Smarter Living: Pets

cat scratching

Photo: Steelheadwill/Flickr

Fleas are obnoxious and if you’ve seen your pet scratching a lot or, worse yet, are bitten yourself, you know how itchy and uncomfortable the jumpy little insects can be. But when it comes to treatment, rather than use chemicals your first moves should be to keep your pet indoors and vacuum and comb to sweep up fleas and eggs. Flea collars and sprays may seem like an easy solution, but they often contain chemicals that can harm your pets, your children and you.

Many flea and tick formulations are safe when used as directed, but two alarmingly toxic chemicals are found in some products. Called tetrachlorvinphos and propoxur these chemicals are potentially harmful to pets and their humans at the levels found in today's flea collars. The humans at greatest risk from these chemicals are young children, especially toddlers who spend a lot of time hugging, stroking, and sleeping with their pets.

Tetrachlorvinphos (TCVP) is used in flea and tick collars, powders, and sprays, while propoxur is found only in the collars. Both chemicals are in products marketed for cats and dogs. Flea collars release the chemicals onto the fur, where they are spread by animals by licking their fur.

These chemicals kill by jamming communications between nerve cells in insects. On the most basic level, however, we humans are not all that different from insects. Our human nervous system (and our pets' nervous systems) utilize the same nerve cell messaging system as the insect's, so TCVP and propoxur can harm not only insects but our pets and us. In high doses, these chemicals can cause nausea, vomiting, diarrhea, wheezing, sweating, and tearing eyes. More severe poisoning can cause muscle twitching, drooling, seizures, and death. Over the past decade, the Humane Society of the United States has received hundreds of complaints of pets experiencing severe reactions or death from flea collars.

Although the amounts in the residue left by flea collars are smaller than the doses that cause acute human symptoms, both TCVP and propoxur may cause long-term health consequences. Propoxur is known to cause cancer in humans, according to the State of California. TCVP is classified by the US EPA as a possible human carcinogen.

TCVP and other chemicals in the family known as organophosphates are also suspected of being linked to neurodevelopmental problems including impulsivity, hyperactivity and learning disabilities in children. A study published in June in the journal Pediatrics found that children with higher exposure to TCVP-like chemicals were more likely to be diagnosed with attention-deficit/hyperactivity disorder (ADHD), although more research needs to be done to see if the association is causal.

Young children are most at risk, because they spend the most time at pets-eye view, playing on floors and putting their hands in their mouths. Children also have developing neurological systems that may be more vulnerable to toxic chemicals.

Through pet collars, children are being exposed to levels of tetrachlorvinphos and propoxur that exceed the US EPA's acceptable levels, according to an NRDC study published in 2009. The study found that after three days, 100 percent of pets wearing a propoxur flea collar and 50 percent of pets wearing a tetrachlorvinphos collar had enough chemical on their fur to exceed the EPA's acceptable dose level for toddlers.

The EPA's acceptable dose is based on the toxicity of the chemical and the safety of the use of a particular product is determined by comparing the expected amount of exposure to the acceptable dose. In the case of flea collar chemicals, the EPA assumes that a typical child spends about two hours per day with his or her pet. But many children spend eight or more hours a day with their pets (including when sleeping), and many children have more than one pet, so a child's exposure can be higher than EPA models predict.

Many consumers assume that whatever is on store shelves must be 100 percent safe for use around pets and children. But both these chemicals have significant health risks. Though still allowed for use in flea collars, propoxur has been banned for use in homes for other pests, although the State of Ohio last year asked EPA to approve it for residential use to treat bed bugs. The EPA denied the request in June, citing the unacceptable risk to children.

What you can do:

  • Start with chemical-free methods and use chemical treatments only when necessary.
  • Wash pet bedding (and your bedding, too, if your pet sleeps with you) in hot, soapy water.
  • Vacuum often to remove flea eggs, and replace the vacuum bag frequently.
  • Comb your pet daily with a fine-toothed flea comb. Dispose of any fleas you find.
  • If needed, try products made with essential oils of lemongrass, cedarwood, peppermint, rosemary or thyme.
  • If you are getting a new cat, keep it indoors so that fleas and ticks will not be a problem.
  • If non-chemical methods haven't worked, look for lower risk products. Check the label to make sure the product does not contain tetrachlorvinphos or propoxur or any of the other high risk chemicals. Make sure the product is suitable for your pet and follow the instructions carefully. The safest options, according to NRDC, are pill-based flea treatments.
  • Visit NRDC's http://www.greenpaws.org for a comprehensive list of brand-name products with their chemical ingredients and more information about health risks from pesticides.

last revised 4/26/2011

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