Polybrominated diphenyl ethers (PBDEs) were discovered at levels 5 to 10 times higher in dogs, and in a previous study, 20 to 100 times higher in cats than levels found in humans in North America. Research indicates dogs metabolize the compounds faster than cats do. A previous study showed that dogs produce an enzyme that breaks down organochlorine pesticides, and a similar mechanism may be at work with brominated compounds.
PBDEs are used as flame retardants in furniture and electronics. The compounds are known to leak from these products into the environment.
The study, Flame Retardants in the Serum of Pet Dogs and in Their Food, was performed at the Indiana University School of Public and Environmental Affairs (SPEA), and published in the journal Environmental Science & Technology.
Research scientists measured the presence and levels of PBDEs in the blood of 17 dogs of various breeds. These were primarily indoor pets. They also measured levels of PBDEs in commercial dry dog food to find out whether the pets' diets were the main source of PBDE exposure.
PBDE levels in dog food samples were found to be much higher than levels found in meat and poultry for human consumption. The study pointed to the probability PBDEs in dog food result from processing rather than from ingredients.
According to Marta Venier, assistant research scientist, IU SPEA:
"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)."
In addition to PBDEs, also identified in the dogs' blood samples in the IU study were other flame retardants including Dechlorane Plus, decabromodiphenylethane, and hexabromocyclododecane.
According to ConsumerAffairs.com, these newer flame retardant chemicals, while chiefly unregulated, are similar in structure to organic pollutants already linked to environmental and human health effects.
The toxicological effects of these flame retardant compounds are not well studied or understood in animals or humans, according to researchers.
PBDEs at Home and at Work
Polybrominated diphenyl ethers (PBDEs) are one of five major brominated flame retardants (BFRs) added to consumer products since the 1970s to reduce injuries and property damage from fires. These compounds, when added to certain consumer products, increase the temperature it takes to make them burn. This in turn makes the products more flame-resistant.
And while these compounds do their intended job as flame retardants, there is increasing evidence of BFR contamination in the environment, wildlife and humans.
PBDEs are found in polyurethane foam products manufactured before 2005, like upholstered furniture, mattresses and pillows. They are also used in electronic equipment. Your exposure (and your pet's) to PBDEs can come from your bed, your living room couch, the padding beneath your carpet, or the seat covers in your vehicle.
Other possible sources in your home are electronic components, kitchen appliances, fans, water heaters and blow dryers.
You can also be exposed through cell phones, your TV or the remote control, video gear, computers, printers, copiers, scanners, faxes and even toner cartridges.
PBDEs leak from products when, for example, a TV or computer heats up during use, when a mattress is slept on, or when products containing the compounds begin to deteriorate.
Known Health Effects of PBDE Exposure
Relative toxicity of PBDEs depends on the specific compound and the amount of exposure. According to Toxipedia.org, PBDEs are biomagnified toxic compounds, meaning they accumulate in the fatty tissues of organisms and are passed up the food chain. A 25-year Swedish study provides evidence that PBDE levels double in humans about every five years
Studies on laboratory mice exposed to PBDEs show the compounds to be neurotoxic chemicals as well as neurobehavioral and developmental toxicants. They are also carcinogenic. They affect the thyroid and liver of all animals.
According to the Environmental Working Group (EWG):
PBDEs are found in the bodies of nearly every American. Laboratory studies show that exposure to minute doses of PBDEs at critical points in development can damage reproductive systems and cause deficits in motor skills, learning, memory and hearing, as well as changes in behavior. In addition, they persist in the environment and therefore bioaccumulate in people.
PBDEs in Pet Food
According to research conducted by Boston University School of Public Health, Department of Environmental Health, and published in the journal Environmental Health Perspectives:
PBDEs may enter the food chain in several ways, including contamination of food during processing or packaging and general contamination of the environment via emissions of PBDEs at various points of the life cycle of consumer products. As PBDE-containing products continue to degrade and enter the waste stream in larger amounts, future exposure to PBDEs may begin to shift more heavily from the indoor environment to the outdoor environment and, consequently, the diet (Harrad and Diamond 2006).
The level of PBDEs measured in the meat and poultry in dry dog food samples used in the Indiana University study was considerably higher than the levels found in human food. The IU researchers concluded the PBDE-contaminated dog food was probably the result of the manufacturing process rather than the ingredients used in the formulas.
There are likely a variety of ways your dog's food can be contaminated during processing.
Fatty fish higher up the food chain, like tuna, and whitefish, salmon and other seafood are well known to be contaminated with PBDEs. The chemicals build up in oceans, lakes, rivers, streams and other bodies of water, and magnify in food chains.
It's likely the most contaminated organ of fish is the skin. Fish skin is a by-product of seafood production, like guts and other fish pieces and parts unfit for human consumption. These by-products are rerouted to the animal feed and pet food industries for use in their formulas.
In a previous study of cats, the IU research scientists tested both dry and canned cat food samples for the presence of PBDEs. Dry food showed higher concentrations than canned food, and seafood-based formulas contained the highest levels of PBDEs.
Cats eating commercial diets containing various kinds of seafood have been found to have exceptionally high levels of PBDEs in their bodies.
It's easy to imagine that commercial dog food formulas can be contaminated during processing by PBDEs left behind during the manufacture of seafood-based cat food products.
There was also a study in the journal Environmental Health Perspectives on butter contaminated with PBDEs. Investigation into the situation revealed the paper wrapper around the butter had PDBE levels over 16 times higher than the butter itself. It is unclear how the wrapping paper became contaminated.
What is clear, however, is that packaging as well as processing can potentially contaminate commercial dog food formulas with pollutants like PBDEs.
There are three common types of PBDEs found in consumer products: deca, octa and penta.
Deca comprises the vast majority -- about 80 percent – of PBDEs currently produced. Deca is used primarily in electronics and electronic equipment including TV casings, textiles and often in mattresses.
Octa PBDEs have not been added to consumer products since 2004.
Penta is a viscous liquid form of PBDE added to textiles and polyurethane foam in products manufactured prior to 2004.
Most new foam products are not likely to have PBDEs added. If you have foam items in your home, office or vehicle that were purchased before 2005, however, they probably contain PBDEs. These items might include: carpet padding, upholstered couches and chairs, mattresses and mattress pads, foam-filled pillows and the seats in your vehicle.
EWG offers some excellent tips to avoid exposing yourself and family members (including the four-legged variety) to PDBE-containing products:
- Exercise caution with foam items. Replace any item in which the foam is exposed or misshapen (an indicator the foam is breaking down and releasing toxic compounds into the environment).
- Use only vacuums with HEPA filters. Vacuums with HEPA filters are better at trapping small dust particles and are more efficient at removing contaminants and allergens from your home or office. The same principle applies to indoor air cleaners with HEPA filters. Even better, consider the Pure & Clear Air Purifier offered by Dr. Mercola.
- Replace rather than reupholster foam furniture. Even PBDE-free furniture can contain other types of fire retardants with potentially harmful effects.
- Remove old carpet with care. The padding beneath may contain PBDEs.
- When buying a new product, ask what type of fire retardant it contains. Try to avoid purchasing items containing BFRs. Go with less flammable materials, for example, cotton, wool and leather. Keep in mind that ‘natural’ latex foam and natural cotton are flammable and by law require the addition of a fire retardant.
An additional suggestion I can offer is to avoid processed pet food altogether by feeding your four-legged family members a balanced, species-appropriate homemade diet.