EPA Examines Ways to Treat Biotoxins in Drinking Water
Agency researchers advance science to help protect the nation's drinking water.
Since 1854, when Dr. Snow first traced a cholera epidemic to a public water supply in London, England health officials and researchers have been working to protect the quality and safety of drinking water. The U.S. Public Health Service set drinking water standards in 1914. Although biotoxins—toxic substances produced by living organisms— have long been a concern for drinking water, the concern that someone would maliciously introduce them into drinking water gained increased attention following attacks in 2001.
“As we continue to implement Safe Drinking Water Act and other homeland security protections, EPA has been identifying and filling data gaps regarding the impacts that biotoxins, such as ricin, SEB (staphylococcal enterotoxin B), botulinum toxin type A, and T-2 mycotoxin, might have on our drinking water,” explains EPA research chemist Matthew Magnuson. Those particular biotoxins can cause fatalities or serious illness.
After conducting a literature review to identify data gaps, researchers tested the ability of off-the-shelf devices to detect biotoxin contamination, and investigated the potential of various technologies to treat water if it became contaminated. All of the detection devices tested used antibodies to detect the biotoxins. They were evaluated to see if they could detect biotoxins added in the laboratory to drinking water samples gathered from around the country.
Results of the testing suggest that some level of water sample field testing may be possible; however all of these devices must be properly used in the context of a program to detect and identify water contaminants. While these off-the-shelf devices may be used as part of an initial threat evaluation, as the investigation of a threat or incident progresses, it is likely that additional laboratory analyses would be needed.
The study also evaluated the effect of several water treatment technologies, including chemical oxidation, coagulation, and boiling. The first two technologies are frequently employed at water treatment plants, and boiling is sometimes suggested for consumers to treat contaminated water. This part of the study concluded that there are notable variations in the effectiveness of treating the four biotoxins tested. For example, only one of four chemical oxidants evaluated was effective against T-2 mycotoxin, and one oxidant had only a limited effect against all of the biotoxins that were tested. High concentrations of coagulants might be useful in removing ricin, SEB, and botulinum type A. Boiling drinking water was effective for all biotoxins tested; however, the results suggest that boiling time must be increased from one minute to 10 minutes when treating T-2 mycotoxin contamination.
Water utilities in conjunction with public health authorities sometimes recommend that consumers boil their water for one to two minutes when the supply is potentially contaminated such as after a major water main break. The results of EPA testing provide important information for water utilities to consider, allowing them to more confidently recommend boiling water for longer periods of time if supplies have been contaminated with the biotoxins that were investigated.
Research results indicated that both detection and treatment technologies may help reduce the risk of public exposure to ingesting water contaminated with biotoxins. EPA is investigating these issues further and is committed to providing the necessary tools to protect drinking water resources.