Exposure of environmental Bisphenol A in relation to routine sperm parameters and sperm movement characteristics among fertile men

Abstract

Although several human studies have examined bisphenol A (BPA) exposure in relation to routine sperm parameters, evidence of BPA's effects on sperm movement characteristics is limited. We examined associations of BPA exposure with sperm parameters including sperm movement characteristics among fertile men. The cross-sectional study was conducted in Sandu County, Guizhou Province, China. Subjects provided semen samples analyzed by computer-aided sperm analysis (CASA) system and urine samples for BPA assay. They were invited to complete an in-person interview with a structured questionnaire to obtain demographics, lifestyle factors, etc. In final analyses, 500 subjects were included. We used multivariate linear regression analyses to estimate associations between BPA and sperm parameters after adjusting for potential confounders. BPA was detected in 73.6% of urine samples, with a geometric mean of 0.44 μg/gCreatinine. Compared with subjects of undetected BPA, subjects with detected BPA had increased Linearity (LIN, β: 2.19, 95% confidence interval (CI): 0.37, 4.0), Straightness (STR, β: 1.47, 95% CI: 0.19, 2.75), Wobble (WOB, β: 1.75, 95% CI: 0.26, 3.25), reduced Amplitude of lateral head displacement (ALH, β: -0.26, 95% CI: -0.5, -0.02) and Mean angular displacement (MAD, β: -2.17, 95% CI: -4.22, -0.11). Subjects in the highest tertile of creatinine-adjusted BPA group had lower sperm concentration than those with undetected BPA. Dose-response relationships of BPA with LIN, WOB, ALH, MAD and sperm concentration were demonstrated by statistically significant trends across tertiles of creatinine-adjusted BPA concentrations. Similar results were obtained using unadjusted BPA concentrations. Exposure to environmental BPA would decrease sperm concentration and sperm swing characteristics (ALH and MAD), and increase sperm velocity ratios (LIN, STR and WOB), which might mediate further effects on impaired male fecundity.

Figure 1

Adjusted dose-response relationship between urinary creatinine-adjusted BPA levels and semen parameters with a reference group of undetected BPA: sperm concentration (A), total count (B), forward mobility (C), sperm motion velocity (D), velocity ratio (E), Amplitude of lateral head displacement (F), Mean angular displacement (G), and Beat-cross frequency (H). With the reference of undetected BPA, the model included 132, 106, 109 and 110 men in undetected BPA group, lowest tertile, middle tertile and highest tertile of detected BPA groups, respectively; There are 43 missing values in creatinine measurements in BPA dectected group. Range of BPA tertiles (μg/gCr): lowest tertile, LOD-0.35; middle tertile, 0.36–1.29; highest tertile: >1.29; Adjusted for age, education, race, smoking, alcohol intake, BMI, abstinence period, history of pesticide usage and occupational exposure to high temperature.