Too much salt, anti-caking agents and microplastics


Anti-caking agents (which include nanomaterials) and microplastics present in salt could constitute emerging food safety risks that have so far been little considered.

Furthermore, food labels only in rare cases allow consumers to make informed purchasing choices. An in-depth analysis, awaiting further analysis and research.

1) Salt and health, introduction

The average intake of salt in the European macro-region, 10,8 g/day, is more than double the safety threshold indicated by the World Health Organization (WHO, 2023). (1) The international scientific community has in fact recognized that the daily consumption of salt must be less than 5 grams.

It is essential to pay attention not only to the salt that is added in the kitchen and at the table, but also and above all to that contained in processed foods. Its excess is in fact associated with premature mortality from all causes and chronic disabling diseases (i.e. cardiovascular, oncological, neurodegenerative, diabetes). (2,3)

2) Sea salt and rock salt

Edible salt, or table salt, is mainly obtained from the sea and mineral deposits:

– sea salt is obtained from sea water, through natural evaporation (thanks to the action of the sun and wind, in salt pans) or by heating the water in special systems. Following evaporation, the salt remains as a solid residue;

– rock salt which preserve it, following the evaporation of ancient seas and salt lakes.

Both the types of salt can be subjected to physical processes aimed at removing any impurities, using optical sorters or magnetic fields (for ferrous bodies) or centrifuges. In addition to refining, through washing, and grinding to obtain the required grain sizes (e.g. coarse salt, fine salt).

3) Salt bleaching

Whitening of salt has the main function of making the product more ‘attractive’ to the eyes of consumers. Salt obtained from natural sources may contain impurities (including other trace elements) which give the product an uneven colour, with shades varying between gray and brown.

Chlorine (sodium hypochlorite) and hydrogen peroxide are the substances most used to whiten salt. They do not remain in the product, which is subject to further rinsing, but they also remove microelements and microorganisms of interest for the nutrition and health of the intestinal microbiota. (4)

4) Anti-caking food additives

Anti-caking agents are a category of food additives used in dusty food matrices to reduce the tendency of particles to stick together (‘packing’). Since salt is highly hygroscopic – that is, capable of absorbing water and humidity – it tends to agglomerate and form blocks.

The salt industry therefore often uses substances useful for preventing obstruction and damage to the systems, as well as guaranteeing the marketability of the product. Below is a brief review of the anti-caking food additives authorized in the European Union in the production of salt.

4.1) Iron tartrate and ferrocyanides

Food Additives Regulation (EC) No 1333/08 authorizes the use of the following anti-caking additives in salt:

– iron tartrate (E534), up to a maximum content of 110 mg/kg of salt. This substance can be hepatotoxic at high levels of ingestion which, however, according to EFSA (2015), do not occur at the established doses of use; (5)

– sodium ferrocyanidespotassium and calcium (E535E536 and E538, respectively) are permitted as anti-caking agents in a variety of food products (e.g. salt, spices, soups, stews, sauces, salads, protein products) at a maximum level of 20 mg/kg;

Potassium ferrocyanide is potentially toxic to the kidneys and the neurological system, due to the release of potassium cyanide which can develop in an acidic environment (i.e. salad with salt, vinegar and/or lemon). EFSA (2018) confirmed the safety of the use of ferrocyanides in salt, evaluating the average intake in the various conditions of consumption and their non-significant absorption. (6)

4.2) Silicates and nanomaterials, emerging food safety risks

Calcium silicate (E 552) in turn falls among the anti-caking additives authorized in salt, within a maximum threshold of 20 g / kg. EFSA (2018) indicated that silicon can accumulate in the kidneys and liver of rats, but at present there is a lack of significant data to evaluate the safety of calcium silicate as an additive. (7)

EFSA also detected the presence in calcium silicate of nanomaterials which should be further investigated. In this regard, reference is made to the assessments expressed by EFSA on the serious food safety risks associated with the intake of titanium dioxide, which is itself composed of nanomaterials and therefore prohibited in foods and food supplements, not also in medicines and toothpastes (8,9) . And the equally serious risks have already emerged in the scientific literature on silicon dioxide, which still appears among the food additives authorized in the EU in the long wait for its reevaluation by EFSA (10,11).

