Drinking water chlorination

Bellar TA, Lichtenberg JJ, Kroner RC. 1974. The occurrence of organohalides in chlorinated drinking waters. Journal of American Water Works Association 66 703-706. 

Simmon VF, Tardiff RG. 1978. The mutagenic activity of halogenated compounds found in chlorinated drinking water. In Water chlorination Environmental impact and health effects. Vol. 2. Ann Arbor, Ml Ann Arbor Science, 417-431. 

Note that some of the risk information is actuarial (based on statistical data, typically collected and organized by insurance companies), and some of it has been derived from the type of risk assessment discussed in this book (chloroform in chlorinated drinking water, afla-toxin in peanut products). While the uncertainties associated with the figures in Table 11.2 are much greater for some risks than for others (not a trivial problem in presentation of risk data), such a presentation, it would seem, is helpful to people who are trying to acquire some understanding of extremely low probability events, of the order of one-in-one million. 

The effects of chronic oral exposure to chloroform, as a by-product of the chlorination of drinking water, were evaluated in four epidemiology studies (Alavanja et al. 1978 Cantor et al. 1978 Saurez-Varela et al. 1994 Young et al. 1981). The association between the incidence of gastrointestinal cancer in humans and the chlorination of drinking water is discussed in Section 2.2.2.8. The data from these studies should be viewed with caution as many other known or suspected carcinogens are known to exist in chlorinated drinking water. 

Cancer. No studies were available regarding eaneer in humans or animals after inhalation exposure to chloroform. Epidemiology studies suggest an association between chronic exposure to chlorinated drinking-water sources and increased incidences of colon cancer (Young et al. 1981), pancreatic cancer (Ijsselmuiden et al. 1982) and bladder cancer (Cantor et al. 1978 McGeehin et al. 1993 Zierler et al. 

However, numerous other potential toxicants known to exist in chlorinated drinking water may easily account for these effects. 

In epidemiologic studies, chloroform is not identified as the sole or primary cause of excess cancer rates, but it is one of many organic contaminants found in chlorinated drinking water, many of which are considered to have carcinogenic potential. These studies are often flawed by a lack of measured chloroform concentrations in drinking water lack of data concerning concentrations of other organics. 

As seen from Figure 2-6, information is available regarding death, systemic effects, and neurological effects in humans after inhalation and oral exposure to chloroform. In addition, information is available regarding carcinogenic effects in humans after oral exposure to chlorinated drinking water. Limited information is available regarding dermal effects in humans after exposure to chloroform. 

Gibs J, Stackelberg PE, Furlong ET, Meyer M, Zaugg SD, Lippincott RL (2007) Persistence of pharmaceuticals and other organic compounds in chlorinated drinking water as a function of time. Sci Total Environ 373 240-249... 

Nitrosamines have been of significant interest since they were discovered to be DBFs in 2002 [42, 43]. Their structures are shown in Fig. 3. A-Nitrosodi-methylamine (NDMA) is a probable human carcinogen, and there are toxicological concerns regarding other nitrosamines. NDMA was initially discovered in chlorinated drinking waters from Ontario, Canada [44], and has since been found in other locations [42, 43, 45]. The detection of NDMA in drinking water is largely due to improved analytical techniques that have allowed its determination at low... 

Thomas RF, Weisner MJ, Brass HJ (1980) The fifth trihalomethane dichloroiodomethane. Its stability and occurrence in chlorinated drinking water. In Jolley RL, Brungs WA, Gumming RB, Jacobs VA (eds) Water chlorination environmental impact and health effects, vol 3. Ann Arbor Science, Ann Arbor, MI, pp 161-168... 

Suzuki N, Nakanishi J (1995) Brominated analogues of MX (3-chloro-4-(dichloromethyl)-5-hydroxy-2 (5H)-furanone) in chlorinated drinking water. Chemosphere 30 1557-1564... 

There is no clear epidemiological evidence for the carcinogenicity of chlorodibromomethane in humans. However, a number of studies suggest an association between chronic ingestion of trihalomethanes in chlorinated drinking water and increased risk of bladder or colon cancer. These smdies cannot provide information on whether any observed effects are due to chlorodibromomethane or to one or more of the hundreds of other by-products that also are present in chlorinated drinking water. 

Current concern regarding TCA arises from chronic low-level exposure via chlorinated drinking water. In 90-day subchronic studies, 5000 ppm in the drinking water caused increased liver- and kidney-to-body weight ratios in rats. Increased hepatic peroxisome activity and histopathologic changes in the liver and kidneys were also observed. 

Chlorinated Drinking-water Chlorination By-products Some Other Halogenated Compounds Cobalt and Cobalt Compounds... 

I ARC (1991) lARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol, 52, Chlorinated Drinking-Water Chlorination By-Products Some Other Halogenated Compounds Cobalt and Cobalt Compounds, Lyon, pp. 337-359... 

Bromodichloromethane is found in chlorinated drinking-water as a consequence of the reaction between chlorine, added during water treatment, and natural organic substances in the presence of bromide. The major route of human exposure is via drinking-water. Bromodichloromethane has also been detected in some untreated waters, but at much lower levels. It is a major component of the organohalides produced by marine algae (lARC, 1991). 

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