Ethylene oxide, a carcinogen that has forced thousands of food withdrawals from the EU Support science

Ethylene oxide, a carcinogen that has forced thousands of food withdrawals from the EU  Support science

In recent months, many people have had difficulty finding certain foods in stores, such as sesame seeds in Spain or hamburger buns in France. This is because many products, more than 7,000, have been withdrawn from the European market due to the presence of ethylene oxide, a toxic substance not allowed in food. Between September 2020 and the time of writing, 578 notifications of this cause from 24 Member States, including Spain, have been registered in the European Rapid Alert System for Food and Feed (RASFF), issuing 38 alerts. This is an anomalous situation due to the number of notifications and products affected, which, due to its size, is reminiscent of the incident recorded in the summer of 2017, when Millions of eggs have been withdrawn from the market due to the presence of an illegal pesticide called fipronil.

The problem became known at the end of August 2020, when the Belgian authorities found high concentrations of ethylene oxide in several batches of sesame seeds imported from India. They found that they were distributed from Belgium to 33 countries (including 24 EU members), so issued a warning at European level. In this way, the representatives concerned (manufacturers, distributors, etc.) were able to withdraw the products from the market. Given the gravity of the problem, the European Commission organized meetings with the crisis coordinators of each Member State to take further concrete action as a matter of urgency. Among other things, it was decided to emphasize controls on imported sesame seeds from India.

“The problem arises in August 2020, when Belgium detects high concentrations of ethylene oxide in batches of sesame seeds.”

This could partly explain the remarkable number of warnings reported, a number that is further explained because the product, sesame seeds, is used as an ingredient in a wide variety of foods, from hamburger rolls to hummus. As if that wasn’t enough, ethylene oxide was also found in many other imported products, not only from India but also from other countries such as China or Turkey: ground coriander, black pepper, curry, spirulina, guar gum, locust bean gum, flaxseed etc., both from conventional production and from organic production, which are commonly used in the production of ice cream, sauces, biscuits and long, etc.

What is ethylene oxide?

Ethylene oxide is a compound that occurs as a gas at room temperature. It is mainly used as a raw material in the chemical industry for the production of other compounds (especially ethylene glycol, which is used as an antifreeze mixture in cold plants). It is also used as a sterilizing agent, especially in heat-sensitive materials such as medical devices or laboratory equipment, because it is able to eliminate unwanted microorganisms. This is possible because it damages DNA and it is precisely what makes it dangerous to human health. Therefore, its use in food is prohibited in the European Union, both in agriculture (for example in phytosanitary establishments) and in the preservation or preparation of food.

“It is used as a sterilizer because it is able to eliminate microorganisms by damaging their DNA.” And that’s exactly what makes health dangerous. “

However, in other countries, such as India, it is used with some frequency, as evidenced by this incident. However, food imported into the European Union from third countries must comply with European legislation. To this end, not only analytical and documentary checks are carried out at the EU’s borders, but also the European Commission regular audits in countries of origin. Recent audit reports in India show that the use of ethylene oxide in this country is relatively recent.

Over the last two decades, sesame seeds imported from India at the EU border have been repeatedly rejected due to salmonella contamination. To try to prevent the development of this pathogen, manufacturers used methyl bromide, but this did not seem to be effective. It is possible that this has led to their replacement by ethylene oxide, which is 10 times more effective in preventing the growth of undesirable organisms such as bacteria, fungi and insects. Judging by the latest food warnings registered under the RASFF, they appear to have eliminated the presence of salmonella in this way, but in return the products are contaminated with traces of this toxic compound.

What risks does this mean?

The main human health problems associated with the use of ethylene oxide are not related to its intake, but are limited to the workplace. This means that they affect people who work with this compound, for example in chemical plants where it is produced or transformed, or in sterilization facilities for medical supplies. In these cases, adverse health effects occur mainly due to accidental exposure, in particular by inhalation, continuously over time (estimated at 10 years or more) and are at increased risk of developing pathological conditions such as leukemia and lymphoma.

As far as food is concerned, exposure to this compound in this way is not common in the EU, as its use is not authorized. In addition, in cases such as contaminated food from these warnings, it occurs in relatively low concentrations when compared to workplace exposure. This is mainly due to the fact that since it is a gas, most of it volatilizes over time.

