By: Pat Ortmeyer
...it seems necessary to adopt a rather conservative attitude toward the involuntary exposure of the general populations. An error on the radical side will not be immediately apparent, but the chickens will inevitably come home to roost at some later date. The National Cancer Institute (NCI) recently released results of its 14-year study showing that fallout of iodine-131 from atmospheric tests conducted in Nevada in the 1950s and early 1960s resulted in thyroid doses to virtually all of the 160 million people living in the United States at the time. The estimated 150 million curies of iodine-131 released from the tests resulted in a cumulative average thyroid dose to the population of 2 rad.2 Children were particularly affected: their doses averaged 6 to 14 rad, with some doses as high as 112 rad. Prior to this study, the most recent estimates of children's thyroid doses from iodine-131 in fallout, reported to Congress in 1959 and cited as recently as 1997, gave a dose range for children of 0.2 to 0.4 rad -- 15 to 70 times less than the NCI dose estimates.3 (Note: These are estimates of thyroid doses, not whole body doses. See Centerfold table on dose.) Thyroid irradiation increases the risk of cancer to children. A 1995 peer-reviewed publication says there is "convincing evidence" of increased thyroid cancer risk to children under age 15 whose thyroids are exposed to 10 rad or more.4 This study mostly concerned individuals exposed to external radiation sources such as X-rays, but the effect on tissues from ionizing radiation from internal sources is essentially the same.5 (See footnote for full explanation.) Thyroid cancer is relatively rare, but the NCI estimates that 10,000 to 75,000 thyroid cancers can be expected as a result of these doses, roughly five to ten percent of which will be fatal. (The upper estimate of 75,000 is more plausible, since the lower estimate assumes that internal radiation doses from iodine-131 are "as little as one-fifth as hazardous" as the same dose of external radiation.6 This assumption is very dubious, not based on human data, and not protective of public health.) About 70% of thyroid cancers due to iodine-131 fallout have yet to be diagnosed, according to the NCI,7 and survivors of thyroid cancer require lifelong treatment with a synthetic thyroid hormone essential for metabolism and other physiological functions. Thyroid irradiation has also been linked to other thyroid disorders, such as autoimmune hypothyroidism, autoimmune thyroiditis, hyperthyroidism incident to Grave's disease, and thyroid nodules.8 Estimates of the level of dose at which these effects occur vary considerably. While NCI has not estimated the number of children who were put at risk due to fallout, simple demographics coupled with the published numbers indicate that millions of people who were under 15 during the period in question may have received over 10 rad. Doses to girls may be of particular significance, as the incidence of thyroid cancer among women is more than twice that of men.9 Iodine can be inhaled, or ingested through contaminated eggs, cottage cheese, or leafy plants and vegetables. But the main pathway was through ingestion of contaminated milk. As fallout settled on fields and pastures after each test, cows and goats would eat the grass and the iodine would become concentrated in their milk. Children received higher doses because in general they consumed more milk than adults, and their thyroids were smaller and growing more rapidly. The estimated 20,000 people in the country at the time who drank goat's milk also received higher doses -- up to 20 times greater than those drinking cow's milk -- because goat's milk concentrates iodine-131 more than cow's milk.10 Doses to goat's milk drinkers could, in the most affected counties, have been as high as 180 to 316 rad. High doses were not limited to those areas directly downwind of the tests. Local precipitation or wind patterns in areas far from the test site caused selective deposition of fallout, or "hot spots," a phenomenon understood by the Atomic Energy Commission (AEC) from the time of the first test, "Trinity," in 1945. As a result, some of the highest estimated thyroid doses in the country were in areas far from Nevada, such as in Meagher County, Montana, with an average dose of 15.8 rad, and Custer County, Idaho with 15.4 rad. Other high doses were estimated throughout the midwest: 8.6 rad in Lyman, South Dakota (26 to 60 rad for children), and 8.1 rad in Lewis County, Missouri (24 to 57 rad for children).11 The Atomic Energy Commission understood early on that locating the test site in the western part of the country would result in fallout spreading over most of the country. In a 1948 memo, an Air Force meteorologist advised the committee assigned to finding a test site that "Because the United States is predominantly under the influence of westerly winds, it seems obvious that the eastern coast areas of the United States may provide a suitable site."12 But the site was located in the west, where the proximity to the weapons laboratories would allow for acceleration of the weapons program. Doses Avoidable Iodine-131 is a relatively short-lived radionuclide with a half-life of 8 days (see Centerfold table on iodine for more information). Therefore, radioactivity levels in contaminated milk would have decreased significantly several weeks after the time of detonation, making most of the iodine-131 doses to the public avoidable. Contaminated milk could have been dumped or diverted from the market and used for products such as dried milk, butter or cheese, which take longer to process and would allow time for the radioiodine to decay. But the government made no such provisions, though they were aware as early as 1953 of the "milk pathway," the primary route of exposure for iodine-131 in humans. Warnings about iodine-131 in milk were also issued at the 1955 United Nations Conference on Peaceful Uses of Atomic Energy, where researchers suggested that the then-allowable air concentration limits for iodine-131 were ten thousand times too high and should be lowered:
