Re‐evaluation of silicon dioxide (E 551) as a food additive

Abstract

The EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re-evaluating the safety of silicon dioxide (E 551) when used as a food additive. The forms of synthetic amorphous silica (SAS) used as E 551 include fumed silica and hydrated silica (precipitated silica, silica gel and hydrous silica). The Scientific Committee on Food (SCF) established a group acceptable daily intake (ADI) 'not specified' for silicon dioxide and silicates. SAS materials used in the available biological and toxicological studies were different in their physicochemical properties; their characteristics were not always described in sufficient detail. Silicon dioxide appears to be poorly absorbed. However, silicon-containing material (in some cases presumed to be silicon dioxide) was found in some tissues. Despite the limitations in the subchronic, reproductive and developmental toxicological studies, including studies with nano silicon dioxide, there was no indication of adverse effects. E 551 does not raise a concern with respect to genotoxicity. In the absence of a long-term study with nano silicon dioxide, the Panel could not extrapolate the results from the available chronic study with a material, which does not cover the full-size range of the nanoparticles that could be present in the food additive E 551, to a material complying with the current specifications for E 551. These specifications do not exclude the presence of nanoparticles. The highest exposure estimates were at least one order of magnitude lower than the no observed adverse effect levels (NOAELs) identified (the highest doses tested). The Panel concluded that the EU specifications are insufficient to adequately characterise the food additive E 551. Clear characterisation of particle size distribution is required. Based on the available database, there was no indication for toxicity of E 551 at the reported uses and use levels. Because of the limitations in the available database, the Panel was unable to confirm the current ADI 'not specified'. The Panel recommended some modifications of the EU specifications for E 551.

Sources, Bioavailability, and Safety of Silicon Derived from Foods and Other Sources Added for Nutritional Purposes in Food Supplements and Functional Foods

“…Silicon dioxide seems to be poorly absorbed; however, Si, considered to be in the form of silicon dioxide, was found in some tissues. Overall, there are no signs of adverse effects, and SAS does not raise any concern for genotoxicity or carcinogenicity when used as a food additive [48].…”

“…In addition, the EFSA provided opinions on OSA-VC and MMST as novel food ingredients used in food supplements and also an opinion on the bioavailability and safety of ch-OSA added for nutritional purposes as a source of silicon in food supplements (Table 3). In 2017, the EFSA provided a re-evaluated opinion on the safety of SiO 2 (E551), used as a food additive (Table 3) [48]. Table 3.…”

“…Table 3. Opinion on the safety and bioavailability of silicon of mineral origin approved for use in the production of food supplements and as a food additive [39][40][41]47,48]. OSA-VC is produced by completely dissolving vanillin powder in 40% ethanol solution at 40 • C. The solution is then diluted with water and acidified to a pH of 1.5-2.5 using phosphoric acid.…”

“…Silicon dioxide (E551) is on the labels of nearly 5000 food products: half of them are dietary supplements, others are, for example, meal replacements, creamers, instant noodles, malt, and drinks. The percentage of foods in each subcategory labeled as containing silicon dioxide (E551) ranged from less than 0.1% to 24.5% in the "vitamins and dietary supplements" subcategory [48]. There are few toxicological studies on silicon, including those in which nano silicon dioxide was examined.…”

How to Address the Adjuvant Effects of Nanoparticles on the Immune System

“…Because no stable cell line fully recapitulates the immunological features of primary DCs [18], studies on NP interactions with DCs use either murine bone marrow-derived DCs (BMDCs) [6,19,20] or more rarely human blood monocyte-derived DCs (MoDCs) [21][22][23], which can both be differentiated in vitro in a DC-like phenotype [24]. Extrapolation from animal to human remains challenging due to poor species overlap notably concerning toll-like receptors (TLR) expression [25]. The aim of this work was to set up a method to assess the adjuvant or "danger like" effect of NP on human DCs.…”