Exposures to drinking water disinfection byproducts and kidney function in Chinese women

Background: Disinfection byproducts (DBPs), the ubiquitous contaminants in drinking water, have been shown to impair renal function in experimental studies. However, epidemiological evidence is sparse. Objective: To investigate exposures to DBPs in associations with renal function among women.Methods: A total of 920 women from December 2018 to January 2020 were abstracted from the Tongji Repro-ductive and Environmental (TREE) Study, an ongoing cohort study in Wuhan, China. Urine samples were gathered at baseline recruitment and analyzed for dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) as biomarkers of DBP exposures. Serum uric acid (UA), creatinine, and estimated glomerular filtration rate (eGFR) were measured as indicators of renal function. Multivariate linear regression and restricted cubic spline (RCS) models were conducted to assess urinary DCAA and TCAA concentrations in associations with renal function indicators. Stratified analyses by age and body mass index (BMI) were also performed.Results: We found null evidence of urinary TCAA in associations with renal function indicators. However, elevated urinary DCAA tertiles were related to decreased eGFR (beta =-1.78%, 95% CI: 3.21%,-0.36%, comparing the upper vs. lower tertile; P for trend = 0.01). This inverse association still existed when urinary DCAA concentration was treated as a continuous variable, and the dose-response relationship was linear based on the RCS model (P for overall association = 0.002 and P for non-linear associations = 0.44). In the stratified analyses, we found an association of urinary DCAA concentration with decreased UA level among women <30 years but an association with increased UA level among women >= 30 years (P for interaction = 0.04).Conclusion: Urinary DCAA but not TCAA was associated with impaired renal function among women undergoing assisted reproductive technology.