Updated: 12/20/10 5:47 p.m.

CHICAGO (CBS) — There’s a new scientific study in the news that says alarming amounts of a cancer-causing metal have been found in Chicago drinking water. CBS 2’s Vince Gerasole reports.

It’s the same metal that was cause for concern in the docu-drama, “Erin Brockovich.”

The researchers, who found varying amounts in the water supplies of over two dozen U.S. cities, say federal guidelines don’t require municipalities like Chicago to test for it or limit its presence in drinking water.

Mixed in the billion gallons a day that Chicago pumps to its citizens, environmental watchdogs have detected a dangerous metal, known simply as “Chromium-6.”

In excessive amounts, Chromium-6 presents a risk of stomach cancer.

Scientists at the independent Environmental Working Group have found concerning levels in Chicago and 30 other U.S. cities.

“What surprised me most was just how widespread this chemical was in our tap water,” said researcher Rebecca Sutton.

Researches believe the metal may enter the Lake Michigan water source from discharge at nearby steel mills in Indiana.

Specifically, in Chicago drinking water, researchers found .18 parts per billion of the metal. That’s three times a safety limit currently proposed by legislators in the state of California.

“I know this, I know that Chicago water is safe,” said Thomas Powers, Commissioner for Chicago’s Department of Water Management.

Powers points out the city’s drinking water supply exceeds federal guidelines. As his staff reviews the findings, he admits there is currently no test required for the metal.

The Federal Environmental Protection Agency is expected to release new guidelines for Chromium-6 next year.

In a statement, the agency says, “…having new science, we already launched a rigorous and comprehensive review of the effects of Chromium-6 on human health.”

“If they require us to test for Chromium-6, then we are ready to make whatever changes necessary,” said Powers.

For perspective, some researches say you would have to drink two liters of water a day, with the Chromium 6 levels found in Chicago, for 70 years, to have a one in a million chance of getting cancer.

But with new science, the EPA is working to better even those odds.