Ninety-two contaminants, primarily from industrial sources, and a smaller portion resulting from sprawl and urban pollutants, were detected in the Ohio tap water. The population exposed to substances in excess of safe limits: 9.6 million residents. The health effects of these contaminants include cancer and a weakened immune system.
10. New Mexico Between 1998 and 2003, nearly 3,000 violations of tap water regulations were reported in New Mexico. About 1.3 million people drank water that contained amounts of arsenic that exceeded health limits set forth by the Environmental Protection Agency (EPA). Arsenic, the consumption of which can cause cancer and blood toxicity, is a metal that enters water either by erosion of natural deposits or from runoff from glass and electronics factories.
9. Ohio [see above]
8. Pennsylvania Testing detected 96 contaminants in the Keystone State's tap water, 44 of which exceeded health limits. The biggest culprits: industrial pollutants. Analysis showed that 9.3 million residents were exposed to total trihalomethanes (TTHMs) -- and 8.8 million were exposed to amounts over health-based limits. TTHMs are water-treatment and distribution byproducts; their potential health effects include cancer.
7. Nevada In Nevada, 85.9 percent of water systems violated the health-based drinking water standards. Possible health effects of the 100 contaminants found in state tap water include cardiovascular or blood toxicity, cancer, developmental toxicity and skin sensitivity.
6. New York One hundred and four contaminants were detected in New York State tap water, including nitrate, barium, copper, chloroform and lead. More than 800,000 New Yorkers were exposed to amounts of chloroform, which can cause cancer and endocrine toxicity, that exceeded health-based standards. Water that contained contaminants that exceeded health-based limits was served in 418 communities.
5. Texas More than 17 million Texans were exposed to contaminants that exceeded healthy limits. Nearly 12 million citizens in over 1,000 communities turned on their taps to water that included, among other compounds, excessive and potentially dangerous amounts of bromodichloromethane, a byproduct of disinfectants that can cause cancer, cardiovascular or blood toxicity, gastrointestinal or liver toxicity, kidney toxicity and neurotoxicity.
4. Florida Among the 17 million people exposed to a combination of over 107 contaminants, 9.2 million were exposed to the mineral barium, which seeps into water from drilling and mining runoff as well as erosion of natural deposits. Of these, 25,000 were exposed to amounts of barium that exceeded health limits. Over 11 million Floridians also may have consumed radium-226, a radioactive element found around uranium deposits that can potentially cause cancer, in their water. And 11,113 people were exposed to excessive amounts of it.
3. North Carolina In this state, 6.1 million citizens were exposed to 59 contaminants that exceeded the EPA's limits. Nitrate, which can have a negative impact on kidneys, blood, the heart and the reproductive systems, was the most common contaminant. The suspected carcinogen enters water through fertilizer runoff, leaching septic tanks and erosion of natural deposits. Bromodichloromethane showed up in amounts that exceeded health limits in 373 communities, exposing 5 million people to potentially dangerous amounts of the toxic compound.
2. Wisconsin One thousand eighty-nine local water systems serve nearly four million people in America's cheese capital. Of those systems, only 51 produced uncontaminated water. The most prolific of the 118 contaminants detected were copper, lead and barium -- from drilling, mining, industrial waste, corrosion of household plumbing systems and the erosion of natural deposits. Copper may harm cardiovascular health. Lead can cause cancer and harm development, among other potential risks. Barium can have a toxic effect on the brain, the lungs and the reproductive organs.
1. California The Golden State's local water systems showed 145 contaminants, nearly half of which exceeded health limits set forth by the EPA. A majority of the people who use this water were exposed to this water that was primarily contaminated by industrial waste, like nitrate, and to a lesser extent acetone and lithium -- substances for which the EPA has not established a legal limit.