n 2009, an Environmental Working Group (EWG) study found that 8 out of 10 major national dog food brands contained fluoride in amounts up to 2.5 times higher than the Environmental Protection Agency's (EPA) national drinking water standard.1
In all eight cases, the suspected ingredients containing excess fluoride were bone meal
and animal byproducts. According to the lead researcher of the EWB-sponsored study, Olga Naidenko, Ph.D.:
"Due to a failed regulatory system and suspect practices by some in the pet food industry, countless dogs may be ingesting excessive fluoride that could put them at risk."
The eight dog foods containing high levels of fluoride contained chicken byproduct meal, poultry byproduct meal, chicken meal, beef and bone meal.
We can conclude from the study results that the primary culprits are animal byproducts
and bone meal. (Not all chicken meals contain internal organs and bones — some are made exclusively from muscle meat.)
However, all byproduct meals contain internal organs and bones. In addition, a certain amount of fluoride from the tap water used to manufacture pet food also gets into the finished product.
Fluoride occurs naturally in rocks, soil and the earth's crust, as well as in some water supplies. But according to the EWG, two-thirds of people living in the U.S., along with their pets and farm animals, are exposed to artificially fluoridated tap water (the fluoride is added to help prevent tooth decay).
Fluoride is also found in certain foods, either as a result of the manufacturing process, or from plants grown in high-fluoride soils or treated with fluoride-based pesticides
. Ingested fluoride accumulates in bones and can damage teeth and the musculoskeletal system.