1. Chemistry of mineral oil hydrocarbons

Mineral oil hydrocarbons (MOHs) are complex chemical mixtures. MOHs are generally derived from crude oil. They mainly consist of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOSH). MOSH comprise open-chain, often branched hydrocarbons (commonly named paraffins) and cyclic, saturated hydrocarbons (commonly named naphthenes). MOAH include mono- or polycyclic aromatic hydrocarbons. Naphthenes and MOAH are generally highly alkylated. Depending on the source of the crude oil and the refining steps, MOAH contents reach up to 35%.

Mineral oil hydrocarbons (MOHs)  Polyolefin oligomeric saturated hydrocarbons (POSH)
MOSHMOAH
Paraffins:
open-chain, saturated, often branched hydrocarbons
Naphthenes:
cyclic, saturated hydrocarbons, generally highly alkylated
Mono- or polycyclic aromatic hydrocarbons, generally highly alkylatedBranched short- and long-chain hydrocarbons, cyclic chain ends; synthetic origin

Polyolefin oligomeric saturated hydrocarbons (POSH) are chemically similar to MOSH. POSH are oligomeric by-products synthesized during the manufacture of e.g. polyethylene (PE) and polypropylene (PP), polymeric additives, synthetic lubricants, and adhesives. They consist of branched short- and long-chain molecules, which may have cyclic chain ends.

Analyses of MOHs and POSH are a complex task. Due to the presence of many different substances with often similar properties, complete separation is difficult to achieve. However, liquid chromatography coupled to one- or two-dimensional gas chromatography (GC) and flame ionization detection allows a certain degree of separation and quantification. Results obtained by this method may be further supported by mass spectrometry (MS). MOH mixtures are typically classified based on their molecular masses using n-alkanes as standards.

2. Sources of MOHs in food

Contamination of food with MOHs originates from different sources: MOHs are intentionally used as additives in many different types of food contact materials (FCMs), e.g. plastics, adhesives, rubber articles, jute and sisal fibers, wax paper and board, and printing inks. During the production of food and/or FCMs, MOHs are further applied as e.g. lubricants and defoaming, cleaning and non-stick agents. Environmental pollution as well as non-intentional contamination of packaging are additional sources of MOHs in food. Especially food packaging made of recycled paper and board contains high levels of MOHs, which mainly originate from mineral-oil-based, non-food grade newspaper inks.

3. Health effects

The composition of a MOH mixture determines its toxicity and strongly depends on the presence of MOAH, which represents the most toxic fraction due to its mutagenic and carcinogenic properties. MOSH are less toxic, but accumulate in human tissues and form microgranulomas. Additionally, MOAH have been identified as potential endocrine disruptors. Non-dietary exposure to MOHs was associated with enhanced autoimmune responses.

4. Migration, exposure & biomonitoring

In the 1990s, first studies reported the migration of MOHs from FCMs, e.g. recycled paper and board, jute and sisal bags, into food. Since 2010, more detailed analyses were published: Especially dry foods packaged in recycled paper and board were regularly contaminated by MOSH and MOAH. Typically, MOSH migration levels were in the range of several mg per kg food and reached more than 100 mg per kg food in some cases. MOAH was generally measured at concentrations up to a few mg per kg food, but some analyses found MOAH levels exceeding 10 mg per kg food.

The European Food Safety Authority (EFSA) estimated the dietary exposure of the European population to MOSH to be in the range of 0.03 to 0.3 mg/kg body weight per day.

Biomonitoring data revealed that MOSH was consistently measured in different human tissues, such as liver, spleen, fat, mesenteric lymph nodes, lung and breast milk. Depending on the type of tissue, the composition of the accumulated MOSH differed: MOSH up to and beyond 45 carbon atoms were measured in liver and spleen, whereas MOSH between 16 and 36 carbon atoms prevailed in abdominal tissue fat. Mean MOSH concentrations in human tissues typically reached more than 100 mg/kg and maximum values of more than 1 g/kg were observed.

5. Technical solutions

The frequent detection of high MOH levels in packaging materials made of recycled paper and board initiated a discussion on how to reduce these contaminations. Recycled paper and board are generally not made of FCM-grade materials. Newspapers, journals and other kinds of paper that are recycled contain e.g. mineral-oil-based printing inks, adhesives, coatings, additives, and contaminants from previous uses. The replacement of mineral-oil-based printing inks would be a first step to reduce the load of MOHs in recycled paper and board in a long-term view. Internal bags or barrier layers are already broadly applied to reduce migration of MOHs from recycled paper and board into the food.

6. Regulation

Europe

The use of mineral oils in different types of food contact materials falls under the general provisions defined in the European Framework Regulation EC 1935/2004 on food contact materials. The Plastics Regulation EU 10/2011 lists three authorized MOHs (FCM #93-95) as additives in its positive list of additives and monomers and further includes a hydrocarbon resin (FCM #97). In 2017, the European Commission (EC) adopted Recommendation EU 2017/84 on the monitoring of MOHs in food and in FCMs (FPF reported).

In Germany, two ordinances are currently under discussion aiming at the prevention of mineral oil migration from recycled paper and board into foods: The 21st draft ordinance amending the Consumer Goods Ordinance (“printing ink ordinance,” version of June 24, 2016) includes a positive list of substances to be used in printing inks. The 22nd draft ordinance amending the Consumer Goods Ordinance (“mineral oil ordinance,” version of March 7, 2017) recommends a specific migration limit of 0.5 mg/kg food for MOAH and the introduction of functional barriers (FPF reported).

In Switzerland, several mineral oils and waxes are included on the list of permitted substances for the manufacture of packaging inks. Additionally, the Swiss Ordinance 817.023.21 on Materials and Articles prohibits the use of recycled paper and board in direct contact with food.

U.S.

In the U.S., MOHs are used as direct and indirect food additives (21 CFR 172.878 and 21 CFR 178.3620). Technical white mineral oil is permitted as indirect food additive in a wide variety of FCMs, e.g. in adhesives, as a component and defoaming agent in paper and paperboard (21 CFR 176.200 and 21 CRF 176.210), in resin-bonded filters, in rubber articles intended for repeated use, in textiles and textile fibers, and as a lubricant (21 CFR 178.3570 and 178.3910). Further permitted applications of (technical) white mineral oil include its use in resinous and polymeric coatings, cellophane as well as in packaging materials intended for radiation. It may further be used as an antioxidant, stabilizer and/or plasticizer in polymers (21 CFR 178.2010 and 178.3740). Additionally, mineral oil is permitted as a feed additive.

7. Selected references

Chemistry of mineral oil hydrocarbons

Sources of MOHs in food

Health effects

Migration, exposure & biomonitoring

Technical solutions

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