	70
STUDY AREA D: MOIRA R.HWY 37	Brown Bullhead	0.136±0.03	0.009±0.01	0.060±0.07	0.052±0.04	10
	Largemouth Bass	0.142±0.05	0.013±0.01	0.020±0.00	0.045±0.04	6
	Northern Pike	0.232±0.10	0.030±0.02	0.020±0.00	0.020±0.00	6
	Pumpkinseed	0.225±0.04	0.016±0.01	0.058±0.04	0.100±0.08	4
	Rock Bass	0.138±0.04	0.022±0.01	0.038±0.04	0.039±0.06	9
	Smallmouth Bass	0.670±0.31	0.017±0.00	0.020±0.00	0.020±0.00	3
	Walleye	0.1000.02	0.0250.02	0.0200.00	0.0200.00	4
Average		0.196±0.16	0.018±0.01	0.037±0.04	0.043±0.05	42

The exposure pathway analysis describes how humans may come into contact with the substances of concern. Considering that human receptors may reside on the river system all year and may come into contact with the chemicals detected in sediments, water and fish, various potential pathways of exposure were examined.

Mean sediment concentrations for each substance present in the study areas at elevated concentrations collected in samples at depths of 1 m or less were used for the exposure modelling (Table 3.4-1). Use of these shallow water sediment samples is appropriate since it is considered unlikely that a child aged 5 - 11 (i.e., receptor) will come into contact with sediments at depths much greater than 1 metre. Exposure was estimated using sediment concentrations, along with receptor body weight, ingestion rate, dermal contact rate, time activity patterns (i.e., time spent swimming) and chemical bioavailability.

Table 3.3-17 is a summary of the exposure pathways that were considered in this assessment.

Table 3.3-17
Summary of Exposure Pathways Considered

Environmental Matrix	Description of Exposure Pathway	Pathway Number
Water	Consumption for drinking water or cooking	1
Water	Accidental ingestion during recreational activities (e.g., swimming)	2
Water	Dermal contact during recreational activities	3
Shallow Water Sediment	Dermal contact while bathing/showering	4
Shallow Water Sediment	Dermal contact while bathing/showering	5
Shallow Water Sediment	Dermal contact during recreational activities	6
Fish	Ingestion of fish from the river system	7

Equations and a detailed description of the input variables that were used for the exposure modelling for each pathway are given in Table 3.3-18 (non-cancer endpoints) and Table 3.3-19 (cancer endpoints).

Table 3.3-18
Exposure Pathway Equations and Input Variables for Non-Carcinogenic Effects

Exposure Pathway	Description of Exposure	Exposure Pathway Calculations	Value
1	Consumption of drinking water where:	DWE = (DWC × CW × OB) /BW DWE = drinking water exposure (µg/kg/day) WC = daily drinking water consumption (L/day) CW = metal concentration in water (µg/L) OB = oral bioavailability (unitless) BW = body weight (kg)	Calculated 1.56 L See Table 3.4-1 See Table 3.4-3 32.9 kg
2	Accidental ingestion of water while swimming where:	AIW = [WI × CW × OB] / BW AIW = accidental ingestion of water (µg/kg/day) WI = water ingestion (L/event) CW = metal concentration in water (µg/L) OB = oral bioavailability (unitless) BW = body weight (kg)	Calculated 0.05L See Table 3.4-1 See Table 3.4-3 32.9 kg
3	Dermal contact with water (recreational) where:	DWE = [C × P × SA × ET × 10 ^-3]/BW DWE = dermal water exposure (µg/kg/day) C = metal concentration in water (µg/L) P = permeability constant SA = surface area of exposed skin (m²) ET = exposure time BW = body weight (kg)	Calculated See Table 3.4-1 0.0001 cm²/hr 7840 cm² 1 hr 32.9 kg
4	Dermal contact with water (bathing/showering) where:	DWE = [C × P × SA × ET × 10^-3]/BW DWE = dermal water exposure (µg/kg/day) C = metal concentration in water (µg/L) P = permeability constant SA = surface area of exposed skin (m2) ET = exposure time BW = body weight (kg)	Calculated See Table 3.4- 0.0001 cm2/hr 13,500 cm2 0.5 hr 32.9 kg
5	Accidental ingestion of sediment where:	AIS = [SI × CS × OB] / BW AIS = accidental ingestion of sediment (µg/kg/day) SI = sediment ingestion (g/day) CS = metal concentration in sediment (µg/g) OB = oral bioavailability (unitless) BW = body weight (kg)	Calculated 0.2 g/day See Table 3.4-1 See Table 3.4-3 32.9 kg
6	Dermal contact with sediment where:	DSE = [C × A × BF × 10^-3] / BW DSE = dermal sediment exposure (µg/kg/day) C = concentration of substance A = soil adherence BF = bioavailability factor BW = body weight (kg)	Calculated See Table 3.4-1 7.8 g/m²/day See Table 3.4-3 32.9 kg
7	Ingestion of fish where:	EFF = DFC × CF × OB / BW EFF = exposure from fish (µg/kg/day) CF = concentration of substance in fish OB = oral bioavailability (unitless) CF = daily fish consumption (g/day) BW = body weight (kg)	Calculated See Table 3.4-1 See Table 3.4-3 20.2 g/day 32.9 kg

Adopted from CanTox, 1999 and Health Canada, 1995.

Table 3.3-19
Exposure Pathway Equations and Input Variables for Cancer Assessment

Exposure e Pathway	Description of Exposure	Exposure Pathway Calculations	Value
1	Consumption of drinking water where:	DWE = (DWC × CW × OB) / BW DWE = Drinking water exposure (µg/kg/day) DWC = daily drinking water consumption (L/day) CW = metal concentration in water (µg/L) OB = oral bioavailability (unitless) BW = body weight (kg)	Calculated See Table 3.3-20 See Table 3.4-1 See Table 3.4-3 See Table 3.3-20
2	Accidental ingestion of water while swimming where:	AIW = [WI × CW × OB × F] / BW × AT AIW = accidental ingestion of water (µg/kg/day) WI = water ingestion (L/event) CW = metal concentration in water (µg/L) OB = oral bioavailability (unitless) F = frequency of events AT = averaging time BW = body weight (kg)	Calculated See Table 3.3-20 See Table 3.4-1 See Table 3.4-3 60 days 365 days See Table 3.3-20
3	Dermal contact with water (recreational) where:	DWE = [C × P × SA × ET × F × 10^-3] / BW × AT DWE = dermal water exposure (µg/kg/day) C = metal concentration in water (µg/L) P = permeability constant SA = surface area of exposed skin (m²) ET = exposure time F = frequency of events AT = averaging time BW = body weight (kg)	Calculated See Table 3.4-1 0.0001 cm²/hr See Table 3.3-20 1 hr 60 days 365 days See Table 3.3-20
4	Dermal contact with water (bathing/showering) where:	DWE = [C × P × SA × ET × F × 10^-3] / BW × AT DWE = dermal water exposure (µg/kg/day) C = metal concentration in water (µg/L) P = permeability constant SA = surface area of exposed skin (m²) ET = exposure time F = frequency of events AT = averaging time BW = body weight (kg)	Calculated See Table 3.4-1 0.0001 cm²/hr See Table 3.3-20 0.5 hr 365 days 365 days See Table 3.3-20
5	Accidental ingestion of sediment where:	AIS = [SI × CS × OB × F] / BW × AT AIS = accidental ingestion of sediment (µg/kg/day) SI = sediment ingestion (g/day) CS = metal concentration in sediment (µg/g) OB = oral bioavailability (unitless) F = frequency of events AT = averaging time BW = body weight (kg)	Calculated See Table 3.3-20 See Table 3.4-1 See Table 3.4-3 60 days 365 days See Table 3.3-20
6	Dermal contact with sediment where:	DSE = [C × A × BF × F × 10 − 3] / BW × AT DSE = dermal sediment exposure (µg/kg/day) C = concentration of substance A = soil adherence BF = bioavailability factor F = frequency of events AT = averaging time BW = body weight (kg)	Calculated See Table 3.4-1 See Table 3.3-20 See Table 3.4-3 60 days 365 days See Table 3.3-20
7	Ingestion of fish where:	EFF = DFC × CF × OB / BW EFF = exposure from fish (µg/kg/day) CF = concentration of substance in fish OB = oral bioavailability (unitless) CF = daily fish consumption (g/day) BW = body weight (kg)	Calculated See Table 3.4-1 See Table 3.4-3 20.2 g/day See Table 3.3-20

Adopted from CanTox, 1999 and Health Canada, 1995.

Other potential pathways of exposure were not considered to be significant pathways of exposure to the substances of concern. For example, inhalation of particulates derived from sediments is possible, but was considered negligible relative to the six pathways identified above.

