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REFERENCES

  1. Agency for Toxic Substances and Disease Registry (ATSDR). Site Review and Up-Date for Eastern Michaud Flats Contamination, Pocatello, Bannock County, Idaho. Atlanta, Georgia: U.S. Department of Health and Human Services, Public Health Service; March 11, 1997.

  2. Bechtel Environmental, Inc. Remedial Investigation Report for the Eastern Michaud Flats Site. San Francisco: Bechtel Environmental, Inc.; August 1996.

  3. ATSDR. Preliminary Public Health Assessment for Eastern Michaud Flats Contamination, Pocatello, Bannock County, Idaho. Atlanta, Georgia: U.S. Department of Health and Human Services, Public Health Service; August 24, 1990.

  4. ATSDR. Toxicological Profile for Arsenic. Atlanta, Georgia: U.S. Department of Health and Human Services, Public Health Service; April 1993.

  5. ATSDR. Toxicological Profile for Beryllium. Atlanta, Georgia: U.S. Department of Health and Human Services, Public Health Service; April 1993.

  6. ATSDR. Toxicological Profile for Lead. Atlanta, Georgia: U.S. Department of Health and Human Services, Public Health Service; April 1993.

  7. Ecology and Environment, Inc. Baseline Human Health Risk Assessment, Eastern Michaud Flats, Pocatello, Idaho. Lancaster, New York: Ecology and Environmental, Inc.; July 1995.

  8. ATSDR. Toxicological Profile for Fluorides, Hydrogen Fluoride, and Fluorine. Atlanta, Georgia: U.S. Department of Health and Human Services, Public Health Service; April 1993.

  9. ATSDR. Toxicological Profile for Cadmium. Atlanta, Georgia: U.S. Department of Health and Human Services, Public Health Service; April 1993.

  10. National Research Council. Health Risks of Radon and other Internally deposited Alpha-Emitters BEIR IV. Washington, D.C.: National Academy Press; 1988.

  11. National Research Council. Health Effects of Exposure to low levels of Ionizing Radiation BEIR V. Washington, D.C.: National Academy Press; 1990.


Table 1.

Maximum Concentration of Various Site-Related Contaminants in Ore, Slag, and Gypsum at the Eastern Michaud Flats Contamination National Priorities List Site, Pocatello, Bannock County, Idaho
Contaminant and Units Maximum Concentration at FMC Maximum Concentration at Simplot Gypsum Background Levels According to EPA ATSDR Comparison Value for Ingestion and Source*
Ore Slag
Arsenic mg/kg 14.6 0.6 0.9 7.5 0.5 CREG
Beryllium mg/kg 1.9 2 2.8 1 0.2 CREG
Cadmium mg/kg 77.8 103 37 1.9 500 Adult EMEG
Fluoride mg/kg 13,200 7,800 7,650 600 35,000 Adult EMEG
Gross Alpha pCi/g ~200 240 ~200 25** 15
Gross Beta pCi/g 400 1,100 46 31** 50
Gross Gamma mrem/h 50 52 30 15** None

* - A description of the various comparison values is presented in Appendix B. Unless indicated otherwise, the comparison values listed are for chronic exposures (greater than 365 days).

** - EPA did not select a background level for gross alpha, gross beta, and gross gamma. The background levels report for these three contaminants were developed by the consultant for the companies.

EPA is the U.S. Environmental Protection Agency
mg/kg is milligrams of contaminant per kilogram of soil.
pCi/g picocurie per gram of soil.
mrem/h is microrems per hour.

 

Table 1.

Maximum Surface Soil Contamination Found at the FMC or J.R. Simplot Facilities, Eastern Michaud Flats Contamination National Priorities List Site, Pocatello, Bannock County, Idaho

Contaminant and Units Maximum Concentration at FMC Maximum Concentration at Simplot Background Levels According to EPA Comparison Value and Source*
Arsenic mg/kg 27.1 55 7.5 0.5 CREG
Beryllium mg/kg 2.9 5.2 1 0.2 CREG
Cadmium mg/kg 5,110 131 1.9 500 Adult EMEG
Fluoride mg/kg 221,000 123,000 600 35,000 Adult EMEG
Lead mg/kg <500 2,370 29.1 400 EPA Screen
Gross Alpha pCi/g 216 406 25** 15
Gross Beta pCi/g 133 13.8 31** 50
Gross Gamma mrem/h 45 25 15** None

* - A description of the various comparison values is presented in Appendix B. Unless indicated otherwise, the comparison values listed are for chronic exposures (greater than 365 days).

