In a response to a lawsuit filed last year, California pet retailers and manufacturers have agreed to put warning labels on flea and tick collars that contain a cancer-causing chemical called propoxur.
The chemical propoxur is listed as a carcinogen in California, so products MUST be labeled with a warning when it is used.
The NRDC has petitioned the Enviromental Protection Agency to order that the chemical is removed from pet products nationwide, but for now, a warning label will have to suffice.
Fleas and ticks are a pain, but cancer is much worse, so check the labels when buying these products for your pets!