November 17, 2000
Susan Kaplan Iodine-131: key issues
http://www.oakridger.com/

The Department of Energy sponsored dose reconstruction research across the country from 1986 to 1993 to quantify releases from the DOE facilities and to determine how much the public has been affected. In Oak Ridge, the Oak Ridge Health Agreement Steering Panel (ORHASP) was assigned that task. The next step of this effort has been to establish health advisory panels, such as the one meeting this week in Oak Ridge.

One of the most significant local releases impacting residents around Oak Ridge that was quantified by ORHASP is radioactive iodine-131. In addition, data on historical releases of iodine-131 from non-local sources have been compiled and also are publicly available.

For example, the National Cancer Institute (NCI) has quantified the number of U.S. counties whose residents received thyroid doses from external iodine-131 exposures from nuclear weapons testing in the 1950s. In addition, NCI quantified dose estimates for those most at risk (i.e., those who were children during this period, particularly females) based on their milk consumption levels.

It should be pointed out that large differences between the reported doses exist when those most at risk are separated out (i.e., per capita data versus data on children only). On a per capita basis, the maximum thyroid dosage range reported in the U.S. is 12 to 16 rad. However, for doses received by children from milk consumption, the maximum thyroid dose range jumps to greater than 30 rad. (Note that doses to individuals on Rongelap Island in the Marshall Islands were as high as 2,000 to 10,000 rad.)

The protective action guide recommended by the Federal Radiation Council in 1965 is 10 rad cumulative dose for a suitably homogeneous sample of children under the age of one year. Presently, the Food and Drug Administration protective action guides are set at 1.5 rad and 15 rad, the former being the preventive action guide (feeding of cows with uncontaminated stored feed) and the latter the emergency action guide (confiscate milk from the market before distribution). At thyroid doses of 25 rad or greater, the administration of stable iodine is recommended by EPA to block the thyroid uptake of I-131. The World Health Organization has recently recommended that stable iodine be administered to a potentially exposed population when necessary to avert possible thyroid doses exceeding 1 rad in children under the age of 18 years.

Regarding the ORHASP reports, there has been some controversy over some of the data reported (and not reported) in the final summary report. . .There were other reported problems with the report as well (e.g., questionable technical assumptions and questions about peer review) that make it a highly controversial document.

Some claim there were significant underestimates of the total iodine-131 exposures to individuals and their children who at the time resided near X-10.

Why should we care about the accuracy of reported historical releases? . . . Having an accurate assessment of cumulative exposure to iodine-131 will be extremely important when the government begins determining eligibility for future health care benefits and other forms of compensation due to radiation exposures. So, it is important to realize that simply using iodine exposures from the local DOE site only may unjustly exclude individuals who have been adversely impacted by cumulative exposures from multiple governmental sources. In addition, we must also consider what should be done for impacted residents as well as workers, although residents are not covered by the recently passed compensation bill. It appears that will likely be the next step in this painful ordeal.

Susan Kaplan is a resident of Solway .