Short Half-times of Caesium-137 in Pregnant Women

Abstract

BENGTSSON et al.¹ reported a patient with a shorter biological half-time for caesium during pregnancy than afterward. Prompted by this finding, and by the marked individual variation in body burden² and biological half-time³ seen in our own studies, we evaluated the equivalent biological half-times in twenty-four pregnant women while the environmental levels of fall-out caesium-137 were still sufficiently high that artificial administration of radioactivity was not required. The equivalent biological half-time is defined as 0.693 times (observed body content/observed excretion rate). Our technique has been described previously⁴.