** - EPA did not select a background level for gross alpha, gross beta, and gross gamma. The background levels report for these three contaminants were developed by the consultant for the companies.

EPA is the U.S. Environmental Protection Agency
mg/kg is milligrams of contaminant per kilogram of soil.
pCi/g picocurie per gram of soil.
urem/h is microrems per hour.

 

 

Table 3.

Maximum Surface Soil Contamination Found Beyond the FMC or J.R. Simplot Facility Fence Lines, Eastern Michaud Flats Contamination National Priorities List Site, Pocatello, Bannock County, Idaho

Contaminant and Units Maximum Concentration Detected Maximum Mean Concentration Detected within a Sector Background Levels According to EPA Comparison Value and Source*
Arsenic mg/kg 18.4 8.28 7.7 0.5 CREG
Cadmium mg/kg 189 62.2 1.9 500 Adult EMEG
Fluoride mg/kg 27,200 7,532 600 35,000 Adult EMEG

* - A description of the various comparison values is presented in Appendix B. Unless indicated otherwise, the comparison values listed are for chronic exposures (greater than 365 days).

EPA is the U.S. Environmental Protection Agency
mg/kg is milligrams of contaminant per kilogram of soil.
pCi/g picocurie per gram of soil.
urem/h is millirems per hour.



 

APPENDIX A

Appendix A - Figure 1

Location Map for the Eastern Michaud Flats Contamination National Priorities List Site, Pocatello, Bannock County, Idaho


Appendix A, Figure 2

Map Delineating Land Ownership near the FMC and J.R. Simplot Company Facilities, Eastern Michaud Flats Contamination National Priorities List Site, Pocatello, Bannock County, Idaho


Appendix A, Figure 3

Location Map of the Surface Soil Sampling Sites not at the FMC or J.R. Simplot Facilities, Eastern Michaud Flats Contamination National Priorities List Site, Pocatello, Bannock County, Idaho

APPENDIX B - COMPARISON VALUES

Comparison values for the Agency for Toxic Substances and Disease Registry (ATSDR) public health assessments and health consultations are contaminant concentrations that are found in specific media (air, soil, and water) and that are used to select contaminants for further evaluation. Comparison values are designed to be conservative and non-site specific, and therefore protective for all probable exposures. Their intended use is only to screen out contaminants which do not need further evaluation. They are not intended to be used as clean-up levels or to be indicators of public health effects. They are derived from toxicological information, using assumptions regarding body weights, ingestion rates, and exposure frequency and duration. Generally, the assumption used are very conservative (i.e., worst case). For example, soil health comparison values are developed for children who exhibit pica behavior. Soil ingestion in pica children (5 to 10 grams per day) greatly exceeds the soil ingestion rate for the normal population (0.1 grams per day).

There are two different types of comparison values, those based on carcinogenic (cancer-causing) effects, and those based on non-carcinogenic effects. Cancer-based comparison values are calculated from the U.S. Environmental Protection Agency's (EPA's) oral cancer slope factor or inhalation unit risk. They are calculated for a lifetime exposure (70 years), with an unacceptable excess lifetime cancer risk of one case per million persons exposed. Non-cancer comparison values are calculated from ATSDR's Minimal Risk Levels, or EPA's Reference Doses or Reference Concentrations. These values are calculated for adults, children, and small children who may eat large amounts of soil.

The comparison values used in the health consultation are listed and described below.

Cancer Risk Evaluation Guides (CREGs) are estimated concentrations that would be expected to cause no more than one excess cancer in a million persons exposed over a lifetime. CREGs are calculated from EPA's cancer slope factors.

Environmental Media Evaluation Guides (EMEGs) are based on ATSDR's minimal risk levels (MRLs) and factor in body weight and ingestion or inhalation rates. Separate EMEGs are developed for specific durations of exposure (acute, 1-14 days; intermediate, 15-364 days, and chronic, 365 days and longer).

