Cytogenetic and DNA damage on workers exposed to styrene

Styrene is a commercially important chemical widely used in the manufacture of synthetic rubber, resins, polyesters and plastics. The highest levels of human exposure to styrene occur during the production of reinforced plastic products. The objective of this work was to evaluate both DNA and cytogenetic damage in styrene-exposed workers, analysing only non-smoker individuals. Environmental levels of styrene and urinary concentrations of mandelic and phenylglyoxylic acids were determined, and genetic damage was studied by means of micronucleus (MN) test, sister chromatid exchanges (SCEs) and comet assay. Fifty-two fibreglass-reinforced plastics workers and 54 controls took part in the study. The mean air concentration of styrene in the breathing zone of workers exceeded the threshold limit value, and 24 workers exceeded the biological exposure index. A strong and significant correlation was found between styrene environmental concentrations and urinary metabolites. Higher SCE rate (P<0.01) was observed in exposed workers than in controls. Besides, significant correlations were obtained for SCE rate with both environmental and internal exposure parameters (r=0.496, P<0.01 and r=0.511, P<0.01, respectively). Results from MN test and comet assay showed slight and non-significant increases related to the exposure. Our data seem to support previous studies reporting genotoxicity associated with occupational exposure to styrene, excluding the confounding influence of smoking, although caution must be taken in the interpretation of these results since the significance of an increase in SCE rate is still unclear.