Neonicotinoids in raw, finished, and tap water from Wuhan, Central China: Assessment of human exposure potential

Neonicotinoid insecticides (NNIs) are emerging insecticides compared to organophosphates and pyrethroids. Their occurrence in the environment is not well documented in China. In this study, raw water samples (n = 20), finished water samples (n = 20), and tap water samples (n = 165) originating from the Han River and the Yangtze River in Wuhan, Central China, were collected during 2018 for the determination of the NNI residues. NNIs were found in all raw water samples with a median sum concentration of 27.7 ng/L (range: 13.4-186 ng/L). Higher concentrations of NNIs were found in July than in May, and higher NNIs were found in the Han River than in the Yangtze River. Most NNIs were not effectively removed during water treatment, except for acetamiprid and thiacloprid which decreased by 40.1% and 20.0%, respectively. At least three NNIs were detected in all tap water samples with the highest sum concentration of NNIs observed in July (median: 96.2 ng/L, range: 16.7-138 ng/L) among the studied months (median: 15.4, range: 2.59-138 ng/L). The estimated daily intake of NNIs via tap water ingestion in July was 8.66 ng/kg body weight/day for infants, about 4 times higher than that for adults. The concentrations observed in tap water are elevated in China relative to previous studies that were conducted in the USA and in Canada. This is the first study reporting residue levels of NNIs in China. (C) 2019 Elsevier B.V. All rights reserved.