Multiple sources of exposure
Nitrates and nitrites are present in our diet due to:
- the natural occurrence of nitrates in soil (nitrogen cycle), at levels that can be increased by agricultural activities, and also in water resources;
- their use as food additives (E249, E250, E251, E252) due to their antimicrobial properties, primarily in delicatessen meat and processed meat;
- their accumulation in plants.
Around two thirds of dietary exposure to nitrates is related to the consumption of plant products, in particular leafy vegetables such as spinach and lettuce; a quarter is associated with drinking water. Less than 4% of dietary exposure to nitrates is due to their use as food additives in delicatessen meat.
Concerning nitrites, over half of our exposure is related to the consumption of delicatessen meat due to the nitrite additives used to prepare it.
Association between colorectal cancer and exposure to nitrites and nitrates
Nitrites and nitrates ingested through food and water are known to generate the formation of nitroso compounds, some of which are carcinogenic and genotoxic to humans.
ANSES has analysed the scientific cancer studies that have been published since the reference work of the European Food Safety Authority (EFSA, 2017) and the International Agency for Research on Cancer (IARC, 2018). It confirms that there is an association between the risk of colorectal cancer and exposure to nitrites and/or nitrates, whether they are ingested via the consumption of processed meat or drinking water. The higher the exposure to these compounds, the greater the risk of colorectal cancer in the population.
The risk of other types of cancer is also suspected but based on the data currently available, no conclusion can be drawn as to a causal relationship. The Agency recommends continuing research in this field in order to confirm or refute such a relationship.
Exposure levels, reference values and courses of action
In France, all exposure sources combined, almost 99% of the population is below the acceptable daily intakes (ADIs) that were established by EFSA and are currently considered relevant for nitrates and nitrites. To take risks related to co-exposure into account, ANSES used an “MOE” (assessment of margins of exposure) approach in its expert appraisal. This led to similar results to those obtained by analysing the ADIs for the large majority of the population. Even so, the Agency recommends conducting a debate to establish an overall health-based guidance value for nitrates and nitrites combined, given their conversion into nitroso compounds.
Although the exposure limits are mainly complied with, exposure is nonetheless associated with the formation of compounds increasing the probability of cancer. That is why the Agency considers that the intentional addition of nitrites and nitrates to food should adhere to an “as low as reasonably achievable” approach based on various courses of action as described below.
Reduce additives in delicatessen meat: a solution for each type of product
In delicatessen meat, nitrates and nitrites are mainly added to limit the development of bacteria responsible for diseases such as salmonellosis, listeriosis and botulism. According to the Agency, their use can be reduced to levels that are as low as reasonably achievable on the strict condition that other measures are taken to control the risk of contamination by these bacteria. These measures should be tailored to each category of product. For example, for cooked ham, reduced nitrite levels could lead to the use-by date being brought forward. For dry-cured ham, salt levels and temperatures during the product's salting, rest and refining stages would need to be strictly monitored.
Plant extracts also contain nitrates and nitrites
Some manufacturers use plant extracts or vegetable broths as substitutes for nitrite additives. This is not a real alternative since these products naturally contain nitrates which, under the action of bacteria, are converted into nitrites. These “no nitrite added” products therefore contain hidden nitrates and nitrites.
Control nitrate levels in water and soil
Not only are nitrates naturally found in the environment; certain human activities actually increase their levels in water resources and soil.
To reduce exposure to nitrates in drinking water, and also via the consumption of fruit and vegetables, the Agency underlines the importance of continuing to optimise certain practices, such as the spreading of fertilisers and livestock manure, by best adapting them to the needs of crops. This reduction should also occur in water supply facilities where the quality limit for nitrates has been exceeded. A specific opinion on this topic will soon be issued by the Agency.
Consume less than 150g of delicatessen meat per week
To limit their exposure to nitrates and nitrites, ANSES also reminds consumers to:
- limit their intake of delicatessen meat to 150g per week;
- eat a varied and balanced diet, with at least five servings of fruit and vegetables from different sources per day.