David Sedlak, Ph.D.
University of California, Berkeley
Common water treatment methods that remove phenols and other hazardous compounds may produce low levels of toxic byproducts, according to a new study by NIEHS grantees. Phenols, which can contaminate drinking water, are often removed with a water treatment process that converts hydrogen peroxide into hydroxyl radicals using ultraviolet (UV) light. In this process, hydroxyl radicals oxidize the phenols, transforming them into other compounds.
Researchers evaluated the toxicity of these transformation products using a technique that assesses the formation of protein adducts, which can indicate disruption of protein structure or function in the body. They demonstrated that phenols can react with hydroxyl radicals to form toxic compounds known as enedials and oxoenals. Although this chemical reaction was previously observed in the gas phase, the authors wrote this was the first experimental evidence of the reaction occurring in water.
According to the authors, the results highlighted the potential risks of using oxidative treatment on contaminated drinking water sources, and the need to understand and address the fate of toxic byproducts throughout the water treatment process. They also showed that their technique could be used as a sensitive method to identify reactive products formed during oxidative water treatment.
Citation: Prasse C, For B, Nomura DK, Sedlak DL. 2018. Unexpected transformation of dissolved phenols to toxic dicarbonyls by hydroxyl radicals and UV light. Proc Natl Acad Sci U S A 115(10):2311–2316.