Southeast Idaho Phosphate Mining Resource Area - Agency for ...

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3. Discussion 3.1 Data and Information Used The data used in this document to assess possible health impacts from contaminants in the Southeast Idaho Phosphate Resource Area are from the following sources: Montgomery Waton reports prepared for the Idaho Mining Association’s Selenium Subcommittee (MW 1999a, 1999b, 1999c, 2000, 2001), Tetra Tech EM Inc. reports prepared for IDEQ (TtEMI 2001, 2002), elk muscle and liver data collected in 2000 (Personal communication: R.L. Clegg, selenium project officer, IDEQ, email, July 2003), former BCEH health consultations (BCEH 2001a, 2001b, 2003), IDEQ’s Public Water System record (1983-2001) (Personal communication: J. Henry, drinking water regulatory analyst, IDEQ, email, September 2001), and Cancer Data Registry of Idaho data. The conclusions reached in this document are based on currently available data, previous health consultations, information obtained from site visits, community concerns, and public and agency input. If additional data or information becomes available, the conclusions may be modified at a later time. 3.2 Evaluation Process The general process by which BCEH evaluates the possible health effects of environmental contaminants is summarized here and described in more detail in Appendix B. BCEH follows a two-step methodology to evaluate public health issues related to the contamination. First, BCEH obtains environmental contamination data for the site of concern and compiles a comprehensive list of site-related contaminants. Second, BCEH uses health-based comparison values (CVs) (Appendix C, Table C-1 and C-2) to screen out those contaminants that do not have a realistic possibility of causing adverse health effects. For the remaining contaminants, BCEH reviews recent scientific studies to determine whether the levels of environmental contamination and exposure indicate a public health hazard. Using CVs provides a way to screen and prioritize the contaminants at a site for further evaluation. CVs are derived for each of the various media (soil, air, water) and reflect an estimated contaminant concentration that is not expected to cause adverse health effects for a given chemical, assuming a standard daily contact rate (e.g., an amount of water or soil consumed) and body weight. CVs are set at levels many times lower than levels where studies show there are no health effects in either animals or, if data is available, humans. CVs are deemed conservative or cautious because they include safety or protective factors that account for more sensitive populations, such as young children. If a contaminant concentration is above its CV, BCEH further analyzes exposure variables (for example, duration and frequency of exposure), the toxicology of the contaminant, other epidemiology studies, and the weight of evidence for health effects. 8
3.3 Exposure Pathways and Public Health Implications To determine if human populations are exposed to contaminants, BCEH evaluates the environmental contamination and human activities that could lead to exposure. Only when there is a completed exposure pathway, is it possible that there may be health effects to the public. A completed exposure pathway exists when all of the following five elements are present: (1) a source of contamination; (2) transport through an environmental medium (air, soil, or water); (3) a point of exposure; (4) a route of human exposure; and (5) a receptor population. Appendix D summarizes the completed exposure pathways in this public health assessment, including soil, surface water, sediment, groundwater, and biota (fish, elk, beef, and plants). The following sections describe the various exposure pathways people could come into contact with contaminants in the Resource Area and any public health implications. For the exposure pathways (groundwater, fish, elk, and beef) which BCEH evaluated in the past health consultations, BCEH reviewed the documents, summarized the major findings and, when available, reviewed and discussed new information or environmental data which were not previously addressed. This health assessment discusses any changes in previously identified exposure pathways and public health implications if review of the new information and environmental data warranted such changes. 3.3.1 Soil Exposure Pathway Soils along stream banks in the Resource Area were sampled by the Idaho Mining Association in the summer of 2001 (TtEMI 2001). Soil samples were collected from locations both upstream and downstream of mining facilities. Areas upstream of mining facilities are referred to as unimpacted (or background) reaches and areas downstream of mining facilities are referred to as impacted reaches. Since the soil along the banks of streams that drain mines may accumulate sediments containing elevated levels of contaminants, and water carrying dissolved contaminants may also enter the soil systems during flooding or under seepage conditions, the levels of contaminants in these soils are assumed to be higher than the soils in other areas. Table C-3 (Appendix C) lists the detected contaminants, their concentrations, and frequency of detection. The surface soil CVs in Table C-1 (Appendix C) are concentrations of contaminants in the soil below which no adverse human health effects should occur based on residential living conditions, and intermediate (15 to 365 days) or long time exposure (more than 365 days). Among the detected contaminants in the soil, only the concentrations of arsenic, cadmium, chromium and vanadium (Appendix C, Table C-3) are above their residential surface soil CVs, and are considered the contaminants of concern in the soil for this public health assessment. It is possible for recreational users (hunters, collectors, and anglers) of the Resource Area to have contact with and/or ingest the contaminated soil. Therefore, for recreational users, a completed exposure pathway for surface soil currently exists, existed in the past, and will exist in the future. However, the areas of high impacts are very limited and 9
