During the water treatment process, toxic compounds are often oxidized into what scientists presumed were less harmful chemicals called “transformation products.” But less is known about these transformation products than scientists thought. “Once the chemical is gone, the job – it would seem – is done, but in fact we don’t always know what removal of the chemical means: does it turn into something else? Is that transformation product harmful?” Explained Carsten Prasse, Assistant Professor of Environmental Health and Engineering at Johns Hopkins University. 

Much is known about chlorination as a water treatment process, but newer processes, such as oxidation with hydrogen peroxide and UV light, are less studied. Prasse and researchers from University of California, Berkeley, are looking at a group of organic chemicals called phenols that are often present in dyes, personal care products, pharmaceuticals, and pesticides. The team wanted to oxidize the phenols to see what transformation products were produced.

They found that one of the products that phenol converted to was 2-butene-1,4-dial, which has known negative effects like DNA damage. The team then exposed 2-butene-1,4-dial to mouse liver proteins and found that 37 protein targets were affected. The targets were involved with processes ranging from energy metabolism to protein and steroid synthesis. Prasse noted that there are links between pesticide exposure and obesity, and this study could “help to explain why that is.” The team also found that the compound affects an enzyme involved in apoptosis, or cell death. Inhibiting apoptosis can lead to cancer growth.

Prasse wants to continue this research by expanding the methodology to study other contaminants and identifying more transformation products. In order to improve drinking water, “we need to able to screen for multiple chemicals at once,” Prasse explains; “the next steps are to investigate how this method can be applied to more complex samples.”

Prasse’s research was recently published in Proceedings of the National Academy of Sciences.