Micronuclei and nuclear anomalies in urinary exfoliated cells of subjects in radionuclide-contaminated regions

¹³⁷Cs contamination in living or agricultural environments may contribute to significant human internal exposure and cause adverse health effects. Contamination by ¹³⁷Cs and other radionuclides was detected in a river valley in northern Taiwan, in the 1990s. Given that the radioactivity appeared to be widely distributed in soil, rice and several other food plants in the areas surrounding several communities in the late 1990s [Y.B. Nabyvanents, T.F. Gesell, M.H. Jen, W.P. Chang, Distribution of ¹³⁷Cs in soil along Ta-han River Valley in Tau-Yuan County in Taiwan, J. Environ. Radioact. 54 (2001) 391], its possible impact on local occupants was further studied. Ten subjects in three families residing continuously in the highly contaminated valley and 10 non-exposed subjects matched for age, sex, and cigarette smoking habits from neighboring communities were evaluated for micronucleus frequencies and for degenerative nuclear changes in urinary exfoliated epithelial cells (EE cells). Micronucleus frequencies (‰) were significantly higher in the exposed subjects (4.79±1.21‰) than in the reference subjects (2.73±0.59‰; Wilcoxon 2-sample test, P value 0.0004). There were also higher frequencies of EE cells with karyolysis and condensed chromatin in the exposed subjects than in reference subjects. These results indicate that genotoxic and/or mutagenic effects on urinary epithelial cells occur in human subjects who have resided for a long time in a radioactively contaminated environment.