| Cancer Incidence among Pesticide Applicators Exposed to Permethrin in the Agricultural Health Study Jennifer A. Rusiecki,1 Rahulkumar Patel,1 Stella Koutros,2 Laura Beane-Freeman,2 Ola Landgren,2 Matthew R. Bonner,3 Joseph Coble,2 Jay Lubin,2 Aaron Blair,2 Jane A. Hoppin,4 and Michael C.R. Alavanja2 1Department of Preventive Medicine and Biometrics, Uniformed Services University, Bethesda, Maryland, USA; 2Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA; 3Department of Social and Preventive Medicine, State University of New York, Buffalo, New York, USA; 4Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA Abstract
Background: Permethrin is a synthetic pyrethroid insecticide widely used in agriculture, in public health, and in many U.S. homes and gardens. Objective: In this study we evaluated the incidence of cancer among pesticide applicators exposed to permethrin in the Agricultural Health Study (AHS) . Methods: A total of 49,093 pesticide applicators were included in this analysis of the AHS, a prospective cohort study of licensed pesticide applicators in Iowa and North Carolina. Detailed information on pesticide exposure and lifestyle factors was obtained from self-administered questionnaires completed in 1993–1997. Average length of follow-up since applicator enrollment in the cohort was 9.14 years. We used two permethrin exposure metrics: a) lifetime days applicators personally mixed or applied permethrin and b) intensity-weighted lifetime days (lifetime days weighted by estimated intensity of exposure) . We used Poisson regression analysis to estimate relative risks (RRs) and 95% confidence intervals (CIs) for malignancies by tertiles of exposure. Results: We found no associations between permethrin and all malignant neoplasms combined, or between permethrin and melanoma, non-Hodgkin lymphoma, leukemia, or cancers of the colon, rectum, lung, or prostate. We found elevated and statistically significant risks for multiple myeloma in the highest tertiles of both lifetime exposure-days (RR = 5.72 ; 95% CI, 2.76–11.87) and intensity-weighted lifetime exposure-days (RR = 5.01 ; 95% CI, 2.41–10.42) , compared with applicators reporting they never used permethrin ; these results are based on only 15 exposed cases. These findings were similar across a variety of alternative exposure metrics, exposure categories, and reference groups. Conclusions: This study found no association with most cancers analyzed. Although the suggested association with multiple myeloma was based on a small number of cases, it warrants further evaluation. Key words: agriculture, cancer, multiple myeloma, occupation, permethrin, pesticide applicator, pesticides, pyrethroid. Environ Health Perspect 117:581–586 (2009) . doi:10.1289/ehp.11318 available via http://dx.doi.org/ [Online 10 November 2008]
Address correspondence to J.A. Rusiecki, Uniformed Services University of the Health Sciences, Department of Preventive Medicine and Biometrics, 4301 Jones Bridge Rd., PMB Room A1039, Bethesda, MD 20814-4799 USA. Telephone: (301) 295-3712. Fax: (301) 295-1854. E-mail: jrusiecki@usuhs.mil We thank the participants of the Agricultural Health Study for their contribution to this important research. This research was supported by the Intramural Research Program of the National Institutes of Health: National Cancer Institute, Division of Cancer Epidemiology and Genetics (Z01-CP010119) and National Institute of Environmental Health Sciences (Z01-ES049030) . The authors declare they have no competing financial interests. Received 31 January 2008 ; accepted 10 November 2008.
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