Breakfast cereal manufacturers in Europe are weighing changes to their packaging after research points to potential harmful health effects from recycled cardboard.

Swiss researchers found mineral oils in packaging that is made from recycled newpapers. Those oils, which come from printing ink, could get into foods such as cereal, pasta and rice, the UK Press Association said Tuesday.

Koni Grob, of the government-run Food Safety Laboratory in Zurich, said toxicologists linked the oils to two effects in rats: inflammation of internal organs and cancer.

"One meal has no real effect on health. It is a matter of long-term exposure," Grob told the BBC. He was referring to a Swiss study where researchers tested 119 products purchased at German supermarkets last year.

Products with thicker and more expensive inner lining bags appeared to block oil from contaminating foods, Grob said. Aluminum foil also worked as a barrier.

Canadian packaging guidelines

British-based cereal marker Jordans has stopped using recycled cardboard, and other manufacturers are moving to packaging that doesn't contain recycled newspaper, the BBC reported.

Kellogg's Canada said it has safely used recycled board in its cereal packaging for almost 100 years, and is confident in the safety and quality of its products.

"We use vegetable-based inks in all of our Canadian cereal packaging and follow all Health Canada packaging guidelines," the company said in an email to CBC News.

The U.K. Food Standards Agency is reviewing the research.

"We are also looking at alternative liners for our packages," Rachel Douglas, manager of brand public relations for Kellogg's Canada said. "However, we believe it’s important to thoroughly understand this study — and perhaps conduct others — before considering a move to a potentially less environmentally sustainable form of packaging."

Mineral oil is approved for use as a food additive in Food and Drug Regulations, Health Canada noted. All listings define maximum levels for each food commodity, and the regulator is not aware of any potential risks associated with mineral oil found in recycled food packaging.

"The Department will review the study in question to assess if the same issue is relevant to North America and if so, it will take action as required," a spokesperson for Health Canada said.

With files from CBC's Melanie Glanz