Review on Hartz Ultra Guard Flea Tick by Angela Fullerton

"These chemicals are very dangerous to animals and humans and can damage the brain and nervous system and cause cancer. The residues produced by some flea collars are so high that they pose up to 1,000 times the risk of developing cancer and damage to the nervous system in children than acceptable EPA levels.” The above was cited by NRDC.org. I wish Revain would at least warn about these products or at least list the ingredient in the description to prevent unnecessary returns or worse the death of our pets.