278 R, A. Conard Rongelap Island remainsslightly radioactively contaminated,but is considered safe for habitation. This is reflected in some increase in body levels of radionuclides since the return of the people to their island. Based on gammaspectroscopy and urinary-excretion rates of isotopes, it has been estimated that during the first year after their return #’Cs increased by factors up to 100 resulting in a body burden of 0-68 we. Zn (which is selectively absorbed by Figure 6. Steel room used for gamma spectroscopy. the fish, a main item of the Rongelap diet) increased concomitantly to an estimated mean body burden of 0-36 wc. Excretion rates of °°Sr increased by a factor of about 20. Increase in body burdens of isotopes occurred equally in unexposed and exposed populations, and the levels in the exposed group are about the same as in the unexposed group living there. Based on preliminary analyses of data from the most recent survey period, eight to twenty months after the return to Rongelap, it appears that the people have begun to attain an equilibrium with their lightly contaminated environment. The }°’Caesium levels appear to be slightly lower than the year before while 85Zinc has increased slightly. The 9°Strontium analyses, unfortunately, are not available yet. The body burdens estimated above are far below the maximum permissible levels; 1’Caesium is about 2 per cent and ®Zinc about 1 per cent of the MPL. Jn figure 7 the increase in bodylevels of isotopes is shown in the spectrographs of a Rongelap man before 1957 and 20 monthsafter returning