An Environmental Protection Agency report warns that propoxur, a flea-killing chemical in flea collars marketed by Sergeant’s Pet Care Products and Wellmark International, is unsafe for children. However, the products can be distributed until two years from now, and retailers can continue to sell them after that until their stock is gone. Veterinary dermatologist Daniel Morris says there are safer products available and urges owners to consult with their veterinarian to determine the best approach.