‘frequencies of “persistent” stable chromosome aberrations in cultured lymphocytes, and mutations at the. glycophorin A locus show somecorrelation with radiation dose among groups of persons who were exposed up to 40 years ago. However, such long-term follow-up studies show considerable variability among persons thought to have received similar doses. Thus, such evaluations provide information that may be useful in comparing radiation dose between groups of persons having low, medium, or high exposures, but do not provide information regarding levels of exposures of specific individuals within groups. Because it has been almost 40 years sincethe residents of Rongelap, Utirik, and Ailingnae were exposed, and the population has since experienced numerous incidental secondary diseases and/or exposures, and no baseline data on similar genetic isolate groups are available, evaluations of chromosomeaberrations in cultured lymphocytes or other types of somatic ceil mutations are not likely to yield any relevant scientific information regarding radiation levels received at the time of the Bravo detonation.