title: Farmworker exposure to organophosphorus pesticide residues during apple thinning in central Washington State.
abstract: The purpose of this study was to characterize worker exposure to azinphos-methyl (Guthion) over an entire 4-6 week apple-thinning season. Twenty workers from three work sites in the Chelan-Douglas County region of Washington state were recruited for the study. Exposure potential was estimated by dislodgeable foliar residue measurements, and individual exposures were estimated by biological monitoring through urinary metabolites. Measureable azinphos-methyl residues were found on apple foliage at all sites throughout the six-week sampling period, indicating continuous exposure potential (median residue level of 0.5 microgram/cm2). Measurable levels of the urinary dialkylphosphate metabolite, DMTP, were found in virtually all urine samples (limit of detection = 0.04 microgram/mL). Mean DMTP concentrations differed significantly across sites (0.53, 0.29, and 0.90 microgram/mL for Sites 1-3, respectively; analysis of variance, p < .002), and intraindividual variability was much greater than interindividual differences. Group mean DMTP concentrations at each site fluctuated according to foliar residue levels. Measurable DMTP concentrations were found in 9% of reference workers, ranging from 0.04-0.18 microgram/mL. Cholinesterase activity levels monitored with a field test kit were not considered reliable due to temperature changes of the instrument.
authors.affiliation: Field Research and Consultation Group, University of Washington, Seattle 98195, USA.
authors.forename: N J
authors.initials: NJ
authors.lastname: Simcox
authors.forename: J
authors.initials: J
authors.lastname: Camp
authors.forename: D
authors.initials: D
authors.lastname: Kalman
authors.forename: A
authors.initials: A
authors.lastname: Stebbins
authors.forename: G
authors.initials: G
authors.lastname: Bellamy
authors.forename: I C
authors.initials: IC
authors.lastname: Lee
authors.forename: R
authors.initials: R
authors.lastname: Fenske
mesh_terms: D000293:Adolescent; D000328:Adult; D000382:Agricultural Workers' Diseases / Q000097:blood / Q000139:chemically induced* / Q000652:urine; D001387:Azinphosmethyl / Q000009:adverse effects / Q000032:analysis*; D016022:Case-Control Studies; D002800:Cholinesterase Inhibitors / Q000009:adverse effects / Q000032:analysis*; D005260:Female; D005506:Food Contamination; D006801:Humans; D007306:Insecticides / Q000009:adverse effects / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis*; D019685:Rosales; D012621:Seasons; D014861:Washington
chemical_list: D002800:Cholinesterase Inhibitors; D007306:Insecticides; D001387:Azinphosmethyl