PRIMARY DNA-DAMAGE IN PERIPHERAL MONONUCLEAR BLOOD-CELLS OF WORKERS EXPOSED TO BITUMEN-BASED PRODUCTS

The genotoxic effect of occupational exposure to bitumen-based product s was determined by the extent of DNA strand breaks and alkali-labile sites of the DNA of peripheral mononuclear blood cells from seven roof ers, 18 road paving workers, and nine bitumen painters. In order to ev aluate short-term genotoxic effect the workers were investigated on Fr idays and on Mondays after a weekend free of occupational exposure. Th e roofers (all cigarette smokers) showed a significantly (P < 0.002) 4 3% higher mean level of alkaline DNA strand breaks on Friday than did the ten smoking controls included in this study. Also, comparison of t he individual levels of alkaline strand breaks on Mondays and on Frida ys revealed a significant increase (P < 0.05, Wilcoxon test) during th e work week. In the road paving workers and the bitumen painters no st atistically significant difference in the mean levels of alkaline stra nd breaks could be found compared to controls either for the measureme nt on Mondays or for that on Fridays. However, interesting tendencies were observed. As in the group of roofers, the mean level of alkaline DNA strand breaks as well as the majority of the individual levels of alkaline strand breaks of road paving workers was higher on Fridays th an on Mondays. In contrast, bitumen painters exhibited a relatively hi gh level of alkaline DNA strand breaks on Mondays and a decreased mean level of strand breaks on Fridays. DNA adducts could be detected at a low level (up to 2.9 adducts per 10(9) bases) in 10 of 14 road paving workers and bitumen painters using the P-32-postlabelling assay. The number of DNA adducts correlated with the years spent in the present j ob. Road paving workers and bitumen painters showed only suggestive ev idence for a possible genotoxic effect due to their occupational expos ure. Because we cannot exclude the formation of DNA cross-links in the se workers, a more detailed investigation of the hazard is urgently ne eded. For roofers, substantial genotoxic damage in peripheral mononucl ear blood cells was observed in this study.