May 1996 Fact Sheet on SE Idaho Phosphorus Slag | Region 10 | US EPA

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May 1996 Fact Sheet on SE Idaho Phosphorus Slag

The U.S. Environmental Protection Agency (EPA), FMC, and Monsanto are pleased to announce a new program in Southeast Idaho to assist individuals in determining their level of exposure to radiation from phosphorus slag. EPA is also distributing the "Graded Decision Guidelines," developed by the Technical Work Group, for use by program participants in evaluating program results. This fact sheet outlines the program and describes the Graded Decision Guidelines.

Exposure Study Testing Program Begins
With the distribution of the Graded Decision Guidelines, EPA believes that all recommendations of the Science Advisory Board have been met and the exposure study should now proceed. The program will begin in June of 1996. This voluntary program will include surveys of public areas, screening of individual homes and business properties, and measurement of individual radiation exposures for those participating in the program.

How do I participate? Homeowners and other property owners who wish to participate in the voluntary exposure study can either call the Phosphorus Slag Information Line (toll-free) at 1-888-905-8800 or return the form on page 7. The information line is answered by Southeastern District Health Department personnel, who can provide information on phosphorus slag, health risks associated with radiation, and options for reducing your exposure to radiation.

If you prefer, you can complete and return the Participation Form (on page 7 of this fact sheet). You will be contacted by the District Health Department to arrange an appointment.

If you have already indicated your desire to participate in the program, you will receive a notification letter shortly.

What is involved in the testing? A technician will make an appointment to visit your home with a small radiation survey instrument. The initial home screening takes approximately 20 minutes. If the levels of radiation are below 20 microrems per hour (approximately equivalent to 100 millirems per year), no further evaluation of your home will be necessary. (The human body's absorbtion of ionizing radiation is measured in units called "rems." Low levels of exposure are measured in thousandths of a rem - millirems or in millionths of a rem - microrems.)

If levels are above 20 rems per hour, EPA recommends that the homeowner elect to participate in a more detailed home survey and/or wear a thermoluminescent dosimeter (TLD) to determine his/her exposure. Arrangements for further evaluation can be discussed during the initial screening.

Some individuals may prefer to wear a TLD before having their home surveyed. Individuals who wish to participate that way need only make their preferences known when signing up to participate.

Who will be given my testing results? No one. The results of the testing will be maintained confidentially by the testing contractor working for the Companies and the District Health Department. Testing results will be reported to EPA and the public in aggregate only (no names and addresses will be used). For example, we might occasionally provide statistics on how many properties have been tested and what the range of results were.

Will this program affect my property value? It shouldn t, given the confidential nature of this program which guarantees that others will not know your test results unless you choose to disclose them. It is currently unclear as to whether slag must be reported under the Idaho Disclosure Law.

Whether you suspect that slag is in your home or not, your test results may be useful information to provide to prospective home buyers. If your home is found to be free of slag, you may want to share that information. Alternatively, if slag is found in your home and test results indicate that actions should be considered to reduce your exposure to radiation, then you will have an opportunity to reduce your exposure based on the Graded Decision Guidelines. Any actions taken to reduce exposure could be useful information to prospective buyers. In some situations, such actions may enhance the value of your property as compared to other homes where action to reduce exposure was warranted, but not taken.

How can I learn more about the program before I sign up? The EPA and the Companies are producing a short video that demonstrates the equipment and techniques for home screening and for individual exposure evaluation. The video will be available to borrow (free of charge) from a number of locations throughout Southeast Idaho, including district health department offices (at 465 Memorial Drive in Pocatello and at 55 East First South in Soda Springs) and the libraries listed below, in addition to many local video rental stores. The video will answer many of your questions about the program. Please feel free to call the Phosphorus Slag Information Line (toll-free) at 1-888-905-8800 for more information, as well.

What can be done to reduce my exposure if I find slag on my property? The Graded Decision Guidelines identify a range of options (which the Companies have agreed to fund) for reducing exposure from slag. These options start with the easiest and least expensive, such as modifying the use of a room that contains slag, and range up to the most difficult and costly such as building an addition to the house. (See pages 4 and 5 of this fact sheet for more information about the Graded Decision Guidelines.)

The following libraries have materials related to the Phosphorus Slag program:
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

What is the "inventory" and how will it be used?
The inventory is a listing or map of locations that have been tested and what the results were. Inclusion on the inventory is voluntary. The EPA Science Advisory Board (see "Background" on page 7 of this fact sheet) recommended that the EPA formally record the location of slag to assure that the radioactivity due to slag is adequately considered when disposing of materials as buildings are eventually replaced due to normal wear and tear. Information on the surveys of public areas will be included in the inventory automatically. Individuals may also elect to have test results for buildings they own (homes and businesses) included in the inventory.

