Drinking Water Contaminants in the United States

The results of human activities described in the previous sections of this chapter have resulted in the release of thousands of pollutants into the environment. In a good portion of the world, ground- and surface waters are treated to disinfect biological agents and remove chemical pollutants prior to human consumption. Despite such treatment, the water consumed by almost all of the world s population is contaminated with chemical toxicants. In the United States, tap water tests from 1998 through 2003 on more than 39,000 water systems in 42 states, serving more than 231 million people detected 260 different pollutants. These are characterized by their sources in Tables 8.2-8.6. The data that follow in these tables, as well as those in Table 8.7, were compiled and reported by the EWGJ64I 

It should be noted that not all water systems contained all the pollutants listed. The data are further broken down by state and local water supply systems on the EWG web site.I64 It should also be noted that many of the individual pollutants have more than one source. Heavy metals in potable 

Aldicarb sulfoxide Aldicarb sufone Metolachlor Carbofuran Aldicarb Atrazine Alaclor EPTC (Eptam) 

5- T Chloramben Dichloroprop Bromomethane Isophorone Alpha-lindane Beta-lindane Aldrin 

Tetrachloroethylene Benzene Bromobenzene /3-Propylbenzene Ethyl-f-butyl ether 

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Trichloroethylene (TCE) and its metabolite trichloroacetic acid (TCA) are cardiac teratogens. Both are common drinking water contaminants in the United States, and exposure to TCE during pregnancy has been shown to produce congenital heart defects in children exposed to it in utero via an unknown mechanism. The risk for congenital heart defects in children whose mothers lived in close proximity to TCE emitting sites is three times more than those whose mothers were not so exposed. I16-18 ... 

AMWA, Cost Estimate to Remove MTBE Contamination from Public Drinking Water Systems in the United States, Association of Metropolitan Water Agencies, Washington, DC, June 2005. 

As regulated by EPA (as of January 1, 2002), the maximum residual disinfectant level (MRDL) for chlorine dioxide is 0.8 mg/L (EPA 2002g) the maximum contaminant level (MCE) for its oxidation product, chlorite ion, in drinking water is 1.0 mg/L (EPA 2002e). The levels of chlorite ion in distribution system waters have been reported as part of the Information Collection Rule (ICR), a research project used to support the development of national drinking water standards in the United States (EPA 2002d). 

Trichloroethylene (TCE) is the most prevalent organic contaminant of drinking water supplies in the United States. Air stripping, the once conventional treatment method, is now largely disallowed. Extensive efforts have been made to develop bacterial systems to remove TCE from water. Efforts to obtain bacteria that... 

The most important of the safe drinking water acts are the Safe Drinking Water Act of 1974, the Safe Drinking Water Act Amendments of 1986, and the Safe Drinking Water Act of 1996. The Safe Drinking Water Act was first enacted on December 16, 1974 to protect pnblic drinking water systems in the United States from harmfnl contaminants. The major provision of this Act reqnires the development of ... 

In an effort to reduce lead emissions into the environment, MTBE has been introduced into petrol as an alternative in a number of countries. Since its introduction in the late 1980s it has become one of the top four chemicals in terms of mass production in the United States. Unfortunately, by the beginning of the twenty-first century many drinking water sources, in the United States in particular, had become contaminated with this chemical, which is of concern for both health and esthetic considerations [50]. 

In addition to the MCLs listed in Table 8.8, there are secondary standards for water quality in the United States. The National Secondary Water Regulations (NSDWRs) are nonenforceable guidelines regulating contaminants that may cause cosmetic effects (such as skin and tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water. I65 Many in the scientific community argue that the chemicals listed do not merely have cosmetic and aesthetic effects, particularly when they are combined with other toxicants. EPA, however, recommends, but does not require, that water systems comply with these secondary standards. States, however, are permitted to adopt these as enforceable standards. The NSDWRs are listed in Table 8.9. 

Focazio Ml, Kolpin DW, Barnes KK, Furlong ET, Meyer MT, Zaugg SD, Barber LB, Thurman EM. A national reconnaissance of pharmaceuticals and other organic wastewater contaminants in the United States ell. Untreated drinking water sources. Sci Total Environ 2008 402 2-3. 

The US. Environmental Protection Agency specifies maximum contaminant levels (MCE) for total radium ( Ra plus Ra) in drinking water in units of pCi/L (picocuries per liter). In the past, perhaps as many as several hundred municipal water supplies in the United States have exceeded permissible levels, which has required finding alternative sources or additional treatment to remove radium. Fortunately, conventional water softening processes, which are designed to take out excessive levels of calcium, are relatively efficient in removing radium from water. 

Pentachlorophenol-contaminated air, rain, snow, surface waters, drinking waters, groundwaters, and aquatic biota are common in the United States (Table 23.3) (Pignatello et al. 1983 Choudhury et al. 1986). Residues of PCP in food, water, and mammalian tissues may result from the direct use of PCP as a wood preservative and pesticide, or as a result of the use of other chemicals that... 

In order to protect people from potential health effects, the EPA banned the production and use of endrin in the United States in 1986. The EPA s proposed maximum contaminant level (MCL) in drinking water is 0.0002 milligrams per liter (mg/L 1 mg/L = 1 ppm). The EPA has also set health advisories which are levels of a chemical in water that are safe. The 1-day and 10-day health advisories for endrin are 0.02 mg endrin per liter of water for both children and adults. 

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