In The Drink: Health Effects
The Health Effects of Common Drinking Water Contaminants
Total Coliform (Monthly): The presence of coliform bacteria in drinking water is generally a result of a problem with water treatment or the pipes which distribute the water, and possible contamination by disease-causing microorganisms (although the coliform themselves are not harmful). Disease symptoms may include diarrhea, cramps, nausea, and possibly jaundice, and any associated headaches and fatigue. EPA has set an MCL to reduce the risk of these adverse health effects. Under this standard, no more than 5 percent of the samples (assuming at least two samples test positive) collected during a month can contain these bacteria.
Total Coliform (Acute): Fecal coliforms or E. Coli, are a particular type of coliform bacteria. Their presence in drinking water is more serious than other coliform bacteria because they are disease-causing, and also indicate that drinking water has been contaminated by sewage or animal wastes that contain other disease causing microorganisms. This type of contamination can cause severe diarrhea, cramps, and nausea. Because fecal coliform contamination is more severe than contamination by other types of coliform bacteria, EPA sets an acute standard indicating that for water to be considered safe it must be free of all fecal coliform.
Treatment Technique Violations: If water is inadequately treated, microbiological contaminants in the water may cause diarrhea, cramps and nausea. Under the Surface Water Treatment Rule (SWTR), EPA has set enforceable requirements for treating drinking water to reduce the risk from disease-causing microorganisms such as shigella, salmonella, cryptosporidium, and giardia. Under the SWTR, drinking water systems filtering their water must ensure that the process is working effectively as demonstrated by turbidity and objective disinfection criteria. Systems not filtering must ensure that their source waters are clean and adequately disinfected.
Turbidity: During the 1993 cryptosporidium outbreak in Milwaukee, an increase in turbidity was the only indication that there was a problem with drinking water quality. Highly turbid water indicated that disease risk from waterborne microorganisms is significantly increased. Turbidity is a measure of the clarity of a water sample and is used as an indicator for effectiveness of treatment processes to control pathogens in drinking water. In addition, high levels of turbidity may reduce the efficiency of disinfection and interfere with measurement of total coliforms.
Gross Alpha Radioactivity is a measure of radioactivity in water. Its presence indicates contamination by radium, radon, uranium, or other naturally occurring radioactive substances. These substances are known human carcinogens. EPA estimates that, over a lifetime, 15,750 people get cancer from drinking radioactive water (EPA 1991).
Radium-226 and -228 is another measure of radioactivity in water. Radium, a byproduct of the decay of uranium, is a naturally occurring, radioactive metal. It is a human carcinogen. Radium-226 is associated with bone sarcomas and head carcinomas, and Radium-228 is associated with bone sarcomas. EPA estimates that, over a lifetime, 15,750 people get cancer from exposure to radioactive drinking water (EPA 1991). Recommended treatment techniques include lime softening, cation exchange, and reverse osmosis.
Total Trihalomethanes: Trihalomethanes, (THMs) are disinfection byproducts, chemicals formed when chlorine used in drinking water disinfection reacts with naturally occurring organic material. More than ten human epidemiological studies have indicated that these chemicals are associated with rectal, bladder, or pancreatic cancers, and a 1993 article in the American Journal of Public Health estimated that annually, 10,700 rectal and bladder cancers may be caused each year by disinfection byproducts like the trihalomethanes (Morris, et al. 1992). A 1993 study by the U.S. Public Health Service suggested that disinfection byproducts are also associated with birth defects, including spine and neural disorders (Bove, et al. 1992). The current EPA standard allows a TTHM concentration of 0.10 mg/l, although in 1987 the National Academy of Sciences recommended that this standard be made more stringent (NRC 1987). Trihalomethane concentrations can be reduced by keeping source water clean, and by reducing or eliminating the "precursors" to these hazardous chemicals (organic material in the water that is necessary for their production) using treatment technologies such as Granular Activated Carbon.
Lead: According to the Department of Health and Human Services, lead is the number one environmental threat to children. For years, many water pipes contained lead, and this lead continues to leach into drinking water. Lead can cause a variety of adverse health effects in humans at low levels of exposure, and the EPA has concluded that there is in fact no "safe" exposure to lead. Exposure to lead in drinking water causes interference with red blood cell chemistry, delays in normal physical and mental development in babies and young children, deficits in the attention span, hearing, and learning abilities of children, and increases in the blood pressure of some adults. EPA has found that lead in drinking water causes over 560,000 children to exceed the CDC's blood-lead level of concern, and that better control of lead could help prevent over 680,000 cases of hypertension. Public water systems that have lead concentrations above 15 parts per billion in more than 10 percent of samples have exceeded EPA's Lead Action Level, and must optimize corrosion control and engage in a public education program to inform consumers of ways they can reduce their exposure to lead in drinking water (NRDC 1993).
Nitrate: Exposure to nitrate in drinking water above the current EPA standard of 10 ppm poses an acute risk to infants of methemoglobinemia, or blue baby syndrome, a condition caused by lack of oxygen. Symptoms of methemoglobinemia include shortness of breath, nausea, vomiting, diarrhea, lethargy, and in more extreme cases loss of consciousness, and even death. In addition, nitrate reacts with other chemicals in the gut to form nitrosamines, potent carcinogenic compounds.
Atrazine is an herbicide used on corn and soybeans and commonly found in drinking water. It is a possible human carcinogen, and has been found to cause cancer of the mammary gland in animal studies. In addition, atrazine has also been found to disrupt the hormonal and endocrine system. Exposure to atrazine above the MCL is a serious concern because the standard is particularly weak, allowing cancer risks that exceed the "negligible" risk standard by a factor of 18. EPA has placed atrazine into Special Review, the first step in a possible ban, due to concerns over the public health impacts of exposure in food and water.
Trichloroethylene is a probable human carcinogen. This chemical is commonly used in metal cleaning or dry cleaning, and it usually contaminates drinking water wells due to improper disposal.