Regional and Seasonal Distributions of N-Nitrosodimethylamine (NDMA) Concentrations in Chlorinated Drinking Water Distribution Systems in Korea

Volatile N-Nitrosamines (NAs), including N-nitrosodimethylamine (NDMA), an emerging contaminant in drinking water, have been reported to induce cancer in animal studies. This study aims to investigate the regional and seasonal distributions of the concentrations of NDMA, one of the most commonly found NAs with high carcinogenicity, in municipal tap water in Korea. NDMA in water samples was quantitatively determined using high-performance liquid chromatography-fluorescence detection (HPLC-FLD) as a 5-dimethylamino-1-naphthalenesulfonyl (dansyl) derivative after optimization to dry the SPE adsorbent and remove dimethylamine prior to derivatization. Tap water samples were collected from 41 sites in Korea, each of which was visited once in summer and once in winter. The average (±standard deviation) NDMA concentration among all the sites was 46.6 (±22.7) ng/L, ranging from <0.13 to 80.7 ng/L. Significant NDMA differences in the regions, excluding the Jeju region, were not found, whereas the average NDMA concentration was statistically higher in winter than in summer. A multiple regression analysis for the entire data set indicated a negative relationship between NDMA concentration and water temperature. High levels of NDMA in Korea may pose excessive cancer risks from the consumption of such drinking water.

Ingestion exposure to nitrosamines in chlorinated drinking water

OBJECTIVES

N-Nitrosodimethylamine (NDMA) is classified as a probable human carcinogen by the United States Environmental Protection Agency (US EPA) and is formed during the chlorination of municipal drinking water. In this study, selected nitrosamines were measured in chlorinated drinking water collected from Chuncheon, Kangwon-do, Republic of Korea, and a risk assessment for NDMA was conducted.

METHODS

Twelve water samples were collected from 2 treatment plants and 10 household taps. Samples were analyzed for 6 nitrosamines via solid-phase extraction cleanup followed by conversion to dansyl derivatives and high-performance liquid chromatography-fluorescence detection (HPLC-FLD). Considering the dietary patterns of Korean people and the concentration change of NDMA by boiling, a carcinogenic risk assessment from ingestion exposure was conducted following the US EPA guidelines.

RESULTS

NDMA concentrations ranged between 26.1 and 112.0 ng/L. NDMA in water was found to be thermally stable, and thus its concentration at the end of boiling was greater than before thermal treatment owing to the decrease in water volume. The estimated excess lifetime carcinogenic risk exceeded the regulatory baseline risk of 10(-5).

CONCLUSIONS

This result suggests that more extensive studies need to be conducted on nitrosamine concentration distributions over the country and the source of relatively high nitrosamine concentrations.