Measurements of External Environmental Radiation in the United States

Abstract

Recent interest in the dose to man from natural radioactivity has been stimulated by the assumption by many geneticists of a linear relationship between radiation dose and the incidence of genetic mutations. Although this has not been demonstrated at the low dose rates prevailing in nature, the likelihood of such a relationship has led to the suggestion that geographical variations in the frequency of spontaneous mutations may be correlated ultimately with differences in the radiation dose to populations (1). This question has recently been reviewed by Gopal-Ayengar (2).The studies of the dose received by man from naturally occurring ionizing radiations can be divided into that received from external and internal sources. The dose to the germ plasm is primarily due to the external radiation, although one internal source, potassium-40, does deliver a dose to the reproductive organs amounting to about 15 mr/ year (3, 4). Studies of the radiation dose from external natural sources have been reviewed by Sievert (3), Libby (4), and Lowder (5), and extensive sets of measurements with particular emphasis on dwellings have been reported by Hultqvist (6) in Sweden. Although measurements have been made in this country byHess--(7) and Neher (8), no systematic study of the environmental radiation dose rate over an extensive area of the United States has.been reported previously.During the summer of 1957 our laboratory made measurements in the United States to establish the approximate range of population exposures to cosmic and terrestrial gamma radiation. An effort was made to obtain results which would be representative of the unperturbed natural background, affected as little as possible by the occasional substantial variations in the observed natural radiation levels produced by localized sources (for example, the proximity of granite buildings, brick paving, and fallout).Measurements were made with a 20lit., air-filled, polyethylene-walled ioniza-versity of Wisconsin.

Air Pollution

“…Solon and others (391) have reported on background radiation exposure of the general population. Rosholt (349) has outlined the results of a major study of quantitative radiochemical methods for determination of the complex of sources of natural radioactivity.…”

Doses populacionais de radiação ionizante na cidade de São Paulo: medidas de dose gama a céu aberto.

“…Tem havido um crescente aumento de interesse na determinação dos níveis de radiação ambiental e a subsequente dose à qual o ser humano está exposto. Tal fato teve como motivação inicial a suposição feita pelos geneticistas das décadas de 40 e 50, de que haveria uma relação linear entre a dose e a incidência de mutações genéticas (Solon et al, 1958).…”