Cardboard packaging for food is often produced from recycled waste paper, such as newspapers. This paper contains, among other things, residues of newspaper printing inks which include mineral oils not approved for food contact. And that's exactly where the problem lies: the mineral oils cannot be completely removed in the recycling process and consequently enter the packaging. Mineral oils contain hydrocarbon compounds which can travel from the cardboard into the foods. Experts call this migration. This can happen even without direct contact between the cardboard and the food: some mineral oil residues already evaporate at room temperature. This mixture of gases disperses inside the packaging and the substances can be absorbed by the food. "Studies by the official Food Safety Authority of the Canton of Zurich have shown that about 30 percent of all migratable substances have entered the food after two months at room temperature," explains Heiko Diehl. The BASF Manager is responsible in the Paper Chemicals division for providing a support service for international brands who specify paper packaging for their foods. Especially products like flour, rice or baking mixes are affected because they can absorb larger amounts of the mineral oil constituents. "Once the contaminants have accumulated in the food, they can no longer be removed or made safe by washing or boiling," adds Diehl.
It is not only the industry that is aware of the potential health risk presented by mineral oils in food packaging. Mineral oil residues in foods and their effects are also being looked at by the attention of the competent supervisory authorities in Switzerland. Control examinations performed by the official scientists have detected high residues of these substances in human tissue. Dr. Konrad Grob of Zurich Food Safety Authority: "The use of cardboard for food packaging is so high that the inclusion of recycled material is unavoidable. No legally binding limits have yet been established, only official recommendations. With normal recycled cardboard, however, for most products stored for prolonged periods these values cannot be complied with without a barrier," says Grob.