The science behind the story
Dioxins and polychlorinated biphenyls (PCBs) are chemicals that get into our food from the environment. They have no immediate effect on our health but can cause problems if they are absorbed into our bodies at high levels for long periods.
Foods high in animal fat, such as fish, meat, eggs and dairy products (and foods produced with them) are the main source of dioxins and PCBs although all foods contains at least low levels of these chemicals. The levels of dioxins and PCBs in any one individual's diet will vary depending on the amounts and types of foods they eat.
The risk to health comes from eating food with high levels of dioxins and PCBs over a long period. They have been shown to cause a wide range of effects in certain animals, including cancer and damage to the immune and reproductive systems, although it appears that people may be less sensitive.