Process contaminants in vegetable oils part 1

Process contaminants in vegetable oils

EFSA safety assessment on process contaminants in vegetable oils and foods

In May 2016, the European Food Safety Authority (EFSA) Panel on Contaminants in the Food Chain (CONTAM Panel) published the results of its assessment of the safety of three substances (contaminants) known as glycidyl fatty acid esters (GE), 3-monochloropropanediol (3-MCPD) and 2-monochloropropanediol (2-MCPD).

Potential safety issues in relation to these compounds were first raised in 2006 and since then the food industry has been involved in research to investigate how these compounds form during processing and how to decrease their content in the food supply

These compounds form during the refining of edible oils at high temperatures, which is carried out in order to achieve quality and safety specifications. The highest levels in foods are present in palm oils and fats and so the main sources in our diets are foods made with these.

Product sources of these contaminants and their health risks



3-MCPD was first identified as a contaminant of soy sauce. It is present in a variety of food products including vegetable fats and oils (in particular palm fats and palm oils), biscuits, pastries and cakes, infant and follow-on formulae, fried or baked potato products and certain meat and fish products.

Health risks

Studies carried out in rats indicate that 3-MCPD can cause kidney toxicity. Using these data, EFSA established a tolerable daily intake (TDI) for 3-MCPD and its esters of 0.8 micrograms per kilogram of body weight per day in humans. A TDI is the maximum amount that can be consumed daily over a lifetime without being harmful to health and includes a very large safety margin.

Using data on the levels of 3-MCPD and its esters found in European food products and dietary survey data, the current exposure levels of European consumers were estimated. The exposure level of each age group was then compared to the TDI. Average exposure levels for infants, toddlers and children under 10 were found to be higher than the TDI; therefore current exposure levels of 3-MCPD and its esters may pose a potential health concern in these age groups.



2-MCPD was also was first identified in soy sauce. The biggest sources of 2-MCPD are fats and oils (especially palm oils and fats) and products containing them including bread, bakery products, certain fish and meat products, fried or roasted meat, and infant and follow-on formulae.

Health risks

EFSA could not draw any conclusions on the safety of 2-MCPD due to the limited availability of toxicological data and therefore a safe level of 2-MCPD intake through the diet could not be set. Additional studies are necessary to form conclusions on whether there is a potential health concern related to the presence of 2-MCPD in food.



Glycidyl esters are formed from compounds called diglycerides or monoglycerides, which are naturally present in all vegetable oils, when they are heated to temperatures > 200ºC e.g. during the deodorisation stages of refining. GE are therefore present in refined vegetable fats and oils (particularly palm oil) and foods containing these such as biscuits , pastries and cakes, infant and follow on formula, margarine, fried or roasted meat and some chocolate (or similar) spreads.

The level of these contaminants is highest in palm oil because diglycerides make up between 4 to 12% of its composition.

Health risks

After consumption through the diet, glycidyl esters are converted into free glycidol, although the extent of this conversion is uncertain. There is evidence from animal studies that glycidol is genotoxic (damages DNA) and carcinogenic (causes cancer).

The CONTAM Panel concluded that at current levels of intake, glycidyl esters are a potential health concern for all younger age groups (infant, toddler and children under the age of 10). The exposure of babies consuming only infant formula to glycidyl esters is of particular concern.

EFSA also concluded that glycidyl esters pose a potential health concern for consumers regardless of age with high levels of exposure (i.e. those eating larger quantities of foods containing glycidyl esters than the average population).

Although levels of GE in palm oil halved between 2010 and 2015 due to voluntary measures taken by manufacturers, current levels are still considered a potential health concern. Therefore the Panel concluded that more needs to be done to reduce the occurrence of these compounds.

Maximum limits set in foods

Maximum levels have been set in European food legislation (Commission Regulation (EC) 1881/2006) for 3-MCPD in hydrolysed vegetable protein (a savoury food ingredient) and soy sauce but no limits have been set for any other ingredient or food. To date, no maximum levels have been set by European authorities for 2-MCPD or glycidyl esters in foods.

What are the next steps?

There was a level of uncertainty in EFSA’s risk assessment caused by many factors including lack of data and the use of information from research carried out in animals. Overall, the Panel concluded that the impact of the uncertainties on the risk assessment is high and that the exposure assessment most likely underestimates the current exposure to these compounds.

Despite the limitations, EFSA’s review of the evidence is important for the food industry to consider.

EFSA’s risk assessment will be used by the European Commission to develop strategies to reduce or eliminate potential health concerns for consumers. This may include, for example, setting maximum limit values for the presence of these contaminants in food products.  EFSA continually monitors and reassesses consumer exposure and risk as new data becomes available.

Research is ongoing to better understand the way that 2 and 3-MCPD esters and glycidyl esters form during the processing of vegetable fats and oils. This information is needed by industry to develop further methodologies to reduce the levels. Analytical techniques for detecting 3-MCPD and glycidyl esters have improved since safety concerns were first raised which allows for better monitoring. The scenario is somewhat complex however because the refinement of oils is required for removing undesirable impurities that can affect quality, safety and taste.

Whilst levels of GE in palm oils and fats halved between 2010 and 2015, levels of 3-MCPD and 2-MCPD have remained relatively similar. The food industry has been encouraged to source oils and fats with low levels of these compounds. Furthermore, EFSA recommends that further monitoring and research is carried out and that industry should continue to collaborate with regulatory and other stakeholders. In particular, long term toxicity data is needed for 2-MCPD and more extensive testing of glycidol is required in order to reduce the current uncertainty.

EFSA has passed their assessment to food safety risk managers in EU Member States (in the UK this is the Food Standards Agency), whose responsibility it is to manage the potential risks to consumers and advise food manufacturers if there are safety concerns for the population.

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