We estimated only by predicting the cloud trajectory to determine whether the cloud has passed a specific area. There is generally little residual radioactivity deposited on the ground fram these clouds. Records of cloud passage are obtained by mobile ground monitors in addition to routine monitoring of large off-site areas near the test site. Milk Milk collections have been made in the vicinity of NTS, and the samples analyzed by the U. S. Public Health Service, under contract with AEC. Tables IV, V, VI and VII present the highest concentrations of I-131 detected in milk during the indicated time periods. In July 1962, the wind trajectories of radioactive clouds from five nuclear tests passed over the Salt Lake City area. Three of these clouds are known to have deposited residual fallout activity in this area. Iodine-131 was detected in milk supplies for a short period of time. The tables show that while the peak value of I-131 in milk in the Salt Lake City area was relatively high, the average levels over a period of time were considerably below those considered to constitute a health hazard, based upon previous studies of effects of I-131 upon human thyroids. . DOE ARCHIVE For ex- ample, the station showing the highest yearly average (Salt Lake City with 102 micromicrocuries of I-13l per liter of milk) might result in a one-half roentgen exposure to the thyroid of young children and lessor amounts to adult thyrolids. ae “7

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