Cytogenetic monitoring of a village population potentially exposed to a low level of environmental pollutants. Phase 1:SCE analysis.

By analogy to the techniques applied for monitoring biological effects of exposure to genotoxic agents in occupational populations, we have carried out cytogenetic monitoring in a group of inhabitants of a village (Mellery, Belgium) suspected to have been exposed to a variety of toxic environmental pollutants. These pollutants probably originated from a neighboring chemical wastes site. A group of 51 environmentally exposed and 52 reference persons (including children) were examined for the frequency of sister-chromatid exchanges (SCE) in their peripheral blood lymphocytes. The technique was further refined by using a high frequency cells (HFC) analysis. Analysis of the reference subgroups showed a significant difference between non-smoking adults and children. The influence of tobacco was clear, too. In the exposed group, no significant differences could be demonstrated between either the smokers or the non-smokers or the children. Furthermore, not only were the mean frequencies of SCE higher than in the respective reference subgroups but comparison between the two groups also showed a higher number of individuals presenting a HFC level above the background in the exposed group. Surprisingly, the difference was more pronounced for the children. A follow-up of the same exposed population carried out 18 months later and after remediation of the atmospheric chemical release, the previously observed tendencies in the exposure parameter remained unmodified.

Increased sister chromatid exchange frequencies observed in a cohort of inhabitants of a village located at the boundary of an industrial dumping ground: phase I.

Since the mid-eighties, a sand pit located at the boundary of Mellery, a small village in Belgium, has been used as a dumping ground for industrial waste. After a particularly dry summer, many people complained of very foul smells coming from the dumping ground. An analysis of the environmental atmosphere detected alkanes and chlorinated saturated and unsaturated hydrocarbons in various concentrations. Consequently, the Belgian Ministry of the Environment requested additional measurements from the dumping site and the surrounding regions. Given the hazards and possible ill health effects associated with simultaneous exposure to low levels of many chemicals, biomarkers of personal exposure were measured in a representative group of people living in this village. The cytogenetic consequences of daily exposure to a mixture of genotoxicants were measured by the Sister Chromatid Exchange assay. The study included a group of 51 environmentally exposed persons (including 11 children) and 52 controls. A significant increase in Sister Chromatid Exchange frequency was detected among the inhabitants of the village compared to that of the control group, especially among the children living in Mellery as compared to the matched control children.

Molecular dosimetry of DNA damage caused by alkylation. II. The induction and repair of different classes of single-strand breaks in cultured mammalian cells treated with ethylating agents.

Cultured Chinese hamster ovary cells were treated with ethylating agents. DNA lesions giving rise to single-strand breaks (SSB) or alkali-labile sites were measured by elution through membrane filters at pH 12.0 and pH 12.6, and by centrifugation in alkaline sucrose gradients after 1 h and 21 h lysis in alkali. Two agents with different tendencies to ethylate preferentially either at N or O atoms were compared, namely N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) and diethyl sulphate (DES). The compounds differed greatly in their potency to induce lesions, but the ratios of SSB, measured with different methods after a treatment for 30 min, did not differ significantly. This suggested that the spectrum of lesions induced by the two compounds is very similar. However, when both agents were studied with alkaline elution at pH 12.0 after a short treatment time (5 min) only ENNG was found to induce rapidly-repairable SSB. Most of these were rejoined already within 5 min after treatment. These results suggest that rapidly-repairable lesions occurring in DNA after treatment of mammalian cells with ethylating agents are due mainly to alkylation at O-atoms.