Risk assessment of N-nitrosamines in drinking and tap water for Koreans through different exposure routes

N-Nitrosamines (NAs) are frequently found in drinking water as disinfection by-products. NAs, which are classified as Group B2 carcinogens by the United States Environmental Protection Agency (EPA), may pose a public health concern. The objective of this study was to assess the risks associated with using various water sources. The current study expands on previous research regarding the distribution of N-nitrosodimethylamine (NDMA) in tap water across the Republic of Korea. Potential risks of developing cancer in humans from the consumption of drinking water, inhalation, and dermal exposure during showering were assessed. The observations during the boiling process revealed a decrease in the concentrations of NDMA and N-nitrosodipropylamine. The distribution of NDMA in tap water was found to correspond to cancer risks of ranged from 10^-8 to 10^-3, indicating the highest exposure through ingestion. The risk levels of 20 commercially available bottled waters were found to be 10^-4. Water purifiers were found to be ineffective in reducing the levels of NDMA in tap water, resulting in an elevated risk level of 10^-3. The widespread presence of NDMA in tap water poses a health risk when consumed untreated. This study strongly recommends implementing proactive management strategies to effectively control the presence of NDMA in drinking water in order to protect public health.