The report honed in on two particular chemicals, tetrachlorvinphos (TCVP) and propoxur, used on national brands of flea collars, including Hartz and Zodiac. TCVP belongs to the class of nerve-damaging chemicals known as organophosphates, most of which are so hazardous that they’ve been banned for residential use or for use on pets. Propoxur belongs to a class of chemicals called carbamates, which also cause nerve damage, and it’s on California’s Proposition 65 list of chemicals known to cause cancer. NRDC was particularly concerned with exposure among toddlers and children, who pet animals and then put their hands in their mouths.
Both classes of pesticides have come under scrutiny in other indoor and outdoor uses. But, says Gina Solomon, MD, senior scientist at NRDC and lead author of the report, “When we took a look at the EPA’s files for these chemicals, we were stunned to discover that, after making decision to leave them on the market, they had no scientific data on which to base their decision. The fact that the EPA hadn’t bothered to see how much residue would end up on fur was a big surprise.”
THE DETAILS: For two weeks, volunteers allowed the NRDC scientists to outfit 10 dogs and cats with flea collars containing these two chemicals. They tested the animals’ fur 3 days after the start of the experiment and again at the end of the 14-day period. After 3 days, 60 percent of the dogs wearing TCVP-treated collars and 100 percent of the dogs wearing the propoxur-treated collars had levels of chemicals on their fur that exceeded the EPA’s recommendations for toddler-age exposure; 100 percent of the cats wearing TCVP collars had similar high levels of residues. The levels of TCVP on fur dropped off significantly after 14 days, but the levels of propoxur remained high. Seventy-five percent of the dogs still had unsafe levels of the chemical on their fur.
WHAT IT MEANS: It’s unlikely that a single exposure to these collars will give you or your toddler cancer, but why take chances on long-term exposure? “For an individual, the risk is pretty small, but if you multiply the risk across the numbers of people who touch these collars, the number is disturbing,” says Dr. Solomon. They estimate that chemical residues from these collars could lead to a risk of 56 to 558 excess cancers per million people exposed. “We really want people to reduce exposures because they’re not necessary,” Dr. Solomon adds. And the collars may not even be effective. She notes that her dog, who was a willing study participant, rarely got fleas before using the collars but, during use, contracted a bad case of fleas near his rump.
Here are a few alternative treatments to keep your dogs and cats flea-free this season:
• Get rid of chemical collars. Despite the potential for harm, there is some good news regarding flea-collar chemicals. “These chemicals are not very persistent in the environment or in our bodies,” Dr. Solomon says. She recommends removing collars and washing your pet and its bedding. Residues wash away, and your body will eventually excrete them, she adds. You could try buying brands that don’t name the above chemicals as active ingredients, but there’s no guarantee they won’t contain the chemicals anyway.
• Baths and combs are your pets’ best defense. Bathing dogs every other week is generally effective at preventing flea infestations, and it also helps to remove ticks if they haven’t already latched onto a pet’s skin. “A flea comb will also remove ticks just as well as it does fleas, assuming they aren’t already attached,” says Dr. Solomon.
• Find less-toxic flea fixes. Look for flea treatments that contain insect growth regulators, or IGRs. These come in a pill prescribed by your vet, and they work by inhibiting a flea’s ability to reproduce. “In the long run, these are more effective because they disrupt breeding cycles of fleas,” Dr. Solomon says, adding that flea collars really only work if an adult flea comes in contact with the fur.
• Treat ticks with care. Solomon says that there really aren’t any safe alternatives for ticks, but given the potential for both pets and owners to succumb to diseases carried by them, it’s worth investing in some of the more potent tick treatments. She recommends fipronil (sold under the brand name Frontline), selamectin (sold as Revolution), and imidacloprid (sold as Advantage) if you’ve got persistent tick problems.
NRDC has compiled a list of the best and worst products on the pet market at its Web site www.greenpaws.org.