Revision 1
March 19, 1998
by Radiation, Science, and Health, Inc.,
Edited by J. Muckerheide

1.2.6
Natural Radiation and Radioactivity

1.2.6.2
Natural Background: Populations

"On the SW coast of India, in an area with 140,000 inhabitants, a sizeable proportion of the population receives exposures exceeding 10 mGy y-1 with the highest personal dose rate of 32.6 mGy y-1 belonging to a resident of a house that registered 38.4 mGy y-1 (Sunta 1993). The average radiation level was estimated to be 15.7 mGy y-1, in contrast to an overall mean of 2.08 mGy y-1 in the nearby control area. Although the dose levels are significant, the results of the demographic survey for dose-genetical effect correlation, and epidemiological studies as well as studies on chromosomal anomalies of human blood cells and plants have shown no conclusive statistically significant biological effects on the population of HLNRAs in India in comparison to control groups (Sunta 1993)."

"In Yangjiang, China, which has been under study since 1972, the average effective dose is 5.4 mSv y-1 which is about three times higher than its mean background of 2 mSv y-1. The results of epidemiological studies over a population of 80,000 have led to a firm conclusion; i.e. no difference was found in mortality rates from all types of cancer or due to leukemia in the HLNRAs of Yangjiang in comparison with the control group studied (Wei et al 1990)."

Table 2

"Some areas in Japan, with exposure rates; (i) below 7.6 uGy h-1, (ii) between 7.6 to 10.5 uG h-1 and (iii) above 10.5 uGy h-1 respectively with population sizes of (i) 2,230,300; (ii) 2,885,787; and (iii) 2,790,818 from 39 areas including 28 cities and 11 towns and villages have been under epidemiological investigations, as reported by Iwasaki and co-workers (1993). The results of cancer mortality rates of public exposed to natural radiation levels in different geological zones in Japan no detectable increase in cancer mortality."