Genetic polymorphisms of GSTM1 and GSTT1 genes: effects on susceptibility to formaldehyde-induced hematotoxicity

Formaldehyde (FA) is a known human carcinogen for the upper respiratory tract. However, its hematotoxicity remains unclear. This study was performed to assess probable effects of FA on blood parameters and to determine the common polymorphisms in the detoxification enzymes GSTM1 and GSTT1 as biomarkers of susceptibility. Sixty-four workers with high occupational FA exposure and 57 non-exposed controls were studied. Complete blood count was performed. Also, GSTM1/GSTT1 genotypes were determined. After adjusting for potential confounding variables, FA exposure was only associated with the levels of hemoglobin, mean corpuscular hemoglobin concentration, and reticulocytes. Notably, workers with homozygous deletions of GSTM1 or GSTT1 had hematological parameters similar to those with active genes. In conclusion, very high FA exposure resulted in only slight alterations in MCHC and no overt hematotoxicity was observed. These findings suggest that even at high exposure levels, FA may not reach the bone marrow in sufficient amounts to cause hematotoxicity. Also, it seems that GSTM1/GSTT1 polymorphisms do not influence the workers' susceptibility to FA-related blood effects.