Occupational pesticide exposure and subclinical hypothyroidism among male pesticide applicators. Issue 2 (3rd August 2017)

• Record Type: Journal Article
• Authors: Lerro, Catherine C; Beane Freeman, Laura E; DellaValle, Curt T; Kibriya, Muhammad G; Aschebrook-Kilfoy, Briseis; Jasmine, Farzana; Koutros, Stella; Parks, Christine G; Sandler, Dale P; Alavanja, Michael C R; Hofmann, Jonathan N; Ward, Mary H
• Is Part Of: Occupational and environmental medicine. Volume 75:Issue 2(2018)
• Page Start: 79
• Page End: 89
• Publication Date: 2017-08-03
• Subjects: thyroid disease -- hypothyroidism -- thyroid stimulating hormone -- agriculture -- pesticides; Medicine, Industrial -- Periodicals; Environmental health -- Periodicals; 616.980305
• DOI: 10.1136/oemed-2017-104431
• Languages: English
• ISSNs: 1351-0711

Abstract

Abstract : Objectives: 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. Methods: 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. Results: Higher exposure to the insecticide aldrin (third and fourth quartiles of intensity-weighted days vs no exposure) was positively associated with subclinical hypothyroidism (ORQ3 =4.15, 95% CI 1.56 to 11.01, ORQ4 =4.76, 95% CI 1.53 to 14.82, ptrend <0.01), higher TSH (ptrend =0.01) and lower T4 (ptrend =0.04). Higher exposure to the herbicide pendimethalin was associated with subclinical hypothyroidism (fourth quartile vs no exposure: ORQ4 =2.78, 95% CI 1.30 to 5.95, ptrend =0.02), higher TSH (ptrend =0.04) and anti-TPO positivity (ptrend =0.01). The fumigant methyl bromide was inversely associated with TSH (ptrend =0.02) and positively associated with T4 (ptrend =0.01). Conclusions: Our results suggest that long-term exposure to aldrin, pendimethalin and methyl bromide may alter thyroid function among male pesticide applicators.