Relationships of Pyrethroid Exposure with Gonadotropin Levels and Pubertal Development in Chinese Boys

Although an acceleration of male pubertal development has been observed, precisely which endocrine-disrupting chemicals (EDCs) might contribute to the advancing onset of puberty in boys remains unclear. Here, pyrethroids, a class of widely used insecticides that have been considered as EDCs, are proposed as new environmental risk factors. In this study, 463 boys at the age of 9-16 years old were recruited in Hangzhou, Zhejiang, China. The common metabolites of pyrethroids, 3-phenoxybenzoic acid (3-PBA), and 4-fluoro-3-phenoxybenzoic acid (4-F-3-PBA), as well as gonadotropins, including luteinizing hormone (LH) and follicle-stimulating hormone (FSH), were analyzed in urine samples. Pubertal development was assessed based on Tanner stages and testicular volume (TV). A positive association between 3-PBA and gonadotropins was found (p0.001), in which a 10% increase in 3-PBA was associated with a 2.4% and 2.9% increase in LH and FSH, respectively. Higher urinary levels of 3-PBA in boys were associated with 275% and 280% increase in the risk of being genitalia stage 3 (G3) and G4, respectively (p0.05). There was a significant (132%) induction in odd of being TV 12-19 mL with increasing 3-PBA concentration compared to being in TV4 mL (p0.05). For the first time to our knowledge, this work reports on an association of increased pyrethroid exposure with elevated gonadotropins levels and earlier pubertal development in boys.