Your pet can't tolerate fleas and ticks, and neither can you, but the wrong cure can be worse than the problem. Flea and tick treatments may contain toxic chemicals that can poison pets and harm people. Even when applied as instructed on the box, these chemicals are not safe, either for pets or for humans. Certain chemicals in flea and tick products are linked to cancer, allergies and asthma and are suspected endocrine disruptors. Pregnant women and small children are especially at risk. 

NRDC Report: Poison on Pets

While some products used to kill fleas and ticks on household pets are safe, others leave harmful chemical residues on our pets' fur and in our homes. These chemicals are highly hazardous to animals and humans, can damage the brain and nervous system, and cause cancer. The April 2009 paper Poison on Pets II details a first-of-its-kind study by NRDC showing that high levels of pesticide residue can remain on a dog's or cat's fur for weeks after a flea collar is put on. Residue levels produced by some flea collars are so high—up to 1,000 times higher than the EPA's acceptable levels—that they pose a risk of cancer and damage to the neurological systems of children.

NRDC checked the listed ingredients of more than a hundred flea and tick products to see which chemicals they contain and to assess the chemicals' toxicity. The results are organized by potential risk in the Greenpaws Flea and Tick Product Guide, which you can search by product, chemical or toxicity level.

Parents need to take particular care with toddlers, whose frequent hand-to-mouth contact  exposes them to toxic residues while crawling on rugs, playing with the pet or pet toys, handling household dust, and more. Toddlers' nervous systems are still developing, so the effects of pesticides such as organophosphates can have lasting damage.

California has already determined that propoxur causes cancer and that consumer warnings are required. NRDC is suing major manufacturers and retailers of flea collars containing propoxur to make them comply with this requirement or pull the products from California shelves. However, California’s laws are not enough—the Environmental Protection Agency (EPA) should step in to ban these dangerous products nationwide. NRDC recommended that the EPA ban the pesticides tetrachlorvinphos and propoxur from pet products and closely scrutinize the safety of the other products on the market.

Retailers should help keep pets and families safe by pulling products that contain tetrachlorvinphos and propoxur from their shelves. But while these products remain on shelves, its up to pet parents to keep an eye on what they put on their pets.

What you can do

Avoid spot treatments which tend to be very concentrated and, according to new studies, may pose a hazard to pets, particularly those with pyrethroid pesticides such as phenothrin and cyphenothrin.

Examine the active ingredients in all flea and tick control products you currently own.

When purchasing new products, check the guide to brand-name flea and tick products to find out which ones could harm your pet or young children, and print out the pocket guide to chemical ingredients in flea and tick treatments.

Learn how to protect your pet without chemicals. Regular combing with a flea comb, bathing and vacuuming can reduce and control fleas.


I have been adopted by a stray/feral cat, approximately 2 to 3 years in age. I had him neutered and ear-tipped as part of my colony last year. He appears to be healthy except for the fact that his hair is falling out--ad not just shedding. He gets blistery looking patches, and when the blisters go away, so does the hair. I took him to my vet, but she really did not know what may be wrong with him. I would like to know, so I can do something to help him.
Has anybody info on the flea, tick, heartworm meds called Revolution? Thanks

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