Effects of Smoking on Chromosomes Compared with Those of Radiation in a High-Background Radiation Area and of Environmental Mutagenic Factors in a Large City

Smoking is the 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 the translocations in the lymphocytes of smokers and nonsmokers in a large city, Beijing, and compared them with those reported by us (W. Zhang et al. J.Radiat. Res. 2004) in a high background radiation area (HBRA) and in its control area (CA), remote villages, in the south of China. The studied residents in Beijing have lived there for longer than 40 years. The level of natural radiation in HBRA is 3-5 times higher than those in CA and in Beijing. The residents in remote villages (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. Peripheral blood was obtained from 18, 10, and 7 smokers in Beijing, HBRA and CA and 20, 15 and 16 non-smokers in Beijing, HBRA and CA, respectively. Their ages were around 60 years old. Peripheral lymphocytes were cultured for 48 hours with PHA and colcemide, and harvested according to our standard method for biodosimetry. Chromosomes #1, #2, and #4 were painted for the analysis of translocations. The number of metaphases analyzed was totally 308,330 (3,585 per subject). Statistical analysis was performed by Mann-Whitney U test.Genome equivalent frequencies of translocation in 1,000 lymphocytes per subject were 10.0+/-3.5, 11.1+/-3.6, and 13.4+/-3.4 in smokers and 9.6+/-5.0, 11.7+/-4.7, and 8.4+/-3.1 in nonsmokers in Beijing, HBRA and CA, respectively. Standard deviations are similar among nonsmoker groups, but varied among smoker groups. CA smokers showed the highest average value among six groups. There was a statistically significant difference (p