Human Exposure Assessment using Drinking-Water and Urinary Trihalomethanes Concentrations in Two Areas with Contrasting Urban Pipe Network Characteristics

Abstract

Complaints about chlorine smells due to high dosing, formation of disinfection by-products, or inadequate chlorination are common issues that authorities frequently deal within urban drinking-water distribution systems. The large spatial variability of trihalomethanes (THM) formation in drinking-water within the same pipe network of a city is perplexing, often influenced by factors, such as water source characteristics, water chemistry within the pipe network and its physical characteristics. This study set out to evaluate the magnitude and variability of human exposures to THM in two urban areas both located in the same city, but carrying contrasting pipe network characteristics (number of pipe leaking incidents, pipe length, pipe material, number of water meters, and average minimum night flow). Our cohort was comprised of 382 volunteers from the general population that completed a questionnaire about drinking-water consumption habits, water source/uses, demographics, and disinfectant use in households. Tap water and first morning urine samples were collected and analyzed for THM using gas chromatography coupled with triple quadrupole mass spectrometry. Results will highlight the spatial variability of THM concentrations using both external (water) and internal (urine) exposure measurements after adjusting for common environmental/ lifestyle covariates. The influence of pipe characteristics, participant water consumption and household disinfection practices on the distribution, formation and subsequent human absorption patterns will be elaborated.