Byproduct of water-disinfection process found to be highly toxic

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Byproduct of water-disinfection process found to be highly toxic

 

 

A recently discovered disinfection byproduct (DBP) found in U.S. drinking water

treated with chloramines is the most toxic ever found, says a scientist at the

University of Illinois at Urbana-Champaign who tested samples on mammalian

cells.

 

The discovery raises health-related questions regarding an Environmental

Protection Agency plan to encourage all U.S. water-treatment facilities to adopt

chlorine alternatives, said Michael J. Plewa [PLEV-uh], a genetic toxicologist

in the department of crop sciences. " This research says that when you go to

alternatives, you may be opening a Pandora’s box of new DBPs, and these

unregulated DBPs may be much more toxic, by orders of magnitude, than the

regulated ones we are trying to avoid. "

 

Plewa and colleagues, three of them with the EPA, report on the structure and

toxicity of five iodoacids [EYE O-doe-acids] found in chloramines-treated water

in Corpus Christi, Texas, in this month’s issue of the journal Environmental

Science & Technology. The findings, which appeared online in advance, already

have prompted a call from the National Rural Water Association for a delay of

EPA’s Stage 2 rule aimed at reducing the amount of previously identified toxic

DBPs occurring in chlorine-treated water. " The iodoacids may be the most toxic

family of DBPs to date, " Plewa said in an interview. One of the five detailed in

the study, iodoacetic acid, is the most toxic and DNA-damaging to mammalian

cells in tests of known DBPs, he said. " These iodoacetic acids raise new levels

of concerns, " he said. " Not only do they represent a potential danger because of

all the water consumed on a daily basis, water is recycled back into the

environment. What are the consequences? The goal of Stage

2 is to reduce DBPs, particularly the ones that fall under EPA regulations, and

especially the ones that have been structurally identified and found to be

toxic. "

 

The use of chloramines, a combination of chlorine and ammonia, is one of three

alternatives to chlorine disinfectant, which has been used for more than 100

years. Other alternatives are chlorine-dioxide and ozone. All treatments react

to compounds present in a drinking water source, resulting in a variety of

chemical disinfectant byproducts.

 

Some 600 DBPs have been identified since 1974, Plewa said. Scientists believe

they’ve identified maybe 50 percent of all DBPs that occur in chlorine-treated

water, but only 17 percent of those occurring in chloramines-treated water, 28

percent in water treated with chlorine-dioxide, and just 8 percent in

ozone-treated water. Of the structurally identified DBPs, he said, the

quantitative toxicity is known for maybe 30 percent. Some DBPs in

chlorine-treated water have been found to raise the risks of various cancers, as

well as birth and developmental defects.

 

Corpus Christi’s water supply has high levels of bromide and iodide because of

the chemical makeup of the ancient seabed under the water source. Local water

sources lead to different DBPs. Whether the types of iodoacids found in Corpus

Christi’s treated water might be simply a reflection of local conditions, and

thus a rare occurrence, is not known. The DBPs in Corpus Christi’s water were

found as part of an EPA national occurrence survey of selected public

water-treatment plants done in 2002. The survey reported on the presence of 50

high-priority DBPs based on their carcinogenic potential. The report, published

in April, also identified 28 new DBPs.

 

Because so many new DBPs are being found in drinking water, Plewa said, two

basic questions should be asked: How many are out there? And how many new ones

will be formed as chlorine treatments are replaced with alternative methods?

More information:www.uiuc.edu

 

 

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