EFSA has published its long-awaited opinion on the risks related to the presence of nitrosamines in food, concluding that there is cause for concern. In fact, the exposure of the European population to these carcinogenic and genotoxic compounds exceeds the warning level for all age groups. (1)
1) EFSA opinion, 10 dangerous nitrosamines.
The opinion was published by EFSA after a two-month public consultation. (2) Considers 10 carcinogenic nitrosamines, assesses their potential harm to humans and animals, and quantifies the level of exposure of European consumers.
Nitrosamines (N-nitrosamines) are chemicals that are part of the nitrogen cycle. Meat and meat products are the main-but not the only-food category contributing to exposure.
2) Certain toxicity
The toxicity of these compounds is known. They are referred to as genotoxic, capable of damaging DNA, as well as causing various forms of cancer.
The population risk assessment performed by the Scientific Panel on Contaminants in the Food Supply Chain (CONTAM) considered as a parameter the main harmful effect related to nitrosamine exposure, liver cancer in rodents.
The carcinogenicity of the most harmful nitrosamine (N-nitrosodiethylamylamine, NDEA) was used as a toxicity parameter to be applied to other nitrosamines in food as well. The worst-case scenario was thus foreshadowed, applying the precautionary principle.
3) Foods at risk of nitrosamines.
The presence of nitrosamines is most common in some foods (as well as in drugs and cosmetics). Indeed, they result from environmental contamination, production and processing processes, and domestic cooking methods.
EFSA experts review the evidence in the scientific literature on the presence of nitrosamines in various foods, pointing out the causes of contamination and methods to reduce it.
3.1) Meats and cold cuts
Cold cuts often contain nitrosamines mainly due to the use of nitrites as a preservative. The issue is on the agenda among public health issues to be addressed by the European Commission.
In France the use of nitrites in processed meats has been the subject of a heated political debate for the past couple of years, which has led, among other things, the National Association of Cured Meat Producers to sue the founders of the app for libel Yuka, engaged together with the Anti-Cancer League in a campaign against the use of nitrites in meat. (3)
EFSA vs.
One controversial issue is the apparent incompatibility between the present opinion on nitrosamines and that issued by another EFSA panel in 2017. In fact, the Expert Panel on Food Additives (ANS Panel) had not established a link between nitrites added in cured meats as preservatives and the presence of nitrosamines in these foods, ruling out ‘a significant human health problem’ with such additives.
The new opinion from EFSA’s CONTAM Panel could offer scientific support for the introduction of new rules on the presence of nitrosamines in food and drinking water. Possibly in drugs as well. Specific limits on the content of these substances are in fact defined, to date, only on elastomer or rubber teats and soothers, cosmetics and toys (4,5,6).
3.2) Processed fish
The presence of nitrosamines (NDMA) in processed fish is attributed to the addition of nitrate during processing and/or its natural occurrence.
The first case includes food fraud aimed at improving the appearance of tuna and other fish, as we have seen. (7)
Fish are also rich in secondary and tertiary amines, and the salt used in the pickling treatment may contain nitrites/nitrates. The reaction between these factors can lead to the formation of nitrosamines at levels as high as 388 μg/kg (IARC, 1993 ). (8) In a more recent study (Iammarino et al., 2013), however, nitrate was detected as an endogenous compound in fish up to 205.3 mg/kg.
3.3) Cheese
Nitrate additives are also allowed in cheese production, up to 150 mg/kg in hard, semi-hard and semi-solid ripened cheeses and related whey cheeses, to prevent swelling during ripening. (8)
The high availability of secondary and tertiary amines in these products, particularly in aged cheese, can lead to the formation of nitrosamines, particularly when sodium or potassium nitrate is added to milk (Glória et al., 1997). The study authors refer specifically to gruyere cheese.
The addition of nitrates as preservatives is not the only source. In fact, nitrate is also an endogenous component of cheese, up to levels of 58.6 mg/kg, and reduction to nitrite can occur by the action of the enzyme xanthine oxidase (Gray et al., 1979; Iammarino et al., 2013).
3.4) Soy sauce and beverages
Several scientific studies report the presence of nitrosamines (NDMA) in soy sauce, up to a concentration of 261.34 μg/kg.
Contamination was attributed in all studies to high levels of nitrates in the process water.
The same source is listed as the origin of nitrosamines found in soft drinks, alcoholic beverages other than beer, and fermented beverages.
3.5) Vegetables, potatoes, soybean oil.
The possible presence of nitrosamines in vegetables, particularly leafy, and pickled vegetables, is attributed to high nitrate levels, low pH, possible presence of good amounts of nitrites, and high concentrations of glucosinolates (natural chemicals perhaps useful to plants as a defense against pests).
Another mechanism of formation is by Fusarium Monoliforme fungi, which can reduce nitrates to nitrites and increase the amount of secondary amines in vegetables.
Cooked potatoes also recorded the presence of nitrosamines (0.6-8.7 μg/kg), attributed to the combination of the high level of nitrates in the raw material and the cooking method.
Finally, soybean oil-the most studied product in the oils and fats category-was found to be contaminated with nitrosamines up to 28 μg/kg.
3.6) Breast milk
The first food of humans, breast milk, also contains nitrosamines. Nonnegligible levels (17.1 μg/kg) were detected in milk collected from women who were breastfeeding after consuming nitrate-rich foods such as bacon, beets, and spinach.
One study also reports contamination of breast milk, even at high levels (2,796 μg/kg), due to migration from rubber products. A risk, as mentioned above, eliminated in the EU through the introduction of specific bans.