Other anti-caking agent authorized only for the salt intended for the surface treatment of mature cheeses (within a threshold of 20 mg / kg of cheese) is the sodium aluminum silicate (E554). EFSA (2020) noted the lack of data to evaluate the food safety of E554, highlighting how the exposure of citizens to the resulting aluminum exceeds the Tolerable Weekly Intake (TWI) established for aluminium. (12) Still awaiting proper risk management by the European Commission. (13)

4.3) Magnesium salts, good news

Magnesium salts – unlike the other anti-caking food additives mentioned above – are not associated with specific health dangers. Indeed, even food products that contain magnesium in significant quantities pursuant to the Food Information Regulation (EU) No 1169/11 can report, in commercial communications, a wide range of health claims. ‘Magnesium contributes to:

– ‘reduce tiredness and fatigue’

– ‘electrolyte balance’

– ‘normal energy metabolism’

– ‘the normal functioning of the nervous system’

– ‘normal muscle function’

– ‘normal protein synthesis’

– ‘normal psychological function’

– ‘the maintenance of normal bones’

– ‘the maintenance of normal teeth’

– ‘the process of cell division’ (14,15)

Magnesium carbonate (E 504) and magnesium chloride (E 511) are authorized – respectively, in all types of salt and in sea salt only – according to the quantum satis principle, i.e. to the extent strictly necessary albeit without defined maximum thresholds.

5) Labels

The labels of food salts, in some cases, report the presence of anti-caking additives (i.e. sodium ferrocyanide, E 535). However, it cannot be ruled out that some salt industries use these and perhaps other substances (eg silicon dioxide) without indicating them on the label, even though they may remain in the finished product.

Such a hypothesis – worthy of inspections during official controls – could be justified by arguing that these substances would be used as technological aids (not subject to mention in the list of ingredients on the label), rather than as food additives. (16)

The test of this circumstance deserves particular attention – during self-control, private audits and public controls – since it is doubtful that the technological function of an anti-caking agent in salt is exhausted in the manufacturing process (and this is the condition for qualifying the substance as a technological adjuvant) without producing any effects on the finished product. (17)

5.1) Whole salt

Whole salt currently lacks harmonized regulation in the European Union. Consequently, the truthfulness and unambiguity of this voluntary information on the label must be verified on a case-by-case basis, in light of the general criteria of loyalty of the information on food products established in the Food Information Regulation (EU) No 1169/11 in Articles 7 and 36.

The disciplinary of some products with Geographical Indication (GI) – such as Trapani PGI sea salt – also offer an excellent example, to be used also during public and private controls, on the meaning of this wording:

– given that ‘Trapani PGI sea salt is processed without any addition of additives or bleaching or anti-caking agents

– ‘salt that is not washed or centrifuged is called brown salt‘. (18)

6) Microplastics

Pollution from microplastics (MPs) is a global problem that has so far been ignored by legislators in every country, beyond the recent reforms to the REACH regulation, in the European Union, which are totally inadequate as we have seen. (19) Water is in any case the primary vector of microplastics, and their genotoxicity – in addition to various others, starting with endocrine disruption and damage to the reproductive system – has been demonstrated on freshwater shrimps among others (Iannilli et al., 2023). (20)

Contamination by microplastics is an emerging food safety risk that must therefore also be considered in relation to sea salt. A recent study published in Ecotoxicology and Environmental Safety (Thiele et al., 2023), in the analysis of 13 types of sea salt from 7 European countries, detected an average of 466 fragments of MPs/kg (with wide variability, from 74 to 1155 fragments) of average size < 150 microns (0,15 mm ). (21) An invisible risk and yet worthy of further investigation.

7) Provisional conclusions

The European Commission continues to manage food safety risks linked to food additives systematically late, privileging the private interests of the industry over its duties to protect public health. As seen in the cases cited in the previous paragraph 3.2 as well as in those of aspartame – declared carcinogenic by IARC and still widespread in numerous chewing gum food drinks (22,23) – and smoke flavourings. (24)

The responsability personal legal rights of the senior managers of the European Commission, for omitted and/or late and inadequate management of food and public health risks, must be affirmed as a counterweight to their unimaginable salaries and privileges for the populations they are supposed to protect. The indifference of the castes of Brussels and Strasbourg to the living conditions of the citizens who maintain them is the first cause of growing anti-Europeanism, which should not be overlooked before it is late.

