Determinantes de los parámetros reproductivos en varones universitarios sanos

Abstract

BACKGROUND: Endocrine Disrupting Chemicals are pervasive environmental toxicants with potential male reproductive function effects. Bisphenol A (BPA) is widely used in industry and commerce to manufacture polycarbonate plastics and food packaging components. Parabens are a group of alkyl esters of p-hydroxybenzoic acid that are commonly added to personal care products, and food processing as antimicrobial preservatives. Benzophenone (BP)-type ultraviolet (UV) light filters are chemicals coming from different sources generally added to personal care products and sunscreens. Exposure to these chemicals is common among the general population, with detectable concentration in more than 80% of study participants, and have been reported to have estrogenic or anti-androgenic effects. However, studies exploring associations between exposure to BPA, parabens and BP-type UV filters and reproductive parameters in men non-selected for testicular function or unaware of their fecundity are very scarce. The objective of this Thesis was to assess the relationships between urinary BPA, parabens and BP-type UV filters concentrations and semen quality and serum reproductive hormone levels in young men. MATERIAL AND METHODS: The Murcia Young Men&apos;s Study (MYMS) is a cross-sectional study of university students 18-23 years old in the Murcia Region. A total of 215 students agreed to participate and completed the study visit between October 2010 and November 2011. All subjects provided urine, blood serum and semen samples on a single day. Environmental chemical concentrations were measured by dispersive liquid-liquid microextraction and ultrahigh performance liquid chromatography with tandem mass spectrometry detection in urine. Semen quality was evaluated by measuring volume, concentration, motility, morphology and total sperm count. Serum samples were analyzed for reproductive hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), total and free testosterone (T), estradiol (E2) and inhibin B. Relationships between urinary concentrations of BPA, parabens and BP-type UV filters and semen quality parameters and reproductive hormone levels were examined using multiple linear regression, adjusting for potential confounders. RESULTS: After adjustment for important covariates, there was a significant positive association between urinary BPA concentrations and serum LH levels (? = 0.07, 95%CI: 0.02; 0.12, p-value <0.01). Urinary BPA concentration was also significantly and inversely associated with sperm concentration (? = ? 0.04, 95%CI: ? 0.07; ? 0.02, p-value<0.01) and total sperm count (? = ? 0.05, 95%CI: ? 0.08; ? 0.02, p-value<0.01). No significant associations were found between BPA and other semen parameters or reproductive hormone levels. Urinary concentrations of parabens or their molar sum were not significantly associated with any semen parameters or reproductive hormone levels. There was a significant positive association between urinary BP-1 and BP-3 concentrations and serum FSH levels (?=0.08, 95%CI: 0.009; 0.15 and ?=0.04, 95%CI: 0.0002; 0.08, respectively). Urinary BP-1 concentration was also significantly positively associated with T/E2 (?=0.04, 95%CI: 0.002; 0.07) and negatively with inhibin B/FSH (?=?0.11, 95%CI: ?0.21; ?0.006) ratio. No significant associations were found between other urinary BP-type UV filters and other reproductive hormone levels or any semen parameters. CONCLUSIONS: Our data support the hypothesis that exposure to BPA is associated with a reduction in Leydig cell capacity (increased LH levels) and decreased sperm count. Urinary concentrations of parabens in young men may not adversely impact reproductive function. So far, limited to no evidence of an association between concurrent urinary parabens and male potential fecundity has been found. Lastly, our results suggest that, in young men, urinary BP-type UV filters may be associated with a modest alteration of some reproductive hormones, but the effects we report on reproductive function are likely to be small, and of unclear clinical significance. Further research is needed to replicate these findings in other male populations.