Abstract
Occupational exposure to benzene has been associated with leukemia, anemia, leukopenia, and thrombocytopenia. Genetic susceptibility to benzene toxicity in humans may be related to variations in benzene metabolizing genes. The main objective of this study was to ascertain whether polymorphism of GSTP1, GSTM1, GSTT1 and CYP2E1 genes might influence susceptibility to the adverse effects of benzene among employees of a petrochemical plant. In this cross-sectional study, 124 employees of a petrochemical plant who had been occupationally exposed to benzene and had one or more abnormal hematological parameter (cases) and 184 subjects with a similar exposure scenario, free from any abnormal hematological parameters (referent) were studied. Atmospheric concentrations of benzene were measured and GSTM1 and GSTT1 genotypes were evaluated using the multiplex polymerase chain reaction (PCR) technique. Additionally, GSTP1 and CYP2E1 genotypes were determined by PCR- restriction fragment length polymorphism (PCR–RFLP). The frequency of null GSTT1 genotype in cases was significantly higher than that of referent group (32.3 vs. 18.5%, OR 2.1, 95% CI 1.23–3.56, p = 0.004). The mean value of platelets in subjects with null GSTT1 genotype was significantly lower than that of individuals with positive GSTT1 genotype (p = 0.015). Conversely, the mean value of leukocytes was significantly higher in subjects with null GSTM1 genotype as compared to those with positive GSTM1 genotype (p = 0.026). Logistic regression analysis showed that, subjects with null GSTT1 genotype had a significantly higher risk for hematological disorders, as compared to those with positive GSTT1 genotype (OR 2.1, 95% CI 1.23–3.56). Moreover, subjects with both null GSTT1 and GSTM1 genotypes had a significantly higher risk for hematological disorders as compared to subjects with positive GSTT1 and GSTM1 genotypes (OR 2.35, 95% CI 1.14–4.8). The results of this study showed that, individuals carrying null GSTT1 or both null STT1 and GSTM1 genotypes had a higher risk and were more susceptible to benzene-induced hematological disorders.
Highlights
Benzene has been classified as a human hematocarcinogen by International Agency for Research on Cancer (IARC) (IARC 2017)
The frequency of null GSTT1 genotype in cases was significantly higher than that of referent group (32.3 vs. 18.5%, OR 2.1, 95% CI 1.23–3.56, p = 0.004)
Lan et al reported decreased white blood cell count (WBC), granulocytes, lymphocytes, B cells and platelets in Chinese workers occupationally exposed to benzene at air levels of 1 ppm or less (Lan et al 2004)
Summary
Benzene has been classified as a human hematocarcinogen by International Agency for Research on Cancer (IARC) (IARC 2017). Some studies have reported genotoxicity, increased levels of persistent chromosome aberrations and reproductive effects as a result of exposure to benzene (Edokpolo et al 2015). Given the hematotoxic potential of benzene, complete blood counts (CBC) has been recognized as an easy and readily available screening tool for assessing the hematotoxicity of this compound (Tunsaringkarn et al 2013). The occupational safety and health administration (OSHA), states that, CBCs should be monitored for workers exposed to benzene (OSHA 2012). Occupational exposures to benzene occur within the petrochemical plants, petroleum refineries (Edokpolo et al 2015), petrol distribution, and in manufacturing industries that require aromatic solvents or glues that contain benzene such as rubber production, shoe manufacturing, and printing (Weisel 2010; Carrieri et al 2012)
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