Perfluoroalkyl substances, sex hormones, and insulin-like growth factor-1 at 6-9 years of age: A cross-sectional analysis within the C8 Health Project

Abstract

Background: Exposure to some perfluoroalkyl substances (PFAS), such as perfluorohexane sulfonate (PFHxS), perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and perfluorononanoic acid (PFNA), may alter levels of sex hormones and insulin-like growth factor-1 (IGF-1) in animals. Human studies on this topic are scarce, and none have been conducted in young children. Objectives: We investigated the relationship between levels of PFAS and estradiol, total testosterone, and IGF-1 in 2,292 children (6-9 years of age) from the C8 Health Project who lived near a chemical plant in the Mid-Ohio Valley (USA) with local contamination from PFOA. Methods: Serum samples were collected in 2005-2006 and analyzed for PFAS, sex hormones, and IGF-1. Results from regression models were expressed as the adjusted percentage difference (95% CI) per sex-specific interquartile range (IQR) increment of each PFAS serum concentration. Analyses by PFAS quartiles were also conducted. Results: Median concentrations of PFHxS, PFOA, PFOS, and PFNA were 8, 35, 22, and 1.7 ng/mL in boys and 7, 30, 21, and 1.7 ng/mL in girls. In boys, PFOA concentrations were significantly associated with testosterone levels (-4.9%; 95% CI:-8.7,-0.8%); PFOS with estradiol (-4.0%; 95% CI:-7.7,-0.1%), testosterone (-5.8%; 95% CI:-9.4,-2.0%), and IGF-1 (-5.9%; 95% CI:-8.3,-3.3%); and PFNA with IGF-1 (-3.5%; 95% CI:-6.0,-1.0%). In girls, significant associations were found between PFOS and testosterone (-6.6%; 95% CI:-10.1,-2.8%) and IGF-1 (-5.6%;-8.2,-2.9%); and PFNA and IGF-1 (-3.8%; 95% CI:-6.4,-1.2%). In both sexes, the magnitudes of the associations decreased monotonically across quartiles for both testosterone and IGF-1 in relation to PFOS, and for IGF-1 and PFNA in girls. Conclusions: To our knowledge, this is the first study suggesting that PFAS are associated with lower levels of IGF-1 and sex hormones in young children.