3.3.3 Receptor Selection

For this assessment, a child aged 5 to 11 years old was identified as the most appropriate human receptor to evaluate potential non-cancer effects. This age group was selected as the critical receptor because the physical characteristics and activity patterns for children of this age make them the most likely to have the greatest exposure on a body weight basis. For example, they generally spend more time outdoors swimming and playing along the river and lakes than either adults or younger children, and are expected to have higher levels of exposure on a body weight basis due to their physical characteristics. Use of this receptor therefore represents a conservative (i.e., protective) approach to the PQRA.

Parameters describing the physiological and behavioural characteristics of the 5-11 year-old child are given in Table 3.3-20. Maximum plausible receptor characteristics such as ingestion rate and body surface area were employed and are expected to overestimate actual exposure.

Table 3.3-20
Receptor Characteristics by Lifestage

	Preschool Child	Child (5-11 years)	Adolescent	Adult
Body Weight	16.5 kg	32.9 kg	59.7 kg	70.7 kg
Sediment Ingestion	0.2 g/day	0.2 g/day	0.1 g/day	0.1 g/day
Water Ingestion	1.35 L/day	1.56 L/day	2.13 L/day	3.014 L/day
Sediment Adherence Factor	10 g/m ²/day	10 g/m ^2/day	10 g/m ^2/day	10 g/m ²/day
Exposed Skin in Summer	0.463 m²	0.784 m ²	1.16 m ²	1.22 m ²
Total Surface Area	0.799 m²	1.35 m²	1.94 m²	2.13 m²
Frequency of Swimming Events	60 day/year	60 day/year	60 day/year	60 day/year

Arsenic is the only substance addressed in this study that may cause cancer by ingestion or dermal contact. To estimate the increased cancer risk associated with arsenic, it is necessary to determine the average daily dose of arsenic to which a person is exposed over an entire lifetime. This dose, termed the Lifetime Average Daily Dose (LADD), is multiplied by the cancer potency factor for arsenic to estimate the associated increased cancer risk. Because it is necessary to model exposures over a lifetime, arsenic exposures over four life stages (i.e., preschool child, child, adolescent and adult) were calculated. The physiological and behavioural characteristics of each life stage used for the exposure modelling are given in Table 3.3-20.

3.3.4 Summary of Conceptual Site Model

Humans may be exposed to substances of potential concern present in the water and shallow sediments from the Moira River system via drinking water and using the river system for recreational activities. Exposure is also possible via the consumption of fish caught in the river system. The CSM, which has been developed for this assessment, is provided in Figure 3.3-1.

3.4 Preliminary Quantitative Risk Assessment

The PQRA is a semi-quantitative process of evaluating the potential risk to human health resulting from exposure to the priority substances identified in the Moira River system. The methodology and assumptions adopted for this assessment were consistent with those used in the environmental health risk assessment conducted for the Village of Deloro (CanTox 1999).

3.4.1 Exposure Assessment

The exposure assessment characterized the potential exposures of the receptor to substances of concern. The methodology, rationale and underlying assumptions used in the exposure assessment are outlined in the following sections (see also Tables 3.3-18 and 3.3-19).

Figure 3.3-1
Conceptual Site Model

A deterministic modelling approach was adopted for this PQRA. Conservative (i.e., health protective) point estimates for all parameters used to describe exposure and toxicity were incorporated into this assessment. For example, maximum plausible estimates of receptor characteristics including body weight, body surface area and water consumption were used. This approach is expected to result in exposure estimates that are greater than actual exposures.

Two concentrations of the substances of potential concern in water were used for the exposure assessment. The annual average concentration of each substance was used to produce a "reasonable maximally exposed" (RME) estimate. Additionally, the ten-year average of the annual maximum concentrations detected in water from 1990 to present was used to represent a worst-case exposure scenario. The water concentrations used for the exposure modelling are given in Table 3.4-1. Exposure estimates were calculated using water concentrations, along with receptor body weight, water consumption rate, accidental ingestion rate, dermal contact rate, time activity patterns (i.e., time spent swimming) and chemical bioavailability.

Mean sediment concentrations for each substance of concern in samples collected at depths of 1 m or less for each study area were used for the exposure modelling (Table 3.4-1). It is considered unlikely that the receptor selected will come into contact with sediments at depths greater than 1 m. The mean metal concentrations presented in Table 3.4-1 are different than the mean concentrations for "near-shore" presented in Section 2 (Table 2.2-5). The "near-shore" concentrations in Table 2.2-5 are for both one-metre and two-metre depths. Exposure was estimated using sediment concentrations, along with receptor body weight, ingestion rate, dermal contact rate, time activity patterns (i.e., time spent swimming) and chemical bioavailability.

Mean fish fillet concentrations of the substances of potential concern from the 1999 MOE sport fish sampling program were used for the exposure modelling and are given in Table 3.4-1.

Table 3.4-1
Chemical Concentrations Employed in Exposure Assessment

Parameter	Area A				Area B
	Water—Average	Water—Average Maximum	Sediment	Fish	Water– Average	Water–Average Maximum	Sediment	Fish
	µ g/L	µg/L	µg/g	µg/g	µ g/L	µg/L	µg/g	µg/g
Arsenic	46.4	160.3	496.0	0.7	28.4	73.9	58.5	0.7
Cadmium	NA	NA	0.6	0.0	NA	NA	NA	0.0
Chromium	NA	NA	59.8	NA	NA	NA	NA	NA
Cobalt	8.3	31.1	339.0	NA	NA	NA	113.8	NA
Lead	NA	NA	20.4	0.0	NA	NA	NA	0.0
Nickel	NA	20.0	358.6	0.0	NA	NA	94.5	0.0

parameter	Area C				Area D
	Water–Average	Water–Average Maximum	Sediment	Fish	Water —Average	Water–Average Maximum	Sediment	Fish
	µg/L	µ g/L	µ g/g	µ g/g	µ g/L	µ g/L	µ g/g	µ g/g
Arsenic	NA	NA	7.1	0.1	NA	NA	25.0	0.2
Cadmium	NA	NA	NA	0.0	NA	NA	0.9	0.0
Chromium	NA	NA	NA	NA	NA	NA	NA	NA
Cobalt	NA	NA	5.7	NA	NA	NA	NA	NA
Lead	NA	NA	NA	0.1	NA	NA	NA	0.037
Nickel	NA	NA	8.9	0.033	NA	NA	NA	0.043

3.4.2 Toxicity Assessment

The toxicological criteria and bioavailability factors used in this assessment were adopted from the environmental health risk assessment conducted for the Village of Deloro (CanTox 1999). Table 3.4-2 is a summary of the toxicological criteria and the bioavailability factors for the substances of potential concern are given in Tables 3.4-3 and 3.4-4. Regulatory agencies such as Health Canada and the US EPA have developed these values. Appendix VI provides a summary of the toxicological properties for arsenic, cadmium, chromium, cobalt, lead and nickel. A more complete description of the toxicological properties of these substances is given elsewhere (CanTox 1999).

Table 3.4-2
Toxicological Criteria of Substance of Potential Concern

Chemical	Route	Toxicological Criterion		Endpoint	Study	Regulator y Agency
Chemical	Route	Type	Value	Endpoint	Study	Regulator y Agency
Arsenic (non-carcinogenic)	Oral	RfD	0.3 µg/kg/day	Hyperpigmentation, keratosis, possible vascular complications (human).	Tseng et al., 1968; Tseng, 1977	U.S. EPA, 1998
Arsenic (carcinogenic)	Oral	q₁	0.0015 µg/kg/day	Skin cancer, basal and squarmous cell carcinoma (human).	Tseng et al., 1968; Tseng, 1977	U.S. EPA, 1998
Cadmium (non-carcinogenic)	Oral (water)

Table 3.4-3
Bioavailability Factors Identified in Literature

chemical	Bioavailability (%)
	Oral	Reference	Dermal	Reference
Arsenic	95% 90% 14%	in drinking water: Pomroy et al., 1980 in food: OMOE, 1994b in soil: Freeman et al., 1995	0.8 - 1.9%	Wester et al., 1993
Cobalt	18-97%	Harp and Scoular, 1952; Sorbie et al., 1971; Valberg et al., 1969	0.06%	Assumed^a
Lead (Child)	42-53	Karhausen, 1973; Alexander, 1974; Ziegler et al., 1978; Mushak, 1991	0.06%	Moore et al., 1980
Nickel	27% 1%	Water Food (Nieboer et al., 1992; ATSDR, 1997)	0.06%	Assumed^a
Cadmium	0.7 15.6%	McLellan et al, 1978	0.5 - 1%	US EPA 1978; CEC 1978; Carson et al, 1986; Westar et al, 1992
Chromium	0.5 2.0%	ATSDR, 1993		No value identified in ATSDR HSDB.

a - assumed to be the same dermal bioavailability as lead due to lack of data.
Information adopted from CanTox, 1999.

