Radioiodine levels in the U.S. Public Health Service Pasteurized Milk Network from 1963-1968 and their relationship to possible sources

Meteorological analysis of the paths of nuclear clouds has been used to assign the source of radioiodine in the milk samples collected in the U.S. Public Health Service Pasteurized Milk Network (PMN). Most of the instances of elevated values between April 1963 and December 1968 are attributed to six atmospheric nuclear explosions in western China. Only one of five cratering events at the Nevada Test Site caused elevated values in the PMN milk. Two periods with relatively low concentrations of radioiodine in milk possess no apparent explanation. By selecting periods with no atmospheric or cratering events, it is argued that at most small amounts of radioiodine in the PMN can be attributed to accidental releases from underground nuclear tests in the United States during the period of analysis. Radioiodine from accidental releases, reactor tests, and cratering events has been detected in a local raw milk network surrounding the Nevada Test Site.