This study was aimed to
This study was aimed to assess a number of esterase activities, namely erythrocyte AChE, plasma BuChE and BeChE, and serum PON1 towards a number of substrates, as well as the major genetic polymorphisms of BCHE and PON1in a cohort of greenhouse workers exposed to low toxicity pesticides under an integrated production system for achieving a sustainable use of pesticides.
Material and methods
Results Results of the cholinesterase and PON1activities toward different substrates for greenhouse workers and controls at the two study periods (low and high pesticides exposure) are presented in Table 1. This table shows the results of a mixed model analysis adjusted for high vs. low exposure period, greenhouse workers vs. controls and the interaction term [high vs. low exposure period] X [greenhouse workers vs. controls]. This analysis takes account of changes of esterase levels from workers and controls across the two study periods. Significant differences for the interaction term were observed for AChE, BeChE and AREase. In the case of AChE, greenhouse workers exhibited lower levels than controls in both periods, but differences became more pronounced at the things of high pesticide exposure. In contrast, BeChE and AREase were always higher in greenhouse workers than in control subjects, with differences being less pronounced in the period of high pesticide exposure. Despite these findings, lower levels of BeChE and AREase were observed in greenhouse workers at the period of higher exposure to pesticides. Table 2 shows the correlation analysis between the esterase activities assayed in the two study periods. An inverse correlation was observed between AChE and all PON1 activities but DHCase in the period of high pesticide exposure. Although AChE was significantly correlated with BeChE in both study periods, no significant association was found for BuChE. However, BuChE showed a positive correlation with AREase in both study periods, and with DZOase and DHCase in the period of high exposure season. AREase was significantly correlated with all cholinesterase activities and with DZOase, but not with POase, ssPOase and DHCase at the low exposure season. When comparing the two study periods, similar correlations (in terms of magnitude and statistical significance) are observed between BeChE and AREase, BeChE and DZOase, BuChE and AREase, DZOase and DHCase as well as between POase and ssPOase. In contrast, a higher coefficient of correlation was found for the pairs AChE-POase, AChE-DHCase, AREase-DZOase, AREase-DHCase at the period of higher pesticide exposure. Linear mixed models with participant as random intercept were adjusted for period of high vs. low exposure to pesticides, greenhouse workers vs. control subjects, sex, age, BMI, nationality, alcohol consumption and BCHE and PON1 genetic polymorphisms as fixed effects (Table 3). Greenhouse workers exhibited higher levels of BeChE, BuChE, POase, AREase, DZOase and lower levels of AChE and DHCase than control subjects. When the period of high pesticide exposure was compared to the one of low exposure, significant (or near-significant) differences were observed for all enzyme activities but AChE, ssPOase and AREase. Regarding gender differences, males showed higher levels of BeChE, BuChE and POase than females. On the other hand, Spanish showed higher levels of the three cholinesterase activities and DHCase than immigrant Moroccan workers. BMI was significantly associated with higher BeChE, BuChE and ssPOase activities, whereas alcohol consumption was associated with increased BuChE and AREase activities. Regarding the modulatory effect of the genetic polymorphisms studied on esterase activities, the BCHE-K variant was associated with higher AChE and lower BeChE, but showed no association with BuChE. Subjects heterozygous for the BCHE-A polymorphism had lower DZOase and DHCase. PON1 192 gene polymorphism was significantly associated with all PON1 activities (though in a different sense for POase/ssPOase versus AREase, DZOase and DHCase) and with AChE. While PON1 -108 gene polymorphism showed a significant association with all PON1 activities (always in the same sense), PON1 55 was found to be significantly associated only with AREase and DZOase.