Dario Dongo and Valentina Vasta


(1) Marta Strinati. WHO report cards on national policies to reduce salt consumptionGIFT (Great Italian Food Trade). 22.3.23

(2) Dario Dongo, Andrea Adelmo Della Penna. Excess salt, chronic disease and premature mortalityGIFT (Great Italian Food Trade). 30.5.20

(3) Marta Strinati. Here’s how excess salt promotes dementia and Alzheimer’sGIFT (Great Italian Food Trade). 1.11.19

(4) Bolhuis, H., Cretoiu, M. S. (2016). What is so Special About Marine Microorganisms? Introduction to the Marine Microbiome—From Diversity to Biotechnological Potential. In: Stal, L., Cretoiu, M. (eds) The Marine Microbiome. SpringerCham

(5) EFSA ANS Panel (EFSA Panel on Food Additives and Nutrient Sources added to Food), 2015. Scientific Opinion on the safety of the complexation product of sodium tartrate and iron(III) chloride as a food additive. EFSAJournal 2015; 13 (1):3980, 30 pp. doi:10.2903 / j.efsa.2015.3980

(6) EFSA ANS Panel (EFSA Panel on Food Additives and Nutrient Sources added to Food), 2018. Scientific Opinion on the re-evaluation of sodium ferrocyanide (E 535), potassium ferrocyanide (E 536) and calcium ferrocyanide (E 538) as food additives. EFSAJournal 2018;16(7):5374, 26 pp.

(7) EFSA ANS Panel, 2018. Scientific opinion on the re-evaluation of calcium silicate (E 552), magnesium silicate (E 553a(i)), magnesium trisilicate (E 553a(ii)) and talc (E 553b) as food additives. EFSAJournal 2018;16(8):5375, 50 pp.

(8) Dario Dongo. Titanium dioxide in food and supplements, stop from 7.2.22GIFT (Great Italian Food Trade). 21.1.22

(9) Marta Strinati. New study on the risks of titanium dioxide present in toothpastes and medicinesGIFT (Great Italian Food Trade). 10.8.23

(10) Marta Strinati. Stop to titanium dioxide, interview with Francesco Cubadda, ISS expertGIFT (Great Italian Food Trade). 8.5.21

(11) Marta Strinati. Silicon dioxide, additive at risk still in useGIFT (Great Italian Food Trade). 20.5.21

(12) EFSA Panel on Food Additives and Flavorings (FAF), 2020. Scientific Opinion on the re-evaluation of sodium aluminum silicate (E 554) and potassium aluminum silicate (E 555) as food additives. EFSAJournal 2020;18(6):6152, 27 pp.

(13) The neurotoxicity of aluminum deserves further investigation also in relation to food contact materials. See the previous article by Marta Singed. Aluminum and food, how to reduce the risk of contaminationGIFT (Great Italian Food Trade). 19.11.19

(14) The ‘nutrient reference value’ (NRV) for magnesium corresponds to 375 mg. The significant quantity corresponds to:

-15% of the NRV, in products other than drinks, per 100 g (or per portion, if the packaging contains only one portion),

-7,5% of the NRV per 100 ml, in the case of drinks (EU Reg. 1169/11, Annex XIII, Part A, daily reference consumption for vitamins and mineral salts)

(15) Regulation (EU) No 432/12 and subsequent amendments

(16) Dario Dongo. Ingredient List, ABCGIFT (Great Italian Food Trade). 6.3.18

(17) Marta Strinati. Technological adjuvants, the additives that the label is silent onGIFT (Great Italian Food Trade). 31.1.22

(18) Sea salt of Trapani IGPGIFT (Great Italian Food Trade). 24.9.14

(19) Dario Dongo. Andrea Adelmo Della Penna. Microplastics, the first restrictions in the Old Continent in a mini-reform of the REACH regulationGIFT (Great Italian Food Trade). 1.10.23

(20) Marta Strinati. Microplastics, new evidence of genotoxicity on freshwater shrimpGIFT (Great Italian Food Trade). 16.5.23

(21) Christina J. Thiele, Laura J. Grange, Emily Haggett, Malcolm D. Hudson, Philippa Hudson, Andrea E. Russell, Lina M. Zapata-Restrepo (2023). Microplastics in European sea salts – An example of exposure through consumer choice and of interstudy methodological discrepancies, Ecotoxicology and Environmental Safety, Volume 255, 114782,

(22) Marta Strinati. Aspartame and health risks, brief scientific reviewGIFT (Great Italian Food Trade). 20.8.23

(23) Marta Strinati. Aspartame, the probable carcinogen in chewing gum and soft drinksGIFT (Great Italian Food Trade). 31.8.23

(24) Marta Strinati. Genotoxic smoke flavourings, the EFSA opinionGIFT (Great Italian Food Trade). 16.11.23

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Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.