Cancer incidence among pesticide applicators exposed to metolachlor in the Agricultural Health Study

Authors

  • Jennifer A. Rusiecki,

    Corresponding author
    1. Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Rockville, MD, USA
    • Uniformed Services University of the Health Sciences, Dept. of Preventive Medicine and Biometrics, 4301 Jones Bridge Rd., PMB Room A1039, Bethesda, MD 20814-4799, USA
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    • Fax: +301-295-1854.

  • Lifang Hou,

    1. Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Rockville, MD, USA
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  • Won Jin Lee,

    1. Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Rockville, MD, USA
    2. Department of Preventive Medicine, College of Medicine, Korea University, Seoul, Republic of Korea
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  • Aaron Blair,

    1. Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Rockville, MD, USA
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  • Mustafa Dosemeci,

    1. Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Rockville, MD, USA
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  • Jay H. Lubin,

    1. Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Rockville, MD, USA
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  • Matthew Bonner,

    1. Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Rockville, MD, USA
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  • Claudine Samanic,

    1. Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Rockville, MD, USA
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  • Jane A. Hoppin,

    1. Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, USA
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  • Dale P. Sandler,

    1. Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, USA
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  • Michael C.R. Alavanja

    1. Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Rockville, MD, USA
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Abstract

Metolachlor is one of the most widely used herbicides in the United States. We evaluated the incidence of cancer among pesticide applicators exposed to metolachlor in the Agricultural Health Study, a prospective cohort study of licensed pesticide applicators in Iowa and North Carolina. A total of 50,193 pesticide applicators were included. Detailed information on pesticide exposure and lifestyle factors was obtained from self-administered enrollment questionnaires completed between 1993 and 1997; average length of follow-up was 7.33 years. Two metolachlor exposure metrics were used : (i) lifetime days personally mixed or applied metolachlor and (ii) intensity-weighted lifetime days (lifetime days × an intensity level). Poisson regression analysis was used to estimate relative risks (RR) and 95% confidence intervals (95%CI) for cancer subtypes by tertiles of metolachlor exposure. No clear risk for any cancer subtype was found for exposure to metolachlor. A significantly decreased RR was found for prostate cancer in the highest category of lifetime days exposure (RR = 0.59; 95%CI, 0.39–0.89) and in the second highest category of intensity-weighted lifetime days exposure (RR = 0.66; 95%CI, 0.45–0.97); however, the test for trend was not significant for either exposure metric. A nonsignificantly increased risk was found for lung cancer with lifetime days exposure in the highest category (RR = 2.37; 95%CI, 0.97–5.82, p-trend = 0.03) but not with intensity-weighted lifetime days. Given the widespread use of metolachlor and the frequent detection of metolachlor in both surface and ground water, future analyses of the AHS will allow further examination of long-term health effects, including lung cancer and the less common cancers. © 2006 Wiley-Liss, Inc.

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