The contaminants include DDT, Dieldrin and polychlorinated biphenyls (PCBs), which have all been identified by the U.S. Environmental Protection Agency (EPA) as “probable” carcinogens and whose use is banned in the United States, Greenpeace said.

The contaminants were found in the fish oil and meal used in pet food and animal feed as nutritional supplements.

“Consumers have a right to know that the products they buy to supposedly improve their health could actually be putting them at risk,” said John Hocevar, Greenpeace oceans specialist.