1470-7926 75 2 2018 Feb Occup Environ Med Occupational pesticide exposure and subclinical hypothyroidism among male pesticide applicators. 79-89 10.1136/oemed-2017-104431 Animal studies suggest that exposure to pesticides may alter thyroid function; however, few epidemiologic studies have examined this association. We evaluated the relationship between individual pesticides and thyroid function in 679 men enrolled in a substudy of the Agricultural Health Study, a cohort of licensed pesticide applicators. Self-reported lifetime pesticide use was obtained at cohort enrolment (1993-1997). Intensity-weighted lifetime days were computed for 33 pesticides, which adjusts cumulative days of pesticide use for factors that modify exposure (eg, use of personal protective equipment). Thyroid-stimulating hormone (TSH), thyroxine (T4), triiodothyronine (T3) and antithyroid peroxidase (anti-TPO) autoantibodies were measured in serum collected in 2010-2013. We used multivariate logistic regression to estimate ORs and 95% CIs for subclinical hypothyroidism (TSH >4.5 mIU/L) compared with normal TSH (0.4-<4.5 mIU/L) and for anti-TPO positivity. We also examined pesticide associations with TSH, T4 and T3 in multivariate linear regression models. Higher exposure to the insecticide aldrin (third and fourth quartiles of intensity-weighted days vs no exposure) was positively associated with subclinical hypothyroidism (OR_Q3=4.15, 95% CI 1.56 to 11.01, OR_Q4=4.76, 95% CI 1.53 to 14.82, p_trend <0.01), higher TSH (p_trend=0.01) and lower T4 (p_trend=0.04). Higher exposure to the herbicide pendimethalin was associated with subclinical hypothyroidism (fourth quartile vs no exposure: OR_Q4=2.78, 95% CI 1.30 to 5.95, p_trend=0.02), higher TSH (p_trend=0.04) and anti-TPO positivity (p_trend=0.01). The fumigant methyl bromide was inversely associated with TSH (p_trend=0.02) and positively associated with T4 (p_trend=0.01). Our results suggest that long-term exposure to aldrin, pendimethalin and methyl bromide may alter thyroid function among male pesticide applicators. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted. Lerro Catherine C CC Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland, USA. Beane Freeman Laura E LE Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland, USA. DellaValle Curt T CT Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland, USA. Environmental Working Group, Washington, DC, USA. Kibriya Muhammad G MG Department of Public Health Sciences, The University of Chicago, Chicago, Illinois, USA. Aschebrook-Kilfoy Briseis B Department of Public Health Sciences, The University of Chicago, Chicago, Illinois, USA. Jasmine Farzana F Department of Public Health Sciences, The University of Chicago, Chicago, Illinois, USA. Koutros Stella S Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland, USA. Parks Christine G CG National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA. Sandler Dale P DP National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA. Alavanja Michael C R MCR Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland, USA. Department of Biology, Hood College, Frederick, Maryland, USA. Hofmann Jonathan N JN Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland, USA. Ward Mary H MH Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland, USA. eng Z01 CP010119 CP NCI NIH HHS United States Z01 ES049030 ES NIEHS NIH HHS United States Z99 CA999999 NULL Intramural NIH HHS United States Journal Article 2017 08 03