BIOMARKERS OF STYRENE EXPOSURE IN LAMINATION WORKERS - LEVELS OF O-6-GUANINE DNA-ADDUCTS, DNA STRAND BREAKS AND MUTANT FREQUENCIES IN THE HYPOXANTHINE-GUANINE PHOSPHORIBOSYLTRANSFERASE GENE IN T-LYMPHOCYTES

Occupational exposure to styrene was studied in nine workers of a hand lamination plant in Bohemia, Personal dosimeters were used to monitor the styrene workplace exposure, and the levels of styrene in blood an d mandelic acid in urine were measured, Blood samples were taken at fo ur occasions during a 7 month period to determine styrene-specific O-6 -guanine DNA adducts in lymphocytes and granulocytes, DNA strand break s and hypoxanthine guanine phosphoribosyltransferase (HPRT) mutant fre quency in T-lymphocytes, Seven administrative employees in the same fa ctory (factory controls) and eight persons in a research laboratory (l aboratory controls) were used as referents, DNA adduct levels determin ed by the P-32-postlabelling method in lymphocytes of laminators were remarkably constant and significantly higher (P < 0.0001) than in fact ory controls at all four sampling times, HPRT mutant frequencies (MF) measured by the T-cell cloning assay were higher in the laminators (17 .5x10(-6), group mean) than in the factory controls (15.7x10(-6), grou p mean) at three of the four sampling times, but the differences were not statistically significant. However, a statistically significant (P = 0.021) difference between MF in the laminators (18.0X10(-6), group mean) and laboratory controls (11.8X10(-6), group mean) was observed a t sampling time 4 (the only sampling time when this latter group was s tudied), This result indicates that styrene exposure may induce gene m utation in T-cells in vivo. DNA strand breaks were studied by the 'Com et assay' at the fourth sampling time, The laminators were found to ha ve significantly higher levels of DNA strand breaks than the factory c ontrols (P = 0.032 for tail length, TL; P = 0.007 for percentage of DN A in tail, T%; and P = 0.020 for tail moment, TM), A statistically sig nificant correlation was also found between the levels of lymphocyte D NA adducts and all three DNA strand break parameters (TL P = 0.046; T% P = 0.026 and TM P = 0.034). On the contrary, no significant correlat ions were found between DNA adduct levels and the HPRT mutant frequenc ies or between the mutant frequencies and DNA strand breaks, Taken tog ether, these results add further support to the genotoxic and possibly mutagenic effects of styrene exposure in vivo. However, no simple qua ntitative relationship seems to exist between the levels of styrene-in duced DNA damage and frequency of HPRT mutation in T-lymphocytes.