EPA Screen are developed by EPA Superfund Office to be used to determine if any soil contamination at or near Superfund sites warrant further investigation.

Maximum Contaminant Levels (MCLs) are enforceable drinking water regulations that are protective of public health to the "extent feasible" National primary drinking water regulations apply to all public water systems including community water systems and transient and non-transient noncommunity water systems. EPA promulgates MCLs.

For radiological contaminants, ATSDR uses information on radiation exposure and its effects related to environmental levels prepared by federal agencies, including EPA, DOE, and the Nuclear Regulatory Commission. The agency also uses other publicly available data sources and recommendations on radiation dose limits. The National Council on Radiation Protection and Measurements (NCRP), the International Commission on Radiological Protection (ICRP), and the United Nations Scientific Committee on the Effects of Atomic Radiation and others develop these sources.

APPENDIX C - PUBLIC COMMENTS AND ATSDR'S RESPONSES

Response to Comments Received during the Public Comment Period for the Eastern Michaud Flats Surface Soil Health Consultation

The Surface Soil Health Consultation for the Eastern Michaud Flats site was available for public review and comment from November 12 through December 19, 1997. We announced the Public Comment Period in The Idaho State Journal and the Sho-Ban News. ATSDR made copies of the health consult available at the Idaho State University Library and the Shoshone-Bannock Tribal Business Center. In addition, we sent the health consultation to 10 persons or organizations.

The comments and ATSDR's responses are summarized below.

Comment:

The health consultation provides only a cursory review of the wealth of knowledge developed for the Eastern Michaud Flats (EMF) site and the characterization of potential exposure which might impact human health. Greater detail and analyses have been incorporated in previously prepared documents and presentations in conjunction with the Remedial Investigation and Feasibility Studies under EPA's oversight.

Response:

ATSDR agrees that the health consultation does not provide an in-depth review of all the data and information available. The purpose of the health consultation is not to give a complete history of how and when the various environmental samples were taken. The health consultation is ATSDR's public health review of the available environmental data and information regarding the information and data concerning the Eastern Michaud Flats Contamination site. People requiring more detailed information about the environmental sampling results should review the referenced documents.

Comment:

The text of the health consultation indicates that the tables are a "summary" of the available sampling data. However, only maximum levels are reported in the table. In addition, the emphasis on maximum exposures overstates the possible risks.

Response:

The purpose of the tables are to select which contaminants may be at levels of health concern. The selected contaminants are then evaluated further in the document. The text of the health consultation has been modified to clarify this issue.

An explanation of comparison values is included in the appendices of the health consultation. This explanation clearly states that comparison values are not intended to be used as clean-up levels or to be indicators of public health effects.

In the discussion section of the health consultation, ATSDR discusses the range of possible exposures that may have occurred. Mean concentrations of exposure were used to determine if people were chronically exposed to contaminants at levels of health concern. Maximum concentrations of exposure were not used to determine if people were exposed chronically to contaminants at levels of health concern.

Comment:

ATSDR should have used the same cadmium bioavailability factor used by the U.S. Environmental Protection Agency (50% instead of 100%). In addition, the U.S. Environmental Protection Agency used a soil ingestion rate of 50 mg/day (ATSDR used 100 mg/day).

Response:

ATSDR has recalculated the soil ingestion exposure evaluation using a cadmium bioavailability factor of 50% and a soil ingestion rate of 50 mg/day.

However, the important public health message is that smokers may already be exposed to levels of cadmium above that which may result in proteinuria, not including any exposures to environmental contaminants. Therefore, any additional exposures to cadmium may increase a smoker's risk of proteinuria. ATSDR has modified the discussion section and the conclusions to clarify this issue.

Comment:

The consultation fails to note that extensive actions have already been implemented by FMC to reduce worker exposures (i.e., roads have been paved and specific areas have been capped to prevent both direct contact and fugitive emission releases).

Response:

ATSDR has added this information to the consultation.

Comment:

The health consultation does not adequately explain the source of environmental data gathered.

Response:

A brief description of when and how the surface soil samples were collected is presented on page 2 of the health consultation. We reference all of the data sources in the health consultation. The purpose of the health consultation is not to give a complete history of how and when the various environmental samples were taken. The health consultation is ATSDR's public health review of the available environmental data and information regarding the surface soil contamination at and near the Eastern Michaud Flats Contamination site.

