Risk assessment of chlorpyrifos (organophosphate pesticide) associated with dermal exposure in chilli-growing farmers at Ubonrachatani province, Thailand

Risk assessment of chlorpyrifos (organophosphate pesticide) associated with dermal exposure in chilli-growing farmers was studied during growing season from December 2009 to January 2010 at Hua-rau sub-district, Muang district, Ubonratchathani province, Thailand. Chlorpyrifos residue on chilli-growing farmers’ hands after spraying were collected using hand-wiping technique from 35 farmers (26 men and 9 women) by using simple random sampling technique from all chilli- growing farmers in this area. The results showed that an age range of the participants was 40-50 years old. The average weight (mean±SD) was 56.3±11.1 Kg. Hand surface areas of male and female were 0.088 sq.m. and 0.075 sq.m., respectively. The mean concentration (±SD) of chlorpyrifos analyzed by using gas chromatograph with a selective detector, flame photometric detector (FPD) was 6.95±18.24 mg/kg/two hands (0.01-98.59 mg/kg/two hands). To evaluate health risk of the chilli-growing farmers in this community, an average daily dose (ADD) was calculated using reasonable maximum exposure (RME) at 95th percentile of chlorpyrifos concentration in order to health awareness and prevention. The ADD of farmers was 2.51 x 10[superscript -9] mg/kg/day and the ADD of male farmers (2.57 x 10[superscript -9] mg/kg/day) was higher than female farmers (2.41 x 10-9 mg/kg/day). Using hazard quotient (HQ) for risk characterization, it indicated that the HQ of farmers was lower than the acceptable level 1.0 (HQ = 1.67 x 10[superscript -6]). Both of the HQ for male and female farmers were lower than the acceptable level, 1.71 x 10[superscript -6] and 1.61 x 10[superscript -6], respectively. In conclusion, the chilli-growing farmers were not at risk with non-carcinogenic effects from dermal exposure. This study suggests that other exposure routes e.g. inhalation and oral should be considered and evaluated because the farmers had mentioned on acute and repeated or prolonged effects of organophosphates after their application.