834 HAWLEY AND MARKEE 7000 PC/G y=3léx-316 ° 0 0 2 o | 4 l 6 8 10 | 12 | 14 | 16 SCINTILLATOR READINGS, NET MR/ HR, 107° l 18 20 Fig. 11—Portable-scintillator readings vs. grass activity levels Human-thyroid-uptake Data In the first test one cow was selected to furnish milk for humanvolunteer consumption. The data from the counting of the human thyroid after ingestion of the milk showed the uptake fraction to be 0.19. In the second test inhalation-thyroid-dose measurements were made on three people who were on the test grid during the time of cloud passage. The infinity thyroid-dose measurements were 14, 7, and 6mrads, averaging 9 mrads. Based on the thyroid uptake factor of 0.19 observed in the first test, the dose to be expected from ingestion of 1 liter of milk per day from the second test is roughly a factor of 100 greater than the inhalation dose. FUTURE RELEASES Later in 1964 a release over dead dry grass is planned. In the Spring of 1965, a release is plannedin which the behavior of radioiodine under inversion conditions will be investigated. During the summer of 1965, at least two more releases will be made involving different chemical forms of radioiodine.

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