Page 1 and 2: SOUTHEAST IDAHO PHOSPHATE MINING RE
Page 3 and 4: Southeast Idaho Phosphate Mining Re
Page 5 and 6: List of Appendices Appendix A Appen
Page 7 and 8: Summary Phosphate has been mined fr
Page 9 and 10: Public Health Action Plan 1. BCEH w
Page 11 and 12: • Eastern district - Smoky Canyon
Page 13: Monsanto and Solutia). Nu-West, J.R
Page 17 and 18: 3.3.2 Surface Water Exposure Pathwa
Page 19 and 20: For non-cancer health effects, the
Page 21 and 22: as the Native American subsistence
Page 23 and 24: about four times higher than the ch
Page 25 and 26: 3.3.5.3 Beef Exposure Pathway For n
Page 27 and 28: Arsenic can also cause cancer. Howe
Page 29 and 30: Cancer incidence (cases), instead o
Page 31 and 32: incidence rates for some cancer typ
Page 33: 7. Authors, Technical Advisors Repo
Page 36 and 37: [EPA] U.S. Environmental Protection
Page 38: Appendix A Map of Southeast Idaho P
Page 41 and 42: Explanation of Evaluation Process S
Page 43 and 44: ecommends secondary standards to wa
Page 45 and 46: Table C-1 Health Comparison Values
Page 47 and 48: Table C-3 Contaminants of Concern i
Page 49 and 50: Table C-5 Contaminants of Concern i
Page 51 and 52: Table C-7 Contaminant Health Guidel
Page 53 and 54: Table C-9 Description of Exposure S
Page 55 and 56: Appendix D Exposure Pathways for So
Page 57 and 58: Appendix E ATSDR Interim Public Hea
Page 59 and 60: Appendix F Health Consultation: Eva
Page 61 and 62: Background and Statement of Issue T
Page 63 and 64: derived are described in the follow
Page 65 and 66:
Reference ATSDR 1996. Toxicological
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Appendix A. Well Sampling Locations
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Appendix G Health Consultation: Sel
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BACKGROUND AND STATEMENT OF ISSUE
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Screening values are target chemica
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Temporary Selenium Fish Advisory Th
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REFERENCES ATSDR 2001. Toxicologic
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PREPARERS OF REPORT AND CERTIFICATI
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Appendix A. Streams of the Upper Bl
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Appendix B. Fish Selenium Concentra
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Appendix H Health Consultation: Eva
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LIST OF ACRONYMS ADI ATSDR BEHS BLM
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phosphate lease. The project area i
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staff with concerns about animals h
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Currently, no data on selenium conc
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MW (2000) believes that sheep recei
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Table 1.0 Levels of Selenium Found
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and what levels of selenium might b
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The EPA=s reference dose (RfD) is d
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may be more susceptible (ATSDR 1996
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Further sampling of livestock, fish
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VI. REFERENCES A.A. Rich and Associ
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Yang, G. , S. Yin, R. Zhou, et. al.
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ATTACHMENT A Map of Southeast Idah
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ATTACHMENT B Summary of Studies Us
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Depuration Study were also reported
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66a, (which contain the central and
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There has also been a great deal of
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Table 1: Interim Public Health Haza
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VIII. PREPARERS OF REPORT AND CERT
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Appendix I Cancer Incidence Evaluat
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Table I-2 Comparison of Cancer inci
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Appendix J ATSDR Glossary of Terms
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Analyte A substance measured in the
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Community Assistance Panel (CAP) A
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occur. The environmental media and
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Health education Programs designed
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Mutagen A substance that causes mut
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Public health advisory A statement
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Sample A portion or piece of a whol
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Uncertainty factor Mathematical adj
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Response to Comments Received durin
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the copper concentrations, BCEH det
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impacting an area covering some 250
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also existed seventeen samples that
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make a decision regarding any possi
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e inadequate. Data collected during
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