Yi Hu1, Zhongjie Zhang2, Kaili Qin3, Yan Zhang3, Rui Pan3, Yiwen Wang4, Rong Shi3, Yu Gao5, Ying Tian6. 1. Department of Environmental Health, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Center for Medical Bioinformatics, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai, China. 2. Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, USA. 3. Department of Environmental Health, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China. 4. MOE and Shanghai Key Laboratory of Children's Environmental Health, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China. 5. Department of Environmental Health, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Electronic address: gaoyu_ciel@sjtu.edu.cn. 6. Department of Environmental Health, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China; MOE and Shanghai Key Laboratory of Children's Environmental Health, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China. Electronic address: tianmiejp@sjtu.edu.cn.
Abstract
BACKGROUND: Pyrethroid insecticides have been extensively used in China and worldwide, while their effects on thyroid functions are rarely explored, especially in susceptible pregnant women. OBJECTIVE: To assess the association between 3-phenoxybenzoic acid (3PBA), a major urinary metabolite of pyrethroids, and thyroid hormone levels in pregnant women in China. METHODS: Three hundred and seventy-four pregnant women were recruited during the admission for delivery (third trimester of pregnancy) in a local hospital in Shandong, China during December 2011 to December 2013. Pyrethoids exposure was assessed by examining urinary metabolite of 3PBA levels. Thyroid hormones were detected by measuring serum concentrations of thyroid stimulating hormones (TSH), total triiodothyronine (TT3), free triiodothyronine (FT3), total thyroxine (TT4) and free thyroxine (FT4). Multiple linear regression models were used to investigate the associations between 3PBA concentrations and thyroid hormones levels. RESULTS: The detection frequency of 3PBA was 90.4%, with a median concentration of 1.14 μg/g creatinine. After adjusted for potential confounders, we found a significant negative relationship between 3PBA and serum FT3 (β = -0.06, 95% CI = -0.11 to -0.01) as well as an inverse dose dependent association (p for trend = 0.023). No significant association was found between 3PBA concentrations and other thyroid hormones. CONCLUSIONS: Our findings indicated that pyrethroid exposure was widespread and negatively associated with serum FT3 concentrations in pregnant women in northern China. Given to the widespread of pyrethroid exposure and critical role thyroid homeostasis plays during pregnancy, more studies are warranted to explore their relationships as well as underlying mechanisms.
BACKGROUND:Pyrethroid insecticides have been extensively used in China and worldwide, while their effects on thyroid functions are rarely explored, especially in susceptible pregnant women. OBJECTIVE: To assess the association between 3-phenoxybenzoic acid (3PBA), a major urinary metabolite of pyrethroids, and thyroid hormone levels in pregnant women in China. METHODS: Three hundred and seventy-four pregnant women were recruited during the admission for delivery (third trimester of pregnancy) in a local hospital in Shandong, China during December 2011 to December 2013. Pyrethoids exposure was assessed by examining urinary metabolite of 3PBA levels. Thyroid hormones were detected by measuring serum concentrations of thyroid stimulating hormones (TSH), total triiodothyronine (TT3), free triiodothyronine (FT3), total thyroxine (TT4) and free thyroxine (FT4). Multiple linear regression models were used to investigate the associations between 3PBA concentrations and thyroid hormones levels. RESULTS: The detection frequency of 3PBA was 90.4%, with a median concentration of 1.14 μg/g creatinine. After adjusted for potential confounders, we found a significant negative relationship between 3PBA and serum FT3 (β = -0.06, 95% CI = -0.11 to -0.01) as well as an inverse dose dependent association (p for trend = 0.023). No significant association was found between 3PBA concentrations and other thyroid hormones. CONCLUSIONS: Our findings indicated that pyrethroid exposure was widespread and negatively associated with serum FT3 concentrations in pregnant women in northern China. Given to the widespread of pyrethroid exposure and critical role thyroid homeostasis plays during pregnancy, more studies are warranted to explore their relationships as well as underlying mechanisms.