Common pipe alloy can form cancer-causing chemical in drinking water

December 03, 2020

Rusted iron pipes can react with residual disinfectants in drinking water distribution systems to produce carcinogenic hexavalent chromium in drinking water, reports a study by engineers at UC Riverside.

Chromium is a metal that occurs naturally in the soil and groundwater. Trace amounts of trivalent chromium eventually appear in the drinking water and food supply and are thought to have neutral effects on health. Chromium is often added to iron to make it more resistant to corrosion.

Certain chemical reactions can change chromium atoms into a hexavalent form that creates cancer-causing genetic mutations in cells. This carcinogenic form of chromium was at the heart of a lawsuit in California's Central Valley by Erin Brockovich, which became the subject of an Oscar-winning movie.

Haizhou Liu, a professor of chemical and environmental engineering at the Marlan and Rosemary Bourns College of Engineering who studies water treatment chemistry, had an inkling that some of the chromium found in drinking water might come from chemical reactions between water disinfectants and the chromium in cast iron corrosion scales.

Along with doctoral student Cheng Tan and postdoctoral scholar Sumant Avasarala, Liu obtained segments of two pipes that had been in service for about five and 70 years respectively and induced corrosion on portions. After scraping the rust off, grinding it to a powder, and measuring the amount and types of chromium present, the researchers put the samples in hypochlorous acid, the form of chlorine typically used in municipal drinking water treatment plants and drinking water distribution systems.

Previous experiments had shown that water disinfectants could transform trivalent chromium into toxic hexavalent chromium, but the group was surprised when zerovalent chromium that was detected in the rusted iron pipes transformed more quickly to the toxic form. They followed up with modeling experiments that showed a range of possibilities for how much hexavalent chromium could come out of the tap under real-world conditions. The worst-case scenario occurred in drinking water with high bromide levels.

"These new findings change our traditional wisdom on hexavalent chromium control in drinking water and shine light on the importance of managing the drinking water distribution infrastructure to control toxic substances in tap water," Liu said.

The paper cautions that as the world's water crisis intensifies, recycled and desalinated water-- both of which tend to contain higher bromide levels--will become more important, highlighting the need to understand and prevent chromium contamination. The paper recommends reduced use of pipes with high levels of chromium alloy and use of a disinfectant less reactive with chromium, such as monochloramine.
-end-
The work was supported by a National Science Foundation CAREER Program grant. The paper, "Hexavalent Chromium Release in Drinking Water Distribution Systems: New Insights into Zerovalent Chromium in Iron Corrosion Scales," is published in Environmental Science and Technology.

University of California - Riverside

Related Drinking Water Articles from Brightsurf:

The dangers of collecting drinking water
Fetching drinking water in low and middle income countries can cause serious injury, particularly for women.

How a toxic chromium species could form in drinking water
The water crisis in Flint, Michigan, brought much-needed attention to the problem of potentially toxic metals being released from drinking water distribution pipes when water chemistry changes.

Is your drinking water toxic? This app may help you find out
Since fracking sites use a diverse mix of chemical ingredients, often individuals and researchers are in the dark about the health consequences of living near a particular well.

New solar material could clean drinking water
Providing clean water to Soldiers in the field and citizens around the world is essential, and yet one of the world's greatest challenges.

Aluminum may affect lead levels in drinking water
Until recently, researchers have not inspected the interplay between three common chemicals found in drinking water.

Natural contaminant threat to drinking water from groundwater
Climate change and urbanisation are set to threaten groundwater drinking water quality, new research from UNSW Sydney shows.

Fresh clean drinking water for all could soon to be a reality in Pakistan
A fresh, clean water supply will be a reality in Pakistan, particularly in South Punjab, following the announcement of an international partnership spearheaded by the Pakistan government, alongside other key stakeholders, and driven by the University of Huddersfield.

Keeping lead out of drinking water when switching disinfectants
Researchers at the McKelvey School of Engineering at Washington University in St.

Solar power with a free side of drinking water
An integrated system seamlessly harnesses sunlight to cogenerate electricity and fresh water.

'Liquid forensics' could lead to safer drinking water
Ping! The popular 1990 film, The Hunt for Red October, helped introduce sonar technology on submarines to pop culture.

Read More: Drinking Water News and Drinking Water Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.