Table 3.4-4
Bioavailability Factors Used for Exposure Modelling

Metal	Bioavailability (percent)
Metal	Water	Sediment	Fish	Dermal
Arsenic	95.00	14.00	90.00	1.35
Cobalt	97.00	57.50	57.50	0.1
Nickel	27.00	1.00	1.00	0.1
Cadmium	15.60	8.15	8.15	1
Chromium	2.00	1.25	1.25	0.1

3.4.3 Risk Characterization

Risk characterization was the final step in the risk assessment and involves comparing the estimated exposures to benchmark values that represent safe or acceptable exposures. Comparison of the estimated exposures to those typically encountered in the general population was also an important aspect of risk characterization, since it provided a frame of reference to evaluate local conditions. This step also identified the relative contribution to total exposure of each individual exposure scenario and allowed specific substances and exposure pathways that required further evaluation or management to be identified. Finally, uncertainties in the assessment, and their impact on its conclusions, were identified.

This section describes the results of the PQRA. Exposure modelling and calculation of Exposure Ratios (ERs) and Cancer Risk Levels (CRLs) was performed using Microsoft Excel™. The calculation of ERs and CRLs was completed individually for Study Areas A through D.

3.4.3.1 Non-Cancer Endpoints

Chemicals that do not cause cancer have a threshold-type dose-response; i.e., effects do not occur unless the dose is above a certain threshold. Risk characterization for these chemicals involves comparing the total estimated daily dose (i.e., exposure) to the Reference Dose (RfD). The RfD defines the amount of chemical that humans, including sensitive sub-populations, may be exposed to on a daily basis for an entire lifetime without an adverse effect. An Exposure Ratio (ER) is calculated by dividing the estimated exposure by the RfD, as summarized below.

Exposure Ratio = Estimated Exposure
RfD

ER values less than one are considered safe, and no adverse effects are expected. Conversely, ER values greater than one may represent a health risk, and therefore, need to be considered further. Because of the conservative nature of this assessment, ER values greater one may not represent a significant risk (see Section 3.4.3.7). In these instances, additional interpretation of the results is needed.

To put into perspective the relative importance of the potential health risks to residents of the Moira River system due to the presence of arsenic, calculated ER values for arsenic in each study area were also compared to ER values for arsenic calculated for a "Typical Ontario Resident" (TOR). The following ER values for arsenic were calculated for the TOR and have been adopted for this assessment.

• ER Values for TOR (Child Aged 5 - 11 Years): 6.31 (plausible maximum), 0.53
(mean), 0.49 (5^th percentile), 2 (50^th percentile), and 4.77 (95^th percentile).

These ER values for the TOR have been described in the environmental health risk assessment for the Village of Deloro (CanTox, 1999), and are representative of the health risks typically encountered by the average Ontario resident as calculated using standard risk assessment methodology. It is clear from ER values for the TOR that even individuals not exposed to localized sources of arsenic may be expected to have ER values greater than one. This illustrates the conservative nature of ER values; i.e., there are several layers of safety built into their estimation. Because of these layers of safety, ER values have to be considerably greater than one to represent significant potential risk.

Additionally, to gain a better understanding of the potential risks associated with the various pathways by which residents may be exposed to substances in the Moira River system, ERs were calculated for two exposure pathway groupings identified as Scenario A (exposure pathways 1 - 7) and Scenario B (exposure pathways 2 - 7). Scenario A assumes that water from the Moira River system is used as a source of potable water and for recreation and fishing, whereas Scenario B assumes that the river system is not used as a source of potable water, but is used for recreation and fishing.

3.4.3.2 Cancer

Carcinogens are usually assumed to have a non-threshold type dose response. So as to not underestimate potential health risks, it is assumed that there is some risk associated with any exposure. This is a conservative assumption that is used to ensure protection of public health. Risk characterization of carcinogens involves calculating a Cancer Risk Level (CRL). The CRL is calculated by multiplying the estimated Lifetime Average Daily Dose (LADD) of a chemical by the cancer potency factor (i.e., slope factor, or q*) of that chemical, as outlined below.

CRL = LADD x q*

The CRL defines the predicted excess risk that an individual has of developing cancer in their lifetime as a result of a particular exposure to a substance. Additionally, it should be noted that the determination of CRLs considers both long-term (chronic) and short-term (acute) exposures.

For carcinogens, the toxicological endpoint of interest is the incremental lifetime risk of developing cancer. Since a lifetime is commonly defined as 70 years, the LADD is calculated by amortizing the total lifetime dose over 70 years, even if the exposure is less than a lifetime. The CRL is calculated by multiplying the LADD by the chemical-specific cancer potency factor (q*). The q* is used to define the ability of a chemical to cause cancer in humans. Comparison of the calculated CRL values to cancer risk levels that are de minimus (i.e., negligible) is done to determine if the calculated cancer risks are acceptable. Regulatory agencies generally consider CRLs ranging from 1 x 10^-6 (1 in 1 million) to 1 x 10^-4 (1 in ten thousand) as de minimus risk levels.

The calculated CRLs were also compared to the CRLs derived for the TOR (composite receptor), as discussed in the environmental health risk assessment for the Village of Deloro (CanTox, 1999). The CRLs for arsenic for the TOR are summarized below. Arsenic is the only metal evaluated in this study that is carcinogenic.

CRL Values for TOR (Composite Receptor): 1.4 x 10^-3 (plausible maximum), 2.6 x 10^-4 (mean), 3.2 x 10^-4 (5^th percentile), 5.4 x 10^-4 (50^th percentile), and 8.2 x 10 ^-4 (95^th percentile).

The calculated CRLs for the TOR are greater than de minimus levels. This indicates that the average Ontario resident is typically exposed to elevated levels of arsenic (predominantly via the uptake of arsenic from food).

3.4.3.3 Moira River from Deloro to Moira Lake (Study Area A)

Non-Carcinogens

The estimated exposure for the child receptor (age 5 to 11 years) to the substances of concern present in Study Area A is given in Table 3.4-5, and the calculated ERs based on these exposure estimates are given in Table 3.4-6. The key findings are as follows.

Cadmium, Chromium, Cobalt, Lead and Nickel: These metals all had ER values less than 1 under all model scenarios. Therefore, these substances do not represent a health risk to users of the Moira River system, and do not require further evaluation.

Arsenic – Scenario A: Assuming the water from the river system is used for drinking water, ER values ranging from approximately 13 (average concentrations) to more than 31 (average of the maximum concentrations) were calculated. Comparison of these ER values to the TOR reveals that residents that consume river water in Study Area A are potentially exposed to levels of arsenic that are at least 2 to 5 times greater than the plausible maximum ER value calculated for the TOR. This finding indicates that residents that consume water from the Moira River in Study Area A are likely to be exposed to greater levels of arsenic than the TOR.

Examination of the seven exposure pathways reveals that more than 83 percent of the total exposure (approximately 18 µg/kg/day) is estimated to be derived from drinking water from the river assuming maximum average arsenic concentrations in water. Recreational uses of the river account for approximately 15 percent of the total estimated exposure. Clearly, consumption of water from the river is the single most important exposure pathway under this scenario.

Table 3.4-5
Estimated Exposures for Child Receptor: Study Area A Non-Cancer Endpoints

Estimated Exposure (µg/kg/day)

Exposure Pathway	Exposure Pathway Description	arsenic		cadium		chromium		cobalt		lead		nickel
Exposure Pathway	Exposure Pathway Description	max	avg	max	avg	max	avg	max	avg	max	avg	max	avg
1	consumption of water	7.221	2.090	na	na	na	na	1.430	0.382	na	na	0.256	na
2	accidental ingestion of water	0.463	0.134	na		na	na	0.092	0.024	na	na	0.016	na
3	dermal contact - swimming	0.004	0.001	na	na	na	na	0.001	0.000	na	na	0.000	na
4	dermal contact - bathing/shower	0.007	0.002	na	na	na	na	0.001	0.000	na	na	0.001	na
5	accidental ingestion of sediment	0.844	0.844	0.001	0.001	0.009	0.009	2.370	2.370	0.143	0.143	0.044	0.044
6	dermal contact with sediment	0.397	0.397	0.000	0.000	0.004	0.004	0.020	0.020	0.001	0.001	0.021	0.021
7	ingestion of fish	0.398	0.398	0.002	0.002	na	na	na	na	0.017	0.017	0.000	0.000
A	total exposure - pathways 1 - 7	9.333	3.866	0.003	0.003	0.013	0.013	3.914	2.797	0.160	0.160	0.339	0.065
B	total exposure - pathways 2 - 7	2.112	1.776	0.003	0.003	0.013	0.013	2.484	2.415	0.160	0.160	0.08	0.065

max estimated based on the ten year average of the annual maximum concentration detected

avg estimated based on average concentration detected

na not applicable - screened out during chemical screening

Table 3.4-6
Calculated Exposure Ratios for Child Receptor: Study Area A Non-Cancer Endpoints

