Abstract
Levels of exposure to dichlorvos by farmers were investigated during or after the application of the organophorous insecticide to an apple orchard. One farmer applied 500 g of the pesticide as an active ingredient to the 30-are orchard for 20 min with an airblast sprayer. During the spraying work, a large amount of the chemical fell on his head and arms, but the quantities on his trunk and legs were smaller. The operator's dermal exposure level was estimated at 4.4 mg (=56μg/kg of b. w.), or 0.0009% of the total amount of dichlorvos sprayed. At 1 hr and 6 hrs after application, two other farmers entered the orchard for 30 min. They were expected to be systemically exposed to a small amount of the pesticide residues through contact with apple plants first entry, and their estimated exposure levels were 105 to 120μg (1.8-2.3μg/kg). However, it was found that the apple growers were not exposed to the residues during the subsequent reentry. The residue of 331 ng/cm2 at the initial entry reduced rapidly thereafter and was not detected on the leaves at 2 days after application. Although the mean level of the pesticide in the air was 13.9μg/m3 at 1 hr, it lowered also rapidly and was not found at 1 day after application. It was considered that the workers in the orchard were not affected at 1 day after the spraying of dichlorvos.
