Swiss researchers, who analysed German food product packaging, found levels of mineral oils 10-100 times higher than WHO-recommended limits.
What was the research?A team led by Dr Koni Grob of the Official Food Control Authority of the Canton of Zurich, in Switzerland, analysed 119 samples of dry food in packets.
It examined the samples for mineral oil-saturated hydrocarbons that had been absorbed by food from the printed card packet into the food.
The researchers found that the levels of these hydrocarbons in food exceeded WHO-recommended limits by a factor of between 10 and 100. Most of the samples were less than three months old and the researchers estimated that these levels might triple by the end of the products' shelf lives.
However, Dr Grob and his colleagues found that some types of lining bag blocked migration of these hydrocarbons. But they said it would be premature to reach conclusions on what type of bag would be best to prevent the hydrocarbons transferring into the food.
Is there a risk to consumers?
A spokesman for the UK's Food Standards Agency (FSA) said the agency was not aware of any firm evidence to suggest that there were food safety risks related to mineral oils in recycled food packaging.
'The research is interesting but, due to incomplete data, the results have not demonstrated that mineral oils in food packaging represent a food safety risk. The FSA is gathering information on the extent of the presence of mineral oils in food packaging on the UK market,' he said.
'The agency is also specifically looking at recycled material to ensure that manufacturing processes successfully remove substances that could present a food safety concern from the finished packaging,' he added.
The FSA said it would take action to protect consumers if evidence showed that it was necessary to do so.
Some manufacturers have chosen to change their packaging as a result of the findings.