Cancer incidence among pesticide applicators exposed to butylate in the Agricultural Health Study (AHS)

• Published in: Environmental research 2009-10, Vol.109 (7), p.860-868
• Main Authors: Lynch, Shannon M., Mahajan, Rajeev, Beane Freeman, Laura E., Hoppin, Jane A., Alavanja, Michael C.R.
• Format: Article
• Language: English
• Subjects: Adult; Agricultural Health Study; Agricultural Workers' Diseases - chemically induced; Agricultural Workers' Diseases - epidemiology; Biological and medical sciences; Butylate; Cancer; Categories; Cohort Studies; Elevated; Exposure; Female; Humans; Iowa - epidemiology; Lymphoma, Non-Hodgkin - chemically induced; Lymphoma, Non-Hodgkin - epidemiology; Male; Medical sciences; Middle Aged; North Carolina - epidemiology; Occupational Exposure - adverse effects; Pesticide; Pesticides; Pesticides - poisoning; Pesticides, fertilizers and other agrochemicals toxicology; Prevalence; Prospective Studies; Prostate; Prostatic Neoplasms - chemically induced; Prostatic Neoplasms - epidemiology; Regression; Risk; Surveys and Questionnaires; Thiocarbamates - poisoning; Toxicology
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2009.06.006

Although limited, epidemiologic studies suggest possible associations between butylate use and cancer risk, specifically prostate cancer and non-Hodgkin lymphoma (NHL). We examined butylate use and cancer risk more broadly in the AHS, a cohort of licensed pesticide applicators in Iowa and North Carolina. Pesticide use information was collected using self-administered questionnaires. Poisson regression was used to calculate rate ratios (RR) and 95% confidence intervals (CI). Two exposure metrics were used: lifetime exposure days (LD) and intensity-weighted lifetime exposure days (IWLD). We used two referent groups: unexposed to butylate and the lowest butylate usage category. This analysis included 19,655 applicators with complete butylate use information; 5297 applicators were exposed to butylate, making this the largest study of butylate to date. The mean follow-up time since enrollment was 9 years. Prostate cancer risk was significantly elevated among applicators in the highest LD category in both referent groups (low-exposed referent: RR LD=2.09, 95% CI=1.27–3.44). We observed a significantly elevated joint effect of prostate cancer family history and high butylate usage across both exposure metrics and both referent groups (low-exposed referent: RR LD=2.00, 95% CI=1.07–3.74), and a non-significant, elevated interaction between butylate use and prostate cancer family history, similar to a previous AHS finding. Statistically significant increased risks and exposure–response trends were seen for all lymphohematopoietic cancers (AL) and NHL for both exposure metrics and referent groups (low-exposed referent: AL:RR LD=2.27, 95% CI=1.18–4.37; NHL: RR LD=3.44, 95% CI=1.29–9.21). Our analysis did not find meaningful associations for other cancers analyzed. Further study is warranted for AL, NHL and prostate cancers.