Effect of smoking on the chromosome aberrations induced by environmental mutagens

Chromosome aberration frequencies have increasingly been used for the study of various occupational and environmental exposures. Factors related to environmental mutagens influence translocation yield. Smoking has impact on the translocation yield and is most influential factor among the environmental mutagens to increase cancer incidence. In order to know how environmental mutagens affect the induction of translocations caused by smoking we analyzed translocations in the lymphocytes of smokers and nonsmokers in a large city, Beijing, a high natural background radiation area (HBRA) and in this control area (CA), remote villages in the south of China (Zhang et al., J. Radiat. Res., 45: 441-446, 2004; Zhang et al., Carcinoge. Teratge. Mutage., 20: 41-43,2008). The results of our analyses are reviewed in this presentation.Studied residents in Beijing have lived there for longer than 40 years and people in HBRA and CA have lived there for several generations. The level of natural radiation in HBRA is 3-5 times higher than those in CA and in Beijing. The residents in HBRA and CA mainly smoke the shredded tobaccos through a water pipe instead of the cigarette which is common in Beijing. Individual radiation dose was measured with a pocket dosimeter (Aloka PDM-10) put on the body for 24 hours and/or estimated from the dose rate measured by a NaI scintillation survey meter (Aloka TCS-166) in their homes. Peripheral blood was from 10, 11, and 7 smokers in Beijing, HBRA and CA, respectively. Their ages were around 60 years old. Peripheral lymphocytes were cultured for 48 hours with PHA and colcemid, and harvested according to our standard method for biodosimetry (Hayata et al., J. Radiat. Res. 33: Supple, 231-241, 1992). Chromosome painting was performed using Biotin-labeled whole chromosome painting probes specific to chromosome 1,2 and 4 (Cambio, UK), representing 22.71% and 22.34% of the human genome in male and in female, respectively. The frequencies of translocations per 1000 cells were scaled to genome-equivalent frequencies by the formula reported by Lucas et al. (Int. J. Radiat. Biol. 62: 53-63, 1992). The number of metaphases analyzed was totally 321,795(3,973 per subject). Statistical analysis was performed by Mann-Whitney U test.Genome equivalent frequencies of translocations in 1,000 lymphocytes per subject were 10.6+/-3.1, 11.3+/-3.4, and 13.4+/- 3.4 in smokers and 9.6 +/-5.0, 11.7 +/- 4.7, and 9.1 +/-3.8 in nonsmokers in Beijing, HBRA and CA, respectively. CA smokers showed the highest average value among six groups. There was a statistically significance difference (p