Exposure Ratios

Exposure Pathway	arsenic		cadmium		chromium		cobalt		lead		nickel
Exposure Pathway	max	avg	max	avg	max	avg	max	avg	max	avg	max	avg
Reference Dose (RfD)	0.30	0.30	1.00	1.00	3.00	3.00	60.00	60.00	1.85	1.85	1.30	1.30
Exposure Pathways 1 - 7	31.11	12.89	0.00	0.00	0.00	0.00	0.07	0.05	0.08	0.09	0.26	0.05

Exposure Pathways 2 - 7	7.04	5.92	0.00	0.00	0.00	0.00	0.04	0.04	0.09	0.09	0.06	0.05

max estimated based on the ten year average of the annual maximum concentration detected

avg estimated based on average concentration detected

exposure ratio greater than 1

The exposure values calculated using average arsenic concentrations in water indicate that nearly 47 percent of the total exposure (2.1 µg/kg/day) is due to drinking water. Approximately 41 percent or 1.8 µg/kg/day of the total arsenic exposure is due to exposure to sediment (dermal contact and accidental ingestion during swimming). This indicates that exposure to sediments via recreational activities also represent an important source of exposure to arsenic in Study Area A.

Arsenic – Scenario B: Assuming that water from the river system is not used for drinking water purposes, ER values of approximately 6 and 7 were calculated based on the average and average of the maximum concentrations detected, respectively. These ER values are approximately 25 percent greater than the 95^th percentile ER value and are marginally elevated relative to the maximum plausible ER value for the TOR, respectively. Relative to the 50^th percentile ER value for the TOR, the calculated ER values are approximately 3 times greater. These data indicate that area residents may be expected to have marginally higher arsenic exposure levels than the TOR.

Examination of the relative importance of the 7 exposure pathways indicates that approximately 75 percent (1.8 µg/kg/day) of the total estimated arsenic exposure under this exposure scenario is due to accidental ingestion of sediment and dermal contact with sediment during swimming. In the absence of these exposure pathways, the corresponding ER value would be approximately 1.5 - 2, which is approximately equal to the 50^th percentile ER value calculated for the TOR. Thus, residents using the river in Study Area A for recreational purposes may be exposed to levels of arsenic greater than the TOR.

It should be noted that approximately 75 percent of the total arsenic exposure for the TOR is derived from food. Since area residents would also be expected to have similar levels of exposure to arsenic via food, any arsenic exposures received by residents in Study Area A would be incremental (in addition) to exposures received by the TOR.

Carcinogens

The estimated daily exposures to arsenic for each life stage are given in Table 3.4-7. The LADD for each scenario and the estimated excess cancer risk associated with these LADDS are given in Table 3.4-8. The key findings are summarized below.

Arsenic – Scenario A: Assuming the water from the river system is used for drinking water, CRL values of 2.5 x 10^-3 to 5.4 x 10^-3 have been calculated for the average and average of the maximum water concentrations detected, respectively. These CRLs are greater than de minimus or negligible cancer risk levels, which are often identified by regulatory agencies as ranging from 1 x 10^-6 to 1 x 10^-4. The calculated CRL values for area residents are between 2 to 4 times greater than the plausible maximum CRL (1.4 x 10^-3) and approximately 10 times greater than the 50^th percentile CRL estimates for the TOR. This result is consistent with the result described above and indicates that residents in Study Area A are likely exposed to levels of arsenic greater than the TOR.

Arsenic – Scenario B: Assuming that water from the river system is not used for drinking water purposes, CRL values of 3.9 x 10^-4 and 4.0 x 10^-4 have been calculated for average and average of the maximum concentrations detected, respectively. These values are approximately 4 times greater than the lower limit of the de minimus risk levels, but they are similar to the CRL values estimated for the TOR. For example, the 50^th percentile CRL value for the TOR is 5.4 x 10^-4.

These results indicate that the potential cancer risks to area residents are not significantly different than the TOR. However, it should be noted that area residents would also be exposed to arsenic from food and, as described above, approximately 75 percent of the total exposure to arsenic by the TOR are derived from food.

Based on the estimated ER values and CRL estimates, residents of Study Area A may be exposed to higher levels of arsenic than the TOR under both exposure scenarios.

Table 3.4-7

Estimated Daily Exposure to Arsenic for Each Life Stage: Study Area A Cancer Effects

Estimated Daily Exposure (µg/kg/day)
Exposure Pathway	Exposure Pathway Description	Preschool Child (7 mo. - 4 yrs)		Child (5 - 11 yrs)		Adolescent (12 -19)		Adult
Exposure Pathway	Exposure Pathway Description	max.avg	avg	max.avg	avg	max.avg	avg	max.avg	avg
1	consumption of water	6.4902	3.6065	3.7613	2.0901	2.8302	1.5727	3.5601	1.3280
2	accidental ingestion of water	0.0395	0.0220	0.0396	0.0220	0.0109	0.0061	0.0092	0.0051
3	dermal contact - swimming	0.0002	0.0001	0.0003	0.0002	0.0003	0.0001	0.0002	0.0001
4	dermal contact - bathing/shower	0.0023	0.0001	0.0020	0.0011	0.0016	0.0009	0.0014	0.0008
5	accidental ingestion of sediment	0.1384	0.1384	0.1388	0.1388	0.0191	0.0191	0.0161	0.0161
6	dermal contact with sediment	0.0384	0.0384	0.0652	0.0652	0.0158	0.0158	0.0050	0.0050
7	ingestion of fish	0.3979	0.3979	0.3979	0.3979	0.2193	0.2193	0.1851	0.1851
A	daily exposure - pathways 1 - 7	7.1069	4.2033	4.4052	2.7153	3.0972	1.8340	3.7772	1.5403
B	daily exposure - pathways 2 - 7	0.6166	0.5968	0.6439	0.6252	0.2670	0.2613	0.2172	0.2123

max avg estimated based on maximum concentration detected

avg estimated based on average concentration detected

Table 3.4-8
Estimated LADD and Lifetime Cancer Risk Due to Arsenic: Study Areas A through D

Exposure Pathway		Study Area A		Study Area B		Study Area C		Study Area D
Exposure Pathway		max	avg	max	avg	max	avg	max	avg
	Lifetime Exposure - Pathways 1 - 7 (µg/kg/day) LADD	91905.77 3.60	43118.56 1.69	40946.39 1.60	27702.90 1.08	9134.19 0.36	981.07 0.04	1490.17 0.06	1490.17 0.06
A	Lifetime Cancer Risk	5.40E-03	2.53E-03	2.40E-03	1.63E-03	5.36E-04	5.76E-05	8.75E-05	8.75E-05
	Lifetime Exposure - Pathways 2 - 7 LADD	6800.42 0.27	6630.96 0.26	5532.13 0.22	6864.08 0.27	1018.43 0.04	981.07 0.04	1490.17 0.06	1490.17 0.06
B	Lifetime Cancer Risk	4.0E-04	3.9E-04	3.3E-04	4.0E-04	6.0E-05	5.8E-05	8.8E-05	8.8E-05

max estimated based on maximum concentration detected

avg estimated based on average concentration detected

na not applicable - screened out during chemical screening

3.4.3.4 Moira Lake (Study Area B)

Non-Carcinogens

The estimated exposure for the child receptor (age 5 to 11 years) to the priority metals present in Study Area B is given in Table 3.4-9, and the calculated ERs based on these exposure estimates are given in Table 3.4-10. The key findings are summarized below.

Cadmium, Chromium, Cobalt, Lead and Nickel: These metals all had exposure values less than 1 under all model scenarios, and therefore, are not expected to represent a health risk to users of the Moira River system.

Arsenic – Scenario A: Assuming that water from the river system is used for drinking water, ER values ranging from approximately 5 (average concentrations) to more than 12 (average of the maximum concentrations) were calculated. Comparison of these ER values to the TOR reveals that residents that consume river water in Study Area B are potentially exposed to levels of that residents that consume river water in Study Area B are potentially exposed to levels ofarsenic that are approximately equal to or twice the plausible maximum ER value calculated for the TOR. This finding indicates that residents that consume water from the Moira River in Study Area B may be exposed to greater levels of arsenic than the TOR.

Arsenic—Scenario B: Assuming that water from the river system is not used for drinking water purposes, ER values of between 1.08 and 1.53 were calculated based on the average and average of the maximum concentrations detected, respectively. These ER values are marginally greater than an ER value of one, but are less than the 50th percentile ER value for the TOR. These data indicate that residents in Study Area B are not expected to have higher arsenic exposure levels than the TOR.

