High levels of flame retardants found in dogs' blood, food

Bloomington, Ind. — Flame-retardant concentrations are five to 10 times higher in dogs than in humans, according to Indiana University researchers. And a 2007 study found concentrations of PBDEs in house cats that were 20 to 100 times higher than levels found in humans. Researchers say that the current evidence shows dogs metabolize the compounds more rapidly than cats.

Even so, researchers weren't expecting to find quite the level of concentration as was discovered in dogs. "The fact of finding detectable levels of PBDEs and flame retardants in general in dogs was a bit surprising, as well as the fact that the levels in dogs are about 10 times higher than those reported in the few studies on humans," says Marta Venier, assistant research scientist, IU School of Public and Environmental Affairs (SPEA).

The study, "Flame Retardants in the Serum of Pet Dogs and in their Food," was published in the journal Environmental Science & Technology, and authored by Venier and Ronald Hites, IU Distinguished Professor in SPEA.

The goal of the research was to determine whether pets, such as dogs, could serve as "biosentinels" for observing human contact with compounds that exist in households.

Researchers measured occurrence of polybrominated diphenyl ethers (PBDEs) in the blood of 17 pet dogs of various breeds that lived mostly indoors and in commercial dog food. PBDEs often are used as flame retardants in household furniture and electronics equipment. Compounds can leak from the products and disperse into the environment.

What researchers discovered was that average concentration of PBDEs in blood from the dogs was about 2 nanograms per gram, which is approximately five to 10 times higher than the levels found in humans in studies of human exposure in North America.

Samples of dry dog food that was part of the dogs' diets also were analyzed to find out whether food was a significant cause of this PBDE exposure.

For dog food samples, PBDEs were at levels averaging about 1 nanogram per gram, which is reportedly much higher than levels found in meat and poultry sold as food for humans. The study indicates the PBDEs in dog food may result from processing rather than from the food sources.

"We confirmed the predominance of one specific compound among PBDEs, BDE-209, in dry dog food (in the cats study we showed that dry food, as opposed to canned food, contained high levels of this compound). We suspect that its presence in the food is not due to the raw materials used (i.e. poultry or meat) but to the industrial processing (i.e. extrusion or packaging)," Venier says.

Using caution is critical, going forward, according to Venier. "Since the effects of these compounds, and their replacements, are not very well studied and understood, it's important to keep monitoring them, especially in indoor environments."