Effects of phthalate exposure on sex hormones among 2, 5, 8 and 11 year old children in Central Taiwan

摘要

Background: Phthalate esters are widely used chemicals found in plastics and other commercial products. Despite evidence of anti-androgenic effects from this chemical, few studies have examined the effects of phthalate exposure on children's sex hormones. We investigated the association between the exposure and sex hormone levels in children from central Taiwan using data from a prospective birth cohort study. Methods: Around 170 children were followed at 0, 2-3, 5-6, 8-9 and 11-12 years of age. Estradiol, testosterone, free testosterone, follicle-stimulating hormone (FSH), progesterone and sex hormone-binding globulin (SHBG) were measured in cord and venous blood. The phthalate metabolites MEHP, 5OH-MEHP, 5oxo-MEHP, MEP, MMP, MnBP, MBzP were measured in urine with LC-MS/MS methods. Simple linear regression stratified by age and gender was conducted to test for the association of phthalate exposure with sex hormone levels in children. Results: Decreased levels of testosterone and estradiol from phthalate exposure are consistent across age groups and both genders. For example, MEHP (β= -0.201, p ＜.0001) was inversely associated with estradiol levels in 5 year olds, particularly girls (β= -0.239, p＜.0001). The inverse association of several phthalates with estradiol was also apparent among infant girls who were prenatally exposed. Since testosterone levels were transformed to 1/√Testosterone for the regressions, having a positive coefficient is evidence of a negative association. For 2 year old children, MEP (β=0.019, p=0.03) was inversely associated with testosterone levels. Decreased testosterone was also associated with MBzP (β=0.019, p=0.046) in this age group, and this association was even more evident in boys. The patterns were similar for the 5 and 11 year old groups. Conclusion: Results showed that phthalate exposure is associated with decreased levels of testosterone and estradiol. This is one of the few longitudinal studies conducted on this topic.