Human genetic studies in areas of high natural radiation--IX. Effects on mortality, morbidity and sex ratio.

Abstract

Abstract Data have been obtained by a genetic-epidemiological survey of a population living in the State of Espirito Santo (Brazil), and subjected to mean levels of natural radiation, per locality, ranging from 7 to 133 μrad/hr. Multiple regression models have been applied to the data, and the results showed no detectable effect of natural radiation on the sex ratio at birth, on the occurrence of congenital anomalies, and on the numbers of pregnancy terminations, stillbirths, livebirths, and post-infant mortality in the children, as well as fecundity and fertility of the couples (these observations contradict some data from the literature, based on official records and without analyses of the concomitant effects of other variables). However, nonsignificant results cannot be considered as disproving harmful effects of natural radiation on mortality and morbidity. These results may simply mean that other causes of mortality and morbidity are so important, under the conditions of the study, the contribution of low-level, chronic natural radiation is made negligible.