Carcinogens

The estimated daily exposures to arsenic for each life stage exposed to arsenic present in Study Area B are given in Table 3.4-11. The LADD for each scenario and the estimated excess cancer risk associated with this exposure is given in Table 3.4-8. The key findings are summarized below.

Table 3.4-9
Estimated Exposures for Child Receptor: Study Area B Non-Cancer Endpoints

Estimated Exposure (µg/kg/day)

Exposure Pathway	Exposure Pathway Description	arsenic		cadmium		chromium		cobalt		lead		nickel
Exposure Pathway	Exposure Pathway Description	max	avg	max	avg	max	avg	max	avg	max	avg	max	avg
1	consumption of water	3.329	1.279	na	na	na	na	na	na	na	na	na	na
2	accidental ingestion of water	0.213	0.082	na	na	na	na	na	na	na	na	na	na
3	dermal contact - swimming	0.002	0.001	na	na	na	na	na	na	na	na	na	na
4	dermal contact - bathing/shower	0.003	0.001	na	na	na	na	na	na	na	na	na	na
5	accidental ingestion of sediment	0.100	0.100	na	na	na	na	0.796	0.796	na	na	0.011	0.011
6	dermal contact with sediment	0.047	0.047	na	na	na	na	0.007	0.007	na	na	0.006	0.006
7	ingestion of fish	0.093	0.093	0.093	0.093	na	na	na	na	0.294	0.294	0.003	0.003
A	total exposure - pathways 1 - 7	3.787	1.603	0.003	0.003	0.000	0.000	0.802	0.802	0.294	0.294	0.020	0.020
B	total exposure - pathways 2 - 7	0.458	0.324	0.003	0.003	0.000	0.000	0.802	0.802	0.294	0.294	0.02	0.020

max estimated based on the ten year average of the annual maximum concentration detected

avg estimated based on average concentration detected

na not applicable - screened out during chemical screening

Table 3.4-10
Calculated Exposure Ratios for Child Receptor: Study Area B Non-Cancer Endpoints

Exposure Ratios
Exposure Pathway	arsenic		cadmium		chromium		cobalt		lead		nickel
Exposure Pathway	max	avg	max	avg	max	avg	max	avg	max	avg	max	avg
Reference Dose (RfD)	0.30	0.30	1.00	1.00	3.00	3.00	60.00	60.00	1.85	1.85	1.30	1.30
Exposure Pathways 1 - 7	12.62	5.34	0.00	0.00	0.00	0.00	0.01	0.01	0.00	0.00	0.02	0.02

Exposure Pathways 2 - 7	1.53	1.08	0.00	0.00	0.00	0.00	0.01	0.01	0.00	0.00	0.02	0.02

max estimated based on the ten year average of the annual maximum concentration detected

avg estimated based on average concentration detected

exposure ratio greater than 1

Table 3.4-11
Estimated Daily Exposure to Arsenic for Each Life Stage: Study Area B Cancer Effects

Estimated Daily Exposure (µg/kg/day)
Exposure Pathway	Exposure Pathway Description	Preschool Child (7 mo.-4yrs)		Child (5 - 11 yrs)		Adolescent (12 - 19)		Adult
Exposure Pathway	Exposure Pathway Description	max	avg	max	avg	max	avg	max	avg
1	consumption of water	2.7982	2.0598	1.6216	1.1937	1.2202	0.8982	1.4580	0.7585
2	accidental ingestion of water	0.0170	0.0125	0.0171	0.0126	0.0047	0.4744	0.0040	0.0029
3	dermal contact - swimming	0.0001	0.0001	0.0001	0.0001	0.0001	0.0001	0.0001	0.0001
4	dermal contact - bathing/shower	0.0010	0.0007	0.0009	0.0006	0.0007	0.0005	0.0006	0.0005
5	accidental ingestion of sediment	0.0163	0.0163	0.0164	0.0164	0.0023	0.0023	0.0019	0.0019
6	dermal contact with sediment	0.0045	0.0045	0.0077	0.0077	0.0019	0.0019	0.0006	0.0006
7	ingestion of fish	0.3979	0.3979	0.3979	0.3979	0.2193	0.2193	0.1851	0.1851
A	daily exposure - pathways 1 - 7	3.2350	2.4918	2.0617	1.6289	1.4491	1.5965	1.6503	0.9495
B	daily exposure - pathways 2 - 7	0.4368	0.4321	0.4400	0.4352	0.2289	0.6983	0.1923	0.1911

max estimated based on maximum concentration detected

avg estimated based on average concentration detected

na not applicable - screened out during chemical screening

Arsenic—Scenario A: Assuming the water from the river system is used for drinking water, CRL values of 1.6 x 10^-3 to 2.4 x 10^-3 have been calculated for the average and average of the maximum water concentrations detected, respectively. These values are greater than the lower limit of the de minimus risk levels, and they are approximately 2 times greater than the plausible maximum CRL (1.4 x 10^-3) for the TOR. This result is consistent with the result described above for non-cancer effects and indicates that residents in Study Area B may be exposed to levels of arsenic greater than the TOR.

Arsenic—Scenario B: Assuming that water from the river system is not used for drinking water purposes, CRL values of 3.3 x 10^-4 and 4.0 x 10^-4 have been calculated for average and average of the maximum concentrations detected, respectively. These values are approximately 3 to 4 times greater than the lower limit of the de minimus risk levels. However, they are similar to the CRL values estimated for the TOR. For example, the 50^th percentile CRL value for the TOR is 5.4 x 10^-4. These results indicate that the potential cancer risks to area residents are not significantly different than the TOR. However, area residents would also be exposed to arsenic form food and, as described above, approximately 75 percent of the total exposure to arsenic by the TOR are derived from food.

Based on the estimated ER values and CRL estimates, residents from Study Area B are unlikely to be exposed to higher levels of arsenic than the TOR unless water from the river system is consumed for drinking water.

3.4.3.5 Stoco Lake (Study Area C)

The estimated exposure for the child receptor (age 5 to 11 years) to the priority metals present in Study Area C is given in Table 3.4-12, and the calculated ERs based on these exposure estimates are given in Table 3.4-13. The key findings are summarized below.

Chromium, Cadmium, Cobalt, Lead, and Nickel: These metals all had exposure ratios less than 1 under all model scenarios, and therefore, are not expected to represent a health risk to users of the river system in Study Area C.

Table 3.4-12
Estimated Exposures for Child Receptor: Study Area C Non-Cancer Endpoints

Estimated Exposure (µg/kg/day)

Exposure Pathway	Exposure Pathway Description	arsenic		cadmium		chromium		cobalt		lead		nickel
Exposure Pathway	Exposure Pathway Description	max	avg	max	avg	max	avg	max	avg	max	avg	max	avg
1	consumption of water	na	na	na	na	na	na	na	na	na	na	na	na
2	accidental ingestion of water	na	na	na	na	na	na	na	na	na	na	na	na
3	dermal contact - swimming	na	na	na	na	na	na	na	na	na	na	na	na
4	dermal contact - bathing/shower	na	na	na	na	na	na	na	na	na	na	na	na
5	accidental ingestion of sediment	0.012	0.012	na	na	na	na	0.040	0.040	na	na	0.001	0.001
6	dermal contact with sediment	0.006	0.006	na	na	na	na	0.000	0.000	na	na	0.001	0.001
7	ingestion of fish	0.069	0.069	0.001	0.001	na	na	na	na	0.055	0.055	0.000	0.000
A	total exposure - pathways 1 - 7	0.086	0.086	0.001	0.001	0.000	0.000	0.040	0.040	0.055	0.055	0.002	0.002
B	total exposure - pathways 2 - 7	0.086	0.086	0.001	0.001	0.000	0.000	0.040	0.040	0.055	0.055	0.00	0.002

max estimated based on the ten year average of the annual maximum concentration detected

avg estimated based on average concentration detected

na not applicable - screened out during chemical screening

Table 3.4-13
Calculated Exposure Ratios for Child Receptor: Study Area C Non-Cancer Endpoints

Exposure Ratios
Exposure Pathway	arsenic		cadmium		chromium		cobalt		lead		nickel
Exposure Pathway	max	avg	max	avg	max	avg	max	avg	max	avg	max	avg
Reference Dose (RfD)	0.30	0.30	1.00	1.00	3.00	3.00	60.00	60.00	1.85	1.85	1.30	1.30
Exposure Pathways 1- 7	0.29	0.29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
776 Exposure Pathways 2 - 7	0.29	0.29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00

max estimated based on the ten year average of the annual maximum concentration detected

avg estimated based on average concentration detected

exposure ratio greater than 1

Arsenic: All ER values were less than one. These results indicate residents in Study Area C are unlikely to have higher arsenic exposure levels than the TOR.

Carcinogens

The estimated daily exposures to arsenic for each life stage exposed to arsenic present in Study Area C are given in Table 3.4-14. The LADD for each scenario and the estimated excess cancer risk associated with this exposure is given in Table 3.4-8. The key findings are discussed below.