European legislation sets maximum limits for the presence of pollutants. In the case of sesame seeds, this limit for ethylene oxide is 0.05 mg / kg, which coincides with the limit of detection in the analyzes, which for practical reasons means that if detected, the product is rejected and cannot be placed on the market. The first alert, notified by Belgium in September 2020, indicated a content of 186 mg / kg, ie 3 700 times the legal limit, although for most products the levels found were between 1-10 mg / kg.

Are these amounts dangerous?

When we talk about toxic compounds, it is common to mention the famous phrase Paracelsus: “Dose makes poison.” This means that the toxicity of a compound depends on the amount we are exposed to, so in fact all substances are potentially harmful: from the water we drink to oxygen. that we breathe (for example, if we drank seven liters of water per hour we could perish). In reality, however, we reserve the label ‘toxic’ for substances that are capable of causing adverse effects on our health, even at low doses, such as cyanide. For most of these substances, the dose-response relationship is usually linear. This means that if we consumed a very low amount of cyanide, we would probably not suffer adverse effects, but as we increase the dose, we will suffer more and more remarkable effects.

There are now substances such as ethylene oxide that are carcinogenic and mutagenic. This means that there is no safe dose of exposure, because any amount is potentially harmful because it is able to damage DNA and cause adverse effects (in this particular case, its consumption is associated with the development of gastric cancer). In addition, the dose-response relationship is not linear but exponential, which means that a small increase in dose may translate into a very significant increase in response.

“Speaking of toxic compounds, Paracelsus is quoted as saying, ‘The dose makes the poison. ‘The toxicity of a compound depends on the amount to which we are exposed’

Of course, it is necessary to take into account the important nuances. This does not mean that mere exposure to small amounts will inexorably cause cancer. This is possible, but unlikely, when we suffer from low exposure to other substances that are also carcinogens, such as tobacco, UV radiation from the sun, alcohol, processed meat or polycyclic aromatic hydrocarbons, which are produced during cooking grilled meat. Therefore, it is possible, but unlikely, that we will develop lung cancer simply by smoking a single cigarette in our lives or sunbathing melanoma without sun protection for a single afternoon, but every time we do, it is likely to happen.

In short, there is no acceptable level of intake for ethylene oxide. This complicates the risk assessment that is necessary for food safety decisions (for example, when managing food alerts). In these cases, an estimate is made of the dose range at which the compound is likely to cause a small but appreciable adverse effect. (reference dose or BMD). Hence, the minimum confidence limit (BMDL10) is considered, which is the dose at which it is statistically likely that the change in response (occurrence of this damage) will be less than 10%. This compares with dietary exposure to this substance, so it is possible to know the exposure limit and get an idea of ​​the “level of hygiene hazard” that allows you to manage decisions and define measures to keep such exposure as low as possible.

For example, there are potentially genotoxic and carcinogenic compounds that are difficult to avoid in food, such as acrylamide, which is formed naturally when we toast too much bread or when we fry potatoes until they are colored. In these cases, limits are set at which the risk of damage is considered to be lower in order to serve as a criterion for the food industry in the preparation of these foods. Also Residents are advised not to bake bread or roast potatoes too much.

Ethylene oxide is not an accidental and unavoidable contaminant, it was added intentionally. A risk assessment carried out on the basis of the concentrations found in the contaminated products and taking into account the amount consumed in a normal diet has made it possible to determine that the ‘level of hygiene hazard’ is serious (in terms of alert management) [al menos según las cifras manejadas por los Países Bajos, donde dicha evaluación se hizo pública]Therefore, it was decided to withdraw the products concerned immediately.

In Spain, the Spanish Food Safety and Nutrition Agency (AESAN) has published a number of information notes on its website since last November promote the situation. They indicate that all measures are being taken to withdraw products made from contaminated ingredients from the market in order to avoid health risks arising from their possible commercialization (in some cases they have already been rejected at the border).

Miguel A. Lurueña (@gominolasdpetro) is a doctor, a graduate of food sciences and technologies, an agri-food technical engineer and a scientific popularizer (

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