[Association analysis between mixed exposure to phenols and semen quality]

Phenols such as bisphenols, parabens, and triclosan are common environmental endocrine disruptors. Previous epidemiological studies have suggested that phenols may affect semen quality, but the results were inconsistent. In addition, most existing studies have been limited to the effects of a single chemical compound, ignoring the health effects of mixed exposure to multiple chemicals. Thus, we aimed to explore the associations between individual and mixed exposure to phenols and various semen quality parameters. In this study, a rapid and sensitive method was used to determine 18 phenolic compounds in urine samples of 799 volunteers who donated sperm samples to the Shanghai Human Sperm Bank. A spot urine sample was collected from each subject on the day of their clinic visit and stored at -20 ℃ until testing. Urine samples (200 μL) were extracted and added with 20 μL of an internal standard and 50 μL of β-glucuronidase solution. The mixtures were then incubated for 12 h at 37 ℃. After hydrolysis, the samples were extracted twice using ethyl acetate (500 μL). The concentrations of the 18 phenolic compounds were measured using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Semen quality parameters were analyzed using a computer-aided semen analyzer. Multiple linear regressions were used to detect the associations between individual phenol exposure and semen quality parameters. In addition, weighted quantile sum (WQS) models were used to explore the associations between mixed-phenol exposure and semen quality parameters. After adjusting for potential covariates, the results of multiple linear regressions showed that exposure to ethyl paraben (EtP) was significantly negatively associated with sperm concentration and total sperm count (P<0.05). In addition, exposure to mixed phenols was significantly associated with decreased sperm concentration; methyl paraben (MeP) and EtP were identified as the main contributors to this decrease. Thus, phenol exposure may be associated with decreased semen quality in young males, particularly with respect to sperm concentration and total sperm count.