EVALUATION OF EXPOSURE REDUCING MEASURES ON PARAMETERS OF GENETIC RISK IN A POPULATION OCCUPATIONALLY EXPOSED TO COAL FLY-ASH

In a previous study we found increased SCE frequencies in peripheral b lood lymphocytes (PBLs) of workers occupationally exposed in a coal fl y ash processing industry, as compared to a non-exposed control popula tion. Shortly after this study, measures were taken in this plant to r educe fly ash levels. The objective of the present study, conducted 2 years later in the same plants, was to evaluate the effect of these me asures with respect to genotoxic risk. A group of 18 male workers of t he coal fly ash processing industry agreed to participate in the study . The control population consisted of 18 male workers from a flour pro cessing industry, who were matched for age and smoking behavior. In co ntrast to our previous study, no increased SCE frequencies were found in PBLs of workers potentially exposed to coal fly ash when compared t o the control group (mean SCEs: 6.4+/-1.2 and 7.0+/-0.9, respectively) . In addition, no differences were observed between the exposed and co ntrol groups for frequencies of gene mutations at the hypoxanthine gua nine phosphoribosyltransferase (hprt) locus in PBLs, for micronucleus frequencies using the cytokinesis block method, or for urinary mutagen excretion measured with Salmonella thyphimurium tester strains TA98 a nd TA97 with and without metabolic activation. In smokers, however, SC E frequencies in PBLs were significantly increased in comparison to no n-smokers (7.1+/-1.1 vs. 6.1+/-0.5; P<0.005), as was 24-h urinary muta gen excretion measured with strain TA98 with S9 mix (2373+/-1870 vs. 1 56+/-211; P<0.001) and with TA98 with S9 mix and beta-glucuronidase/ar ylsulfatase (2361+/-1958 vs. 538+/-396; P<0.005). In addition, hprt va riant frequencies in PBLs were higher in smokers than in non-smokers ( 15.0+/-23.5 x 10(-6)6 vs. 2.6+/-2.8 x 10(-6); P<0.05). No differences were observed for micronucleus induction between smokers and non-smoke rs. It is concluded that the protective measures taken in the coal fly ash processing plant appear to have been sufficient, since an effect of exposure to coal fly ash on parameters of genetic risk was not foun d any longer.