September 1995 Fact Sheet on SE Idaho Phosphorus Slag | Region 10 | US EPA

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September 1995 Fact Sheet on SE Idaho Phosphorus Slag

Public Comment Invited

The U.S. Environmental Protection Agency (EPA) would appreciate your comments on two documents related to potential public health impacts of radiation exposure to phosphorus slag in southeast Idaho. EPA is accepting comments over a 30 day period from September 18 to October 17, 1995.

The first document is the "Exposure Study Workplan." This workplan identifies the equipment and techniques that will be used during a program for southeast Idaho residents to voluntarily participate in a study of individual exposure to radiation from slag.

The second document contains recommendations from the Phosphorus Slag Technical Work Group for "Graded Decision Guidelines" designed to assist individuals in interpreting results from the exposure study.

These documents are summarized in this fact sheet. We recommend that you read the two documents to gain a better understanding of the upcoming radiation exposure measurement program. These documents are available in the following area libraries:

Pocatello Public Library
113 South Garfield
Pocatello, ID 83204

Soda Springs Public Library
149 South Main
Soda Springs, ID 83276

Idaho State University Library
Government Documents Department
9th and Terry
Pocatello, ID 83209

Shoshone-Bannock Library
Pima and Bannock
Fort Hall, ID 83203
(208)238-3700 ext. 3882

Portneuf District Library
5210 Stuart Street
Chubbuck, ID 83202

Written comments should be mailed to: Bill Adams, Project Manager, U.S. Environmental Protection Agency, 1200 Sixth Avenue, M/S HW-113, Seattle, WA 98101 Phone: (206) 553-2806 or 1-800-424-4EPA, Fax: (206) 553-0124

Monsanto, FMC, and EPA will be hosting three open houses during the comment period to help provide the information you will need to comment. Come anytime during the open houses to ask questions and provide your comments. Representatives from Monsanto, FMC, EPA, and the Technical Work Group will be available to talk with you. Please attend one or more of the following:

Tuesday September 26th
Idaho State University Student Union Building
Salmon River Suites, 4th floor
Session 1: 2:00 - 4:00pm
Session 2: 7:00 - 9:00pm

Fort Hall Indian Reservation
Wednesday September 27th
Tribal Council Chambers
Agency Road and Bannock Drive
5:00 - 7:00pm

Soda Springs
Thursday September 28th
Caribou County Courthouse 159 South Main
Session 1: 3:00 - 5:00pm
Session 2: 7:00 - 9:00pm

EPA will consider your comments as the two documents are finalized to ensure that the program meets the needs of the both the agency and residents of southeast Idaho.


The Idaho Radionuclide Study
In May 1990, the EPA issued a report on the Idaho Radionuclide Study. The study concluded that some citizens in Pocatello and Soda Springs could be at increased risk of contracting cancer because of long-term exposure to low-level radiation from slag in building foundations, streets, and sidewalks.

The slag is a byproduct of the elemental phosphorus industry. An EPA Science Advisory Board (SAB) reviewed the study and provided recommendations for further action that included additional testing of actual radiation exposures to individuals and the development of "graded decision guidelines" to help the public interpret testing results.

Slag in Buildings
Slag has historically been used extensively in Southeast Idaho for construction purposes as aggregate in concrete and asphalt, roadbed fill, backfill, and railroad ballast. In the 1950s, 60s, and early 70s, it was also used in the concrete poured for some basements and building foundations. Limited surveys have been conducted in Pocatello and Soda Springs to identify slag in structures. These surveys positively identified slag in several hundred homes in Soda Springs and found elevated levels of radiation in both communities.

The Technical Work Group
Monsanto and FMC (historical producers of phosphorous slag in Southeast Idaho) recognize the importance of close cooperation with EPA and the communities to successfully implement the SAB s recommendations. The Phosphorous Slag Technical Work Group (TWG) was established to address complex technical and socioeconomic issues associated with the studies and the graded decision guidelines. The TWG is composed
of two Monsanto and FMC representatives; two EPA representatives; two company-selected and two EPA-selected radiation experts; and one representative each from the city of Pocatello, the city of Soda Springs, the State of Idaho, and the Shoshone-Bannock Tribes.

Exposure Study Workplan

The purpose of the voluntary exposure study is to assess individual radiation dose (dose is the amount of radiation absorbed by the body), identify sources of radiation exposure, and to locate phosphorous slag in the communities. The individual dose results can be used in combination with the Graded Decision Guidelines to help individuals decide what, if any, action should be taken to reduce radiation exposure from slag.

