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Download fileCarcinogenic risk of N‑Nitrosamines in Shanghai Drinking Water: Indications for the Use of Ozone Pretreatment
journal contribution
posted on 2019-05-14, 00:00 authored by Zhiyuan Chen, Lan Yang, Yu Huang, Peter Spencer, Weiwei Zheng, Ying Zhou, Songhui Jiang, Weimin Ye, Yuxin Zheng, Weidong QuN-Nitrosamines are drinking water disinfection
byproducts that pose a high carcinogenic risk. We hypothesized that
raw water treatment processes influence the types and concentrations
of nitrosamines in drinking water, thereby posing differential health
risks. We compared the finished water of two water treatment plants
(WTP-A, WTP-B) serving Shanghai, China. Both plants use the Qingcaosha
reservoir as a water source to generate drinking water with conventional
but distinct treatment processes, namely preoxidation with sodium
hypochlorite (WTP-A) vs ozone (WTP-B). Average nitrosamine concentrations,
especially that of the probable human carcinogen (2A) N-nitrosodimethylamine, were higher in finished (drinking) water from
WTP-A (35.83 ng/L) than from WTP-B (5.07 ng/L). Other differences in mean nitrosamines in drinking
water included N-nitrosodipropylamine (42.62 ng/L) and N-nitrosomethylethylamine (26.73 ng/L) in WTP-A in contrast to N-nitrosodiethylamine
(7.26 ng/L) and N-nitrosopyrrolidine
(59.12 ng/L) in WTP-B. The estimated adult cancer
risk from exposure to mixed nitrosamines was 1.83 times higher from
WTP-A than from WTP-B drinking water. Children exposed to nitrosamines
had a significantly higher cancer risk than adults (p < 0.05). Disease burden exceeded 106 person-years.
Taken together, these data suggest that use of ozone in the preoxidation
step can reduce nitrosamine formation in drinking water and thereby
lower the population cancer health risk.