Effect of para-nitrophenol concentration in urine of healthy adults on thyroid function based on US NHANES

[Background] Parathion and methyl parathion are typical organophosphorus insecticides and para-nitrophenol（PNP） is their main specific metabolite. Previous studies have shown that parathion and methyl parathion may play a role as endocrine disrupting chemicals, but the evidence is limited.[Objective] Our aim is to evaluate association between urinary PNP concentration and thyroid function among healthy adults and whether this association has gender differences.[Methods] The study was based on the 2007-2008 US National Health and Nutrition Examination Survey（NHANES）. A total of 1 071 subjects aging from 20 to 64 years with data on both urinary PNP and serum thyroid function indicators were finally enrolled. Thyroid function was evaluated by measuring serum thyroid stimulating hormone（TSH）, free triiodothyronine（FT3）, free thyroxine（FT4）, total triiodothyronine（TT3）,total thyroxine（TT4）, thyroglobulin（TG）, and thyroglobulin antibody（TG-Ab）. A generalized linear model was used to analyze the relationship between