Associations of Blood Trihalomethanes with Repeated Measurements of Semen Quality among 1199 Healthy Chinese Men Screened as Potential Sperm Donors

Abstract

TPS 931: Water and foodborne chemicals, Exhibition Hall, Ground floor, August 28, 2019, 3:00 PM - 4:30 PM Background: Trihalomethanes (THMs) have demonstrated adverse effects on male reproductive system in animals, but human evidence has been limited and divergent. Most studies to date used small sample size and were limited by inadequate individual exposure estimation. Objectives: To investigate the association of blood THMs with repeated measurements of semen quality parameters among 1199 healthy men screened as potential sperm donors. Methods: From April to December 2017, healthy men who came to the Hubei Province Human Sperm Bank for donation screening were recruited. Those who met the donation criteria were required to provide 8-15 additional semen samples at different time points over an approximately 3-month period; those who did not meet the criteria were asked to provide 2-4 samples for further screening. Each man had a blood sample drawn, which was analyzed for 4 THMs [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM) and bromoform (TBM)]. We used linear regressions to assess the cross-sectional associations of categorical concentrations of blood THMs with semen quality parameters tested at enrollment, and mixed-effect models to estimate differences in repeated measures of semen quality in relation to blood THMs, accounting for various confounders. Results: In the cross-sectional analysis, suggestively or significantly inverse dose-relationships were found between blood TCM concentrations and sperm count, total motility and progressive motility, and between blood DBCM, Br-THMs (sum of BDCM, DBCM and TBM) and total THMs (TTHMs; sum of TCM and Br-THMs) and sperm count and concentration (all p for trend < 0.10). In the repeated analysis, the inverse association of blood TCM, DBCM, Br-THMs and TTHMs with sperm count were further confirmed. Conclusion: Our results suggest that exposure to THMs from drinking water may contribute to decreased semen quality in humans.