Flea-fighting products that contain a synthetic insecticide have come under fire recently . The Environmental Protection Agency has called for stronger warning labels . Products like Capstar and Comfortis go to work quickly , killing any adult fleas a few minutes after being consumed . Hide Caption 1 of 7 Photos:Photos: Deadly pesticides in the U.S.
Flea-fighting products that contain a synthetic insecticide have come under fire recently . The Environmental Protection Agency has called for stronger warning labels . Hide Caption 1 of 7 Photos:Photos: Deadly pesticides in the U.S.