People requiring more detailed information about the environmental sampling results should review the referenced documents.

Comment:

The health consultation does not address the potential for Tribal members to be exposed to contaminants through the food chain.

Response:

ATSDR has discussed this concern with the Tribal Business Council. ATSDR has agreed to evaluate the potential for Tribal members to be exposed to contaminants through the food chain in a separate health consultation. To conduct this evaluation, ATSDR has requested that the Tribes give ATSDR specific information concerning the particular plants and animals Tribal members may consume.

Comment:

Because years have passed since the Remedial Investigation was conducted at the Eastern Michaud Flats Contamination site, ATSDR should sample the soil in and near the site to ensure that the soil contamination has not increased in concentration.

Response:

The surface soil contamination found near the Eastern Michaud Flats Contamination site occurred primarily because of the air discharges (1949 to present) from the two facilities. These discharges have been significantly reduced in the last 10 years. Therefore, it is doubtful that the surface soil contamination has significantly increased since the surface soil samples were taken in 1992-5.

Comment:

ATSDR should gather more information about community concerns.

Response:

To date, ATSDR has conducted four community availability/public meetings regarding the Eastern Michaud Flats Contamination site. During those meetings, ATSDR has been available so that the public could present their concerns. In addition, ATSDR staff is available to talk with the community via telephone or letter. Various members of the community have contacted ATSDR and we will continue to be available to talk with the community. The public will have other opportunities to discuss their concerns at future ATSDR meetings.

Comment:

ATSDR should use health data during their evaluation of the Eastern Michaud Flats Contamination site.

Response:

As promised, ATSDR is collecting the available health data from the State of Idaho and the Indian Health Service. We will evaluate and present this data to the community in a separate health consult.

Comment:

In the Discussion section on cadmium, the report states: "The particle sizes of surface soil are probably too large to be deposited into the lung..." The data available from the air monitoring stations near the site do not support this finding.

Response:

The referenced section only discusses surface soil contamination. ATSDR agrees that particulates discharged to the air from the facilities are within the range that could be deposited into the lung. We will evaluate and discuss these discharges in the air health consultation that ATSDR is presently preparing.

Comment:

ATSDR should evaluate the maximally exposed individuals (rail road workers, highway crews, and the public that uses the frontage road). Also, the public participation at the drag-races on FMC property should be considered.

Response:

On page 3 of the health consultation, ATSDR states that the public, which includes all of the individuals discussed above, is unlikely to come in contact with site-related surface soil contamination for a sufficient amount of time (a significant portion of a lifetime continuously). ATSDR further states that people attending or participating in the drag races or softball/baseball games directly across the street from the two facilities are unlikely to come in contact with a significant amount of surface soil contaminants.

Comment:

ATSDR should evaluate the additional radiation information available from the Tribes.

Response:

The additional radiation information is from air sampling activities conducted by the Tribes and the U.S. Environmental Protection Agency. ATSDR will evaluate this information along with all of the other air sampling information in the air health consultation presently being developed.

Comment:

The health consultation concludes that deed restrictions have been placed on the property across from the plants. The Land Use Policy Commissioners of the Tribes is not aware of any deed restrictions on the property.

Response:

Information provided by FMC indicates that actions have been or are being taken to assure that any area which might pose health risks are restricted from future residential land use. FMC has already deed restricted FMC-owned properties. FMC has also indicated that other off-site areas of potential concern will also be precluded from residential use as a part of the Record of Decision with the U.S. Environmental Protection Agency.

Comment:

ATSDR should recommend that appropriate remedial actions be taken to prevent the surface soil contaminants from becoming airborne and accessible to the public.

Response:

The health consultation states in the conclusion section that it is unlikely that the public has been, is currently or will be exposed to significant levels of site-related surface soil contamination. Therefore, it would not be appropriate for ATSDR to make a recommendation similar to what is stated in the comment.

Comment:

ATSDR should issue a "Summary" report that combines all of the risks the site may present through multiple pathways of exposure.

Response:

ATSDR will issue a "Summary" report. The report will be a public health assessment. Each of the health consultations developed by ATSDR will be included in the appendix of the public health assessment.

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