A comparative biomonitoring study of populations residing in regions with low and high risk of lung cancer using the chromosome aberration and the micronucleus tests

Chromosome aberration (CA) and micronucleus (MN) tests were performed in peripheral blood lymphocytes from people residing in two districts of Chiang Mai, Thailand, a high-risk area, Saraphi (n = 107), where the lung cancer incidence is three-fold higher than in a low-risk area, Chom Thong (n = 118). The percentage of cells with CAs was significantly lower in the Saraphi population than in the Chom Thong population (0.47 ± 0.91 versus 1.04 ± 1.18, P = 0.0001) as was the percentage of CAs (0.49 ± 0.91 versus 1.08 ± 1.21, P < 0.0001) and the mitotic indices (1.25 ± 0.44 versus 1.33 ± 0.33, P = 0.025). The frequency of MN in binucleated (BN) cells, however, was significantly higher in the Saraphi population (12.01 ± 3.57 versus 9.99 ± 3.11, P < 0.0001) as was the percentage of BN cells with MN (1.14 ± 0.31 versus 0.93 ± 0.23, P < 0.0001). There was no difference in the nuclear division indices (1.49 ± 0.07 versus 1.47 ± 0.11, P = 0.1759) between the two populations. With regard to the effect of confounding factors, it was found that cigarette smoking influenced both CA and MN frequencies, and that the chewing of fermented tea leaves or betel nuts affected CA and sex affected MN frequencies. An increasing of CA and MN frequencies were seen in smokers and chewers over non-smokers and non-chewers, with CA frequencies being higher in Chom Thong smokers and chewers and MN frequency being higher in Saraphi smokers. However, pesticide exposure and alcohol consumption had no impact on CA and MN frequencies. Due to the conflicting results obtained in the two tests, we cannot make a clear statement regarding the potential effects of the environmental exposures in the two study populations.