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  • To investigate the simultaneous effects

    2021-11-25

    To investigate the simultaneous effects of possible confounding factors in the urinary 1-OHP excretion, multivariate regression analysis was performed (Table 3). Based on stepwise regression analysis, four independent variables (age, CYP1A1⁎4, GSTM1 and GSTP1 polymorphisms) entered into the final model when the exposed group was analyzed. The GSTP1 and CYP1A1⁎2A polymorphisms did not contribute significantly to the prediction of urinary 1-OHP levels. In the non-exposed group, increasing age decreased the 1-OHP levels (P<0.05).
    Discussion Our study was targeted at the exposure of sugarcane workers to PAHs, on which there are few studies available in the literature. We assessed the influence of the CYP1A1, GSTM1, GSTT1 and GSTP1 polymorphisms on the effects of occupational exposure to PAHs in two different moments, during harvesting time (exposed) and during non-harvesting time (non-exposed). This evaluation of the same group in two different moments has the advantage of minimizing interindividual differences in metabolism and life-style. The urinary level of the pyrene metabolite 1-OHP has been suggested as a biomarker of exposure to PAHs, due to the high sensitivity of the analytical method, and also in order to take into account all the exposure routes (Alexandrie et al., 2000). Furthermore, in occupational settings the urinary content of 1-OHP may be increased 10–100-fold (Alexandrie et al., 2000, Kato et al., 2004). Our results agree with this finding. The level of 1-OHP in the exposed group was nine times higher than in the non-exposed. Large variations in urinary 1-OHP were found among the sugarcane workers. The mean concentration of urinary 1-OHP was significantly higher in the exposed than in the non-exposed sugarcane workers. There was also a significant difference between the cisapride australia of 1-OHP in the group of exposed sugarcane workers and in the group of non-occupationally exposed subjects. When the urinary levels of 1-OHP of the non-exposed sugarcane workers were compared with those of the control group, no significant difference was found. These data indicate that, when the workers were not exposed to burnt sugarcane fields, their urinary 1-OHP levels were equivalent to those found in non-occupationally exposed individuals. The half-life of 1-OHP is reported to be 18.6 h (Lu et al., 2002), and the urine of the sugarcane workers during the non-harvest time was collected three months after the harvest time. In only two individuals, the 1-OHP urinary levels were higher during the non-harvesting time. This may be attributable to the ingestion of fried, grilled or barbecued meat and the proximity to smokers or other sources which could also lead to the inhalation of smoke components in the 24 h preceding the urine sampling. Analysis for outliers was done and the result remained the same. Only nonsmokers were selected for this study, once the smoking habit has a strong effect on the urinary concentrations of 1-OHP (Clonfero et al., 1995). Additionally, Hung et al. (2004) reported that inducibility of PAH metabolism contributes to cancer risk in smokers and Hecht et al. (2005) showed that smoking induces the diol epoxide metabolic activation pathway of phenanthrene. A number of other factors have shown to influence the concentration of PAHs, such as habitation, transportation and seasonal variation (Sato et al., 1995, Adonis et al., 2003). We consider that these factors did not affect our results since the sample analyzed was composed by sugarcane workers living in non-polluted small towns and were all transported to work by buses. The non-occupationally exposed individuals also got to work by bus or car. Some studies have shown higher concentration of airborne particulate material during the winter and spring (e.g., Sato et al., 1995) while other studies failed to detect seasonal variation of PAHs concentration (e.g., Merlo et al., 1998). We are confident that the levels of PAHs were not influenced by seasonal variation because the urine samples of the exposed workers and of the non-occupationally exposed individuals were collected practically in the same period (winter and spring) and the level of the first group were significantly higher than the last.