β-Glucuronidase activity is a sensitive biomarker to assess low-level organophosphorus insecticide exposure

Acetylcholinesterase and butyrylcholinesterase (BChE) activities in blood are widely used as the biomarkers for organophosphorus insecticide (OP) exposure. In the present study, we conducted a cross-sectional study to evaluate plasma β-glucuronidase (BG), a sensitive biomarker candidate for OP exposure, BChE activities and urinary dialkyl phosphates (DAPs), OP metabolites. We assessed the relationship between these biomarker levels in the following groups: 32 controls (control), 21 pest control operators and their co-workers who had not sprayed OPs within 3 days prior to sample collection (PCO1), and 21 pest control operators who sprayed OPs within those 3 days (PCO2). Logarithmically transformed age-adjusted means of DAPs were 3.88, 5.62 and 6.45 nmol/g creatinine for control, PCO1 and PCO2, respectively (P < 0.001 for difference, P < 0.001 for trend). Logarithmically transformed age-adjusted means of BG were 1.40, 1.52 and 1.85 μmol/L/h for control, PCO1 and PCO2, respectively. BG activity, but not BChE, was increased according to their OP exposure level (P = 0.038 for difference, P = 0.026 for trend). It was concluded that plasma BG activity is more sensitive biomarker as well as urinary OP metabolites than BChE for low-level exposure in humans.