9 March 1998
In the NCI report published in October 1997, the thyroid doses to people resulting from atmospheric weapons tests conducted at the Nevada Test Site in the 1950s and the 1960s were estimated for five diets in which only the data related to the thyroid doses resulting from the ingestion of fresh cows' milk were varied. This was accomplished by considering cows' milk of various origins (i.e., milk produced locally from backyard cow, commercial milk produced within each county, commercial milk pooled from nearby counties and/or more distant areas), resulting in differing 131I concentrations in the milk consumed, and by using a range of milk consumption rates (high, average, and none). The consumption rates of the other foodstuffs contaminated with 131I that are considered in the dose assessment (i.e., cottage cheese, goats' milk, leafy vegetables, and eggs) were assumed to be the same, for a given age class, in all counties of the contiguous United States, and these foodstuffs were assumed to be produced locally, so that only one 131I concentration was estimated for each foodstuff and each county, following each nuclear weapons test. Different procedures were used for the assessment of the thyroid doses from fresh cows' milk and from all other foodstuffs because the most important contribution, by far, to the thyroid dose was, for most people, due to the ingestion of fresh cows' milk. In the five diets considered, the consumption rate and origin of fresh cows' milk were varied in such a way that the resulting estimated doses were considered to represent a broad spectrum of possible doses, and people interested in estimating their own thyroid doses could do so on the Web site: http://rex.nci.nih.gov/massmedia/Fallout. The procedure to be followed consists in clicking on "Report Contents", then on "Full Data Set (Annexes and Sub-annexes)", and on "Data Indexed by State and County". At this stage, one is asked to select the state and county of interest, the date of birth, sex, and the type of milk consumed (in this case: Cows' milk). Clicking on "Submit" produces the estimates of thyroid dose for each test series and for all tests. Results are provided for the five diets that are considered.
With regard to foodstuffs other than cows' milk considered in the dose assessment, it was deemed sufficient to use simplifying assumptions to estimate their 131I concentrations in each county following each nuclear weapons test, and to assume the same average consumption rates, in a given age class, throughout the contiguous U.S. The per capita consumption rates were obtained as the quotients of the annual production rates of the foodstuffs in the U.S. and of the population of the country. The average consumption rates for a given age class were then derived from the per capita consumption rates, taking into account estimated variations of the consumption rates according to age. For leafy vegetables and eggs, which were consumed by a large fraction of the population, this methodology leads to reasonable estimates of their contributions to the thyroid dose. However, for goats' milk, which was consumed by a very small fraction of the population, the methodology used in the NCI report leads to estimates of very small consumption rates for the general population, and, consequently, to small overestimates of the thyroid doses for the large fraction of the population who did not drink goats' milk, but to large underestimates for the small fraction of the population who drank goats' milk. In fact, because the 131I concentrations in goats' milk were typically greater than the 131I concentrations in cows' milk by up to an order of magnitude or more, the people drinking large amounts of goats' milk received thyroid doses that were generally much greater than did the people who drank only cows' milk.
The information provided in the Annexes of the October-1997 NCI report can be used to estimate thyroid doses via the consumption of goats' milk. However, this requires calculations that readers may find difficult to make. For that reason, thyroid dose estimates incurred through the ingestion of goats' milk have been prepared as an addition to the report. Three sets of thyroid dose estimates have been obtained by combining the estimated 131I concentrations in locally produced goats' milk with the consumption rates relevant to: (a) people with average consumption rates of goats' milk, equal to the average consumption rates of cows' milk used in the NCI report, (b) people with "high" consumption rates of goats' milk, equal to the "high" consumption rates of cows' milk used in the NCI report, and (c) for comparison purposes, people who did not drink goats' milk. In addition, the thyroid doses received by breast-fed infants whose mothers drank goats' milk were calculated. In these calculations, it is assumed that the consumption rates of cottage cheese, leafy vegetables, and eggs are the same as in the NCI report but that there was no consumption of cows' milk.Thyroid dose estimates for persons who drank goats' milk for a given nuclear weapons test series or for all tests can be obtained from the Web site: http://rex.nci.nih.gov/massmedia/Fallout. The procedure to be followed is similar to that described above for the estimation of thyroid doses from cows' milk. It consists in clicking on "Report Contents", then on "Full Data Set (Annexes and Sub-annexes)", and on "Data Indexed by State and County". At this stage, one is asked to select the state and county of interest, the date of birth, sex, and the type of milk consumed (in this case: Goats' milk). Clicking on "Submit" produces the estimates of thyroid dose for each test series and for all tests. Results are provided for the four diets that are considered (high, average, and no consumption of goats' milk, plus breast-fed infants whose mothers drank goats' milk).