Photo by Courtesy Flickr/EMERY_WAY
Dogs that chew on plastic training devices and toys may be exposed to hormone-altering chemicals, according to research at Texas Tech University.
The researchers found that bisphenol A (BPA) and phthalates--ingredients of hard plastics and vinyl--readily leach from bumper toys, which are used to train retrieving dogs.
The new study is one of the first to examine dog products as a potential source of exposure for pets. No one knows, though, whether the traces of the chemicals pose any health risk to dogs. Previous research has focused on the risks to infants and toddlers from baby bottles, toys and other items that contained the chemicals.
"A lot of plastic products are used for dogs, so to understand the potential for some of the chemicals to leach out from toys is a new and important area of research," said veterinarian Safdar Khan, senior director of toxicology research at the American Society for the Prevention of Cruelty to Animals' Poison Control Center in Illinois. Dr. Khan was not involved in the current study.
Philip Smith, a toxicologist at The Institute of Environmental and Human Health at Texas Tech, became interested in chemical exposures from bumpers after using them to train his own Labrador retrievers.
"Some of the dogs are exposed to plastic bumpers from the time they are born until the day they die. We all want our pets to be healthy," said Smith, co-author of the as-yet unpublished study, which was presented this month at the Society of Environmental Toxicology and Chemistry conference in California.
In humans and rodents, BPA and phthalates have been linked to a number of health issues, including impaired development of reproductive organs, decreased fertility and cancers. The United States and the European Union have banned some phthalates in children's toys, and in July the U.S. Food and Drug Administration banned BPA in baby bottles and sippy cups.
The researchers, led by Kimberly Wooten, a graduate student in environmental toxicology at Texas Tech, studied factors that affected how much BPA and phthalates leached from plastic bumpers into dishes filled with artificial dog saliva.
They tested orange and white bumpers from two unidentified makers. The bumpers subjected to simulated chewing leached more BPA and phthalates than brand new bumpers and those left outside to weather for a month.
"Think of the molecules that comprise plastics as bricks in a wall. With pet toys, wear and tear from chewing would place stress on the chemical bonds--the mortar--allowing individual molecules to be released," said Laura Vandenberg, a reproductive scientist from Tufts University in Massachusetts.
Because researchers used simulated saliva, it is difficult to say how much actual leaching would occur in a dog's mouth. "We don't have enough information at this time to begin to estimate actual exposure," Smith said.
Smith said they suspect that the levels of chemicals observed from the bumpers would be considered very high when compared with children's toys.
The researchers also looked at phthalates and BPA from pet toys sold through major retailers. They found higher concentrations leaching from bumpers than from other toys, but preliminary results suggest some store-bought toys might have leached other hormonally active chemicals.
A previous study by the Environmental Working Group found that dogs' blood and urine contained the breakdown products of several phthalates at levels ranging from 1.1 to 4.5 times higher than the average found in people.
"Dogs are closer to the ground than humans, so house dust is another potential source of exposure to environmental chemicals," Dr. Khan said.
But little is known about any potential health risks for dogs exposed to hormone-mimicking chemicals, and because little toxicity data exist for dogs, it is difficult to evaluate risks, Smith said. Nonetheless, "consumer education about potential risk seems to be warranted based on our data," he said.
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