Your dog could be exposed to fluoride levels as much as 2.5 times greater than the national standard for drinking water set by the EPA in their dog food, according to independent testing funded by the Environmental Working Group. Out of 10 national brands tested, the amount of fluoride detected in eight brands of dog food exceeded levels that were linked to a greater risk of bone cancer among young boys in a Harvard study conducted three years ago.

The likely culprit: Ingredients described as a "animal meal" product -- think chicken meal and beef and bone meal -- consist of ground bones that are cooked, dried and made to be a cheap filler for dog food. The eight brands under the under scrutiny contained almost 9 milligrams per kilogram.

Putting the percentages into perspective, the average canine may drink as much as 0.5-1.0 milligrams of fluoride from tap water per kilogram of body weight. Feeding your 10-pound dog a cup of dog food may expose him to as much as .25 milligrams of fluoride every day.

For the record, more than 8,000 dogs are diagnosed annually with osteosarcoma, the most common kind of malignant bone cancer, at a rate nine times greater than their owners.

Environmental Working Group June 26, 2009

Environmental Working Group Research June 2009