BIOLOGICAL MONITORING OF EXPOSURE TO CHLORPYRIFOS-METHYL BY ASSAY OF URINARY ALKYLPHOSPHATES AND 3,5,6-TRICHLORO-2-PYRIDINOL

The results of biological monitoring by assay of urinary 3,5,6-trichlo ro-2-pyridinol and alkylphosphates (DMP, DMTP) in groups of 9 and 2 wo rkers exposed to chlorpyrifos-methyl during vine spraying and manual l eaf thinning 5-11 d after spraying, respectively, are reported. The re sults are compared with those of a control group of 46 subjects not oc cupationally exposed to organophosphate insecticides. Significantly hi gher urinary excretion of metabolites (Mann-Whitney U-test) was found in both groups than in controls. Levels of 3,5,6-trichloro-2-pyridinol (mean +/- SD) were 15.9 + 10.6 nmol/g creatinine (n = 33) for control s, 92.4 + 162.5 nmol/g creatinine (n = 20) for manual workers, and 675 .5 + 1110.8 nmol/g creatinine (n = 48) for workers spraying and mixing the insecticide. Levels of DMP (mean +/- SD) were 63.8 + 100.1 nmol/g creatinine (n = 42), 123.0 + 79.0 nmol/g creatinine (n = 20), and 577 .2 + 1003.2 nmol/g creatinine (n = 67), respectively, for the same 3 g roups. Levels of DMTP (mean +/- SD) were 153.4 + 764.4 nmol/g creatini ne (n = 43), 489.3 + 288.3 nmol/g creatinine (n = 20), and 297.6 + 215 .4 nmol/g creatinine (n = 61), respectively, for the same 3 groups. Go od correlations were found between urinary excretion of 3,5,6-trichlor o-2-pyridinol and DMP (r = .776 for manual workers; r = .775 for worke rs mixing and spraying the insecticide) or DMTP (r = .558 and r = .746 , respectively for the same 2 groups). The peak of excretion of the th ree metabolites war found in urine samples collected the night after t he spraying or leaf thinning operations.