Spatial/Temporal Distribution and Multi-Pathway Cancer Risk Assessment of Trihalomethanes in Low TOC and High Bromide Groundwaters
This study aims (1) to determine the seasonal and spatial distribution of THMs formation in chlorinated groundwaters containing low organic matter (0.4-0.8 mg/L) and low to high bromide (40-380 µg/L), (2) to evaluate the multi-route cancer risks associated with them. The study was conducted in Kayseri (Turkey), where drinking water is supplied from groundwater after chlorination only. THM formation in 50 water samples from 18 storage tanks and 32 distribution points were investigated to evaluate spatial and temporal changes in THM concentrations for 12 months. The lifetime cancer risk of THMs through multi exposure pathways (i.e., oral ingestion, dermal absorption, and inhalation) was estimated for males and females. For 12 months sampling period, minimum and maximum THM concentrations varied from 2 µg/L and 17 µg/L and from 2 µg/L to 29 µg/L in storage tanks and distribution points, respectively. The range of median concentrations of THM were 5 µg/L to 9 µg/L in storage tanks and 5 µg/L to 12 µg/L in distribution points. In all samples dibromochloromethane was the dominant specie, followed by bromoform, chloroform, and bromodichloromethane. The average values of total cancer risk associated with exposure to THMs via oral ingestion, dermal absorption, and inhalation for females and males were 1.31E-05 and 1.25E-05 in storage tanks, and 1.46E-05 and 1.39E-05 in distribution points, respectively. Although THMs concentrations were very low, cancer risk values are 1.0E-06<CR<1.0E-04 which is higher than negligible risk level (1.0E-06).