MOSH and MOAH in Food: Regulatory and Analytical Developments

The presence of mineral oil hydrocarbons (MOH), including MOSH (Mineral Oil Saturated Hydrocarbons) and MOAH (Mineral Oil Aromatic Hydrocarbons), continues to be a significant issue in European food safety discussions. Mineral oils are complex mixtures of hydrocarbons in the C10–C50 range, predominantly originating from fossil, petrogenic sources. While MOSH mainly consist of saturated hydrocarbons that can accumulate in human tissues such as the liver and spleen, MOAH include aromatic structures, some of which — particularly those containing three or more aromatic rings — are associated with genotoxicity and potential carcinogenicity.

In September 2023, the European Food Safety Authority published its Scientific Opinion on mineral oil hydrocarbons in food. EFSA concluded that dietary exposure to MOSH is not considered a concern for any age group. In contrast, for MOAH, both exposure scenarios assessed through the Margin of Exposure (MOE) approach indicated a possible health concern. EFSA confirmed that genotoxicity is mainly linked to MOAH with three or more aromatic rings, although substantial data gaps remain regarding oral toxicity, alkylation effects and the toxicological relevance of one- and two-ring MOAH. The opinion forms the scientific basis for the planned introduction of binding maximum levels.

Sources and Pathways of Contamination

Mineral oil hydrocarbons can enter food through a wide variety of environmental, technological and material-related pathways. Environmental contributions occur via air, soil and aquatic ecosystems. Atmospheric contamination may occur through particulate matter, which predominantly contains higher molecular weight hydrocarbons (above approximately n-C20), whereas migration through the gas phase, such as from paperboard into dry foods, is generally limited to more volatile hydrocarbons below roughly n-C24.

Machinery used during harvesting and processing can introduce MOH through lubricants and hydraulic oils. Mineral oil products may also be used intentionally as processing aids or additives, or may migrate unintentionally from food contact materials (FCMs), especially recycled paperboard. In addition, adhesives, transport packaging and storage materials may contribute to contamination. Frequently, contamination results from a combination of several sources. For example, studies have shown that pasta packaged in recycled paperboard may receive MOH not only from the box itself, but also from adhesives and transport cartons, while the wheat flour used as a raw material may already contain background levels of MOSH.

Historically, the widespread and relatively uncontrolled use of mineral oil products was identified in the late 1980s and early 1990s by the Cantonal Laboratory of Zurich. This authority investigated contamination sources and implemented reduction measures. Several major uses were progressively phased out, including mineral oil-based release agents for bakery products (notably toast bread), surface treatments for rice, cleaning agents in edible oil refineries and certain feed additives. As a result, consumer exposure decreased substantially, possibly by up to two orders of magnitude. Additional reductions followed public awareness of contaminated Ukrainian sunflower oil in 2008 and the issue of migration from recycled paperboard packaging.

A key challenge is that MOH detected as contaminants often have compositions similar or identical to authorised mineral oil products. Differentiating between authorised uses and contamination is therefore analytically difficult and sometimes unclear. Furthermore, mineral oil products vary significantly in molecular mass distribution and MOAH proportion. They may also contain additives or impurities such as viscosity modifiers, or form oxidation products during combustion and environmental exposure. Biotransformation by microorganisms, plants or animals can alter the hydrocarbon profile, sometimes enriching fractions that are poorly metabolised and more likely to accumulate in humans. Consequently, identifying the source is crucial for interpreting analytical findings and assessing toxicological relevance.

Legislative Developments and Regulatory Framework

At the end of 2023, the European Commission presented a first Draft Regulation establishing maximum levels for MOAH, intended to be integrated into Regulation (EU) 2023/915. The draft has undergone several revisions, with Revision 7 introducing further modifications for cereal products, cocoa products, confectionery and food additives produced from food sources. Adoption of the regulation is currently planned for the end of 2025, with applicability expected from 2027.

The draft proposes fat-content-based general maximum levels for MOAH (C10–C50), derived from previously harmonised limits of quantification used in official controls. These levels are 0.5 mg/kg for products containing up to 4% fat or oil, 1.0 mg/kg for products containing more than 4% and up to 50% fat or oil, and 2.0 mg/kg for products containing more than 50% fat or oil. Specific maximum levels are foreseen for a wide range of product groups including oilseeds, fats and oils, nuts, pulses, cereal grains and products, milk and dairy products, cocoa and chocolate products, spices and dried herbs, baby food, food supplements and, newly included, food additives produced from food sources. From 2030, processed and compound foods containing certain listed ingredients will also be covered.

The use of processing factors under Article 3 of Regulation (EU) 2023/915 will be permitted. Where processing results in lower levels, those reduced levels do not apply.

Parallel discussions are ongoing to introduce MOAH limits into food additive specifications under Regulation (EU) No. 231/2012. Additives produced from food would instead fall under the Contaminants Regulation, with explicit reference that raw materials must comply with Regulation (EU) 2023/915.

In addition, sampling and analytical requirements for mineral oil hydrocarbons are planned to be incorporated into Regulation (EU) No. 333/2007 via an amending regulation. A new proposal foresees higher permissible limits of quantification for analytically complex matrices such as spices, herbs, essential oils, supplements and marine oils, potentially up to 5 mg/kg, compared with the current 1–2 mg/kg requirements.

A monitoring recommendation for MOSH and MOAH is also under discussion. This aims to define indicative MOSH values and risk minimisation requirements, and to extend MOAH monitoring to products not fully covered by the draft regulation, such as coffee, tea, fruits, vegetables and essential oils.

Analytical Considerations

The standard analytical method used in official control is online LC-GC-FID. While suitable for quantifying total MOSH and MOAH fractions (n-C10 to n-C50), this technique cannot reliably distinguish between mineral oil contamination and naturally occurring hydrocarbons or technologically introduced substances, which may lead to overestimation.

More advanced two-dimensional techniques such as GCxGC-MS-FID and GCxGC-ToF-MS/FID allow improved characterisation, including mass spectrometric identification and quantification of the toxicologically relevant tri- to polyaromatic fraction (TPAF). These methods support more accurate source identification and toxicological assessment, which will become increasingly important under the forthcoming regulatory framework.

Conclusion

The control of MOAH in food is entering a decisive regulatory phase. With adoption of binding maximum levels expected by the end of 2025 and applicability from 2027, food operators must prepare for stricter compliance requirements. Although MOSH exposure is currently not considered a health concern, MOAH — particularly fractions containing three or more aromatic rings — remain toxicologically relevant and are driving regulatory action.

Given the diversity of contamination sources, analytical complexity and evolving legislative requirements, proactive supply chain management, appropriate analytical strategies and continuous monitoring will be essential for ensuring compliance and protecting consumer health.