The estimated cancer risks due to arsenic range from 5.8 x 10^-5 to 5.4 x 10^-4 under all exposure scenarios and water concentrations. Even the highest CRL value is equal to the 50^th percentile CRL value for the TOR (5.4 x 10^-4). Only under exposure pathway Scenario A and assuming maximum average concentrations in water do the risks exceed typical de minimus or negligible cancer risk levels (i.e., 1 x 10-6 to 1 x 10^-4).

Based on the above results, arsenic in Study Area C does not represent a health risk to area residents.

3.4.3.6 Moira River Downstream of Stoco Lake (Study Area D)

Non-Carcinogens

The estimated exposure for the child receptor (age 5 to 11 years) to the priority metals present in Study Area D is given in Table 3.4-15, and the calculated ERs based on these exposure estimates are given in Table 3.4-16. The key findings are summarized below.

Arsenic had the highest ER value at 0.57. All other metals had ER values less than 0.25. These results indicate that none of the substances examined in this assessment represent a potential health risk to users of the river system in Study Area D.

Table 3.4-14
Estimated Daily Exposure to Arsenic for Each Life Stage: Study Area C Cancer Effects

Estimated Daily Exposure (µg/kg/day)
Exposure Pathway	Exposure Pathway Description	Preschool Child (7 mo.-4yrs)		Child (5 - 11 yrs)		Adolescent (12 - 19)		Adult
Exposure Pathway	Exposure Pathway Description	max	avg	max	avg	max	avg	max	avg
1	consumption of water	0.6413	na	0.3716	na	0.2796	na	0.3341	na
2	accidental ingestion of water	0.0039	na	0.0039	na	0.0011	na	0.0009	na
3	dermal contact - swimming	0.0000	na	0.0000	na	0.0000	na	0.0000	na
4	dermal contact - bathing/shower	0.0002	na	0.0002	na	0.0002	na	0.0001	na
5	accidental ingestion of sediment	0.0093	0.0093	0.0094	0.0094	0.0013	0.0013	0.0011	0.0011
6	dermal contact with sediment	0.0026	0.0026	0.0044	0.0044	0.0011	0.0011	0.0003	0.0003
7	ingestion of fish	0.0685	0.0685	0.0685	0.0685	0.0378	0.0378	0.0319	0.0319
A	daily exposure - pathways 1 - 7	0.7259	0.0805	0.4581	0.0823	0.3210	0.0401	0.3685	0.0333
B	daily exposure - pathways 2 - 7	0.0846	0.0805	0.0864	0.0823	0.0414	0.0401	0.0344	0.0333

max estimated based on maximum concentration detected

avg estimated based on average concentration detected

na not applicable - screened out during chemical screening

Table 3.4-15
Estimated Exposures for Child Receptor: Study Area D Non-Cancer Endpoints

Estimated Exposure (µg/kg/day)

Exposure Pathway	Exposure Pathway Description	arsenic		cadmium		chromium		cobalt		lead		nickel
Exposure Pathway	Exposure Pathway Description	max	avg	max	avg	max	avg	max	avg	max	avg	max	avg
1	consumption of water	na	na	na	na	na	na	na	na	na	na	na	na
2	accidental ingestion of water	na	na	na	na	na	na	na	na	na	na	na	na
3	dermal contact - swimming	na	na	na	na	na	na	na	na	na	na	na	na
4	dermal contact - bathing/shower	na	na	na	na	na	na	na	na	na	na	na	na
5	accidental ingestion of sediment	0.043	0.043	na	na	na	na	na	na	na	na	na	na
6	dermal contact with sediment	0.020	0.020	na	na	na	na	na	na	na	na	na	na
7	ingestion of fish	0.108	0.108	0.000	0.000	na	na	na	na	0.020	0.020	0.000	0.000
A	total exposure - pathways 1 - 7	0.171	0.171	0.000	0.000	0.000	0.000	0.000	0.000	0.020	0.020	0.000	0.000
B	total exposure - pathways 2 - 7	0.171	0.171	0.000	0.000	0.000	0.000	0.000	0.000	0.020	0.020	0.000	0.000

max estimated based on the ten year average of the annual maximum concentration detected

avg estimated based on average concentration detected

na not applicable - screened out during chemical screening

Table 3.4-16
Calculated Exposure Ratios for Child Receptor: Study Area D Non-Cancer Endpoints

Exposure Ratios
Exposure Pathway	arsenic		cadmium		chromium		cobalt		lead		nickel
Exposure Pathway	max	avg	max	avg	max	avg	max	avg	max	avg	max	avg
Reference Dose (RfD)	0.30	0.30	1.00	1.00	3.00	3.00	60.00	60.00	1.85	1.85	1.30	1.30
Exposure Pathways 1 - 6	0.57	0.57	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Exposure Pathways 2 - 6	0.57	0.57	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00

max estimated based on the ten year average of the annual maximum concentration detected

avg estimated based on average concentration detected

exposure ratio greater than 1

Table 3.4-17
Estimated Daily Exposure to Arsenic for Each Life Stage: Study Area D Cancer Effects

Estimated Daily Exposure (µg/kg/day)
Exposure Pathway	Exposure Pathway Description	Preschool Child (7 mo. - 4 yrs)		Child (5 - 11 yrs)		Adolescent (12 -19)		Adult
Exposure Pathway	Exposure Pathway Description	max	avg	max	avg	max	avg	max	avg
1	consumption of water	na	na	na	na	na	na	na	na
2	accidental ingestion of water	na	na	na	na	na	na	na	na
3	dermal contact - swimming	na	na	na	na	na	na	na	na
4	dermal contact - bathing/shower	na	na	na	na	na	na	na	na
5	accidental ingestion of sediment	0.0078	0.0078	0.0078	0.0078	0.0011	0.0011	0.0009	0.0009
6	dermal contact with sediment	0.0022	0.0022	0.0037	0.0037	0.0009	0.0009	0.0003	0.0003
7	ingestion of fish	0.1083	0.1083	0.1083	0.1083	0.0597	0.0597	0.0504	0.0504
A	daily exposure - pathways 1 - 7	0.1182	0.1182	0.1197	0.1197	0.0616	0.0616	0.0516	0.0516
B	daily exposure - pathways 2 - 7	0.1182	0.1182	0.1197	0.1197	0.0616	0.0616	0.0516	0.0516

max estimated based on maximum concentration detected

avg estimated based on average concentration detected

na not applicable - screened out during chemical screening

Carcinogens

The estimated daily exposure to arsenic for each life stage exposed to arsenic present in Study Area D are given in Table 3.4-17. The LADD for each scenario and the estimated excess cancer risk associated with this exposure is given in Table 3.4-8.

The estimated cancer risks due to arsenic in Study Area D is 8.8 x 10^-5. This is within the range of de minimus or negligible cancer risk levels (i.e., 1 x 10^-6 to 1 x 10^-4).

Based on the above results, arsenic in Study Area D does not represent a potential risk to human health.

3.4.3.7 Uncertainty Analysis

In a risk assessment, the doses and benchmarks are estimated from the available information about how exposure might take place and the doses that cause effects. There is always uncertainty associated with these estimations, depending on the quality, quantity and variability associated with the available information. When information is uncertain, it is standard practice in a risk assessment to make assumptions that are biased towards safety, so that even if there is uncertainty, human health will still be protected. Every effort is made to ensure that assumptions are specific to the site being evaluated.

There are several layers of safety applied in this PQRA. For instance, the sediment exposure pathway models assumed that an individual is exposed to sediments 120 times per year (60 days x 2 events per day). There were limited data on shallow water sediment concentrations and activity use patterns for residents in the study areas. In Study Area A, the areas of sediment accumulation were localized and where observed, consisted of fine-grained materials deposited in shallow backwater areas (see Section 2.2.3). In general, these areas did not appear attractive for recreational use because of the fine muddy nature of the bottom sediments and the fact the water is too shallow for swimming. Also, depending on the river flow and sediment deposition dynamics, exposure to sediments in at least some portions of the river is unlikely. Taken together, it is probable that the potential sediment exposure has been overestimated.

The exact amount of time a child spends outside in contact with sediments was uncertain because it varies with the weather, other activities of the child's family, and the child's own preferences. The risk assessment assumed, as a worst case, that a child would spend time in contact with water and sediments every day for 60 days. This is conservative since children would be spending time in other activities as well.

The maximum and average concentrations of each metal in water were used to help address the uncertainty associated with differences in chemical concentrations in water. Comparison of the exposure estimates for the maximum versus average water concentrations revealed that differences in water concentrations were much more important when it is assumed that the river water is used as a source of drinking water (i.e., Scenario A).