Homeowners whose test results were negative (either at the time of the initial screening or after taking actions to reduce exposures) may be particularly interested in being included in the inventory.
Surveys are performed with instruments that measure radiation directly and can identify specific locations in the home where radiation levels are highest. 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 present in your home. Without extensive time spent measuring and modeling at various locations in your home, however, 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-occurring uranium, thorium, radium, radon, and potassium in the earth. The average background level for Soda Springs and Pocatello is approximately 105 mrems per year.

Thermoluminescent Dosimeters (TLDs) are small devices that measure radiation dose over time. They can be worn to measure radiation dose to a person wherever he or she goes, or they can be fixed in a place to measure the radiation dose at that location over 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 the presence of slag may in your home. TLDs could help in determining whether you are currently receiving radiation in excess of background.


Graded Decision Guidelines

The Graded Decision Guidelines recommended by the Technical Work Group (TWG) include various options that may be considered by property owners in responding to the results of the Exposure Study. The recommendations are based on three levels of exposure from phosphorus slag:

Copies of the Graded Decision Guidelines can be obtained by calling the Phosphorus Slag Information Line (toll-free) at 1-888-905-8800. Copies have also been placed at the libraries listed on page 2 of this fact sheet.

Issues Considered by the Technical Work Group during Development of its Guidelines

The TWG considered a variety of issues in developing its recommendations for the Graded Decision Guidelines, including risks, costs, and feasibility of various actions. The following is a summary of some of these issues.

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. More is known about the effects of radiation than for most chemicals, however, and current evidence suggests that exposure to radiation at very low levels poses some risk of cancer. Instead of attempting to resolve these contentious questions, the TWG agreed to proceed using two assumptions:

1.The risk of cancer increases as exposure to radiation increases, and

2.Actions should be taken to reduce exposure only when they will result in more good than harm.

The TWG recommendations are therefore based on limiting exposure to radiation as much as practical while allowing homeowners the flexibility to make informed and educated decisions on actions they believe are necessary for their home and community.


In developing the guidelines, the TWG had little difficulty in establishing the point of no action (100 mrems per year above background) and the point at which all potential options should be considered (500 mrems per year inclusive of background). In the range between those two levels, however, it was more difficult for the TWG to reach consensus about how to balance risks and costs. There was general agreement that simpler and easier options would be more appropriate for lower doses (near 100 mrems per year) and more difficult options would be more appropriate at higher doses.

Many members of the TWG did not feel that this approach would provide sufficient guidance to individuals, however. As a result, the TWG developed a "menu" of possible options for specific dose levels. EPA didn t want individuals to feel restricted by the menu; the TWG members agreed that the options outlined in the menu were intended only as guidance.(It should be noted that the options are not mutually exclusive and several (or all) could be utilized, if necessary. The level of financial assistance provided by the Companies may depend, however, on the exposure level (i.e., the most expensive options may not be funded by the Companies when there is only a low level of exposure.) The TWG did recommend that cost effective risk reduction options be considered on a case-by-case basis and that each homeowner should have the opportunity to discuss any specific concerns with a radiation risk professional and the Companies. The Companies have agreed to consider other options in good faith and to work to resolve disputes with individuals who may be dissatisfied.

Through its involvement in the TWG, EPA has tried to balance the potential risks from slag with such issues as costs and community acceptance. The TWG's recommendations are less conservative than EPA's usual approaches to environmental protection under most environmental laws. That is, the Graded Decision Guidelines call for less risk reduction than EPA would ordinarily find necessary. Under most laws and regulations, EPA is required to address risks from known or suspected carcinogens(chemicals associated with cancer) that increase the probability of developing cancer by more than 1 in 10,000 or 1 in 1,000,000 over a normal lifetime. By comparison, the 100 mrems per year screening level proposed by the TWG represents an increase in risk of approximately 3.5 in 1,000. EPA supports the TWG s recommendations for several reasons.

First of all, there are many differing viewpoints about what actions might be appropriate for dealing with slag. Second, there is a great deal of uncertainty about the actual risk associated with slag. Third, the Graded Decision Guidelines are not being employed in a regulatory context, but rather as part of a voluntary program. Fourth, they were developed with significant input from community representatives for the unique circumstances associated with previous slag use, particularly for individual residences. Fifth, they are not intended to be used in any other circumstance, including evaluation of future uses of slag. In conclusion, EPA supports the use of these guidelines as a way to move forward with the process of determining where risks exist and what might be done about them.

