Re-evaluation of silicon dioxide (E 551) as a food additive in foods for infants below 16 weeks of age and follow‐up of its re‐evaluation as a food additive for uses in foods for all population groups

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Disclaimer

  • This Plain Language Summary (PLS) is a simplified communication of EFSA Re-evaluation of silicon dioxide (E 551) as a food additive in foods for infants below 16 weeks of age and follow‐up of its re‐evaluation as a food additive for uses in foods for all population groups. The full EFSA opinion can be found here.
  • The purpose of the PLS is to enhance transparency and inform interested parties on EFSA’s work on the topic using simplified language to present a summary of the main findings.
     

Background to the scientific opinion

  • Silicon dioxide (E 551) is an anticaking agent, which means it prevents dry powdered food from sticking together. It is approved for use in a range of foods, including those for infants under 16 weeks.
  • In 2018, the EFSA Panel on Food Additives and Nutrient Sources (ANS Panel) re-evaluated the safety of E 551. This scientific opinion was part of a broader re-evaluation of all food additives already permitted in the EU before 2009.
  • At the time, the ANS Panel concluded that the available information was insufficient to adequately characterise E 551 and to set an Acceptable Daily Intake (ADI). The ANS Panel was also unable to provide a safety assessment of the use of E 551 in foods for infants under 16 weeks because the required scientific guidance was still in development.

What was EFSA asked to do?

  • The European Commission (EC) asked the EFSA Panel on Food Additives and Flavourings (the FAF Panel) to address the gaps identified in the 2018 scientific opinion, including an assessment of the risk for infants under 16 weeks of age. 

How did EFSA carry out this work?

  • EFSA issued a public call for data to gather information from the industry involved in the manufacture and/or use of E 551.
  • As E551 particles and their aggregates were found to be in the nano range, the FAF Panel carried out a risk assessment at the nano scale in addition to a conventional risk assessment[1].
  • EFSA used its Guidance of 2017 on the risk assessment of substances present in food intended for infants below 16 weeks for the risk assessment for this age group[2] .

What data were used?

The following information guided the current assessment: 

  • data collected from industry in response to EFSA’s public call,
  • data from a literature search and unpublished studies submitted by industry on the request of EFSA,
  • information on the safety of widely used medicines containing silicon dioxide in infants under 16 weeks.

In addition, the conclusions and recommendations from the 2018 scientific opinion were considered by the FAF Panel.

What were the uncertainties?

The FAF Panel identified the following main uncertainties::

  • There is currently a lack of information regarding the proportion of particles of E 551 occurring as isolated nanoparticles, nano-sized aggregates and agglomerates in food, as well as on the level of agglomeration of E 551 in food.
  • Additionally, there are limited toxicological studies that specifically address the potential harmful effects of nano-sized particles/aggregates of E 551, leading to uncertainty in assessing their associated health risks.

What were the outcomes and their implications?

Characterisation

  • E 551 can be described as a synthetic amorphous silica (SAS) without a crystalline structure that has not been coated or modified at its surface.
  • SAS consists of almost spherical nano-sized (mostly between 2 and 28 nm) particles that clump together in complex aggregates.
  • According to the different manufacturing processes, there are different types of SAS: 
    • fumed silica, made by heating chlorosilanes (e.g. silicon tetrachloride) at a very high temperature,
    • precipitated silica, silica gel and hydrous silica, made by the wet method (see Glossary).
  • Lead, mercury, aluminium and arsenic can be present in E 551 as impurities.

Safety

  • The systemic bioavailability of E 551 in humans is likely to be very low but it was not possible to quantify precisely the absorption of silicon dioxide into the body because of the lack of appropriate data. 
  • The FAF Panel considered it appropriate to apply a margin of exposure (MOE) approach rather than setting an ADI due to the limitations in the available data.
  • The FAF Panel concluded that E 551 does not raise a safety concern in any population group, including infants under 16 weeks. 

Key recommendations

Toxic elements like lead, mercury, aluminium and arsenic may be present in E 551 at certain concentrations. E 551 is not the only dietary source of these impurities. To limit the exposure of the EU population to these toxic elements, the FAF Panel recommended that the EU’s existing specifications on E 551 should be amended by:

  • lowering the maximum limits for lead, mercury and arsenic in E 551,
  • setting a maximum limit for aluminium.

Glossary 

Acceptable daily intake (ADI): An estimate of the amount of a substance in food or drinking water that can be consumed daily over a lifetime without presenting an appreciable risk to health. It is usually expressed as milligrams of the substance per kilogram of body weight and applies to chemical substances such as food additives, pesticide residues and veterinary drugs.

Margin of exposure (MOE): A tool used in risk assessment to explore safety concerns arising from the presence of a potentially toxic substance in food or animal feed. It is the ratio of the reference point (the dose at which a low but measurable adverse effect is observed) to the level of exposure to the substance in a given population.

Wet method: A chemical manufacturing method for producing various forms of silica, such as precipitated silica, silica gel and hydrous silica. It can include, among other procedures, mixing aqueous alkali metal silicates (e.g. water glass) with diluted acids (e.g. sulfuric acid) in a controlled environment. The silica compounds produced are hydrates or contain surface adsorbed water.

[1]EFSA Scientific Committee, 2021b. Guidance on risk assessment of nanomaterials to be applied in the food and feed chain: human and animal health. EFSA Journal 2021;19(8):6768. https://doi.org/10.2903/j.efsa.2021.6768
[2]EFSA Scientific Committee, 2017. Guidance on the risk assessment of substances present in food intended for infants below 16 weeks of age. EFSA Journal 2017;15(5):4849. https://doi.org/10.2903/j.efsa.2017.4849 

Reference

Re-evaluation of silicon dioxide (E 551) as a food additive in foods for infants below 16 weeks of age and follow‐up of its re‐evaluation as a food additive for uses in foods for all population groups

DOI: https://doi.org/10.2903/j.efsa.2024.8880 

Food additives