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Bruce H. Alexander,¹ Jack S. Mandel,² Beth A. Baker,^1,3 Carol J. Burns,⁴ Michael J. Bartels,⁴ John F. Acquavella,^5,6 and Christophe Gustin⁵

¹University of Minnesota, School of Public Health, Minneapolis, Minnesota, USA; ²Emory University, Rollins School of Public Health, Atlanta, Georgia, USA; ³University of Minnesota, School of Medicine, Minneapolis, Minnesota, USA; ⁴The Dow Chemical Company, Midland, Michigan, USA; ⁵Monsanto Company, St. Louis, Missouri, USA; ⁶Amgen, Thousand Oaks, California, USA

Abstract
Objective: We estimated 2,4-dichlorophenoxyacetic acid (2,4-D) exposure and systemic dose in farm family members following an application of 2,4-D on their farm.

Methods: Farm families were recruited from licensed applicators in Minnesota and South Carolina. Eligible family members collected all urine during five 24-hr intervals, 1 day before through 3 days after an application of 2,4-D. Exposure profiles were characterized with 24-hr urine 2,4-D concentrations, which then were related to potential predictors of exposure. Systemic dose was estimated using the urine collections from the application day through the third day after application.

Results: Median urine 2,4-D concentrations at baseline and day after application were 2.1 and 73.1 µg/L for applicators, below the limit of detection, and 1.2 µg/L for spouses, and 1.5 and 2.9 µg/L for children. The younger children (4–11 years of age) had higher median post-application concentrations than the older children (≥ 12 years of age) (6.5 vs. 1.9 µg/L) . The geometric mean systemic doses (micrograms per kilogram body weight) were 2.46 (applicators) , 0.8 (spouses) , 0.22 (all children) , 0.32 (children 4–11 years of age) , and 0.12 (children ≥ 12 years of age) . Exposure to the spouses and children was primarily determined by direct contact with the application process and the number of acres treated. Multivariate models identified glove use, repairing equipment, and number of acres treated as predictors of exposure in the applicators.

Conclusions: We observed considerable heterogeneity of 2,4-D exposure among farm family members, primarily attributable to level of contact with the application process. Awareness of this variability and the actual magnitude of exposures are important for developing exposure and risk characterizations in 2,4-D–exposed agricultural populations.

Key words: 2, 4-D, biomonitoring, epidemiologic studies, herbicide, pesticide exposure. Environ Health Perspect 115:370–376 (2007) . doi:10.1289/ehp.8869 available via http://dx.doi.org/ [Online 14 December 2006]

Address correspondence to B.H. Alexander, Division of Environmental Health Sciences, School of Public Health, University of Minnesota, MMC 807 Mayo Building, Room 1260, 420 Delaware St. S.E. Minneapolis, MN 55455 USA. Telephone: (612) 625-7934. Fax: (612) 626-4837. E-mail: balex@umn.edu

We thank participating families for their cooperation and the FFES Advisory Panel, chaired by H. Pastides, for their guidance.

This study was funded by a grant to the University of Minnesota from Bayer, Dow, DuPont, FMC, Monsanto, Syngenta, and the American Chemistry Council.

C.J.B. and M.J.B. are employed by Dow Chemical Company, which manufactures the chemical 2,4-D. J.F.A. was previously and C.G. is currently employed by Monsanto, which manufactures agricultural chemicals. J.S.M. formerly worked for Exponent, a consulting firm whose clients include chemical manufacturing companies that produce agricultural chemicals.