Accumulating evidence indicates that phthalate exposures may affect human semen quality. Epigenetic modifications such as DNA methylation might be linked chemical exposure and spermatogenesis epigenetic reprogramming. In the present study, we investigated associations between phthalate exposures, DNA methylation and sperm quality in undergoing fertility assessment male population. Urine was used for phthalate exposures monitoring, six selected metabolites (i.e., monomethyl phthalate (MMP), monoethyl phthalate (MEP), mono-n-butyl phthalate (MBP), monobenzyl phthalate (MBzP), mono-(2-ethylhexyl) phthalate (MEHP) and mono (2-ethyl-5-oxohexyl) phthalate (MEOHP)) were measured by using HPLC-MS/MS. Sperm quality parameters were determined by computer-assisted semen analysis (CASA). Sperm DNA methylation patterns (long interspersed nuclear element-1(LINE-1), H19 and LIT1) were analysed employing high-melting resolution (HRM) PCR. Urinary MMP, MEHP, MEOHP, sum of DEHP metabolites (∑DEHP) and sum of selected phthalates metabolites (∑PAEs) were significantly positively associated with sperm motility. Sperm LINE-1 DNA methylation were found to be negatively associated with ∑DEHP exposure and sperm quality (ejaculate volume, total sperm number and motility). Epigenetic modification LINE-1 DNA methylation demonstrated mediating effects in association between DEHP exposure and sperm motility, and 20.7% of the association was mediated by serum LIEN-1 DNA methylation. These results extend the previous studies in association between phthalate exposures and classical semen parameters, mainly of inverse association, and sperm DNA methylation may be linked phthalate exposures and male reproductive health outcome.

The phthalates metabolites concentrations (ng/mL urine) distribution and association with sperm quality in male of different population. Green color means positive association, black means no significant association and red means negative association. Bottom box represents first quartile, band inside the box represents the median and top box represents third quartile. China 1: Liu et al. (2012), China 2: Pan et al. (2015), China 3: Wang et al. (2015), USA1: Wirth et al. (2008), USA2: Hauser et al. (2006), USA3: Bloom et al. (2015), USA4: Duty et al. (2004), Sweden1: Axelsson et al. (2015), Sweden2: J0nsson et al. (2005), Japan: Toshima et al. (2012), Poland: Jurewicz et al. (2013), German: Herr et al. (2009). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)