The Exposure Study Workplan is a product of IT Corporation, a contractor working for Monsanto and FMC. This document has been developed, in cooperation with and with the approval of EPA, to measure individual radiation exposure to phosphorous slag.

The proposed exposure study begins with an initial screening conducted with survey instruments to determine if there are elevated levels of radiation in the building. The second step, if requested by the resident, is a more detailed evaluation using Thermoluminescent Dosimeters (TLDs) and/or other survey instruments which will provide information on individual radiation exposure. The second step is recommended if initial results are significantly above background, or the homeowner hs reason to believe there is slag in or around the home.

Specific details on who to contact to participate in the study, when, and what risk reduction options will be available will be announced in a second fact sheet released after the public comment period. The second fact sheet will also announce the approval of the radiation exposure study workplan and outline the EPA's final Graded Decision Guidelines.


Surveys are performed with instruments that measure radiation directly and can identify specific locations isn the home where radiation levels are sdhighest. During the survey, you will be able to directly observe radiation levels in your home and around your property. Surveys measure the rate of radiation dose (for example, dose per hour) and in most cases can tell you whether your home has radiation levels above background, indicating that slag may be spresent in your home. However, without extensive time spoent measuring and moideling at various locations, survey instruments cannot measure an individual's dose.

Background radiation varies by location and is a combination of cosmic radiation from space and radiation from naturally occuring uranium, thoriium, radium, radon, and potassium in the earth. The average background level for Soda Springs and Pocatello is approximately 13 microroentgen per hour ( R/hr) or 105 mrem/year.

TLDs are small devices that measure radiation dose over time. they can be worn to measure radiation dose to a person wherever they go, or they can be fixed in a place to measure the radiation dose at the location for a period of time. Normally, TLDs are used for a period of three months and then processed to determine the total dose accumulated during the period of exposure. TLDs are worn routinely by radiation workers and medical personnel to monitor their exposure. Use of TLDs alone will not tell you whether your home has radiation levels above background indicating slag may be present in your home. TLDs could help in determining whether you are currently receiving radiation in excess of background.

Graded Decision Guidelines (What do the Results Mean)

The EPA SAB is an independent group of scientists who act as consultants to the EPA Administrator. In 1992, the SAB reviewed the Idaho Radionuclide Study and recommended that EPA establish a set of "Graded Decision Guidelines" to help individuals interpret radiation exposure study results and determine if any action should be taken to reduce exposure. The TWG assisted EPA in this task by preparing a set of recommendations for the guidelines based upon a variety of technical and economic factors.

What follows is a summary of the TWG recommendations for evaluating exposure results. Although EPA participated in the TWG, it's recommendations do not represent the agency's final policy. However, public comments on this preliminary proposal by the TWG will be helpful in forming an EPA position, recognizing
that the task of issuing a final set of Graded Decision Guidelines rests with EPA. We encourage you to review the entire document created by the TWG in order to help you make specific comments. Appendix A includes a perspective on the different radiation doses in excess of natural background radiation as compared to various standards, risk, and exposure to phosphorous slag. The TWG recommendations are based on three levels of exposure from phosphorus slag. These levels are based on established national and international guidelines.

The TWG's recommendations do not address, and were not intended to address, the following two issues. EPA believes that these issues are best resolved at the national level.

1. Differences of opinion regarding the health effects of exposure to low levels of radiation.

Scientific opinion differs about how much low-level radiation an individual can be exposed to without harm. The possibility exists that there may be a threshold level of radiation exposure, below which there are no adverse health effects. Consequently, exposure to natural background levels may not pose any health risks. However, current evidence suggests that exposure to radiation at very low doses poses some risk of cancer. Rather than resolve this question, the TWG proceeded as recommended by the National Academy of Sciences, the National Council on Radiation Protection, and other international scientific bodies. Based on the assumption that the risk of cancer increases as exposure to radiation increases, the TWG recommended that any action taken to reduce exposure should result in moregood than harm.

2. Decisions regarding continued or future use of phosphorus slag

To date, the EPA has not restricted use of phosphorus slag through any regulatory program. FMC and Monsanto have voluntarily stopped sales of slag.

EPA endorses this voluntary halt until the issue of future use of phosphorus slag can be resolved at the national level. Various private industries, companies, and local governments have continued to use slag from stockpiles for a variety of purposes. EPA discourages continued use of this material.

If phosphorous slag was used in the construction of your home, you may be exposed to more radiation than you would otherwise receive. Factors that affect the dose that a person receives include: how long and how often a person is exposed, how far away the person is from the source of radiation, and how much shielding or absorbing material there is between the person and the source of radiation.