Excerpts from "The Phosphorus Slag Issue: Response to Public Comments"
Question: What happens if either I don t want to participate in the program or I only partially participate?
Response: Nothing. The testing is entirely voluntary and an individual can decide not to participate at any time.
Question: How long will the testing program be offered?
Response: Based on input received during the comment period, EPA and the Companies have agreed to conduct an initial phase of testing for approximately two years. After this initial period, the testing will be available for an indefinite period of time for those individuals that would like to participate. The extended offer will be particularly useful to either new residents or individuals that would like to have a residence re-tested.
Question: The focus of the exposure study seems to be the communities of Pocatello and Soda Springs. Can individuals outside these communities participate in the testing program?
Response: Yes, individuals in surrounding communities are welcome to participate in the program.
Question: Who will pay for the testing program and implementation of the Graded Decision Guidelines?
Response: FMC and Monsanto.
Question: How were the 20 rems per hour and 100 mrems per year screening levels established?
Response: The 100 mrems per year level was selected primarily because it is a level at which it is practical to distinguish between exposures from natural background radiation and slag-influenced radiation. It is also consistent with the "widely accepted population exposure guide of 100 mrems per year in excess of natural background" noted by the Science Advisory Board. Taking "occupancy factors" into account, the 20 rems per hour level was selected as a screening level below which it would be unlikely that anyone would actually receive 100 mrems in a year of normal occupancy.
Question: What level of radiation is safe?
Response: No one knows for sure.

Public Comment

Last fall, through a series of open houses and a fact sheet, EPA invited public comment on two documents, the "Exposure Study Workplan" and "TWG s Recommendations for Graded Decision Guidelines". The Exposure Study Workplan identified the equipment and techniques to be used to screen buildings for radiation and to measure individual exposure to radiation from slag. The TWG s Recommendations for Graded Decision Guidelines were developed to assist individuals in interpreting results from the exposure study.

EPA did not receive significant comments on either document. As a result, neither document was changed as a result of public comment and the voluntary program is about to begin according to the Exposure Study Workplan.

EPA has prepared detailed responses to the questions and comments received on the two documents during the public comment period. The responses are included in a document entitled "The Phosphorous Slag Issue: Response to Public Comments" which is available at the libraries on page 2 of this fact sheet.

EPA received many positive comments on the TWG s Recommendations. Many community members and local officials felt that the recommendations offered a reasonable approach for addressing the risk from phosphorus slag. There were some individuals that felt that the 100 mrems per year "no action" level was too high, however, and that the proposed risk reduction options would not adequately protect public health. These divergent opinions had been considered by the Technical Workgroup as they developed the Graded Decision Guidelines and are discussed in more detail on pages 4 and 5 of this fact sheet.


In May 1990, the EPA issued a report called the Idaho Radionuclide Study. The study concluded that some citizens in Pocatello and Soda Springs could be at increased risk of developing cancer as a result of long-term exposure to low-level radiation from phosphorus slag used as a construction material in building
foundations, streets, and sidewalks. (The slag is a by-product of the elemental phosphorus industry.) The EPA Science Advisory Board (SAB) reviewed the study and provided recommendations for further action that included additional testing of actual exposure to individuals and development of the Graded Decision Guidelines to help the public interpret testing results.

The SAB recommended that the Graded Decision Guidelines be based on technical and economic factors for both short-term and long-term exposure due to past uses of slag. The SAB also recommended that EPA make risk assessments for those persons exposed within the decision guidelines and provide them with information for making informed decisions. The SAB recommended that the information include: (a) the risks estimated for various exposures, (b) the associated uncertainties of estimating risks to individuals, (c) the options available to individuals under various programs to lower their risks, and (d) the costs of potential options to reduce exposures and who will pay for them.

In 1992 EPA, FMC, and Monsanto signed an agreement for implementing the SAB recommendations. This agreement included the creation of a TWG to assist EPA in addressing technical and socioeconomic issues. The TWG was tasked to develop the Graded Decision Guidelines as there are no national standards that specifically address phosphorus slag. The TWG was composed of one Monsanto and one FMC representative; 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. The TWG assisted EPA by preparing recommendations for guidelines to help the public interpret the testing results.

What About Radon?

The members of the TWG believe that risk from radon, although not associated with phosphorus 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. Occurrence is typically higher in areas with naturally occurring uranium in soil, such as in the Western U.S. Of the homes previously evaluated in Southeast Idaho, 14 exceeded EPA recommendations for radon.

Radon is an invisible, odorless gas and a natural part of the environment not manmade. 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 increased lifetime 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 sub-slab ventilation. A typical radon problem can be solved for $1,000 to $1,500.

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

Michele Hall, Southeastern District Health Department, (208) 233-8800 or

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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