Malondialdehyde-deoxyguanosine adduct formation in workers of pathology wards: the role of air formaldehyde exposure

Abstract

Formaldehyde is an ubiquitous pollutant to which humans are exposed. Pathologists can experience high formaldehyde exposure levels. Formaldehyde-among other properties-induce oxidative stress and free radicals, which react with DNA and lipids, leading to oxidative damage and lipid peroxidation, respectively. We measured the levels of air-formaldehyde exposure in a group of Italian pathologists and controls. We analyzed the effect of formaldehyde exposure on leukocyte malondialdehyde-deoxyguanosine adducts (M(1)-dG), a biomarker of oxidative stress and lipid peroxidation. We studied the relationship between air-formaldehyde and M(1)-dG adducts. Air-formaldehyde levels were measured by personal air samplers. M(1)-dG adducts were analyzed by a (32)P-postlabeling assay. Reduction room pathologists were significantly exposed to air-formaldehyde with respect to controls and to the pathologists working in other laboratory areas (p < 0.001). A significant difference for M(1)-dG adducts between exposed pathologists and controls was found (p = 0.045). The effect becomes stronger when the evaluation of air-formaldehyde exposure was based on personal samplers (p = 0.018). Increased M(1)dG adduct levels were only found in individuals exposed to air-formaldehyde concentrations higher than 66 microg/m(3). When the exposed workers and controls were subgrouped according to smoking, M(1)-dG tended to increase in all of the subjects, but a significant association between M(1)-dG and air-formaldehyde was only found in nonsmokers (p = 0.009). Air-formaldehyde played a role positive but not significant (r = 0.355, p = 0.075, Pearson correlation) in the formation of M(1)-dG, only in nonsmokers. Working in the reduction rooms and exposure to air-formaldehyde concentrations higher than 66 microg/m(3) are associated with increased levels of M(1)-dG adducts.

Fig. 1

Correlation between air-FA and minutes spent in reduction rooms in subjects “true exposed”.

Fig. 2

M₁dG adduct pattern in 10 mM MDA treated human leukocyte DNA (A), in pathologists working in the reduction rooms (B), and in controls (C).

Fig. 3

Detection of DNA adducts after mass tagging by MALDI-TOF-MS in MDA-treated, NaBH₄-reduced calf thymus DNA. Relative to the accurate masses that are seen in the spectrum from one spot, the exact masses are as follows using the M nomenclature of Goda and Marnett (1991): M1dG (581.166); M1dA (583.182); M2dG (653.187); M3dC (667.192); M3dA (693.219); and, in the inset (from another MALDI spot), M3mdC (681.207).

Fig. 4

Pearson’s correlation between M₁dG adduct level and personal air-FA (r = 0.355, p = 0.075) in the all 27 non smokers among the 40 subject selected for M₁dG.