Tap Water May Cause Cancer And Gastrointestinal Problems

(CNN) - Tap water in 31 of 35 American cities was found to contain high levels of a cancer-causing chemical known as chromium-6.

Chromium-6, or hexavalent chromium, is most commonly known as the dangerous chemical in the movie "Erin Brockovich," where the substance was discovered in the water supply in Hinkley, CA, and caused a massive lawsuit against a utility company.

The chemical has been found to cause stomach cancer and tumors, and the Environmental Protection Agency (EPA) cited significant cancer risks when exposed to the contaminant in drinking water in a draft form in September.

The results were found in a study conducted by the Environmental Working Group. According to their website, the organization is dedicated to using public information to protect public health and the environment.

Norman, OK, was the most affected city studied with a concentration level of 12.9 parts per billion (ppb). The next most polluted city was Honolulu, HI, with 2 ppb.

The study in its entirety can be found at http://www.ewg.org/chromium6-in-tap-water.

In another report, six studies, examining a combined total of almost 8,000 people, have indicated that higher consumption of tap water can increase the risk of bladder cancer in men.

Men who drank more than 2 liters of tap water a day ran a 50 percent higher risk of bladder cancer than those who drank half a liter or less. Both straight tap water and tap water from other sources, such as coffee, were examined in the study.

Other beverages were not found to have the same associated risks.

Sources:

  International Journal of Cancer April 15, 2006; 118(8): 2040-2047 

Older studies done suggest that some tap water -- despite being filtered and treated with chlorine -- may still be able to cause gastrointestinal problems in children, 10% of the serious gastrointestinal illness case in children -- the ones bringing the kids into the hospital -- are attributable to the drinking water, said the researchers at the Harvard School of Public Health.

Up to one-third of gastrointestinal illness may be related to drinking water that meets current federal standards, according to the report. And those illnesses can have a substantial impact on the economy, costing $5.9 to 24.3 billion, according to one 1991 estimate, which included direct medical costs of treatment as well as indirect costs, such as lost productivity and leisure time.

Children are not the only ones at risk from such gastrointestinal illnesses. Adults with weakened immune systems are also at risk, including those with AIDS, cancer patients undergoing chemotherapy or radiation treatment, or the elderly.

Epidemiology (1997;8:615-620)