"This limit should be reduced by four orders of magnitude to assure radiation safety for grazing animals. Approximately the same reduction is required for the safety of humans eating large quantities of fresh garden produce and drinking milk from cows grazing on iodine 131-contaminated pasture."13 An Oxford University delegation to the conference stressed that "human beings whose diet consists largely of milk, notably infants . . .because of their youth may be considered super-susceptible to the effects of radiation."14 The advice of the UN delegates, while ignored by the AEC, was heeded by British officials in 1957 when, after a reactor accident that resulted in a release of 16,000 to 27,000 curies of iodine-131, ordered that milk within a 200-square mile area around the plant be dumped as a health precaution. But even in the early 1960s, when the milk pathway was widely understood, the US government refused to acknowledge the risk of iodine-131 contamination or take measures to reduce it. In 1962 officials in Utah and Minnesota diverted possibly contaminated milk from the market when iodine levels exceeded radiation guidelines set by the Federal Radiation Council (FRC). In response, the FRC, whose members included the chairman of the AEC and the Secretary of Defense, declared that they did "not recommend such actions" and that such "countermeasures may have a net adverse rather than favorable effect on the public well-being."15 Further, the FRC made the remarkable determination that their own radiation guidelines should not be applied to fallout without further detailed studies because "any possible health risk which may be associated with exposures even many times above the guide levels would not result in a detectable increase in the incidence of disease"16 (emphasis added). Since thyroid cancers can develop many years after radiation exposure and are therefore not immediately detectable, this reassurance was highly misleading. While the public was not warned to refrain from milk consumption and was continually reassured that fallout posed no danger, the AEC was providing advance notice of tests, including "forecasts of contaminated areas based on meteorological data"17> to the National Association of Photographic Manufacturers. This was done so that they could "anticipate local contamination and take preventive action"18 to protect photographic film from being ruined by radiation exposure. The warning to the photographic industry began in 1951 -- the first year of testing in Nevada -- as a result of the Eastman Kodak Company's threat to sue the AEC over damaged film from nuclear fallout. The warnings continued throughout the atmospheric testing program but were not extended to the public. Other Doses from Fallout The United Nations Scientific Committee on the Effects of Atomic Radiation estimates that globally, iodine-131 doses comprise only about 2% of the overall radiation dose from weapons testing (dose integration time to the year 2000).19 Ninety-eight percent of the dose is from other radionuclides. These calculations do not take hot spots into account, which may increase the relative share of iodine-131 dose. In addition, in areas of high precipitation both in the US and in other countries, hot spots probably resulted in high concentrations of other radionuclides besides iodine-131. Further work is needed to clarify which populations were most affected by testing throughout the world. Soviet and Chinese testing could have affected populations in Alaska, for example, and there may be incidences of hot spots in the Pacific, including Hawaii, from French, British, and US Pacific area testing. There is also evidence from the NCI study that hot spots occurred in Canada and may have occurred in northern Mexico from Nevada tests. A thorough assessment of the effects of all nuclear testing -- not just US tests -- is needed so that those at risk of high doses can receive proper screening. Soviet tests, for example, had a larger total fission yield than US tests (110.9 megatons compared to 72.1 megatons), and the combined fission yield of Chinese, British and French tests was 34.2 megatons. IEER estimates that only a small fraction of the cesium-137 in the soil in the eastern United States is due to fallout from detonations at the Nevada Test Site. In light of the NCI findings, we make the following recommendations:
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Institute for Energy and Environmental Research
Comments to info at ieer.org
Takoma Park, Maryland, USA
January, 1998
Updated April 15, 2009