In September 2010, scientists at the Environmental Protection Agency came to a startling conclusion: Even a small amount of a chemical compound commonly found in tap water may cause cancer.

The compound, hexavalent chromium, gained infamy in the Oscar-winning film Erin Brockovich, based on the David-vs.-Goliath legal duel between desert dwellers in Hinkley, Calif., and Pacific Gas & Electric Co. The film ends in Hollywood fashion, with the corporate polluter paying $333 million to people suffering from illnesses.

But in real life, the drama continues. More than 70 million Americans drink traces of chromium every day, according to the Environmental Working Group, a nonprofit research organization.

And now, more than a decade after the film, EPA scientists cite “clear evidence” that the chemical compound, also known as chromium (VI), can cause cancer. The federal agency was poised to announce its findings in 2011, a step almost certain to trigger stricter drinking-water standards to prevent new cancers and deaths.

The chemical industry’s trade association and chief lobbyist, the American Chemistry Council, urged the EPA to wait for more research, a common practice to delay action on toxic chemicals. However, Vincent Cogliano, the soft-spoken head of EPA’s chemical-assessment program, rebuffed the powerful group, writing in an April 2011 letter that “strong” new research was already available.

In 2007, when Deborah Rice was appointed chair of an Environmental Protection Agency panel assessing the safety levels of flame retardants, she arrived as a respected Maine toxicologist with no ties to industry.

Yet the EPA removed Rice from the panel after an intense push by the American Chemistry Council (ACC), an industry lobbying group that accused her of bias. Her supposed conflict of interest? She had publicly raised questions about the safety of a flame retardant under EPA review.

Rice’s travails through the EPA’s Integrated Risk Information System, or IRIS, program reveal the flip side of industry’s sway. Not only does the ACC back many scientists named to IRIS panels, it also has the power to help remove ones it doesn’t favor.

The ruckus over the Maine scientist surfaced six years ago, but its lesson echoes today.

To Rice, her removal points up an irony borne out by a Center for Public Integrity investigation: Scientists with deep ties to industry are allowed to continue on IRIS panels. But she — with no financial link to industry — was booted.

“It wasn’t like I was a consultant, saying this stuff is really bad because someone is paying me to do it. I was the toxicologist working for the state of Maine asked by my department to do these reviews,” she said. “That was the basis on which they said I was in conflict.”

Another irony: Rice’s assessment was on target. Two years later, the EPA moved to cease production of decaBDE, a chemical it views as a possible carcinogen. In Maine, Rice’s research had supported a state ban on the chemical.