LOS ANGELES: A type of chromium highlighted in the film Erin Brockovich causes cancer in lab animals when they drink it in water, and it could be harmful to people, the US National Institutes of Health said on Wednesday.

Hexavalent chromium, also called chromium 6, already has been shown to cause lung cancer when inhaled and is controlled by the Environmental Protection Agency as well as by states. It is best known as the contaminant exposed by campaigner Erin Brockovich, whose battle against a polluter was dramatised in the May 2000 movie of the same name.

"I am relieved and pleased and sorry because there are a lot of people who have ingested chromium 6," said Brockovich, who still works in Los Angeles as a legal consultant on environmental issues.

"It is high time but it is no surprise to me," she said. "This is a chemical that there have been ongoing arguments about, and now a third party has concluded that it can cause cancer by ingestion."

Environmentalists, who have been fighting for decades for tighter limits on how much chromium can be present in drinking water, said the findings offered a basis for such restrictions.