The TWG developed additional guidance, which incorporates consideration of cost and feasibility, to aid individuals in reducing risk for various levels of exposure above 100 mrem per year. (While many scientific bodies believe that doses below 100 mrem per year pose some risk, they are not easily measured due to limitations in measurement techniques and the presence of naturally occurring background radiation). The options listed start with the easiest and least expensive and range up to the most difficult and costly. It is the TWG s view that simpler and easier options are more appropriate for lower doses (near 100 mrem above background), while more costly options would be more appropriate at higher doses.

The TWG stated that these options are intended only as guidance and are likely to be appropriate in many cases. The recommendations are not intended to prevent consideration or selection of options other than those which are listed with a particular dose level. EPA, FMC, and Monsanto will be negotiating a voluntary agreement which will make assistance available to homeowners who wish to take actions recommended by the Graded Decision Guidelines. Because EPA and the companies have agreed to base this agreement under the Resource, Conservation, and Recovery Act, EPA does not have the authority or funds to support recommended actions. (In 1990, EPA committed to resolving this issue outside the Superfund remedial process in response to community concerns.)

The TWG anticipates that cost-effective risk reduction options will be considered on a case-by-case basis and each homeowner will have an opportunity to discuss any specific concerns with a radiation risk professional.

Options to Reduce Exposure

More than 100 mrem per year above background levels (Background radiation levels for southeast Idaho are an average of 105 mrem/yr of exposure from naturally occurring radiation, not including radon.)

Recommended Option:

After participation in the exposure study, individuals would receive information on how to reduce risk by changing patterns of use in a home. For example, spending less time in a basement containing slag could significantly reduce total exposure.

Attrition involves removing slag in the future when the building is replaced. This would involve listing of the building on an inventory and removing of the slag to an appropriate disposal location. This option will not reduce current annual radiation doses for those unable to modify home use.

More than 200 mrem per year above background levels

Recommended Option:
Modification of Use

Space that contributes to radiation dose would be actively converted to an alternative use. For example, a basement bedroom would be converted to a use in which individuals spend less time in the room. This option would reduce exposures for current residents, provided they can abide by the changes. This option would also provide long-term effectiveness if future occupants adopted the modified use. This option does not reduce either total slag radiation in the building or potential risks if the modified use not be continued.

More than 300 mrem per year above background levels

Recommended Option:
Remodeling/Shielding/Partial Removal

This option involves reducing exposure through physical changes to the building either through removal or shielding of the slag areas. This optin would permanently reduce exposures to current and future residents of a building, and would reduce the total radiation exposure to people from slag in the building.

More than 500 mrem per year including background levels

Recommended Option:
Additional Living Space

This option would provide additional living space to replace areas that contribute to an elevated dose. For example, building a new bedroom or other home addition to replace a basement bedroom would reduce current dose. Future exposure would also be reduced if new residents adopted the modified use of the building (i.e., not using the basement). This option does not reduce the total radiation exposure from slag in the building.

What About Radon?

The members of the TWG believe that risk from radon, although not associated with phosphorous slag, should be taken into consideration by homeowners when evaluating overall risk from radiation and risk reduction strategies. Accordingly, the proposed exposure study workplan includes free home testing for radon so that homeowners can factor the results into decisions on reducing overall radiation risks.

Radon can be found in all areas of the U.S. Occurence is typically higher in areas with naturally occuring uranium in soil, such as in the Western U.S. Of the 50 homes previously evaluated in southeast Idaho, 14 exceeded EPA recommendations.

Radon is an invisible, odorless gas and a natural part of the environment--not mandmade. slag does not release significant quantities of radon. The costs to reduce radon in a home are generally low, and radon remediation is often effective in reducing risks from radiation. EPA has a national program to reduce public exposure to radon and recommends that all individuals test their homes and take action if levels associated with an average ecess lifteime cancer risk of approximately 1.3 in 100 are found. Radon remediation involves such things as sealing basement cracks, ventilating spaces with high radon levels, and installing subslab ventilation. A typical radon problem can be solved for $1,000 to $1,500.

Appendix A: Radiation Dose Comparison

All people continually receive radiation from a variety of sources. Some of these sources are naturally occurring, such as cosmic radiation, and some sources are manmade, such as medical X-rays. A perspective on different radiation doses that an individual could receive above natural background radiation levels
compared to various standards and recommendations, is illustrated in Figure 1.

