Quality and Safety of Drinking Water
Author: Winston Craig, MPH, PhD, RD.
Hitting the Bottle!
Many Americans are concerned about the quality and safety of their drinking water. Since rivers and lakes are easily polluted by industrial wastes and agricultural run-off, underground water has become the major source of drinking water. However, such water may not always be safe. Recently, a significant percent of wells supplying drinking water were found to be contaminated. Water pollution is now ranked as a major environmental threat to our health.
Unfortunately, most of the water contaminants are invisible, and contaminated water may not necessarily smell or taste bad. The U.S. government has set legal limits for some 80 potential water contaminants. It is the responsibility of the EPA to regulate the purity of community drinking water under the provisions of the Safe Water Drinking Act. About 10% of the 55,000 public water systems in the United States have been found, at one time or another, to exceed those EPA limits for drinking water contaminants.
The most widely occurring contaminants in the water supply are chlorine disinfection byproducts, such as trihalomethanes. High exposure to these byproducts increases the risk of developing bladder cancer, and possibly colon cancer. Pregnant women who were exposed to high levels of these byproducts were twice as likely to experience a miscarriage.
Four million Americans are exposed to high nitrate levels in their drinking water. About 3 percent of the rural population have private well water that exceeds the EPA standard of 10 ppm for nitrates. High nitrate levels in groundwater usually result from agricultural run-off, chemical fertilizers and feed-lot wastes. Nitrates can be converted in the body to nitrosamines, commonly known as carcinogens.
Water that comes in contact with old pipes and lead solder joints can be contaminated with lead, especially if the water is warm, acidic or softened. Children with elevated blood lead levels may experience growth retardation, learning disabilities, behavioral problems, and anemia. Lead exposure is also associated with a greater risk of reproductive problems.
One of our largest waterborne-disease outbreaks occurred in 1993 in Milwaukee in which 403,000 people became ill with cryptosporidosis. In healthy individuals, the nausea, diarrhea and flu-like symptoms last about 7-10 days. Death can result in persons with a compromised immune system. Cryptosporidium parvum, the protozoan responsible for the outbreak, is frequently found in lakes and rivers contaminated by sewerage or animal wastes. It is highly resistant to chlorine and other disinfectants and can cause illness at fairly low levels. Boiling the water is the most effective way of killing Cryptosporidium. It can be removed from tap water by filtering the water by reverse osmosis or with a special filter.
Concerns regarding pesticides, lead, chlorination by-products, industrial solvents, nitrates, PCBs, and other water contaminants has led many to turn to bottled water believing that it is more healthful, cleaner, and safer. Bottled water comes in different formats. Spring water, which makes up 75% of bottled water sold in the United States, is water flowing from an underground spring. The springs are supposed to be protected from pollution. Drinking water, such as Aquafina and Dasani, is derived from city water supplies and is usually filtered or disinfected before being bottled. Purified water normally has been distilled or treated by reverse osmosis or some other similar process.
Per capita consumption of bottled water in North America is currently about 15 gallons a year, with about one out of every 15 Americans drinking bottled water regularly. Many others treat their tap water with a home filtering device. A major reason for the popularity of bottled waters is the taste. Bottled water is disinfected with ozone, a gas that leaves no residual taste, so that it is more palatable than chlorinated water. But is bottled water any cleaner and safer than tap water? Maybe. However, bottled water does not have to be any purer or meet higher health standards than tap water. Recent tests covering a wide selection of domestic and imported brands of bottled water found that many brands contained some of the same chemicals and by-products that occur in tap water, such as trihalomethanes, nitrates, and undesirable metal ions. About one-quarter of all bottled water being sold is actually treated tap water drawn from a public water supply.
Bottled water may be collected bulk from a dispensing machine in the supermarket in which the water is purified by distillation or reverse osmosis. Anyone with a well and wishing to have their water tested at a certified lab can contact the state health department or contact the EPA Water Resource Center. They also have a hotline on this topic at 1-800-426-4791. Water filters can be installed in the house and vary widely in price and function. Anyone interested in reliable information about a water filter can call NSF International, a nonprofit independent water testing organization, at 1-877-867-3435.
Remember that a filter should be properly serviced and may need to be replaced periodically to function effectively. Since pure water is essential to good health securing a clean water supply should be a high priority. We should do all we can to protect our water resources.
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Health authorities recommend that one citrus fruit and one cruciferous vegetable be eaten daily. Less than 10 percent of Americans regularly consume these foods.