Pesticide Exposure Linked to Increased Risk for Thyroid Cancer
According to an investigation done on male pesticide applicators, exposure to pesticides such as metalaxyl and lindane was associated with an increased risk for thyroid cancer (Environ Int. 2021 Jan. Epub ahead of print).
“Many pesticides are known to have thyroid-disrupting properties. However, few studies have evaluated the association between specific pesticide ingredients and risk of thyroid cancer. We investigated self-reported pesticide use and incident thyroid cancer in the Agricultural Health Study (AHS), a large cohort of occupationally-exposed male pesticide applicators,” explained Catherine C. Lerro, PhD, MPH, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland, and colleagues.
The AHS prospective cohort consists of licensed pesticide applicators from Iowa and North Carolina; participants reported the use of 50 pesticides. Cox regression was used to estimate hazard ratios (HR) and 95% CI in incident thyroid cases (n = 85) among male participants.
Researchers discovered that use of both the fungicide metalaxyl (HR, 2.03; CI, 1.16-3.52) and the organochlorine insecticide lindane (HR, 1.74; CI, 1.06-2.84) was linked to an increased risk of thyroid cancer.
Meanwhile, the herbicide chlorimuron-ethyl was inversely related to risk when restricted to papillary thyroid cancer (HR, 0.52; CI, 0.28-0.96). Furthermore, extensive use of the insecticide carbaryl was inversely associated with thyroid cancer (HR, 0.20; CI, 0.08-0.53; P = .001).
“In this large cohort study, we observed increased risk of thyroid cancer associated with use of metalaxyl and lindane, and an inverse association with carbaryl. More work is needed to understand the potential role of these chemicals in thyroid carcinogenesis,” concluded Dr Lerro et al.—Alexandra Graziano
