From packaging to food: mineral oil migration

Recycled paper and board used in food packaging materials (boxes, paper bags) often causes migration of mineral oil into food at levels that are claimed to be unacceptable, according to present toxicological assessments.

Dry foodstuffs such as rice, breadcrumbs or pasta are frequently packed into cardboard made of recycled paper. Current analyses by the Official Food Control Authority of the canton of Zurich have shown that such recycled cardboard can contain mineral oil. The mineral oils stem from ink which is commonly used in newspaper printing. If food is packaged in such cardboard boxes, it is possible that mineral oils can migrate to the foodstuff. Animal studies have shown that mineral oil mixtures are stored in the body and can lead to damage in the liver, heart valves and lymph nodes. The German Federal Institute for Risk Assessment (BfR) has provided possible action that can be taken in order to reduce potential consumer health risk.

When foods in recycled board are densely packed into larger boxes or onto pallets, most of the hydrocarbons up to n-C₂₀ may migrate into the packed food within a few weeks, those up to n-C₂₈ at a decreasing rate. Unprinted recycled board contained 300-1000 mg/kg mineral oil <n-C₂₈. The main sources of the mineral oils are the inks used for printing newspapers: newspapers contain roughly 3000 mg/kg mineral oil <n-C₂₈.

The Joint FAO/WHO Expert Committee on Food Additives established a tolerable daily intake of 0.01 mg/kg body weight for these mineral oils.

Using standard assumptions for calculating specific migration limits, a maximum tolerable concentration in food of 0.6 mg/kg is derived. This evaluation assumes highly refined white oils, whereas gas chromatographic analysis of the technical-quality oils found in recycled board has shown they contain 15-25% aromatic compounds, predominantly with 1-3 aromatic rings. This finding precipitates authorities into a dilemma: recycling is supported for the sustainable use of materials but, on the basis of present toxicological assessments, the migration is often far beyond acceptable.

What is mineral oil?

Mineral oil mixtures found in cardboard consist of saturated hydrocarbons and aromatic hydrocarbons.

In chemical terms, saturated hydrocarbons are chain- and ring-shaped hydrocarbons (MOSH). The abbreviation MOSH stands for ‘mineral oil saturated hydrocarbons’. Aromatic hydrocarbons are referred to as MOAH - ‘mineral oil aromatic hydrocarbons’. MOAH consist of a complex mixture of predominantly alkylated polycyclic aromatic hydrocarbons.

How does mineral oil enter cardboard food packaging?

Cardboard is produced using recycled paper, including printed newspaper. Most commonly used newspaper inks contain mineral oils. These cannot be removed sufficiently during the recycling process and are thus able to enter cardboard food packaging.

Does all cardboard food packaging contain mineral oil with adverse health effects?

If newspaper is not used as a resource in cardboard and paper production for direct food contact and, instead, only completely blank paper or virgin fibres are used, then the mineral oil content in the packaging can be kept at a minimum. However, if the food packaging is printed on, the migration of mineral oil may also be possible.

Are there certain foods packaged in recycled cardboard that might be more affected than others?

At this time, data on the migration of mineral oils from packaging material into various foodstuffs is rare. The BfR assumes that foods with large surface areas such as flour, semolina, rice, breadcrumbs or breakfast cereals are likely to be affected by mineral oil migration from packaging.

In order to improve the data available, a broad basis of data is necessary to provide experimental results on the migration of mineral oils from cardboard packaging into various foods with large surface areas.

Does mineral oil in food packaging pose a health risk for consumers?

Thus far, only a few studies exist on the migration of mineral oil from cardboard packaging into food. The Official Food Control Authority of the canton of Zurich has found a mineral oil mixture in rice that was stored in a cardboard box for eight months. It can be reasonably assumed that the detected migration is largely the result of the outgassing of mineral oils from the cardboard. However, due to incomplete data, BfR is, at present, unable to determine which adverse effects this special chemical mixture may have on humans.

The mineral oil mixture found in rice consisted of saturated hydrocarbons (MOSH). These were detected at levels of 15.4 mg MOSH per kg rice. The MOSH had a chain length of 28 hydrocarbon atoms. Furthermore, the mineral oil mixture found in rice contained aromatic hydrocarbons (MOAH) at 4.0 mg MOAH per kg rice.

For the BfR these data served as the basis for a sample calculation in which the intake amount was estimated. The institute assumed the worst case scenario, ie, very high consumption of contaminated rice and the resulting high intake of mineral oil. The result of the calculation: if a person weighing 60 kg were to eat one portion of the rice analysed (100 g), he or she would take in 0.026 mg MOSH and 0.007 mg MOAH per kg body weight.

At this time, a characterisation of the mineral oil composition sufficient to facilitate a health assessment is not available. For example, the chain length of hydrocarbons is a determining factor in how easily hydrocarbons are absorbed by the human body. The shorter the chain length, the greater is the risk that they are stored in the body.

Which health risks are known to result from mineral oil?

In food packaging (cardboard made of recycled paper) high amounts of mineral oils with saturated and aromatic hydrocarbons were detected.

Short chain saturated hydrocarbons (MOSH) are easily absorbed by the human body and can be stored in several organs. Animal studies have shown that such mineral oil mixtures can lead to accumulations and damage in the liver, heart valves and lymph nodes. The exact composition of chemical mixtures in printing inks, especially those that contain polycyclic aromatic hydrocarbon compounds (MOAH), is unknown. The complex mixtures primarily consisting of alkylated polycyclic aromatic hydrocarbons, to which MOAH also belong, also include carcinogenic substances.

In general, such foodstuff contamination is adverse. BfR finds that the migration of mineral oil from recycled paper and cardboard to foodstuffs should be minimised immediately.

Has BfR carried out a risk assessment?

Due to insufficient data, BfR has found it impossible to carry out a risk assessment at present. Recycled cardboard typically contains 300-1000 mg/kg mineral oil. However, it is unknown to what extent foodstuffs are contaminated by the migration of mineral oil from cardboard packaging, and which chemical mixtures that are found in mineral oils are actually involved.

There is no toxicological study available for the specific mineral oil mixtures found in cardboard. A risk assessment is, therefore, currently not possible. BfR cannot, at the present time, rule out that MOAH also contain carcinogenic aromatic compounds.

An adequate health assessment of this compound, especially, requires that the amount absorbed by the human body is known. It can be reasonably assumed that the mixtures ingested are eliminated only slowly from the human body and could, thus, accumulate in the body.

What does BfR suggest in order to solve the problem?

BfR has discussed the problem of mineral oil migration from cardboard packaging to foodstuffs with various experts and manufacturers of food packaging. They all agree that the migration of mineral oil from inks from recycled packaging materials to foodstuffs should be reduced.

For ecological reasons, cardboard packaging material is largely manufactured from recycled paper. The contamination of foodstuffs through packaging can be minimised if those foods that are especially susceptible to the migration of mineral oil are filled into an inner bag, which is impermeable for these substances, or if the use of recycled paper for food packaging is discontinued.

Furthermore, it should be reviewed whether the efficiency of the recycling process can be improved with regard to the removal of mineral oil components.

In the long term, the composition of inks used for newspaper printing should be changed, so that mineral oils that are unsafe for human health are no longer used. This also appears preferable in light of the aspect that skin contact could also lead to the intake of mineral oil.

BfR deems it imperative that all involved industries (printing inks, newspaper printing, paper recovery, paper production, packaging materials production, food packaging) cooperate in implementing these recommendations.