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Toluene is an organic solvent used in numerous processes and products, including industrial paints. Toluene neurotoxicity and reproductive toxicity are well recognized; however, its genotoxicity is still under discussion, and toluene is not classified as a carcinogenic solvent. Using the comet assay and the micronucleus test for detection of possible genotoxic effects of toluene, we monitored industrial painters from Rio Grande do Sul, Brazil. The putative involvement of oxidative stress in genetic damage and the influences of age, smoking, alcohol consumption, and exposure time were also assessed. Although all biomarkers of toluene exposure were below the biological exposure limits, painters presented significantly higher DNA damage (comet assay) than the control group; however, in the micronucleus assay, no significant difference was observed. Painters also showed alterations in hepatic enzymes and albumin levels, as well as oxidative damage, suggesting the involvement of oxidative stress. According to multiple linear regression analysis, blood toluene levels may account for the increased DNA damage in painters. In summary, this study showed that low levels of toluene exposure can cause genetic damage, and this is related to oxidative stress, age, and time of exposure.

We studied the utilization of protein-hydrolyzed sweet cheese whey as a medium for the production of beta-galactosidase by the yeasts Kluyveromyces marxianus CBS 712 and CBS 6556. The conditions for growth were determined in shake cultures. The best growth occurred at pH 5.5 and 37 degrees C. Strain CBS 6556 grew in cheese whey in natura, while strain CBS 712 needed cheese whey supplemented with yeast extract. Each yeast was grown in a bioreactor under these conditions. The strains produced equivalent amounts of beta-galactosidase. To optimize the process, strain CBS 6556 was grown in concentrated cheese whey, resulting in a higher beta-galactosidase production. The beta-galactosidase produced by strain CBS 6556 produced maximum activity at 37 degrees C, and had low stability at room temperature (30 degrees C) as well as at a storage temperature of 4 degrees C. At -4 degrees C and -18 degrees C, the enzyme maintained its activity for over 9 weeks.

Twenty pharmacists and nurses handling anti-neoplastic drugs in a hospital were monitored during a working week, from Monday to Friday, in the morning (only on Monday) and afternoon (all days). Genotoxicity was analysed by the comet assay and the micronucleus (MN) test, while oxidative stress was analysed in serum by thiobarbituric acid reactive substances (TBARS) and by measurements of the antioxidant enzymes superoxide dismutase (Sod) and catalase (Cat). The exposed workers presented increased DNA damage levels by the comet assay as compared to the controls. The comet assay results have also shown significant positive correlation with the day of the week and with alcohol consumption. MN frequency was significantly higher in the exposed workers and presented noteworthy correlation with age and working time. In the oxidative stress parameters, only Cat presented a significant increase in the exposed group, considering all the samplings. However, TBARS data showed interesting results, considering the different sampling times; the exposed group presented a significant correlation with the working days and significantly higher results on Friday as compared to the controls and Monday morning. Monitoring occupational risk during a longer time, e.g. during a working week as done in this study, introduces additional aspects of risk behaviour, which can improve risk management. This study demonstrates the usefulness of evaluating oxidative stress also in genotoxic risk assessment since both events often result from the same factors.

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