Cantox Environmental - Deloro Village Exposure Assessment and Health Risk Characterization for Arsenic and Other Metals - Final Report

704 Pages·1999·21.8 MB·English

by  Ontario Ministry of the Environment

ENVIIRONMENTAL
DELORO VILLAGE
EXPOSURE ASSESSMENT AND HEALTH RISK
CHARACTERIZATION FOR ARSENIC AND OTHER
METALS
FINAL REPORT
-
PREPARED FOR: Ontario Ministry ofthe Environment
40 St. Clair Avenue W., 7"^ Floor
ON
Toronto,
M4V 1M2
CH2M &
Gore Storrie Limited
180 King Street South, Suite 600
Waterloo, Ontario
N2J 1P8
December, 1999
CANTOX ENVIRONMENTAL
INC.
2233 Argentia Road, Suite 308, Mississauga, Ontario, Canada L5N 2X7
Phone: [phone] Fax: [phone] www.cantoxen\ironmentaI.com
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DELORO VILLAGE
EXPOSURE ASSESSMENT AND HEALTH RISK CHARACTERIZATION FOR
ARSENIC AND OTHER METALS
Table ofContents
Executive Summary
PART INTRODUCTION
1
1.0 Introduction
2.0 References
PART GENERAL METHODOLOGY
2
1.0 Problem Formulation
2.0 Exposure Assessment
3.0 Toxicological Assessment
4.0 Risk Characterization
5.0 References
PART 3 REVIEW OF EXPOSURE TO ARSENIC IN THE VICINITY OF MINING
OPERATIONS/SMELTERS
1.0 Sources and Fate ofArsenic in the Environment
2.0 Background Arsenic Exposure in Ontario And/or Canada
3.0 Mine and Smelter Arsenic Exposure Issues
4.0 Magnitude ofArsenic Exposure in Vicinity ofMining/Smelting Activity
5.0 Strategies to Mitigate Human Arsenic Exposure at Mine/Smelter Sites
6.0 References
PART 4 TOXICOLOGICAL REVIEW FOR ARSENIC AND OTHER METALS
1.0 Introduction
2.0 Arsenic: Pharmacokinetics and Toxicology
3.0 Toxicological Review: Cobalt
4.0 Toxicological Review: Lead
5.0 Toxicological Review: Nickel
6.0 Toxicological Review: Silver
PART 5 HUMAN HEALTH RISK ASSESSMENT
1.0 Problem Formulation
2.0 Exposure Assessment: Deterministic and Probabilistic
3.0 Toxicological Assessment
4.0 Risk Characterization: Results and Discussion
5.0 Urinary Arsenic Evaluation
6.0 Uncertainty and Sensitivity Analysis
7.0 References
Figures 5-1 to 5-34
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DELORO VILLAGE
EXPOSURE ASSESSMENT AND HEALTH RISK CHARACTERIZATION FOR
ARSENIC AND OTHER METALS
Table ofContents (Continued)
PART 6 RISK MANAGEMENT: EXPOSURE AND/OR RISK MITIGATION
PART DISCLAIMER
7
APPENDIX A MODELLING PARAMETERS: RECEPTOR PARAMETERS AND
ESTIMATION OF INHALATION BIOAVAILABILITY
APPENDIX B ENVIRONMENTAL CONCENTRATION DATA
APPENDIX C DETAILED RESULTS
APPENDIX D RESPONSE TO PEER REVIEW
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DELORO VILLAGE
EXPOSURE ASSESSMENT AND HEALTH RISK CHARACTERIZATION FOR
ARSENIC AND OTHER METALS
EXECUTIVE SUMMARY
The Village ofDeloro, located on the Moira River in southeastern Ontario and home to a
population of 140 people, is the focus ofan extensive risk assessment and remediation effort
by the Ontario Ministry ofthe Environment (OMOE). The village is located along the
property line ofa former mine and refinery, and contamination ofthe former mine site and
the village ofDeloro is the result ofa century ofthese mining and refining activities. The
current effort is aimed at quantifying and mitigating exposures and risks to the residents of
Deloro which are associated with the contamination ofthe former mine site by heavy metals
and radiological agents and the subsequent emission ofcontaminants fi-om the mine site via
liberation ofdusts, volatilization, and/or leaching into the Moira River watershed. The
OMOE
conducted a screening level risk assessment on the contaminated soils ofthe village
ofDeloro, and have identified several heavy metals (arsenic, cobalt, lead, nickel and silver)
as well as radiological agents as being ofpotential health concern to residents.
Under the leadership ofOMOE and CH2M Gore & Storrie Limited (COS), Cantox
EnvironmentalInc. has conducted an exposure assessment and health risk characterization
for the residents ofDeloro, Ontario, based on concentrations ofarsenic, cobalt, lead, nickel
and silver in the air, water, soil, and food throughout the village.
The objectives ofthis assessment were as follows:
(i) to review the exposures and/or risks posed to the public in the vicinity ofother mining
or smelting operations in North America;
(ii) to review the sources and levels ofexposure ofchemicals ofconcern to typical
