Cardboard packaging made from recycled newspapers have been linked by Swiss scientists to health complaints in lab rats, ranging from the inflammation of internal organs to cancer, the UK Daily Mail reported in March. Researchers at the Food Safety Laboratory in Zurich said that mineral oils in ink from newspapers that are then recycled and made into cardboard boxes can make their way into foods such as cereal, pasta and rice - even passing through inner plastic bags. More than half of Europe's cardboard is made from recycled materials.

In one study for the German food ministry last year, the researchers analysed a total of 119 products bought from German supermarkets. According to their findings a majority of samples - approximately 90 - contained traces of mineral oils higher than agreed levels. Toxicological testing had linked these mineral oils to an increased risk of health complaints in laboratory rats, the researchers added.

However, a spokesperson for the UK's Food Standards Agency said there is no need for immediate action and pointed out that a "great quantity" of contaminated food would have to be consumed to present any significant threat to health. "The research has uncovered an elevated quantity of these mineral hydrocarbons. But we are still talking extremely low quantities. If you have a healthy, varied diet there is very little chance that consumption of foods packaged in recycled cardboard will have an impact on health," the spokesperson said.

Kellogg's said they are working with their suppliers for new packaging that will contain lower levels of mineral oil in printing ink, while they may have to choose recycled packaging that does not contain recycled newspaper. British muesli maker Jordans has switched from using boxes made with cardboard from recycled paper. The UK Food Standards Agency is carrying out its own investigation into the presence of mineral oils in food packaging and is expected to report back in the summer.