The metal concentrations in sediment were uncertain because the information was based on a limited number of samples at one time period and/or there was considerable variability in concentrations of metals between samples in the area. In this case, a layer of safety was added by calculating exposure based on the maximum observed metal concentration, even if this was only in one very small area.

To address the uncertainty associated with differences in receptor water usage characteristics, two different exposure pathway scenarios were evaluated. Scenario A assumed that river water is used for drinking and cooking, whereas Scenario B assumed that the river is not used for drinking or cooking. Both scenarios consider consumption of fish from, and recreational uses of, the Moira River system.

There was also uncertainty associated with estimating benchmark doses. Benchmark doses are based on toxicity information available from government databases and published scientific literature. The majority of toxicity information comes from the results of experiments with laboratory animals. Some additional information on human health effects is also available for some substances where cases of workplace exposures and associated health effects have been documented. There is some uncertainty in extrapolating from animal studies and workplace case studies to the possible effects that may result from exposure to arsenic in sediments in Study Area

A. To add a layer of safety, it is standard practice in a risk assessment to assume that people are more sensitive to the toxic effects of a chemical than laboratory animals. Therefore, the benchmark dose for human health is set at a much lower level than the animal benchmark (typically 100 to 1000 times lower). This large margin of safety ensures that minor exceedances of these benchmark doses will not cause adverse health effects.

Because of all of the layers of safety incorporated into the calculation of an ER, values that are at or marginally greater than one do not indicate that adverse effects are occurring or are likely to occur. Minor exceedances of the benchmark (resulting in ER values slightly above one) are within the layers of safety incorporated into the risk assessment.

There were some sources of uncertainty that had an unpredictable effect on the level of conservatism of the assessment. In using methodology consistent with Cantox (1999), this assessment assumed that individuals would be exposed only to inorganic arsenic, which has in the past been considered more toxic than organic forms. However, in recent years, a number of studies suggest that some organic arsenic species may be more toxic than some inorganic forms (for example, Aposhian et al. 2000; Petrick et al. 2000). Inorganic arsenic in groundwater and surface water can be reduced (methylated) by micro-organisms, albeit to a limited extent. Therefore, it is likely that a portion of the arsenic measured in sediment and water samples along the river system is present in the organic form. The potential impact of this uncertainty cannot be determined at this time, as the identification and study or toxic organic arsenic species is a relatively new area of study for this metalloid.

Exposure estimates were adjusted for bioavailability using literature information (tabulated in Table 3.4-3). The bioavailability factors selected (tabulated in Table 3.4-4) represent the best available. However, it is difficult to accurately determine bioavailability in humans under various conditions. Complicating this issue is the complex chemistry of arsenic, which may occur in many inorganic and organic forms, and which may be converted by biological or physicochemical processes into other species.

The screening procedure used to identify substances of potential concern involved comparing chemical concentrations in samples from the Moira River system with corresponding concentrations in similar samples collected from reference locations. It is possible that an unusually high reference value (due, for example, to specific local geology) could lead to a substance being inadvertently eliminated from further evaluation. However, this is considered unlikely, as reference locations and sample types were selected to be similar to locations along the Moira River system.

On balance, the PQRA was conservative, with several layers of safety built into the analysis. Therefore, elimination of concern about particular metals or exposure pathways was possible and defensible. This was because if estimated exposures were less than benchmark values even with several layers of safety, then it could be concluded that there was no risk to human health. Furthermore, because of the use of several layers of safety, identification of arsenic as a concern in Study Area A does not imply that there is, in fact, a significant risk to human health. Rather, the focus provided by the PQRA called attention to issues in Study Area A that required additional study and/or risk management.

3.4.3.8 Multimedia Approach

Given the scope of work, a multimedia assessment has not been conducted as part of this PQRA. It is recognized that there are other significant sources of exposure to these metals such as diet, as outlined in the environmental health risk assessment conducted for the Village of Deloro (CanTox, 1999). To account for other sources of exposure, it is often assumed that 20 percent of the total allowable (safe) intake is apportioned to any single source (i.e., the river system). Examination of the ERs reveals that with the exception of arsenic, most ER values are less than 0.2. This indicates that a multimedia approach is unlikely to have changed the findings of this study.

3.5 Conclusions

This PQRA identified how humans may be exposed to substances released by the Deloro Mine Site and which are present in the Moira River system. It was a semi-quantitative screening level assessment that was used to identify and eliminate the substances and exposure pathways not requiring further assessment, as well as to identify exposure scenarios requiring further evaluation. This assessment is not designed to quantify health impacts.

No findings in this report should be taken to confirm that adverse health impacts are occurring among river system users.

Cadmium, chromium, cobalt, lead, and nickel do not represent a potential health risk in any study area and further assessment of the potential health risks posed by these metals is not required.

Arsenic in Study Areas C and D is not expected to lead to significantly elevated exposures compared to the TOR, and further assessment of the potential health risks posed by this substance in these areas is not warranted.

The PQRA showed that residents of Study Areas A and B (from the Deloro Mine Site to the outlet of Moira Lake) would have greater estimated levels of exposure to arsenic than the TOR under the conditions assumed in the assessment. Use of water from the river system for drinking water is the most significant pathway of exposure to arsenic. The reminder issued by the MOE and the Hastings and Prince Edward Counties Health Unit to residents of Study Areas A and B advising them not to drink untreated surface water was, and continues to be, appropriate. The reminder is not only appropriate because of concerns about arsenic, but also because of the risk of exposure to pathogens in untreated water.

The section of the river above Moira Lake (Study Area A) is not well suited for in-water recreational activities and has only a limited number of residences. However, recreational use of this section of the river system may be an important exposure pathway, at least for some individuals. The amount of exposure through this pathway, both in absolute terms and relative to total arsenic exposure, requires further study. (This study was completed and is presented in Appendix X).

Based on the findings of MOE (1999), metals of concern in fish fillets from the Moira River system are at concentrations below those that could require restrictions of fish consumption. CanTox (1999), who reported that levels of arsenic in fish considered in the Deloro Village risk assessment study were consistent with those observed elsewhere in Ontario, supports this. No further assessment of this pathway (i.e., ingestion of fish) is required.

It should be noted that fish consumption advice published in MOE's "Guide to Eating Ontario Sport Fish 1999-2000" includes some restriction on certain sizes of certain species of sport fish in Moira Lake, Stoco Lake and the two reference lakes, Consecon Lake and Round Lake. Although a range of metals and other chemicals was measured in fish sampled collected from each of the lakes, only mercury warranted consumption restrictions. Consumption restrictions based on mercury are widespread throughout Ontario's lakes and rivers, due in part to natural geological presence of mercury and the likelihood of its accumulation in the flesh of larger predatory sport fish. Mercury is not related to discharges from the Deloro Mine Site.

3.6 References

Ariza, M., Bijur, G. and Williams, M. 1999. Environmental metal pollutants, reactive oxygen intermediates and geotoxicity. Kluwer Academic Publishers, Boston.

Aposhian, V.H., Gurzau, E.S., Le, X.C., Gurzau, A., Healy, S.M., Lu, X., Ma, M., Yip, L., Zakharyan, R.A., Maiorino, R.M., Dart, R.C., Tirus, M.G., Gonzalez-Ramirez, D., Morgan, D.L., Avram, D., Aposhian, M.M. 2000. Occurrence of monomethylarsenous acid (MMA III) in urine of humans exposed to inorganic arsenic. Chem. Res. Toxicol.

165:74-83

ATSDR. 1993. Toxicological profile arsenic. Agency for Toxic Substances and Disease Registry, April 1993.

ATSDR. 1993. Toxicological profile cadmium. Agency for Toxic Substances and Disease Registry, April 1993.

ATSDR. 1993. Toxicological profile chromium. Agency for Toxic Substances and Disease Registry, April 1993.

ATSDR. 1993. Toxicological profile lead. Agency for Toxic Substances and Disease Registry, April 1993.

Cantox. 1999. Deloro Village exposure assessment and health risk characterization for arsenic and other metals. Prepared by Cantox Environmental Inc. December, 1999.

CCME. 1995. Canadian Council of Ministers of the Environment. Canadian water quality guidelines (Revised December, 1995).

Goyer, R. Toxic effect of metals. C. Klaassen ed. Casarett & Doull's toxicology the basic science of poison. 5^th ed. McGraw-Hill; 1996.

MOE. 1999. Guide to Eating Ontario Sport Fish 1999-2000. Ministry of the Environment. Twentieth Edition, Revised.

Ontario Ministry of Environment (MOE). 1997. Guideline for use at contaminated sites in Ontario. Ministry of the Environment and Energy (MOE). Revised February, 1997. Queens Printer for Ontario, Toronto, ON.

Ontario Ministry of Environment (MOE). 1996. Guidance on site specific risk assessment for use at contaminated sites in Ontario. Queens Printer for Ontario, Toronto, ON.

