Human pesticide exposure analysis: Urine biomarkers of organophosphorus insecticides, malathion, 2,4-D, and triclopyr

Pesticides are still the most widely used chemical technology in pest management. Their risk assessment is critical for their safe use and any involved uncertainties need to be investigated. Three individual studies were performed to resolve those uncertainties in exposure assessment.; Organophosphorous (OP) insecticide metabolism in treated produce yields dialkylphosphates (DAPS). OP metabolism in humans also produces urinary DAPs. Dosage cannot be reliably estimated from urinary DAPs. Produce samples positive for OPs were selected from the channels of trade and further analyzed for 6 DAPs residues. Ninety-one of 153 (60%) samples contained more DAPs than OPs. Mole ratios of DAPs: OP ranged 0.02 to 73 with a median 1.7. Preformed DAPs represent false positives when OP exposure is estimated from urinary DAPs.; Previous studies found moisture could enhance pesticide transferability and absorption. To investigate the impact of moisture under the actual exposure scenario, 24 strawberry harvesters were randomly assigned to work either in the morning or afternoon in a malathion treated strawberry field. Dislodgeable foliar residue (DFR), gloves dosimetry, clothing dosimetry, and urine biomonitoring were included. Morning malathion sleeves residues were 4 to 9 times higher than afternoon residues. Glove residues were 3 to 12 times higher while malathion biomarkers were similar following AM or PM exposure. Therefore, foliage moisture increases malathion transferability but was not associated with absorbed dose.; The third study concerned the consistency of exposure monitoring strategies for workers using backpack sprayers to apply 2,4-D and triclopyr concurrently for weed control in forestry. Using coveralls, triclopyr and 2,4-D exposures were 2.50 +/- 1.55 and 0.75 +/- 0.52 mg equiv/day while whole body dosimeters gave 0.22 +/- 0.23 and 0.14 +/- 0.17 mg equiv/day, respectively. The absorbed doses and dosages based on urinalysis were 5.2 +/- 4.3 mug equiv/day and 0.072 +/- 0.057 mug equiv/kg-day (triclopyr); 3.8 +/- 3.4 mug equiv/day and 0.052 +/- 0.044 mug equiv/kg-day (2,4-D). Exposure estimates from coveralls were more than 2 orders of magnitude greater than biomonitoring estimates.; These studies indicated the pre-formed DAPS, moisture, and concurrent use of passive dosimetry and biomonitoring can be significant determinants in pesticide exposure assessment.