Focus on ethylene oxide and 2-chloroethanol

The BfR has published new preliminary health-based reference values for the ethylene oxide reaction product 2-chloroethanol

April 2026. In its Opinion No 017/2026 dated 26 February 2026, the German Federal Institute for Risk Assessment (BfR) published new, provisional, health-based reference values for 2-chloroethanol. Recent studies using gene mutation tests have shown that, unlike ethylene oxide, 2-chloroethanol is highly unlikely to be genotoxic within the exposure range relevant for residues. Based on these findings, the BfR proposes a provisional acute reference dose (ARfD) of 0.13 mg/kg body weight and an acceptable daily intake (ADI) of 0.02 mg/kg body weight/day for 2-chloroethanol. The BfR also recommends establishing separate maximum residue limits (MRLs) for ethylene oxide and 2-chloroethanol in future^[1,2].

This article provides an overview of the most significant changes and their implications, alongside the legal classification, mechanism of action and formation of ethylene oxide and 2-chloroethanol.

Changes in the BfR’s assessment and their significance

The BfR’s current assessment of ethylene oxide and 2-chloroethanol marks the first significant departure from the previous practice of equating the two substances. Previously, due to insufficient data, it was assumed that 2-chloroethanol possessed mutagenic and carcinogenic properties comparable to those of ethylene oxide. For CMR substances (carcinogenic, mutagenic, and toxic to reproduction) such as ethylene oxide, no safe intake levels can be defined. Accordingly, a so-called dose of low concern of 0.037 µg/kg body weight/day (equivalent to 0.000037 mg/kg body weight/day) was determined for both substances, forming the basis for risk management.

Based on the BfR’s current findings, the European Food Safety Authority (EFSA) must now conduct a final human toxicology assessment at the EU level. As a result, the MRLs for ethylene oxide could be further lowered in the future, while safe MRLs for 2-chloroethanol for certain products could also be set above the limit of determination^[1,2].

Legal regulation and ban on ethylene oxide in the EU

Until 1981, the use of ethylene oxide in plant protection products was permitted in Germany. In the rest of the European Union (EU), it was also approved as a plant protection product in some cases until 1991.

The fumigation of food and feed with ethylene oxide was permitted in the EU until 2011 to protect them from fungal and bacterial contamination during transport and storage. Since 2011, all such uses have been banned. In Germany, the marketing of ethylene oxide in biocidal products is permitted only until 3 June 2026, and its use only until 30 November 2026. This applies to disinfection and sterilisation outside the food sector, for example for sterilising medical devices or artefacts in museums.

Outside the EU, the sterilisation of food with ethylene oxide is permitted and common practice in many countries. For instance, separate maximum residue limits for ethylene oxide and 2-chloroethanol are defined for various products in the United States and Canada. Depending on the product, these limits range from 7 mg/kg to 50 mg/kg for ethylene oxide, and 940 mg/kg for 2-chloroethanol^[4,5,6].

Maximum residue limits for ethylene oxide and 2-chloroethanol

According to Regulation (EC) No. 396/2005, ethylene oxide is not approved as a plant protection product for food and feed. Product-specific lower analytical limits apply as maximum residue limits for the sum of ethylene oxide and its main reaction product, 2-chloroethanol. Depending on the product, these range from 0.02 mg/kg to 0.1 mg/kg.

Furthermore, the sterilisation of food additives with ethylene oxide is prohibited under the Annex II Regulation (EU) No 231/2012, which sets specifications for food additives. A maximum level of 0.1 mg/kg has been set for the combined presence of ethylene oxide and 2-chloroethanol^[4,5,6,7,8].

Mechanism of action of ethylene oxide

Ethylene oxide is an effective sterilant. It is highly reactive and causes alkylation of important biomolecules in the cells of microorganisms, such as DNA and enzymes.

This denatures these molecules, causing them to lose their function. Essential cellular functions are thus blocked and fungi, bacteria and spores are killed.

However, ethylene oxide also causes alkylation of important biomolecules in more highly developed organisms and can impair vital processes as well as have mutagenic and carcinogenic effects.

Relationship and formation of ethylene oxide and 2-chloroethanol

In the presence of ubiquitously occurring chloride ions, ethylene oxide rapidly reacts to form 2-chloroethanol, the main reaction product of ethylene oxide. 2-Chloroethanol is an important industrial chemical used in the production of dyes, insecticides and plasticisers, as well as ethylene oxide itself. Furthermore, 2-chloroethanol can be formed from the reaction of other chlorine-containing chemicals, meaning that additional potential pathways of entry for this parameter are also conceivable^[3,4].

The ethylene oxide crisis of the early 2020s

From the second half of 2020 onwards, inspections increasingly revealed elevated levels of ethylene oxide and 2-chloroethanol in sesame seeds from India as well as in products made from them. In response to the first alerts in the European Rapid Alert System for Food and Feed (RASFF), testing for ethylene oxide and 2-chloroethanol was expanded. This revealed that other products, such as thickening agents (e.g., locust bean gum) and products made from them, as well as spices, were in some cases heavily contaminated. These were recalled on a large scale or prohibited from being imported into the EU.

Consequently, products such as okra, spices, instant soups, food additives, and dietary supplements were included in Annexes I and II of Implementing Regulation (EU) No 2019/1793. This regulation deals with the temporary intensification of official controls and on emergency measures regarding the entry of certain goods from certain third countries^[9].

Warnings concerning excessive levels of ethylene oxide and 2-chloroethanol continue to account for a significant proportion of alerts in the European Rapid Alert System for Food and Feed (RASFF). This underscores the importance of reliable analysis of ethylene oxide and 2-chloroethanol as part of quality control for food and feed.

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Sources

[1] BfR Opinion No. 016/2026 as of 27 Feb 2026: 2-chloroethanol. Re-assessment of its mutagenic potential and derivation of provisional acute and chronic oral reference values (ARfD, ADI)
[2] Updated Opinion No 024/2021 of the BfR dated 1 Sep 2021: Health assessment of ethylene oxide residues in sesame seeds
[3] Centers for Disease Control and Prevention (CDC): Ethylene Oxide "Gas" Sterilization", Date accessed: 10 March 2026
[4] BfR FAQ dated 27 Feb 2026:Health risks of ethylene oxide and its metabolite 2-chloroethanol in food (in German)
[5] Code of Federal Regulations (eCFR): § 180.151 Ethylene oxide; tolerances for residues. Abrufdatum: 10.03.2026
[6] relana^® Communication Note 21-02: Ethylene oxide and 2-Chloroethanol, Version 2021/05/11
[7] Regulation (EC) No 396/2005 on maximum residue levels of pesticides in or on food and feed of plant and animal origin
[8] Commission Regulation (EU) No 231/2012 laying down specifications for food additives listed in Annexes II and III to Regulation (EC) No 1333/2008
[9] Commission Implementing Regulation (EU) 2019/1793 on the temporary increase of official controls and emergency measures governing the entry into the Union of certain goods from certain third countries