Chromium in water can cause cancer: U.S. agency

WASHINGTON (Reuters) - A type of chromium sometimes found in drinking water causes cancer in laboratory animals when they drink it in water and it could be harmful to people, the U.S. National Institutes of Health said on Wednesday.

Hexavalent chromium, also called chromium 6, already has been shown to cause lung cancer when inhaled.

It is best known as the contaminant exposed by campaigner Erin Brockovich, whose battle against a polluter was dramatized in a movie of the same name.

High doses given to rats and mice in drinking water caused malignant tumors, the two-year study by the National Toxicology Program found.

"Previous studies have shown that hexavalent chromium causes lung cancer in humans in certain occupational settings as a result of inhalation exposure," said Michelle Hooth, who worked on the report. "We now know that it can also cause cancer in animals when administered orally."

The toxicology program, part of the National Institute of Environmental Health Sciences, was reviewing a compound called sodium dichromate dihydrate. Sodium dichromate dihydrate contains hexavalent chromium.

Hexavalent chromium compounds are often used in electroplating, leather tanning, and textile manufacturing and have been found in some drinking water sources, the NIH said.

The lowest doses given to the rats and mice in the study were 10 times higher than what humans could consume from the most highly contaminated water sources identified in California, the researchers said.

"We found that hexavalent chromium is absorbed from the gastrointestinal tract," Hooth said. "After it is orally administered, it is taken up by the cells in many tissues and organs."