Insights to estimate exposure to regulated and non-regulated disinfection by-products in drinking water

BACKGROUND: Knowledge about human exposure and health effects associated with non-routinely monitored disinfection by-products (DBPs) in drinking water is sparse. OBJECTIVE: To provide insights to estimate exposure to regulated and non-regulated DBPs in drinking water. METHODS: We collected tap water from homes (N = 42), bottled water (N = 10), filtered tap water with domestic activated carbon jars (N=6) and reverse osmosis (N=5), and urine (N=39) samples of participants from Barcelona, Spain. We analyzed 11 haloacetic acids (HAAs), 4 trihalomethanes (THMs), 4 haloacetonitriles (HANs), 2 haloketones, chlorate, chlorite, and trichloronitromethane in water and HAAs in urine samples. Personal information on water intake and socio-demographics was ascertained (N=39) through questionnaires. Statistical models were developed based on THMs as explanatory variables using multivariate linear regression and machine learning to predict non-regulated DBPs. RESULTS: Chlorate, THMs, HAAs, and HANs were quantified in 98-100% of tap water samples (medians: 214, 42, 18, and 3.2 µg/L). Multivariate linear regression had similar or higher goodness of fit (R²) versus machine learning. Linear models for several non-regulated DBPs showed good predictive ability (R² = 0.8-0.9). Activated carbon filters reduced DBPs variably (27-80%); reverse osmosis reduced ≥98%. Only chlorate was detected in bottled water (3/10; median 13.0 µg/L). Creatinine-adjusted trichloroacetic acid (TCAA) was most frequently detected in urine (69.2%) and moderately correlated with estimated drinking water intake (r = 0.48). SIGNIFICANCE: Findings provide valuable insights for DBP exposure assessment in epidemiological studies. Validation of predictive models in larger samples and different settings is warranted. IMPACT STATEMENT: We assessed occurrence of several DBP classes in drinking water and developed exposure models with good predictive ability for non-regulated DBPs.