Associations between urinary biomarkers of exposure to disinfection byproducts and semen parameters: A repeated measures analysis

Toxicological studies have demonstrated that disinfection byproducts (DBPs), particularly haloacetic acids, cause testicular toxicity. However, evidence from human studies is sparse and inconclusive. This study included 1230 reproductive-aged men from the Tongji Reproductive and Environmental (TREE) cohort to investigate the associations between repeated measures of DBP exposures and semen parameters. Urinary dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) as biomarkers of DBP exposures and semen parameters in up to three samples from each man were assessed. The linear mixed effect models were applied to explore the associations between urinary biomarkers of DBP exposures and semen parameters. We found inverse associations of urinary DCAA with sperm count, progressive motility, and total motility (e.g., -14.86%; 95% CI: -19.33%, -10.15% in sperm total motility for the highest vs. lowest quartiles; all P for trends < 0.05). Moreover, urinary TCAA modeled as a continuous variable was negatively associated with sperm progressive motility and total motility, while the inverse associations across increasing urinary TCAA quartiles were seen among leaner men (BMI < 25 kg/m(2)). Exposure to DBPs reflected by urinary DCAA and TCAA was inversely associated with sperm motility such effects were more evident among leaner men.

Automated summary

Toxicological studies have shown that disinfection byproducts (DBPs), specifically haloacetic acids, can have toxic effects on the testicles. However, there is limited and inconclusive evidence from human studies. This study examined the associations between DBP exposures and semen parameters in 1230 reproductive-aged men. The results revealed inverse associations between urinary biomarkers of DBP exposures and sperm count, motility, and overall quality, particularly among leaner men.