title: Distributions and determinants of pre-emergent herbicide exposures among custom applicators.
abstract: Custom applicators intensively apply herbicides to corn and soybean fields each spring. The primary objective of this study was to characterize the exposure distributions of the herbicides alachlor, atrazine, 2,4-D 2-ethylhexyl ester (2,4-D EH), and metolachlor among a group of applicators during the spring pre-emergent spray season. A secondary objective was to evaluate determinants of exposure and to estimate within- and between-worker variance components. Fifteen applicators were sampled using a systematic design that included spray and non-spray days and multiple measurements (five to seven) on each applicator. Air, patch, and handwash samples were collected on 89 applicator-days. Applicator-days were classified into three categories: target herbicide sprayed, non-target herbicide sprayed, and no herbicide sprayed. Mixed-model regression analysis was used. For all exposure metrics, adjusted mean herbicide exposures were significantly higher on days when target herbicides were sprayed as compared to non-spray days. For 2,4-D EH only, adjusted mean exposures on non-target herbicide spray days were significantly higher than on non-spray days. Wearing gloves significantly reduced adjusted mean hand exposure for all herbicides (4-20 fold) and adjusted mean thigh exposure for three herbicides (8-53 fold) on days the herbicides were sprayed; however, wearing gloves significantly increased adjusted mean atrazine hand and thigh exposures (9 and 7 fold, respectively) on days that non-atrazine herbicides were sprayed. Few of the other covariates were consistent determinants of exposure. For all exposure metrics, the within-worker variability (GSD(W) 2.1-5.6) was greater than the between-worker variability (GSD(B) 1.2-2.7).
authors: National Institute for Occupational Safety and Health, 4676 Columbia Parkway, Cincinnati, OH 45226, USA. cjh8@cdc.gov
authors: C J
authors: CJ
authors: Hines
authors: J A
authors: JA
authors: Deddens
authors: S P
authors: SP
authors: Tucker
authors: R W
authors: RW
authors: Hornung
mesh_terms: D000328:Adult; D000383:Agriculture; D004867:Equipment Design; D017575:Gloves, Protective; D006540:Herbicides / Q000009:adverse effects; D006801:Humans; D016013:Likelihood Functions; D008875:Middle Aged; D016273:Occupational Exposure / Q000032:analysis / Q000517:prevention & control / Q000706:statistics & numerical data*; D009820:Ohio; D012044:Regression Analysis
chemical_list: D006540:Herbicides