There is a very large population potentially exposed to disinfection byproducts through drinking water. Over 200 million people are served by water systems which apply a disinfectant (e.g., chlorine) to water in order to provide protection against microbial contaminants. While these disinfectants are effective in controlling many harmful microbes, they combine with natural organic and inorganic matter in the water and form disinfection byproducts, some of which may pose health risks. One of the most complex questions facing water supply professionals is how to minimize the risks from these disinfection byproducts and still control microbial contaminants.
In 1990, the United States Environmental Protection Agency's (USEPA) Science Advisory Board (SAB), an independent panel of experts established by Congress, cited drinking water contamination as one of the most important environmental risks and indicated that disease-causing microbial contaminants (i.e., bacteria, protozoa, and viruses) are probably the greatest remaining health risk management challenge for drinking water suppliers (USEPA SAB 1990). This view was prompted by the SAB's concern about the number of waterborne disease outbreaks in the U.S. Between 1980 and 1994, 379 waterborne disease outbreaks were reported, with over 500,000 cases of disease. During this period, a number of agents were implicated as the cause, including protozoa, viruses, and bacteria, as well as several chemicals. Most of the cases (but not outbreaks) were associated with surface water, and specifically with a single outbreak of cryptosporidiosis in Milwaukee (over 400,000 cases).
Pathogen information in the ICR is being collected from raw untreated sources.