Summary
- Glycidyl esters (GEs) are contaminants formed during food processing, as in the refining and deodorisation of fats and oils. Palm oil and food products containing palm oil tend to have higher levels of glycidyl esters.
- Once ingested, glycidyl esters are metabolised and broken down into glycidol in the human body, which is a genotoxic carcinogen. The International Agency for Research on Cancer (IARC) classifies glycidol as a Group 2A carcinogen, considering it to be “probably carcinogenic to humans". Glycidol can have toxic effects on the nervous, urinary, and reproductive systems in experimental animals.
- The Codex Alimentarius Commission and the Macao authorities have not established limits for glycidyl esters and glycidol levels in cooking oils, while the European Union has established maximum limits for glycidyl esters in cooking oils.
- The food sector is advised to give priority to refined vegetable oils or fish oils with a lower level of glycidyl esters. Before purchase of cooking oils, it is essential to make sure they meet the required hygiene standards.
- The public is advised to maintain a balanced and diversified diet, avoid excessive intake of food products with high fat and oil content and food products containing refined fats and oils. It is also advisable to buy cooking oils of a variety of brands.
Introduction
During an investigative survey on food, IAM found out that the levels of glycidyl esters (indicated by the presence of epichlorohydrin) detected in some cooking oils and fats were higher than the limits established by the European Union. The Consumer Council of Hong Kong also announced that some sesame oils and sesame powders commercially on the market were found to contain levels of glycidyl esters exceeding the action levels established by the Centre for Food Safety of Hong Kong. So, what exactly are glycidyl esters? Why are they detected in food? And how harmful are they to human health? The following will explore these questions one by one.
Sources of glycidyl esters in cooking oils and associated health risks
Glycidyl esters are contaminants formed during the processing of oils, primarily during the deodorisation of refined fats and oils. During this process, the oil is heated to temperatures of 200oC or higher, triggering a series of reactions where fats and oils are broken down, leading to the formation of glycidyl esters.
Glycidyl esters are commonly found in cooking oils (e.g. margarine, sesame oil and peanut oil) and food products (e.g. biscuits and French fries) where cooking oils are used in their production. Although the levels of glycidyl esters vary across different food products, but in general, palm oil and food products containing palm oil tend to have higher levels of glycidyl esters, as compared to that of in other fats and oils, and in similar food products.
Once ingested, glycidyl esters are metabolised and broken down into glycidol in the human body, which is a genotoxic carcinogen. The International Agency for Research on Cancer (IARC) has classified glycidol as a Group 2A carcinogen based on sufficient evidence derived from experimental animals, considering it to be “probably carcinogenic to humans". Glycidol can have toxic effects on the nervous, urinary, and reproductive systems in experimental animals.
International and local regulatory aspects
International bodies have regulatory measures in place to reduce the levels of glycidyl esters in cooking oils, primarily by establishing maximum limits for glycidyl esters in food products, enhancing monitoring, and optimising food processing technologies. Currently, neither the Codex Alimentarius Commission nor the Macao authorities have established limits for levels of glycidyl esters and glycidol in cooking oils, while the European Union has already established the maximum limits for glycidyl esters in cooking oils.
In 2019, the Codex Alimentarius Commission promulgated a “Code of Practice for the Reduction of 3-monochloropropane-1,2-diol esters (3-MCPDEs) and Glycidyl Esters (GEs) in Refined Oils and Food Products Made from Refined Oils", which puts forward several recommendations, such as adopting good manufacturing practices during oil extraction and refining process, and use of refined oils with lower levels of glycidyl esters in food production (including infant formula).
The Department of Food Safety of the Municipal Affairs Bureau (IAM) is committed to ensuring food safety and hygiene. It carries out random inspections and testing of imported food products and commercially available food products on a regular basis. It gathers and analyses food safety information from around the world through the food safety information monitoring system. Moreover, IAM carries out targeted food surveillance and collects samples of them for testing purposes at regular intervals, including investigation into levels of glycidyl esters in cooking oils. If abnormalities are found in the testing results of routine food surveillance or targeted food surveillance, or if there are information related to the safety of food products commercially available in Macao, IAM will promptly take appropriate preventive and control measures to contain the distribution of the unsafe food products, and issue press releases to inform the public accordingly.
Advice to the food sector
- Choose high-quality cooking oils from reliable sources, prioritising refined vegetable oils or fish oils with lower levels of glycidyl esters. Before purchase of cooking oils, it is essential to make sure they meet the required hygiene standards.
Advice to the general public
- The public is advised to maintain a balanced and diversified diet to reduce the risk of excessive ingestion of certain contaminants from eating only a limited range of food. In general, maintaining a healthy and low-fat diet can reduce the overall intake of glycidyl esters through food consumption.
- It is preferable to use fresh ingredients to prepare food at home and avoid excessive consumption of food products (e.g. margarine) with high fat and oil content and food products containing refined fats and oils (e.g. fried food) to reduce intake of glycidyl esters through food.
- It is advisable to buy cooking oils of a variety of brands, and do not use or consume the same brand of cooking oil for an extended period of time.
- Consumers should pay close attention to the information on food safety released by IAM and to news reports. If consumers do have in possession of the affected food product, they have to stop consuming the product at once. If there are doubts about the safety of any food product, do not buy or consume it.
References:
1. Summary report of the eighty-third meeting of JECFA (JECFA). 2016
http://www.fao.org/3/a-bq821e.pdf
2. (EU) 2018/290 of 26th February 2018 amending Regulation (EC) No. 1881/2006 as regards maximum levels of glycidyl fatty acid esters in vegetable oils and fats, infant formula, follow-on formula and food for special medical purposes intended for infants and young children (European Union). 2018
https://eurlex.europa.eu/legalcontent/EN/TXT/PDF/?uri=CELEX:32018R0290&from=EN
3. Codex Alimentarius Commission. Code of practice for the reduction of 3- monochloropropane-1,2-diol esters (3-MCPDEs) and glycidyl esters (GEs) in refined oils and food products made with refined oils. (FAO). 2019
4. China Food and Drug Administration released a risk analysis on “Chloropropanol Esters and Glycerol Esters" (Foodmate.net). 2017
https://news.foodmate.net/2017/03/422968.html
5. Food Safety Focus (211st Issue, February 2024) – Article 2, Understanding Glycidyl Ester in Food (Centre for Food Safety of HKSAR). 2024
https://www.cfs.gov.hk/sc_chi/multimedia/multimedia_pub/multimedia_pub_fsf_211_02.html
6. Risk Assessment Studies, Report No. 62 - Glycidyl Esters in Edible Fats and Oils and in Infant Formula. (Centre for Food Safety of HKSAR). 2020
https://www.cfs.gov.hk/tc_chi/programme/programme_rafs/files/RA_Report_on_GE.pdf
7. Announcement on Amendment to Maximum Limits for Glycerol Fatty Acid Esters in Edible Fats and Oils (Ministry of Health and Welfare, Taiwan region) 7 June 2022
https://www.mohw.gov.tw/cp-16-69774-1.html
BRR 004 DAR 2025