3.7) Beer, problem solved
In the past , beer was also often contaminated with nitrosamines (NDMA) due to two factors:
- the reaction, during the malting process, of two amines (hordenine and dimethylamine) in germinated barley,
- The use of water contaminated with trace amounts of NDMA as a potential disinfection byproduct.
Evolving food technologies have eliminated the problem, thanks to new methods of cooking malt and increased attention to water quality. From 70% of NDMA-positive samples in the 1970s, this dropped to 5% in the 1990s, to only 1-2% in the 2000s.
4) The role of cooking temperature
An important role in the formation of nitrosamines in food lies in processing, including home preparation.
The high cooking temperature of foods can have a dual and opposite effect on nitrosamine formation:
- due to the marked volatility of several compounds, it can reduce their presence in the final product, but at the same time
- can accelerate and promote some reactions that form harmful compounds.
Most of the studies on this subject are in meat products, with some significant findings in fish as well. The maximum formation of nitrosamines emerged in cooking at high temperatures, such as grilling and frying.
5) Drinking water
Only trace amounts of nitrosamines are detectable in drinking water , at levels much lower than those found in food.
The sources are byproducts of disinfectant treatment of water and various forms of environmental pollution (from fertilizers to manure in animal husbandry to emissions from diesel vehicles).
Elimination of nitrosamines from drinking water can be achieved by several methods including UV radiation, removal of precursors by activated carbon, deactivation of precursors by oxidants, ozone and chlorine.
6) How to reduce nitrosamines in food.
Among the solutions available to inhibit the formation of nitrosamines in food dominates the addition of certain compounds to the product formulation:
- ascorbic acid/ascorbates (E300-E302) and erythorbic acid/sodium erythorbate (E315-E316) are additives that accelerate the chemical conversion of nitrite to nitric oxide, inhibiting the formation of nitrosamines. Therefore, it is common to find them in processed meats with nitrite/nitrate added. The solution is not perfect. ‘Nitric oxide could promote other types of reactions, such as nitrosylation and the formation of potentially toxic compounds,’ EFSA experts report,
- polyphenols. Trials of green tea proanthocyanidins in combination with ascorbic acid are reported in the literature. The combination was effective against nitrosamines in dry fermented sausages (Li et al., 2013). And again, a mix of green tea polyphenols, grape seed extract and α-tocopherol reduced the residual level of nitrosamines in cured bacon (Wang et al., 2015). For the same purpose, other possible ingredients are mentioned in red wine, pomegranate extract, sulfur compounds found in garlic, onion and strawberries.
6.1) Other solutions
Other dietary processes found useful in reducing nitrosamine levels and described in the literature are
- pasteurization,
- The partial substitution of meat in frankfurters with an Alaskan pollock surimi,
- The addition of Lactobacillus pentosus R3 in raw, fermented, and cooked sausages (with efficacy comparable to sodium erythorbate),
- Gamma irradiation of the flesh. Trials with doses as low as 30 kGy (the potency used to sterilize packaging and medical devices) reduced the concentration of nitrosamines in several products.
7) Efsa opinion on nitrosamines, the conclusions
Experts on EFSA’s CONTAM Panel conclude the opinion by highlighting that the European population of all ages is exposed to dangerous levels of nitrosamines in food.
It is recommended to further research and improve data collection on breast milk and processed foods other than processed meats (e.g., raw meats, vegetables, cereals, milk and dairy products, fermented foods, pickled canned foods, spicy foods, etc.) and products cooked in different ways, with and without the addition of nitrates and nitrites.
Epidemiological studies are also needed , controlling more carefully for confounding factors (e.g., use of drugs, alcohol and other carcinogenic chemicals in food, occupational exposure, smoking).
Marta Strinati
Notes
(1) EFSA Panel on Contaminants in the Food Chain (EFSA CONTAM Panel). Risk assessment of N-nitrosamines in food. EFSA Journal. 28.3.23 https://doi.org/10.2903 /j.efsa.2023.7884
(2) Dario Dongo, Ylenia Patti Giammello. Nitrites, nitrates and nitrosamines, EFSA revises risk analysis. GIFT (Great Italian Food Trade). 19.10.22
(3) Marta Strinati. Nitrites in cured meats, the Court of Appeal of Aix-en Provence agrees with Yuka. GIFT (Great Italian Food Trade). 10.12.22
(4) Commission Directive 93/11/EEC of March 15, 1993 on the release of N-nitrosamines and N-nitrosatable substances from elastomer or rubber teats and soothers. https://eur-lex.europa.eu/legal-content/IT/ALL/?uri=CELEX%3A31993L0011
(5) Regulation (EC) No. 1223/2009 of the European Parliament and of the Council of 30 November 2009 on cosmetic products. https://eur-lex. europa.eu/legal-content/IT/ALL/?uri=celex:32009R1223
(6) Directive 2009/48/EC of the European Parliament and of the Council of 18 June 2009 on the safety of toys. https://eur-lex.europa.eu/legal-content/IT/LSU/?uri=celex:32009L0048
(7) Dario Dongo. Thawed tuna with additives, the giant food fraud unpunished in the EU. GIFT (Great Italian Food Trade). 15.7.21
(8) IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Some Naturally Occurring Substances: Food Items and Constituents, Heterocyclic Aromatic Amines and Mycotoxins. Lyon (FR): International Agency for Research on Cancer; 1993. (IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, No. 56.) https://www.ncbi.nlm.nih.gov/books/NBK513574/
(8) Regulation (EC) No. 1333/2008 of the European Parliament and of the Council of 16 December 2008 on food additives. OJ L 354, 31.12.2008, pp. 16-33. https://eur-lex. europa.eu/legal-content/IT/TXT/PDF/?uri=OJ:L:2008:354:FULL&from=BG
Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
