OBJECTIVES: The purpose of this study was to determine if polymorphisms in microsomal epoxide hydrolase, an enzyme involved in the metabolism of reactive intermediates of vinyl chloride (VC), contribute to the variable susceptibility to the mutagenic effects of vinyl chloride among exposed workers. MATERIALS AND METHODS: Polymorphisms at codons 113 and 139 were determined in DNA samples from 211 French vinyl chloride workers. Genotypes were stratified into low, medium and high activity groups and odds ratios and 95% confidence intervals were determined for the presence of one or both of two VC-induced mutant biomarkers (mutant ras-p21 and mutant p53) by logistic regression adjusting for age, smoking, drinking and cumulative VC exposure. RESULTS: Compared to the low-activity microsomal epoxide hydrolase genotype stratum, the odds ratio for the presence of the VC-induced mutant biomarkers increased to 1.16 (95% CI: 0.64-2.10) in the medium-activity genotype stratum and to 1.35 (95% CI: 0.66-2.77) in the high-activity genotype stratum. The test for trend was not statistically significant and was in the opposite direction from that expected based on increasing removal of reactive intermediates with increasing activity. CONCLUSIONS: The results suggest that polymorphisms in microsomal epoxide hydrolase do not play a significant role in susceptibility to the mutagenic effects of vinyl chloride.
OBJECTIVES: The purpose of this study was to determine if polymorphisms in microsomal epoxide hydrolase, an enzyme involved in the metabolism of reactive intermediates of vinyl chloride (VC), contribute to the variable susceptibility to the mutagenic effects of vinyl chloride among exposed workers. MATERIALS AND METHODS: Polymorphisms at codons 113 and 139 were determined in DNA samples from 211 French vinyl chloride workers. Genotypes were stratified into low, medium and high activity groups and odds ratios and 95% confidence intervals were determined for the presence of one or both of two VC-induced mutant biomarkers (mutant ras-p21 and mutant p53) by logistic regression adjusting for age, smoking, drinking and cumulative VC exposure. RESULTS: Compared to the low-activity microsomal epoxide hydrolase genotype stratum, the odds ratio for the presence of the VC-induced mutant biomarkers increased to 1.16 (95% CI: 0.64-2.10) in the medium-activity genotype stratum and to 1.35 (95% CI: 0.66-2.77) in the high-activity genotype stratum. The test for trend was not statistically significant and was in the opposite direction from that expected based on increasing removal of reactive intermediates with increasing activity. CONCLUSIONS: The results suggest that polymorphisms in microsomal epoxide hydrolase do not play a significant role in susceptibility to the mutagenic effects of vinyl chloride.