Each day, Chicago processes close to 1 billion gallons of drinking water from Lake Michigan. Before it reaches the tap, the water is treated and tested for hundreds of chemicals, including the metal chromium.
Now, a study of drinking water in 35 U.S. cities -- Chicago among them -- shows drinking water containing varying levels of a chromium compound called Hexavalent Chromium, or Chromium-6, which is a carcinogen.
The study by Environmental Working Group, ewg.org, shows Chicago with .18 parts per billion. Milwaukee has the same level. Madison, Wis., is at 1.58 parts per billion and the highest of all the cities sampled is Norman, Okla., at 12.90 parts per billion. Read the full report.
The U.S. EPA does limit the amount of chromium in water, but there are no specific lesser limits for Hexavelent Chromium. California is considering a proposal to regulate it at no more than .06 parts per billion.
A decade ago, activist Erin Brockovich sued California's Pacific Gas and Electric over Chromium-6 in the groundwater. Her fight was later told on the big screen.
"We have found a known carcinogen in the Chicago area. Does it mean you'll get cancer? No. Should it be a cause of concern for folks in the Chicago area? Absolutely," said Alex Formuzis, Environmental Working Group. "We are pushing the Environmental Protection Agency here in Washington to set a safe limit for drinking water and enforce that around the country. It would give guidance to local water utilities."
"A level of .18 in Chicago water of Chrome-6 - a known carcinogen is a level of concern. We ought to be looking for ways to reduce that, and we ought to be monitoring for it so that we are aware of that and other carcinogens in the water," Dr. Peter Orr, University of Illinois at Chicago, said.
Dr. Orr, chief of occupational and environmental medical services at UIC, said the Chrome 6 report should lead to more study, but not alarm. It doesn't mean stop drinking Chicago water.
"We have our technical people taking a look at that report, looking at the methodology," said Dr. Orr.
Chicago and other cities are not disputing the study conclusions, but want to know how the study arrived at those conclusions. If more specific testing is warranted, Chicago's water commissioner said that can happen.
"Our water meets or exceeds every standard by U.S. EPA and the Illinois EPA and it is 100 percent safe," said Thomas Powers, Chicago water commissioner.
The compound Chromium-6 occurs in nature, but its source is more often industrialized waste from chrome plating of metals and the manufacture of plastics and dyes. Earlier this year, the U.S. EPA began its own review of the effects on Chromium-6 on human health, and the organization said it'll be looking at that and the environmental working group's study to see if new standards need to be set. The EPA will also provide technical help to water systems.
Illinois senators Dick Durbin and Mark Kirk say they'll meet with the head of the EPA on Tuesday about the report.