Ontarians, including home grown and market basket foods, soils, drinking water, and
air;
(iii) to determine ifthe concentrations ofarsenic and the other metals ofconcern in
various media in Deloro would pose a risk ofadverse health effects for adults and
children dwelling in the village, and to compare results to exposures in other
mining/smelter areas as well as exposures oftypical Ontario residents;
(iv) to compare the results ofexposure assessment to those ofbiological monitoring
efforts (specifically urinary arsenic determinations); and,
(v) review various options ofexposure and risk mitigation and make estimates of
possible risk reductions.
Deloro VillageExposureandRiskAssessment Pagei
ExecutiveSummary December. 1999
W^&iSiorlvSJlA.
Review ofExposure to Arsenic
Arsenic is a naturally-occurring element which is found in terrestrial and aquatic
environments, which is capable ofextensive cycling through both biotic and abiotic
components ofthese systems. Therefore, while exposures to arsenic maybe exacerbated by
human activity such as mining {i.e., point sources), even populations without direct contact
with such point sources will be exposed to arsenic at some level. Environment Canada has
estimated that the total average daily intake ofinorganic arsenic by Canadians without direct
contact to point sources ranges from 0.1 to 2.6 |ig/kg body weight/day, with the greatest
OMOE
exposure occurring in infants and young children. The examined the relative
contribution ofvarious pathways ofexposure to total daily intake ofinorganic arsenic via
ingestion for Ontario residents, and identified as major contributors both food (84%) and
drinking water (15%). Soil/dust ingestion pathways contributed less than 1% to the total.
Environment Canada estimated daily intakes ofinorganic arsenic by Canadians living near
point sources ofarsenic contamination, from all exposure pathways, to range from <0.1 to 35
^ig/kg bodyweight/day, with the greatest exposure occurring in infants and young children.
Analysis ofconcentrations ofarsenic compounds in the urine is considered to be a reliable,
non-intrusive technique for evaluating recent arsenic exposure, and thus serves as an
indicator ofthe health status ofpopulations exposed to arsenic. Total urinary arsenic
concentrations reflect intakes ofall forms ofarsenic, including inorganic arsenic (considered
to be responsible for toxicological effects associated with arsenic) as well as organic
arsenicals (which are considered to be without significant toxicological effects). Therefore,
speciated arsenic measurements, reflecting concentrations ofonly inorganic forms ofarsenic
and their metabolites (arsenic III, arsenic V, monomethylarsonic acid and dimethylarsonic
acid) are generally considered the appropriate measure for use in health assessment.
Populations not exposed to a point source ofarsenic have average urinary speciated arsenic
concentration ofabout 8 ng/L, in comparison to 52 ^g/L reported for populations in the
vicinity ofmining or smelting operations, and 233 |ig/L in populations exposed to arsenic
occupationally or via high endemic concentrations in drinking water.
Exposure andRiskAssessmentResults
The human health risk assessment was undertaken in order to characterize the risks posed to
receptors ofall age classes (infant, preschool child, child, adolescent and adult) by exposures
via all relevant pathways (oral, inhalation or dermal contact with air, water, soil, dust and
food). The exposure pathways considered in the risk assessment are shown in Figure 1. Two
analytical techniques were used to assess risk in the Village ofDeloro: deterministic and
probabilistic analyses. In a fully deterministic analysis, single values, or point estimates,
were used for parameters describing exposure and toxicity. Because these point estimates
were typically selected to maximize exposure and risk, the deterministic analysis can be
considered to be a "worst-case" assessment. In probabilistic analysis, probability
distributions were assigned to the exposure or risk parameters used in the assessment and the
risk estimates were expressed as cumulative distribution ftinctions.
Deloro VillageExposureandRiskAssessment Pageli
ExecutiveSummary' December. 1999