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Veterinary Forum May 2008 (Vol 25, No 5)

Chemical levels high in pets

    The Environmental Working Group (EWG) recently released results of a new study that found high levels of industrial chemicals in America's pets.

    Dogs and cats ingest pollutants in tap water, play on lawns with pesticide residue and breathe indoor air contaminants, and with their shorter life spans, pets also may develop health problems from these exposures sooner than people would, the EWG said.

    The researchers pooled samples of blood and urine from 20 dogs and 37 cats collected at a Virginia veterinary clinic and found that they were contaminated with 48 of the 70 industrial chemicals tested. The average levels of many chemicals were higher in pets than is typical for people, with 2.4 times higher levels of perfluorochemicals in dogs, 23 times more polybrominated diphenyl ethers (PBDEs) in cats and more than 5 times the amount of mercury, compared with average levels in people.

    Canaries in the coal mine

    "I think it is an important study. Our pets are sentinels, and they are pointing out some ways they are being exposed through food and contact, which are the same chemicals we are exposed to," said pathologist Lawrence D. McGill, DVM, PhD, DACVP, who is technical vice president at ARUP Laboratories in Salt Lake City, Utah.

    Although the study is interesting, it does not prove that the chemicals cause any illness, McGill added. That link still needs to be determined by more research.

    "I don't know if we're seeing enough levels to say it is causing disease in our animals. It will take awhile before anyone proves a cause and effect in animals," he said.

    The EWG agreed, but added that the chemicals have been linked to serious human health effects. Dog samples were contaminated with 35 chemicals, including 11 carcinogens, 31 chemicals toxic to the reproductive system and 24 neurotoxins. The carcinogens are of particular concern because dogs have much higher rates of many cancers than do people, including 35 times more skin cancer, 4 times more breast tumors, 8 times more bone cancer and twice the incidence of leukemia, according to the Texas A&M University Veterinary Medical Center.

    Cat samples contained 46 chemicals, including 9 carcinogens, 40 chemicals toxic to the reproductive system, 34 neurotoxins and 15 chemicals toxic to the endocrine system. Endocrine toxins raise particular concerns for cats because hyper­thyroid­ism is a leading cause of illness in older cats.

    Pets' unique behaviors may place them at risk for higher exposures from chemical pollutants in the home and outdoors.

    As cats groom themselves, they lick off accumulated dust that studies show can be contaminated with PBDEs and reproductive toxins called phthalates that were found in the cats tested by the EWG. A dog that eats scraps from the floor also may swallow dirt and dust that has been contaminated with heavy metals and pesticides and then tracked in from outdoors.

    "I am worried about the mercury exposure in cats," Lawrence added. "A lot of people feed fish to their cats as a source of protein." He suggested that perhaps cats should eat less fish, just as pregnant women and children are advised to avoid eating certain fish.

    McGill recommended that if owners ask about the study, veterinarians should give the same advice that dermatologists give if the animal is allergic to tree pollens: Wipe its paws and legs after taking it for a walk, which may reduce outdoor environmental contaminants.

    It will be much harder to avoid indoor contaminants, he admitted, since flame retardant and other chemicals are in bedding, etc. A page from the dermatology treatment handbook may help, though: Recommend that owners vacuum and dust frequently, as well as give their animals baths more often.

    If an owner is concerned, McGill said, "the veterinarian should say, 'Remember how your pet acts. It likes to lick. If you think it is going to touch anything that is a concern, rub your pet down and clean off its coat. Try to make sure that when you use housecleaning products on the floors to rinse them off. Also, cycle some of the food for kitty cats, and monitor anything that you see is going wrong.

    'If you see anything that is abnormal, call the office. Also, bring your pet in every 6 months so we can examine it closely to catch any problems early.'"

    Pets face chemical exposures that in some ways are similar to those of infants and toddlers who have limited diets, play close to the floor and put their hands and household objects into their mouths far more often than adults do, according to the EWG.

    "The presence of chemicals in dogs and cats sounds a cautionary warning for the present and future health of children as well," the EWG said.

    NEXT: Clinical Report: Atopic dermatitis—every little bit adds up


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