Coke oven workers study: the effect of exposure and GSTM1 and NAT2 genotypes on DNA adduct levels in white blood cells and lymphocytes as determined by 32P-postlabelling.

The DNA adduct levels in total white blood cells (WBC) and lymphocytes (LYM) isolated from the blood of the same individuals were evaluated using the 32P-postlabelling assay for bulky aromatic adducts. In this study, 68 male coke oven workers and 56 machines workers as a matched control were enrolled. Personal monitors were used to evaluate exposure to eight carcinogenic PAHs, including B[alpha]P, during an 8-h working shift. The exposure among coke even workers ranged widely from 0.6 to 547 micrograms/m3 and from 2 to 62,107 ng/m3, for carcinogenic PAHs and B[alpha]P, respectively. The respective values in controls were from 0.07-1.64 microgram/m3 and from 1-63 ng/m3. A significant correlation between WBC- and LYM-DNA adduct levels was found (r = 0.591, P < 0.001). DNA adduct levels in both WBC and LYM were significantly elevated in coke oven workers as compared with controls, but adduct levels were generally low (WBC: medians 2.61 vs. 1.83 LYM: 2.47 vs. 1.65 adducts/10(8) nucleotides). LYM-DNA adduct levels were significantly higher for smokers as compared with nonsmokers in both the exposed and control groups. No such differences in WBC-DNA adduct levels were observed. Positive significant correlations were found at the individual level between DNA adducts in both cell types and carcinogenic PAHs and/or B[alpha]P in the inhaled air (r = 0.38-0.45, P < 0.001). A significant correlation at the individual level between LYM-DNA adducts and urinary cotinine was also observed (r = 0.37, P < 0.001). No differences in DNA adduct levels could be attributed to GSTM1 or NAT2 genotype in either group. Nor was there any clear association of DNA adduct levels with combined GSTM1/NAT2 genotypes. The effect of personal exposure to carcinogenic PAHs on DNA adduct levels in both cell types was also investigated using a logistic regression model with adjustment for possible modulating effect of confounders (smoking, GSTM1, NAT2, age, plasma levels of vitamins A and E, body mass index and diet). The results showed that coke oven workers had a significantly (P < 0.05) increased adjusted Odds Ratio (OR = 4.2 and 3.9 for WBC and LYM-DNA adducts) for occurrence of higher DNA adduct levels as compared to controls. The results also showed that the relative risk of an increased prevalence of 'abnormal' values of DNA adduct levels was exposure-dose related. The influence of confounding variables was found not to be significant in this study of relatively limited size. In spite of this, the results suggest that the DNA adduct levels in LYM seem to be affected by smoking (OR = 1.8 for smokers) and are modulated by the influence of NAT2 genotypes (OR = 1.6 for slow acetylators). Our findings indicate that both cell types are generally suitable to monitor occupational exposure to PAHs, and the results suggest that coke oven workers, smoking individuals and slow acetylators sustain more genetic damage in their LYM-DNA from exposure to carcinogenic PAHs than individuals without these actors.

Influence of GSTM1 and NAT2 genotypes on placental DNA adducts in an environmentally exposed population.

The placenta bulky DNA adducts have been studied in relation to metabolic genotypes for glutathione S-transferase M1 (GSTM1) and N-acetyl transferase 2 (NAT2) in 158 mothers (113 nonsmokers and 45 smokers) living in two regions with different annual average air pollution levels of sulphur dioxide, nitrogen oxides, particulate matter < 10 microns, and polycyclic aromatic hydrocarbons. One region was the district of Teplice as the polluted industrial region with mines and brown coal power plants, and the other was the district of Prachatice, an agricultural region without heavy industry. DNA adduct levels were determined by using a butanol extraction enrichment procedure of 32P-postlabeling. GSTM1 and NAT2 genotypes were studied by using polymerase chain reaction. The total DNA adduct levels included a diagonal radioactive zone (DRZ) and one distinct spot outside DRZ (termed X), which was detected in almost all placenta samples and correlated with DRZ (r = .682; P < .001). We found the total DNA adduct levels 2.12 +/- 1.46 (0.04-7.70) and 1.48 +/- 1.09 (0.11-4.98) adducts per 10(8) nucleotides for Teplice and Prachatice districts, respectively, indicating significant differences between both regions studied (P = .004). Elevated DNA adduct levels were found in smoking mothers (10 or more cigarettes per day) by comparison with nonsmoking mothers (3.21 +/- 1.39 versus 1.32 +/- 0.88 adducts per 10(8) nucleotides; P < .001). Placental DNA adduct levels in smokers correlated with cotinine measured in plasma (r = .432; P = .003). This relation indicates that cigarette smoking could be predominantly responsible for DNA adduct formation in placentas of smoking mothers. DNA adduct levels were evaluated separately for non-smokers (1.50 +/- 1.00 vs. 1.09 +/- 0.66 adducts/10(8) nucleotides for the Teplice and Prachatice districts, respectively; P = .046) and smokers (3.35 +/- 1.47 vs. 2.91 +/- 1.20 adducts/10(8) nucleotides for Teplice and Prachatice districts, respectively; P = .384) to exclude the effect of active cigarette smoking on the district variation. These findings indicate that the effect of the environmental pollution in cigarette smokers is practically overlapped by tobacco exposure. No seasonal variation was observed for DNA adduct levels in the overall population studied and no relation between total DNA adduct levels in placenta and levels of vitamins A, C, and E in venous and cord blood was found. A positive GSTM1 genotype was detected in 78 subjects, while negative GSTM1 genotype was found in 80 subjects. Higher DNA adduct levels were detected in the group with GSTM1-negative genotype by comparison with GSTM1-positive genotype (2.05 +/- 1.30 vs. 1.66 +/- 1.39 adducts/10(8) nucleotides; P = .018). This finding is more pronounced in the Teplice district (2.33 +/- 1.36 vs. 1.88 +/- 1.56 adducts/10(8) nucleotides; P = .053) than for the Prachatice district (1.61 +/- 1.09 vs. 1.36 +/- 1.10 adducts/10(8) nucleotides; P = .248) and for nonsmokers (1.45 +/- 0.82 vs. 1.18 +/- 0.93 adducts/10(8) nucleotides; P = .029) more than for smokers (3.45 +/- 1.14 vs. 2.95 +/- 1.62 adducts/10(8) nucleotides; P = .085). Significant district and seasonal differences were found in subgroups with GSTM1-negative genotype. DNA adduct levels in placentas of the GSTM1-negative subgroup were higher in mothers living in the polluted district of Teplice than in Prachatice (P = .012). The adduct levels in placentas sampled in the summer period were higher than in the winter period in the GSTM1-negative population (P = .006). No effect of the NAT2 genotype on DNA adduct levels was observed.