Activity of O6-methylguanine DNA methyltransferase in mononuclear blood cells of formaldehyde-exposed medical students

A recent study reported that exposure of student embalmers in Cincinnati to high concentrations of formaldehyde (2 mg/m³) reduced the activity of the DNA repair protein O⁶-methylguanine DNA methyltransferase (MGMT). Reduction in a DNA repair enzyme may strongly increase the cancer risk not only with respect to the repair-enzyme causing agent but with respect to all carcinogens causing lesions subject to repair by the enzyme in question. Thus, we examined whether formaldehyde exposure of 57 medical students during their anatomy course at two different Universities in Germany influenced MGMT activity in mononuclear blood cells. Mean formaldehyde exposure of 41 students was 0.2 ± 0.05 mg/m³ for 6 h per week. MGMT activity was 133.2 ± 14.9 fmol MGMT/10⁶ cells before the beginning of the formaldehyde exposure, 131.1 ± 15.8 fmol MGMT/10⁶ cells after 50 days (P = 0.56) and 128.2 ± 19.0 fmol MGMT/10⁶ cells after 111 days of exposure (P=0.92). Similarly, no significant influence of formaldehyde exposure was observed, when smoking habits, alcohol consumption, allergic disease and sex of students were considered. In addition no significant difference was obtained in MGMT activity between 16 students with mean formaldehyde exposure of 0.8 ± 0.6 mg/m³ and students without formaldehyde exposure (n=51; P=0.37). In conclusion, exposure of the medical students in western Europe to formaldehyde did not decrease MGMT activity in mononuclear blood cells. Received: 22 September 1998 / Accepted: 4 November 1998