U.S. government scientists have found evidence the chemical hexavalent chromium in drinking water causes cancer in lab animals.

The two-year study by the National Toxicology Program shows hexavalent chromium, also known as chromium 6, caused animals that drank to develop malignant tumors.

"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, National Toxicology Program study scientist. "We now know that it can also cause cancer in animals when administered orally."

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

The study's findings were announced at the National Institute of Environmental Health Sciences, which is part of the National Institutes of Health.

Copyright 2007 by United Press International