The following radiation doses should be considered in southeast Idaho:

It is important to note that an average of 1 in 4 people develops some form of cancer. Excess lifetime cancer risks resulting from exposure to radiation are calculated in addition to this number. For radiation protection purposes, risk estimates assume that even small amounts of radiation pose some risk. At exposures comparable to external background radiation, however, the possibility that there may be no risks cannot be ruled out.

The total number of observed cancers in Southeast Idaho is low by national standards. Healthy lifestyles, rural living, and a low incidence of smoking and drinking likely contribute to the lower overall incidence of cancer in this area. Despite low cancer rates in the region, however, EPA remains concerned about possible increases in cancer risk that may be associated with slag. As in similar communities, like those close to uranium mines, EPA recommends action when risks are increased by at least one in 10,000 over existing cancer risks. For that reason, EPA is hopeful that area residents will participate in the voluntary exposure study.

Comparing these risk levels is very difficult because people perceive risks differently, depending on the nature of the risk and their individual experiences. For example, some people judge the riskiness of a hazard based solely on the likelihood of its having adverse effects, while others are concerned mainly about the hazard's potential effects, regardless of the likelihood; who the hazard affects; and how widespread, familiar, and dreaded the effects are. People's perception of risk is influenced also by whether they think they have a choice and control over the situation (i.e., risks may appear riskier if people have not voluntarily agreed to bear them or if they have no control over the source and management of the risks). People's perceptions of risk also are influenced by the benefits derived from accepting the risks, and by the fairness, equity, and the distribution of risks and benefits.

As an example, many people oppose nuclear power plants, because they dread the potential destructive effects from accidental release of large amounts of radiation to the environment; the technology is unfamiliar; and they feel like they have no control over the plants' operation. However, these same people may engage in statistically more risky but voluntary activities, such as smoking, mountain climbing, or driving a car. Other people may be less concerned about nuclear power because they perceive that the likelihood of a catastrophe is very low, compared to being involved in an automobile accident, for example. Many people also perceive that manmade hazards are far more risky than natural hazards.

Additional examples of radiation exposure standards and recommendations can be found in the TWG recommendations.
Figure 1
Examples of Radiation Exposures, Standards, and Recommendations
We Need Your Comments

EPA welcomes any comments on the exposure study workplan. However, we
would also appreciate your responses to and comments on the following

1.If you were to fully participate in the exposure study, you would learn the following about your home:
Presence of slag

Maximum possible exposure

Current exposures

Radon level

Is there any other information that you would like to see provided during or after the exposure study?
2.Should testing of homes be offered for a specific period of time or
3.Do you have any particular concerns or comments related to the testing such as confidentiality, scheduling of testing, home access, etc.
image - chart of annual dose levels
4.EPA would like your input on the development of an inventory of buildings containing slag.

The SAB recommended that EPA record the location of slag to assure that the radioactivity due to slag content is considered in disposing of the materials when these areas are eventually replaced due to normal attrition. This clearly makes sense for public areas such as streets and sidewalks where there appears to be no immediate concern. The proposed exposure study will provide this kind of information on community areas. However, development and maintenance of an inventory for buildings with slag presents a dilemma for the agency for the following reasons:

5.EPA would like your comments on whether future residents should be informed about slag radiation and, if so, how?
6.EPA would like your comments on the proposed approach to reduce risk from slag.

The options recommended by the TWG offer guidance in reducing radiation exposure. However, only Option 4, Remodeling/Shielding/Partial Removal, would permanently reduce exposure to radiation from slag in a building. Options 1 through 3 are not permanent and depend on some modification in use of the building through changes in lifestyle. The success of such an approach is largely dependent on a current or future homeowners ability to accommodate the necessary use changes on a permanent basis. While these guidelines are not intended to prevent selection and consideration of options other than those listed, it is uncertain whether funds will be available to take action outside these guidelines.

For More Information:

If you have any questions about the contents of this fact sheet, please contact one of the following:

Bill Adams, EPA Site Manager, at (206) 553-2806

Misha Vakoc, EPA Community Relations Coordinator, at (206) 553-8578

Tom Gesell, Technical Work Group Spokesperson, at (208) 236-3669

Trent Clark, Monsanto, at (208) 547-4300 (ext. 348)

Mike Smith, FMC, at (208) 343-4100

For those with impaired hearing or speech, please contact EPA's telecommunication device for the deaf TDD) at (206) 553-1698.

To ensure effective communication with everyone, additional services can be made available to persons with disabilities by contacting one of the EPA staff above.

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