Modulation of hematology changes by polymorphism of glutathione S-transferase M1 and T1

Workers in the petroleum distribution trades experience relatively low-level exposures to gasoline vapors whose consequences have not been fully elucidated. The purpose of this study was to investigate changes in the hematological parameters among filling station workers who were occupationally exposed to gasoline. The target group for the study consisted of 41 workers from eight filling stations of Shiraz (south of Iran). The control group consisted of 27 healthy subjects matched for age and sex from general population. The complete blood count analysis was done in one laboratory. Using PCR-based method, the genotypes of glutathione S-transferase T1 (GSTT1) and M1 (GSTM1) were determined. Workers were divided into three exposure groups according to employment history: duration less than 1 year, 1-5 years, and more than 5 years. Comparison was performed using Kruskal-Wallis test. In the individuals with the presence of both GSTT1 and GSTM1 functional alleles, comparison between four exposure groups revealed no significant difference for studied hematological variables. There were statistically significant differences between study groups, with only one functional allele, either GSTT1 or GSTM1, for relative number of lymphocytes (chi(2)=9.147, df=3, P=0.027) and neutrophils (chi(2)=9.951, df=3, and P=0.019), and absolute number of lymphocytes (chi(2)=9.135, df=3, and P=0.028), and RBC (chi(2)=10.586, df=3, and P=0.014). These findings could indicate the possible protective effect of concurrent presence of GSTM1 and GSTT1 enzymes on the hematopoietic system of filling station workers.