title: Assessment of a pesticide exposure intensity algorithm in the agricultural health study.
abstract: The accuracy of the exposure assessment is a critical factor in epidemiological investigations of pesticide exposures and health in agricultural populations. However, few studies have been conducted to evaluate questionnaire-based exposure metrics. The Agricultural Health Study (AHS) is a prospective cohort study of pesticide applicators who provided detailed questionnaire information on their use of specific pesticides. A field study was conducted for a subset of the applicators enrolled in the AHS to assess a pesticide exposure algorithm through comparison of algorithm intensity scores with measured exposures. Pre- and post-application urinary biomarker measurements were made for 2,4-D (n=69) and chlorpyrifos (n=17) applicators. Dermal patch, hand wipe, and personal air samples were also collected. Intensity scores were calculated using information from technician observations and an interviewer-administered questionnaire. Correlations between observer and questionnaire intensity scores were high (Spearman's r=0.92 and 0.84 for 2,4-D and chlorpyrifos, respectively). Intensity scores from questionnaires for individual applications were significantly correlated with post-application urinary concentrations for both 2,4-D (r=0.42, P<0.001) and chlorpyrifos (r=0.53, P=0.035) applicators. Significant correlations were also found between intensity scores and estimated hand loading, estimated body loading, and air concentrations for 2,4-D applicators (r-values 0.28-0.50, P-values<0.025). Correlations between intensity scores and dermal and air measures were generally lower for chlorpyrifos applicators using granular products. A linear regression model indicated that the algorithm factors for individual applications explained 24% of the variability in post-application urinary 2,4-D concentration, which increased to 60% when the pre-application urine concentration was included. The results of the measurements support the use of the algorithm for estimating questionnaire-based exposure intensities in the AHS for liquid pesticide products. Refinement of the algorithm may be possible using the results from this and other measurement studies.
authors.affiliation: US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA. thomas.kent@epa.gov
authors.forename: Kent W
authors.initials: KW
authors.lastname: Thomas
authors.forename: Mustafa
authors.initials: M
authors.lastname: Dosemeci
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Coble
authors.forename: Jane A
authors.initials: JA
authors.lastname: Hoppin
authors.forename: Linda S
authors.initials: LS
authors.lastname: Sheldon
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Chapa
authors.forename: Carry W
authors.initials: CW
authors.lastname: Croghan
authors.forename: Paul A
authors.initials: PA
authors.lastname: Jones
authors.forename: Charles E
authors.initials: CE
authors.lastname: Knott
authors.forename: Charles F
authors.initials: CF
authors.lastname: Lynch
authors.forename: Dale P
authors.initials: DP
authors.lastname: Sandler
authors.forename: Aaron E
authors.initials: AE
authors.lastname: Blair
authors.forename: Michael C
authors.initials: MC
authors.lastname: Alavanja
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000032:analysis* / Q000652:urine; D000383:Agriculture; D000395:Air Pollutants, Occupational / Q000032:analysis / Q000652:urine; D000465:Algorithms; D015415:Biomarkers / Q000652:urine; D004390:Chlorpyrifos / Q000032:analysis* / Q000652:urine; D015331:Cohort Studies; D004781:Environmental Exposure / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007484:Iowa; D016014:Linear Models; D009657:North Carolina; D016273:Occupational Exposure / Q000032:analysis*; D010575:Pesticides / Q000032:analysis* / Q000652:urine; D018570:Risk Assessment / Q000379:methods*; D012869:Skin Absorption; D011795:Surveys and Questionnaires
chemical_list: D000395:Air Pollutants, Occupational; D015415:Biomarkers; D010575:Pesticides; D015084:2,4-Dichlorophenoxyacetic Acid; D004390:Chlorpyrifos