In 2001, Julia Roberts won the Academy Award for Best Actress in “Erin Brockovich,” a film about a woman who discovers residents in a California town are being poisoned by water that’s contaminated by a local power company. The water’s contaminant, hexavalent chromium (also known as chromium-6) is a known carcinogen.
On Dec. 20, 2010, the Environmental Working Group released results of a nationwide study revealing that high levels of the same toxin – hexavalent chromium – was in tap water in 31 of 35 cities tested. More than 26 million people in these cities use the polluted tap water.
California is the only state to set a standard on acceptable levels of hexavalent chromium in drinking water, and anything higher than 0.06 parts per billion (ppb) is deemed hazardous. According to the study results, Norman, Okla., residents have 12.90 ppb in their tap water.
Other cities with high levels included Honolulu, Hawaii, with 2.00 ppb; Riverside, Calif., with 1.69 ppb; Madison, Wis., with 1.58 ppb, and San Jose, Calif., with 1.34 ppb.
The toxin wasn’t found in all tap water, though. The six cities with the lowest amounts included Indianapolis, Ind., Plano, Texas, Las Vegas, Nev., and San Antonio, Texas, all with 0.00 ppb, and Boston, Mass., and Cincinnati, Ohio, with 0.03 ppb.
A technical explanation
Hexavalent chromium is a highly toxic form of chromium – not all chromium is bad, though. In fact, trivalent chromium, or chromium-3, is an essential nutrient.
Hexavalent chromium can enter the water system by contamination from textile and electroplating manufacturing factories. And, interestingly enough, chlorine has the ability to transform the harmless trivalent chromium into the harmful hexavalent chromium, posing a challenge with chlorine-based water purification methods.
Humans and animals are exposed by contaminated water, food, air, and soil particles. While it’s known that hexavalent chromium is a carcinogen when inhaled, research is starting to prove that it also is a carcinogen when ingested.
High risk groups
Some people are more susceptible to damage from hexavalent chromium than others – mainly, fetuses, infants, children, and people of all ages with less acidic stomachs.
A possibility for danger comes when infant formula is mixed with polluted tap water. Even boiling tap water for formula only removes bacteria – not carcinogens.
What can you do?
Unfortunately, there’s no way of knowing how much hexavalent chromium is in the water supply of every city. California is the only state to test water specifically for hexavalent chromium – all other states test for chromium (including both the safe chromium-3 and the toxic chromium-6). And it’s impossible to guess levels based on a particular region or state. For example, while Madison, Wis., had 1.58 ppb, Milwaukee, Wis., only had 0.18 ppb. Similarly, San Jose, Calif., had 1.34 ppb, while nearby Sacramento, Calif., had 0.16 ppb.
There is good news, though. Reverse osmosis filters do remove hexavalent chromium from tap water – they also remove the toxins arsenic and perchlorate (rocket fuel). Skip using a carbon filter, though. While carbon filters – both pitchers and tap-mounted units – are cheap and easy to use, they only remove contaminants like lead – NOT chromium-6.
The other huge no-no is to stop drinking bottled water. While the bottled water could come from a pure source, it also could be contaminated tap water. Because bottled water companies aren’t required to publish water quality tests, there’s no way to know what’s safe or dangerous.
The safest, healthiest, and most environmentally friendly option is to drink tap water filtered by a reverse osmosis filter – and use a drinking glass, stainless steel canteen, or BPA-free container. (More on those choices in an upcoming post.)
Look for yourself
Want to know more details? Check out the Environmental Working Group’s study for yourself.
“Chromium-6 Is Widespread in US Tap Water.” Environmental Working Group. Dec. 20, 2010.
“EPA acts to address carcinogen in U.S. tap water.” Wendy Koch. USA Today. Dec. 23, 2010.
“Probable carcinogen hexavalent chromium found in drinking water of 31 U.S. cities.” Lyndsey Layton. The Washington Post. Dec. 19, 2010.
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