Radioiodine(131I) in animal thyroids during nuclear tests in both hemispheres.

Abstract

In mid-1974 a small increase of $sup 131$I was observed in animal thyroids following a nuclear test in China. In late 1974 there was no public announcement of an atmospheric nuclear test in the Northern Hemisphere, but $sup 131$I was readily measured in animal thyroids. This latter increase occurred while animals in the Southern Hemisphere accumulated $sup 131$I from nuclear tests in the Southern Hemisphere. It is suggested that in late 1974 the Northern Hemisphere was contaminated by either late fallout from tests in June or by interhemispheric mixing or by a combination of these sources. (auth)