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The Next Generation of Disinfection By-Products
Citation:
RICHARDSON, S. D. The Next Generation of Disinfection By-Products. Presented at ISC 2008 - 27th International Symposium on Chromatography, Munster, GERMANY, September 21 - 25, 2008.
Impact/Purpose:
Characterize risks associated with drinking water sources, treatment, distribution, and use.
Description:
The disinfection of drinking water has been rightly hailed as a public health triumph of the 20th century. Millions of people worldwide receive quality drinking water every day from their public water systems. However, chemical disinfection has also produced an unintended health hazard: the potential for cancer and reproductive/developmental effects that are associated with chemical disinfection by-products (DBPs). Chemical disinfectants are effective for killing harmful pathogens in drinking water, but they are also powerful oxidants, oxidizing the organic matter, anthropogenic contaminants, and bromide/iodide naturally present in most source waters (rivers, lakes, and many groundwaters). Chlorine, ozone, chlorine dioxide, and chloramines are the most common disinfectants in use today, and each produces its own suite of DBPs in drinking water. Out of more than 600 DBPs known, only 11 are currently regulated in the United States. And, those that are regulated do not cause the primary type of cancer (bladder cancer) that is observed in the human epidemiologic studies. Recent research has identified 'emerging', unregulated DBPs that are more cytotoxic and genotoxic than those that are currently regulated, and the use of newer alternative disinfectants (chloramines, ozone, chlorine dioxide) can increase their formation. This is important because many drinking water utilities in the U.S. are changing from chlorine to alternative disinfectants to meet stricter regulations. Emerging DBPs include iodo-acids, iodo-trihalomethanes (lodo-THMs), bromonitromethanes, haloamides, and nitrosamines (including nitrosodimethylamine, NDMA). New research on emerging DBPs will be presented, along with results from an occurrence study of iodo-acids and iodo-THMs and new research on high molecular weight DBPs. Finally, results from a new EPA study (the Four Lab Study), which involves the chemical and toxicological evaluation of complex drinking water mixtures treated with chlorine and alternative disinfectants, will be briefly discussed, along with other important new health effects information. Research in the discovery of new, emerging DBPs has included the use of gas chromatography (GC) with low and high resolution mass spectrometry (MS), as well as liquid chromatography (LC)/MS(/MS). Details on the use of these techniques will also be presented.