Poison on Pets II: Toxic Chemicals in Flea and Tick Collars
Poisoning in Animals
Children and Pets
This April 2009 report concludes "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 an animal. Residue levels produced by some flea collars are so high that they pose a risk of cancer and damage to the neurological system of children." Includes the full report and links to related content. From the National Resources Defense Council (NRDC).
National Resources Defense Council (NRDC)