Occurrence and exposure risk evaluation of polyhalogenated carbazoles (PHCZs) in drinking water

Although polyhalogenated carbazoles (PHCZs) can be generated and detected in drinkingwater, their occurrence and potential health risks to humans via drinking water ingestion are not well known. In this study, 11 PHCZs were screened in drinking water samples fromWuhan, themost populous city in central China. The total concentration of PHCZs could be up to 53.48 ng/L with a median level of 8.19 ng/L, which was comparable to polychlorinated biphenyls and poly- and perfluoroalkyl substances reported in the literatures for drinking water. Composition profiles revealed that 3,6-dichlorocarbazole, 3-chlorocarbazole, 3-bromocarbazole and 3,6dibromocarbazole were the predominant PHCZ congeners in the tested samples. Regional differences in the levels and patterns of PHCZs suggested that anthropogenic releases should be the dominant source compared to natural generation. Boiling of the water samples caused no significant change in PHCZs concentrations after correcting the volume change due to evaporation. Potential health risks associated to the levels of PHCZs in drinkingwaterwere assessed using the toxic equivalent (TEQs) method. The estimated daily intake of PHCZs via drinking water ingestion is up to 0.38 pg-TEQ/kg body weight/day for infants, nearly 4.5 times higher than that for adults, and appears to reach the maximum permissible concentration set by certain authority agencies. Overall, drinking water ingestion represents an important exposure pathway for PHCZs. This is the first comprehensive study on the abundance and health risks of PHCZs in drinking water. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The study in Wuhan, China, revealed the presence of polyhalogenated carbazoles (PHCZs) in drinking water samples, with anthropogenic releases as the main source. Infants were found to have a higher estimated daily intake of PHCZs through drinking water ingestion compared to adults, potentially exceeding maximum permissible concentrations set by certain authority agencies.