Precursor characteristics of mono-HAAs during chlorination and cytotoxicity of mono-HAAs on HEK-293T cells

Hao Weng; Chuantian Wang; Ting Ye; Zeqiong Xu; Hongjie Sun; Hongjun Lin; Wen-Jing Deng; Fuyong Wu; Huachang Hong

doi:10.1016/j.chemosphere.2022.134689

Precursor characteristics of mono-HAAs during chlorination and cytotoxicity of mono-HAAs on HEK-293T cells

Chemosphere. 2022 Aug:301:134689. doi: 10.1016/j.chemosphere.2022.134689. Epub 2022 Apr 22.

Authors

Hao Weng¹, Chuantian Wang¹, Ting Ye¹, Zeqiong Xu¹, Hongjie Sun¹, Hongjun Lin¹, Wen-Jing Deng², Fuyong Wu³, Huachang Hong¹

Affiliations

¹ College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua, 321004, China.
² Department of Science and Environmental Studies, The Education University of Hong Kong, Tai Po, N.T, Hong Kong.
³ College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, PR China.

PMID: 35469898
DOI: 10.1016/j.chemosphere.2022.134689

Abstract

Monohaloacetic acids (mono-HAAs), a class of disinfection by-products widely occurred in drinking water, receives significant attention due to their extremely high toxicity. Many studies on the biological toxicity of mono-HAAs have been reported, yet the toxic effects of mono-HAAs on human renal cells (kidney is one of the target organs for disinfection by-products) has not been involved. Studies on organic precursors for mono-HAAs formation were also very limited due to their lower levels as compared to di-HAAs and tri-HAAs. Based on this, the formation of mono-HAAs after chlorination of some typical source water samples and their relationship with water quality parameters were investigated. Meanwhile, the cytotoxicity of monochloroacetic acid (MCAA), monobromoacetic acid (MBAA), and monoiodoacetic acid (MIAA) were tested using human embryonic kidney cells (HEK-293 T cells). The results showed that the levels of mono-HAAs formed during chlorination of source water samples were between 0.44 and 0.87 μg/L. Formation of MBAA positively (p < 0.05) correlated with bromide ion and dissolved organic carbon, but negatively (p < 0.01) correlated with SUVA₂₅₄ (specific UV absorbance at 254 nm), while formation of MCAA was only positively (p < 0.05) related with SUVA₂₅₄. These results suggested that although MCAA and MBAA both belong to the mono-HAAs, the characteristics of their organic precursors differ significantly. MCAA precursors have high aromaticity and are more hydrophobic, yet MBAA precursors have low aromaticity and are more hydrophilic. The half-lethal concentrations (LC₅₀) of MCAA, MBAA, and MIAA on HEK293T cells were 1196-1211 μM, 16.07-18.96 μM, and 6.08-6.17 μM, respectively. An in-depth analysis showed that the cytotoxicity of mono-HAAs on HEK 293 T cells could not be explained by the parameters concerning cellular uptake (e.g., logP and pKa), but the S_N2 reaction of C-X bond with cellular molecules (e.g., glyceraldehyde-3-phosphate dehydrogenase, etc) may be the relevant cause for the cytotoxicity of mono-HAAs on HEK 293 T cells.

Keywords: Cytotoxicity; Mechanism of toxicity; Monohaloacetic acid; Precursor.

MeSH terms

Acids
Disinfectants* / chemistry
Disinfection
HEK293 Cells
Halogenation
Humans
Trihalomethanes / analysis
Water Pollutants, Chemical* / analysis
Water Purification* / methods

Substances

Acids
Disinfectants
Trihalomethanes
Water Pollutants, Chemical