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COMPARATIVE RISK DILEMNAS IN DRINKING WATER DISINFECTION [EDITORIAL]
Citation:
Rossman*, L A. COMPARATIVE RISK DILEMNAS IN DRINKING WATER DISINFECTION [EDITORIAL]. JOURNAL OF ENVIRONMENTAL ENGINEERING. American Society of Civil Engineers (ASCE), Reston, VA, 124(9):781, (1998).
Impact/Purpose:
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Description:
Disinfection of drinking water supplies has been one of the most succesful public health interventions of the twentieth century. It has virtually eliminated outbreaks of serious waterborne infectious diseases, such as cholera and typhoid. there are still, however, an average of about 15 confirmed water-borne outbreaks, reported each year in the United States, and it is thought that many more unreported incidences of gastro-intestinal (GI)-related illnesses can be attributed to drinking water. The etiological agent in many of these outbreaks has been one of the parasitic protozoa, Giardia or Cryptosporidium. Althouth mainly an uncomfortable nuisance for most people, infections from these parasites can be life threatening for the very young, the very old, and individuals with weakened immune systems. The 1993 Cryptosporidium outbreak in Milwaukee, Wis., caused 400,000 illnesses, 1,000 hospitalizations, and 50 deaths.
In the 1970s it was discovered that halogenated byproducts are formed when chlorine used for disinfection reacts with the natural organic matter present in water. Since then it has been recognized that hundreds of organic compounds can result from chlorination, only several of which have been identified. Unwanted byproducts are also produced from other disinfectants, such as ozone and chlorine dioxide. Some of these disinfectants, such as ozone and chlorine dioxide. Some of these disinfection byproducts (DBPs), such as chloroform, dichloroacetic acid, and bromate ion, have been shown to produce cancer in laboratory animals. There is also partial, but inconclusive epidemiological evidence at this time linking these compounds to human cancers, reporoductive failures (e.g. miscarriages and still births), and development disorders. Estimates of excess cancer cases attributable to chlorinated drinking water range from 200 to as many as 10,000 per year.
