Abstract
To prospectively investigate the associations of urinary phthalate metabolite concentrations measured at four time points spanning pubertal development with semen parameters in Russian men. 516 boys were enrolled at ages 8-9 years (2003-2005) and followed annually. Urine samples were collected annually and pooled into four exposure windows [prepuberty, early puberty, late puberty and sexual maturity] based on physician assessed Tanner genitalia stages and testicular volume. Fifteen phthalate metabolites were quantified using isotope dilution HPLC-MS/MS at Moscow State University. We calculated molar sums (∑) of di-2-ethylhexyl phthalate (DEHP), di-isononyl phthalate (DiNP), di-isodecyl phthalate (DiDP) and anti-androgenic phthalate (AAP) metabolites. At sexual maturity (ages 18-19 years), the men provided 1-2 semen samples for analysis. We estimated the associations of quintiles of urinary ∑phthalate metabolites as well as mono-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP), and mono-benzyl phthalate (MBzP) at each pubertal window, with semen parameters by fitting generalized linear mixed models with random intercepts and adjusting for confounders. A total of 223 men who provided semen samples had phthalates measured at one or more pubertal windows. Higher urinary concentrations of ∑DiNP metabolites during late puberty were related to poorer semen quality (men with the highest quintile of urinary ∑DiNP had 30% lower sperm concentration, 32% lower count and 30% lower progressive motile count, compared to men in the lowest quintile). Also, young men with higher urinary concentrations of MiBP metabolites in early puberty tended to have poorer semen quality. No associations were observed for ∑DEHP metabolites, ∑DiDP metabolites, ∑AAP, MBzP or MnBP metabolites with semen quality parameters. ∑DiNP metabolites measured during late puberty and MiBP metabolites at early puberty were related to poorer semen quality, highlighting the importance of considering specific windows of exposure when investigating chemical exposures in relation to measures of reproductive health in men.
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