Chemical in food packaging examined

Wednesday March 9 2011

Several newspapers have reported that recycled cardboard food packaging could be potentially harmful to health. The Independent said that “the cereal packet on your breakfast table could be a health hazard” while The Daily Telegraph reported Swiss research which found that recycled cardboard packaging may contaminate the foodstuffs stored inside.

The issue has been reported after research found that recycled cardboard boxes may leak chemicals called mineral oils into the foodstuffs they contain. Most of these mineral oils are thought to have originated from the ink in the newspapers that were recycled to make the cardboard boxes. While these reports have linked the chemicals to health problems such as cancer, there is currently only limited evidence showing how the body might be affected.

What is the basis for these current reports?

The reports are based on research looking at the possibility of the mineral oils found in some food packaging transferring themselves into foodstuffs they contain, and whether these mineral oils pose a potential health risk. In a recent study, Swiss researchers analysed samples of dry food stored in recycled “paperboard” boxes and found that the amount of mineral oil they contained was frequently between 10 to 100 times greater than the “safe limit” set by international organisations. The study also estimated that on average about a quarter of the migrating mineral oil came from the printing ink used on the box.

What are the substances they contain?

Tests on recycled packaging found it contained mineral oil, a component of printing ink. Mineral oil consists of various types of hydrocarbon molecules that can exist as mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH). Recycled cardboard contains different types of mineral oils, including that found in solvents, waxes and adhesives. It is thought that producing paperboard by recycling newspaper increases the level of mineral oil it contains due to the mineral oil content in newspaper print. Mineral oil hydrocarbons usually migrate by evaporating into gases that slowly enter foodstuffs over time.

According to the UN Food and Agriculture Organization/World Health Organization (FAO/WHO) Joint Expert Committee on Food Additives, the safe upper limit for mineral oil saturated hydrocarbons (MOSH) in foodstuffs is 0.6mg/kg.

What does the research say?

There have been several different studies on the migration of mineral oils into foodstuffs, but the one the press focused on was undertaken by Dr Koni Grob and other researchers from the Food Safety Laboratory in Zurich, Switzerland. The researchers say that they conducted the research in response to calls that the migration of mineral oil from recycled paperboard into dry food should “urgently be minimised”. Their study follows previous research suggesting that mineral oil concentration in recycled paperboard was too high for use in food packaging.

In this recent study, researchers analysed 119 samples of dry food on the German market, including cereals, biscuits, pasta and rice. The food samples were on average two to three months old, had been stored in mostly recycled paperboard packaging, and were intended by manufacturers to be stored for extended periods of time. The samples were collected in April 2010 and analysed for mineral oil content one to three weeks later.

This study of foodstuffs showed that the limit considered safe for mineral oil saturated hydrocarbons (MOSH) (0.6 mg/kg), as set by the FAO/WHO Joint Expert Committee on Food Additives, was “frequently exceeded” by a factor of 10-100. Concentrations of MOAH in the food frequently exceeded 10mg/kg. The researchers point out that, as yet, a safe limit for MOAH has not been prescribed.

Products without an internal bag or with a bag of paper or polythene contained higher levels of mineral oil, while those with bags made of other materials such as polypropylene, or which had an aluminium layer, seemed to block migration. The study estimated that on average about a quarter of the migrating mineral oil came from printing ink used for decorating the box (rather than from the recycled fibres).

The researchers also estimate that by the time the products reached the end of their shelf life (one to three years), the migration of mineral oils would almost triple, to reach 31mg/kg on average.

What are the health risks of these products?

Although the research into mineral oil found in packaged foodstuffs has raised an important issue, this study has not looked directly at the possible health risks of mineral oil in humans, and these are largely unknown at the current time.

The BfR German Federal Institute for Risk Assessment, which has extensively reviewed the available evidence on this issue, says that few studies have so far been conducted and it is not currently possible to carry out a health risk assessment as “it is unknown to what extent foodstuffs are contaminated by the migration of mineral oil from cardboard packaging”.  The institute also says that it is not known which chemical mixtures found in mineral oils are actually involved.

The BfR does say that MOSH chemicals are known to be easily absorbed by humans and stored in several organs. Animal studies have also demonstrated that “such mineral oil mixtures can lead to accumulations and damage in the liver, heart valves and lymph nodes”. The organisation also highlights that, although the exact composition of chemical mixtures in printing inks (especially those that contain MOAH) is unknown, these complex mixtures are known to include carcinogenic substances. In general, they believe that such foodstuff contamination is adverse and that migration of mineral oil from recycled paper and cardboard to foodstuffs should be minimised.

So are mineral oils harmful?

To perform an adequate health assessment would require information on the exact amount of these compounds absorbed, stored and eliminated from the human body, and data in this area is currently insufficient to judge the impact of mineral oil contamination. Dr Grob, study author and researcher at the Food Safety Laboratory in Zurich, has reportedly stressed that food substances involved would contain only a minute dose.

In an interview with The Guardian, a representative from the UK’s Food Standards Agency (FSA) said it is aware of no firm evidence to suggest that there are food safety risks related to mineral oils in recycled food packaging. The FSA is quoted as saying that the research is “interesting”, but, due to the incomplete data provided by current studies, “the results have not demonstrated that mineral oils in food packaging represent a food safety risk”.

Much further research is needed before it is known what level of mineral oil could pose a potential health risk.

Will these products be phased out?

Several food manufacturers are reportedly planning to change their packaging to reduce its mineral oil content, while others have recently done so. The UK’s Food Standards Agency (FSA) says it is currently gathering information on the presence of mineral oils in food packaging on the UK market.

The FSA is also looking at recycled material to ensure that manufacturing processes successfully remove substances that could present a food safety concern from the finished packaging. A spokesman said: “The Agency continues to review evidence in this area and will act to protect consumers if the evidence shows it is necessary to do so.”                                                

Analysis by Bazian
Edited by NHS Choices