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DISINFECTION BY-PRODUCTS AND OTHER EMERGING CONTAMINANTS IN DRINKING WATER
Citation:
Richardson, S D. DISINFECTION BY-PRODUCTS AND OTHER EMERGING CONTAMINANTS IN DRINKING WATER. TRENDS IN ANALYTICAL CHEMISTRY 22(10):666-684, (2003).
Impact/Purpose:
(1) Use toxicity-based approach to identify DBPs that show the greatest toxic response. (2) Comprehensively identify DBPs formed by different disinfectant regimes for the 'Four Lab Study'. (3) Determine the mechanisms of formation for potentially hazardous bromonitromethane DBPs.
Description:
Although drinking water disinfection by-products (DBPs) have been studied for the last 30 years, significant, new concerns have arisen. These concerns include adverse reproductive and developmental effects recently observed in human populations, concerns that the types of cancer observed in laboratory animals (for regulated DBPs) do not correlate with the cancers observed in human populations (indicating that other DBPs may be important), and concerns arising from human exposure studies that show that other routes besides ingestion (i.e., inhalation and dermal adsorption) are also significant sources of DBP exposures. In addition, many drinking water utilities are changing their primary disinfectant from chlorine to alternative disinfectants (e.g., ozone, chlorine dioxide, and chloramines), which generally reduce regulated trihalomethane and haloacetic acid levels, but can increase the levels of other potentially toxicologically important DBPs. For example, results of a new U.S. nationwide DBP occurrence study (discussed in this review) demonstrated that bromo-trihalonitromethanes, iodo-trihalomethanes, dihaloaldehydes, MX (MX is 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone), and brominated forms of MX were formed at higher levels when alternative disinfectants were used to treat drinking water. Specific DBPs of emerging toxicological interest include brominated and iodinated compounds including bromonitromethanes, iodo-trihalomethanes, iodo-acids, and brominated forms of MX--as well as nitrosodimethylamine (NDMA). In addition to DBPs, there are also new concerns over the presence of pharmaceuticals, organotins, methyl-tert-butyl ether (MTBE), perchlorate, and algal toxins in drinking water. This article will discuss these drinking water contaminants of emerging concern and the analytical methods currently being used for their determination.