New disinfection by-product issues: emerging DBPs and alternative routes of exposure

This paper discusses current issues with drinking water disinfection by-products (DBPs), which include emerging (unregulated) DBPs that can be formed at greater levels with alternative disinfectants (as compared to chlorine) and routes of human exposure (which include inhalation and dermal exposure studies, in addition to ingestion). Health effects driving DBP research include the recently observed reproductive/developmental effects (including spontaneous abortion) observed in epidemiologic studies, as well as the discrepancy between the types of cancer observed in animal studies for regulated DBPs (mostly liver cancer) and the types of cancer observed in human epidemiologic studies (mostly bladder cancer). Emerging DBPs discussed in this paper include iodo-acids, bromonitromethanes, iodo-trihalomethanes (THMs), brominated forms of MX, bromoamides, a bromopyrrole, and nitrosodimethylamine (NDMA) and other nitrosamines. Recent toxicity studies have revealed that several of these DBPs are more genotoxic (in isolated cells) than many of the DBPs currently regulated, and new occurrence data have revealed that many of these DBPs can, in some cases, be present at levels comparable to regulated DBPs. Of the alternative disinfectants, chloramination appears to increase the formation of iodo-acids, iodo-THMs, and NDMA and other nitrosamines, relative to chlorine. Preozonation appears to increase the formation of halonitromethanes.

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Developmental effects and genotoxicity of 10 water disinfection by-products in zebrafish

Journal of Water and Health ◽

10.2166/wh.2014.006 ◽

2014 ◽

Vol 13 (1) ◽

pp. 54-66 ◽

Cited By ~ 21

Author(s):

Elisabet Teixidó ◽

Esther Piqué ◽

Javier Gonzalez-Linares ◽

Joan M. Llobet ◽

Jesús Gómez-Catalán

Keyword(s):

Developmental Toxicity ◽

Tail Length ◽

Water Disinfection ◽

Dichloroacetic Acid ◽

Sodium Bromate ◽

Developmental Effects ◽

Increased Risk ◽

Drinking Water Disinfection ◽

Tribromoacetic Acid ◽

By Products

Disinfection by-products are contaminants produced during drinking water disinfection. Several DBPs have been implicated in a variety of toxic effects, mainly carcinogenic and genotoxic effects. Moreover, DBPs exposure has also been associated with an increased risk of developmental effects. In this study, the developmental toxicity and genotoxicity of 10 DBPs (four trihalomethanes [THMs], five haloacetic acids [HAAs] and sodium bromate) in the zebrafish embryo model were evaluated. Embryos exposed for 72 hours were observed for different endpoints such as growth, hatching success, malformations and lethality. THMs exposure resulted in adverse developmental effects and a significant reduced tail length. Two HAAs, tribromoacetic acid and dichloroacetic acid, along with sodium bromate were found to cause a significant increase in malformation rate. Chloroform, chlorodibromomethane and sodium bromate produced a weak induction of DNA damage to whole embryos. However, developmental effects occurred at a range of concentrations (20–100 μg/mL) several orders of magnitude above the levels that can be attained in fetal blood in humans exposed to chlorinated water. In conclusion, the teratogenic and genotoxic activity observed by some DBPs in zebrafish reinforce the view that there is a weak capacity of disinfection products to cause developmental effects at environmentally relevant concentrations.

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