Distribution and human health risk of N-nitrosamines in tap water in the central region of South Korea

This study aims to evaluate the concentrations and potential risks associated with seven volatile N-nitrosamines (NAs), a category of disinfection by-products, present in tap water, while considering realistic human exposure. Tap water samples were collected across four seasons from three central regions (Gangwon State, Gyeonggi-do, and Seoul Metropolitan City) in South Korea and analyzed for the NAs using high-performance liquid chromatography with fluorescence detection, following solid-phase extraction and derivatization. Among the NAs examined, three compounds, namely N-nitrosomorpholine (NMOR), N-nitrosodimethylamine (NDMA), and N-nitrosodiethylamine (NDEA), were identified in all samples. NDMA had the highest concentration at 53.4 ± 19.5 ng/L, while NMOR and NDEA had 3.83 ± 10.56 ng/L and 37.5 ± 25.6 ng/L, respectively. These compounds exhibited similar concentrations across the three regions, with higher levels observed during winter than other seasons. The estimated cancer risk of NDEA was above 10-6, which is a concern. However, actual risk might be even lower when considering Korean drinking water intake patterns such as hot soups and stews. Nevertheless, it is imperative to improve regulatory practices to comprehensively address health risks from food intake, air contamination, and other sources.