8-Hydroxydeoxyguanosine (8-OHdG) levels in urinary samples of pesticide sprayers on exposure to organophosphorus pesticides.

ABSTRACT

Background: Free radicals and other reactive species are constantly generated in vivo and cause oxidative damage to biomolecules. DNA is probably the most biologically significant target of oxidative attack. Among numerous types of oxidative DNA damage the formation of 8-hydroxyguanosine (8-OHdG) is a sensitive biomarker of oxidative stress, an adduct formed as a result of biochemical reaction between ROS and DNA. Chronic exposure to Organophosphorus (OP) pesticides is implicated in many health conditions that result from the induction of oxidative stress, including cytogenetic damage. The main objective of the study was to evaluate the biochemical levels of 8-OHdG in spot urinary samples under the exposed OP pesticide sprayers and farm workers. Methods: In this study, 51 male pesticide sprayers and 39 farm workers in the age group of 18-47 years having exposure ranged from 3 to 15 years in duration were selected. The referents (n=31) were selected on the same criteria as well as they were never exposed to pesticides at any time. This study was conducted during the growing season (January, 2009 – September, 2010). The most commonly used OP pesticides like chlorpyriphos, Diazinon, Dimethioate, Monocrotofos etc., were used in this study. Urine samples from each participant were taken in sterile tubes and were stored at -200C till analysed. The concentration of 8-OHdG in samples were analyzed using ELISA. Results: The urinary levels of 8-OHdG were found to be significantly higher in the farm workers and pesticide sprayers in contrast to the level observed in the control group (p<0.05). When the data was analyzed in the exposed groups in relation to duration of exposure it was found that both the farm workers and sprayers who were exposed to OP pesticides for less than 5 years showed the maximum mean values of 8-OHdG in comparison to those exposed to for more than 10 years. Conclusions: In view of this regular bio monitoring studies in target human populations are imperative necessary due to frequent changes in pesticide formulations and introduction of newer pesticides. Despite that several life style factors may influence the urinary concentrations of 8-OHdG but still this non-invasive bio-marker 8-OHdG is preferred over other invasive techniques to evaluate the environmental and occupational exposure effect of OP pesticides on the genotoxicity of the exposed workers.