j- tt tae nm eo ~~ A we a ae ee ee a>. DS DePBWW 6 a . . ; : 131 Tia state results almost always confirm the presence of I 3 in milk wnen tho the radioisotope appears in the PMN, lower than the PMV concentration. sometimes higher and sometimes Durine the oyveriocds with no I 131 in a we Dindings aiso contTirm the absence of radioiodine in Pray milk, tne state yn oad . Jn a mil in the United States, with two minor exceptions. On September 12, 1966, Vv of 40 pCi/L for March 1957. ower. These elevated The general lack of I>-+ Again, other California milksheds were much values in the state networks are not accounted for. in milk semples collected by the states is not a conclusive verification of its absence in the PMY because of infrequent sexpiing, limited reporting, and the monthly averaging. Comoerison or PMY with SWRHL milk network: ated Tae Southwest Radiological Health Laboratory of the U. S. Public Health Service (SWRSL) operates a milk sampling network which surrounds the Nevada Test Site. Milk is routinely sampled each month from dairy farms and individual family cows in Nevada, western Utah and eastern California. . In the event of a release of airborne radioactivity from the testing activities (at the NES some 155 producing dairies in 1l western states can be alerted by telephone to collect milk samples. The SWRHL conducts a continuous survey of off-site milk sampling locations. A summary of ist findings in milk in the SWRHL network appears in Table 3 for nuclear rocket tests, cratering tests, and unscheduled venting Prom underground tests. Levels of radioiodine in the SWREL milk network following the reactor tests in Jackass Flats of the NTS show a peak value of 240 pcei/l. The farthest farm from the test site with a concentration in excess of 30 pCi/1 (from oe a test on February 23, 1967) was located at a distance of 250 miles. There was no detectable zist in the SWRHL milk network for about half of the reactor events. Four of the five cratering events resulted in readily detectable concentrations of radioicdine in the SWRHL network. The Sulky cratering event created a mound rather than a conventional crater and only very small. amounts of radioactivity were released to the atmosphore. Thus, it is now surprising that no detectable amounts of radioiodine could be found in milx. Todine-131 from the Palanquin cratering event provided the highest