Ontario Ministry of Environment and Energy (MOE). 1999a. Water management policies: guidelines provincial water quality objectives. Queen's Printer for Ontario, Toronto, ON.

Ontario Ministry of Environment and Energy (MOE). 1999b. Guideline for use at contaminated sites in Ontario. Queen's Printer for Ontario, Toronto, ON.

Petrick, J.S., Ayela-Fiero, F., Cullen, W.R., Carter, D.E., Aposhian, H.V. 2000. Monomethylarsenous acid (MMA III) is more toxic than arsenite in Chang human hepatocytes. Toxicol. Appl. Pharmacol. 163:203-20

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3. ASSESSMENT OF RISKS TO HUMAN HEALTH DOWNSTREAM OF THE FORMER DELORO MINE SITE

3.1 Introduction

3.1.1 Scope of Work

3.1.2 Study Area Selection

3.1.3 Report Organization

3.2 Study Approach

Step 1) Data Compilation and Analysis

Step 2) Problem Formulation

Figure 3.2-1 Environmental Risk Components

Step 3) Preliminary Quantitative Risk Assessment

3.3 Problem Formulation

3.3.1 Chemical Screening

3.3.1.1 Surface Water

Moira River from Deloro to Moira Lake (Study Area A)

Moira Lake (Study Area B)

Moira River Downstream of Stoco Lake (Study Area D)

Table 3.3-1

Area A Exceedances for Yearly Maximum Concentrations

Table 3.3-2Area A Exceedances for Average Concentrations

Table 3.3-3Area B Exceedances for Yearly Maximum Concentrations

Table 3.3-4 Area B Exceedances for Average Concentrations

Table 3.3-5 Area C Exceedances for Yearly Maximum Concentrations

Table 3.3-6 Area C Exceedances for Average Concentrations

Table 3.3-7 Area D Exceedances for Yearly Maximum Concentrations

Table 3.3-8 Area D Exceedances for Average Concentrations

Table 3.3-9 Substances in Water Which Require Further Assessment in the PQRA

3.3.1.2 Sediment

Table 3.3-10 Reference Sediment Samples (µg/g dry weight), Sampled April 1, 1999

Moira River from Deloro to Moira Lake (Study Area A)

Table 3.3-11Study Area A Sediment Samples (mg/g dry), Sampled April 1, 1999

Moira Lake (Study Area B)

Stoco Lake (Study Area C)

Table 3.3-12 Study Area B Sediment Samples (µg/g dry), Sampled April 1, 1999

Table 3.3-13 Study Area C Sediment Samples (µg/g dry), Sampled April 1, 1999

Moira River Downstream of Stoco Lake (Study Area D)

Table 3.3-14 Study Area D Sediment Samples, Sampled April 1, 1999

Summary of Substances of Potential Concern in Sediments:

Table 3.3-15 Substances in Sediment Which Require Further Assessment in the PQRA

3.3.1.3 Fish

3.3.2 Exposure Characterization

Table 3.3-16 Average Metal Concentration (and Standard Deviation) in Sport Fish Fillets per Location (µg/g wet weight)

Table 3.3-17 Summary of Exposure Pathways Considered

Table 3.3-18 Exposure Pathway Equations and Input Variables for Non-Carcinogenic Effects

Table 3.3-19 Exposure Pathway Equations and Input Variables for Cancer Assessment

3.3.3 Receptor Selection

Table 3.3-20 Receptor Characteristics by Lifestage

3.3.4 Summary of Conceptual Site Model

3.4 Preliminary Quantitative Risk Assessment

3.4.1 Exposure Assessment

Figure 3.3-1 Conceptual Site Model

Table 3.4-1 Chemical Concentrations Employed in Exposure Assessment

3.4.2 Toxicity Assessment

Table 3.4-2 Toxicological Criteria of Substance of Potential Concern

Table 3.4-3 Bioavailability Factors Identified in Literature

Table 3.4-4 Bioavailability Factors Used for Exposure Modelling

3.4.3 Risk Characterization

3.4.3.1 Non-Cancer Endpoints

3.4.3.2 Cancer

3.4.3.3 Moira River from Deloro to Moira Lake (Study Area A)

Non-Carcinogens

Table 3.4-5 Estimated Exposures for Child Receptor: Study Area A Non-Cancer Endpoints

Estimated Exposure (µg/kg/day)

Table 3.4-6 Calculated Exposure Ratios for Child Receptor: Study Area A Non-Cancer Endpoints

Exposure Ratios

Carcinogens

Table 3.4-7

Estimated Daily Exposure to Arsenic for Each Life Stage: Study Area A Cancer Effects

Table 3.4-8 Estimated LADD and Lifetime Cancer Risk Due to Arsenic: Study Areas A through D

3.4.3.4 Moira Lake (Study Area B)

Non-Carcinogens

Carcinogens

Table 3.4-9 Estimated Exposures for Child Receptor: Study Area B Non-Cancer Endpoints

Estimated Exposure (µg/kg/day)

Table 3.4-10 Calculated Exposure Ratios for Child Receptor: Study Area B Non-Cancer Endpoints

Table 3.4-11 Estimated Daily Exposure to Arsenic for Each Life Stage: Study Area B Cancer Effects

3.4.3.5 Stoco Lake (Study Area C)

Table 3.4-12Estimated Exposures for Child Receptor: Study Area C Non-Cancer Endpoints

Estimated Exposure (µg/kg/day)

Table 3.4-13 Calculated Exposure Ratios for Child Receptor: Study Area C Non-Cancer Endpoints

3.4.3.6 Moira River Downstream of Stoco Lake (Study Area D)

Table 3.3-2
Area A Exceedances for Average Concentrations

Table 3.3-3
Area B Exceedances for Yearly Maximum Concentrations

Table 3.3-4
Area B Exceedances for Average Concentrations

Table 3.3-5
Area C Exceedances for Yearly Maximum Concentrations

Table 3.3-6
Area C Exceedances for Average Concentrations

Table 3.3-7
Area D Exceedances for Yearly Maximum Concentrations

Table 3.3-8
Area D Exceedances for Average Concentrations

Table 3.3-9
Substances in Water Which Require Further Assessment in the PQRA

Table 3.3-10
Reference Sediment Samples (µg/g dry weight), Sampled April 1, 1999

Table 3.3-11
Study Area A Sediment Samples (mg/g dry), Sampled April 1, 1999

Table 3.3-12
Study Area B Sediment Samples (µg/g dry), Sampled April 1, 1999

Table 3.3-13
Study Area C Sediment Samples (µg/g dry), Sampled April 1, 1999

Table 3.3-14
Study Area D Sediment Samples, Sampled April 1, 1999

Table 3.3-15
Substances in Sediment Which Require Further Assessment in the PQRA

Table 3.3-16
Average Metal Concentration (and Standard Deviation) in Sport Fish Fillets
per Location (µg/g wet weight)

Table 3.3-17
Summary of Exposure Pathways Considered

Table 3.3-18
Exposure Pathway Equations and Input Variables for Non-Carcinogenic Effects

Table 3.3-19
Exposure Pathway Equations and Input Variables for Cancer Assessment

Table 3.3-20
Receptor Characteristics by Lifestage

Figure 3.3-1
Conceptual Site Model

Table 3.4-1
Chemical Concentrations Employed in Exposure Assessment

Table 3.4-2
Toxicological Criteria of Substance of Potential Concern

Table 3.4-3
Bioavailability Factors Identified in Literature

Table 3.4-4
Bioavailability Factors Used for Exposure Modelling

Table 3.4-5
Estimated Exposures for Child Receptor: Study Area A Non-Cancer Endpoints

Table 3.4-6
Calculated Exposure Ratios for Child Receptor: Study Area A Non-Cancer Endpoints

Table 3.4-8
Estimated LADD and Lifetime Cancer Risk Due to Arsenic: Study Areas A through D

Table 3.4-9
Estimated Exposures for Child Receptor: Study Area B Non-Cancer Endpoints

Table 3.4-10
Calculated Exposure Ratios for Child Receptor: Study Area B Non-Cancer Endpoints

Table 3.4-11
Estimated Daily Exposure to Arsenic for Each Life Stage: Study Area B Cancer Effects

Table 3.4-12
Estimated Exposures for Child Receptor: Study Area C Non-Cancer Endpoints

Table 3.4-13
Calculated Exposure Ratios for Child Receptor: Study Area C Non-Cancer Endpoints

Table 3.4-14
Estimated Daily Exposure to Arsenic for Each Life Stage: Study Area C Cancer Effects

Table 3.4-15
Estimated Exposures for Child Receptor: Study Area D Non-Cancer Endpoints

Table 3.4-16
Calculated Exposure Ratios for Child Receptor: Study Area D Non-Cancer Endpoints

Table 3.4-17
Estimated Daily Exposure to Arsenic for Each Life Stage: Study Area D Cancer Effects