Children bore the brunt of US nuclear tests in 1950

The institute’s 100,000-page report, parts of which have trickled out in recent days, found unexpectedly high levels of exposure to radioactive Iodine-131 in at least a dozen states from the Cold War-era weapon tests. The greatest exposure came from children drinking contaminated milk.

The `Hot Spots’ with the highest estimated exposures were scattered in parts of 12 midwest and western states.

The study has not been released, although parts have been obtained by the Associated Press and other news organizations in recent days.

Researchers projected exposure rates by using radiation monitoring data from the energy department as well as data on where cows grazed and on milk production and distribution. Radioactive iodine decays relatively quickly in the environment, but also concentrates in milk and eventually in the thyroid.

Because children drink more milk, concerns have been raised about the fallout in the 1950s causing an undetermined number of thyroid cancer cases in people who were exposed to the radiation as children.

According to the study, some of the highest doses of the fallout were received by milk-drinking children in the farm belt. Because of a variety of factors including weather patterns and different milk consumption rates, the exposure levels varied widely, with isolated hot spots of exposure, according to the study.

Researchers did not test any people. But based on mathematical models, they estimated the average thyroid dose nationally as two rads about the same amount of radiation a person absorbed from a common medical test of that era. A rad is a measurement of the amount of energy absorbed by the flesh from radiation.

But exposure to young children may have been 10 times that average in the worst hot spots, the study concludes. It does not attempt to determine whether any exposure was enough to cause thyroid cancer.

Congress ordered the study by the National Cancer Institute more than 15 years ago. Some of its findings — a summary and other key data — have been circulating in the energy department. Only recently have some key findings become public.

Members of Congress as well groups that represent people living near nuclear weapon facilities have complained about the delays in making the findings known.