Haloacetic acids

Haloacetic acids are carboxylic acids in which a halogen atom takes the place of a hydrogen atom in acetic acid. In a monohaloacetic acid, a single halogen replaces a hydrogen atom; for example, in bromoacetic acid. Further substitution of hydrogen atoms with halogens can occur, as in dichloroacetic acid and trichloroacetic acid.

Bromoacetic acid
Trichloroacetic acid
Examples of haloacetic acids

The inductive effect caused by the electronegative halogens often result in the higher acidity of these compounds by stabilising the negative charge of the conjugate base.

Contaminants in treated water

Haloacetic acids (HAAs) are a common undesirable by-product of water treatment by chlorination. Exposure to such disinfection by-products in drinking water, at high levels over many years, has been associated with a number of health outcomes by epidemiological studies.[1]

HAAs can be formed following chlorination, ozonation or chloramination of water, as chlorine from the water disinfection process can react with organic matter and small amounts of bromide present in water. HAAs are highly chemically stable, and therefore persist in water after formation.[2]

A study published in August 2006 found that total levels of HAAs in drinking water were not affected by storage or boiling, but that filtration was effective in decreasing levels.[3]

HAA5

In the United States, the EPA regulates the five HAAs most commonly found in drinking water, collectively referred to as "HAA5."[4] These are:

The regulation limit for these five acids combined is 60 parts per billion (ppb).[5]

HAA9

The designation "HAA9" refers to a larger group of HAAs, including all of the acids in HAA5, along with:

The level of these four acids in drinking water is not regulated by the EPA.[6][7]

See also

References
  1. "Drinking Water". cehtp.org. Archived from the original on 2019-04-08. Retrieved 2016-08-15.
  2. "Occurrence Assessment for the Final Stage 2 Disinfectants and Disinfection Byproducts Rule". United States Environmental Protection Agency. Retrieved 27 October 2023.
  3. Levesque, S; Rodriguez, MJ; Serodes, J; Beaulieu, C; Proulx, F (2006). "Effects of indoor drinking water handling on trihalomethanes and haloacetic acids". Water Res. 40 (15): 2921–30. doi:10.1016/j.watres.2006.06.004. PMID 16889815.
  4. "Haloacetic Acids (five) (HAA5): Health Information Summary" (PDF). New Hampshire Department of Environmental Services. Retrieved 27 October 2023.
  5. "Disinfection Byproducts: A Reference Resource". United States Environmental Protection Agency. Retrieved 27 October 2023.
  6. "Column Name: HAA9". United States Environmental Protection Agency. Retrieved 27 October 2023.
  7. "Haloacetic acids (HAA9)". Environmental Working Group. Retrieved 27 October 2023.

Further reading
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.