The safety of nanostructured synthetic amorphous silica (SAS) as a food additive (E 551)

Abstract

Key messages Particle sizes of E 551 products are in the micrometre range. The typical external diameters of the constituent particles (aggregates) are greater than 100 nm. E 551 does not break down under acidic conditions such as in the stomach, but may release dissolved silica in environments with higher pH such as the intestinal tract. E 551 is one of the toxicologically most intensively studied substances and has not shown any relevant systemic or local toxicity after oral exposure. AbstractSynthetic amorphous silica (SAS) meeting the specifications for use as a food additive (E 551) is and has always been produced by the same two production methods: the thermal and the wet processes, resulting in E 551 products consisting of particles typically in the micrometre size range. The constituent particles (aggregates) are typically larger than 100 nm and do not contain discernible primary particles. Particle sizes above 100 nm are necessary for E 551 to fulfil its technical function as spacer between food particles, thus avoiding the caking of food particles. Based on an in-depth review of the available toxicological information and intake data, it is concluded that the SAS products specified for use as food additive E 551 do not cause adverse effects in oral repeated-dose studies including doses that exceed current OECD guideline recommendations. In particular, there is no evidence for liver toxicity after oral intake. No adverse effects have been found in oral fertility and developmental toxicity studies, nor are there any indications from in vivo studies for an immunotoxic or neurotoxic effect. SAS is neither mutagenic nor genotoxic in vivo. In intact cells, a direct interaction of unlabelled and unmodified SAS with DNA was never found. Differences in the magnitude of biological responses between pyrogenic and precipitated silica described in some in vitro studies with murine macrophages at exaggerated exposure levels seem to be related to interactions with cell culture proteins and cell membranes. The in vivo studies do not indicate that there is a toxicologically relevant difference between SAS products after oral exposure. It is noted that any silicon dioxide product not meeting established specifications, and/or produced to provide new functionality in food, requires its own specific safety and risk assessment.

Challenges in Determining the Size Distribution of Nanoparticles in Consumer Products by Asymmetric Flow Field-Flow Fractionation Coupled to Inductively Coupled Plasma-Mass Spectrometry: The Example of Al2O3, TiO2, and SiO2 Nanoparticles in Toothpaste

“…Following separation by AF4, signals were recorded on-line with three detection methods: LS, ICP-MS and UV-visible absorption. Typical fractograms recorded using LS and ICP-MS ( 27 Al, 28 Si, and 47 Ti signals, all normalized to internal standard signal 103 Rh) are shown in Figure 2. 27 Al, 28 Si, and 47 Ti signals (normalized to the internal standard 103 Rh), respectively.…”

“…Internal standard (50 or 10 µg/L Rh) was added on-line via a t-piece using the peristaltic pump. The isotopes 27 Al, 47 Ti, 28 Si, and 103 Rh were monitored with 0.5 s integration time per isotope. Mass calibration was done by post-channel calibration with Al and Ti standard mix solutions (0 µg/L, 2.5 µg/L, 5 µg/L, 7.5 µg/L, and 10 µg/L) in 2% v/v HNO 3 .…”

“…Alpha-Al 2 O 3 is the most common form of Al 2 O 3 and is used as an abrasive agent in certain whitening toothpastes for its superior polishing/abrasive properties [25][26][27]. Hydrated silica consists of synthetic amorphous SiO 2 produced by wet synthesis that can contain surface-or pore-bound water and is added to toothpaste as abrasive and binding/thickening agent [16,[27][28][29]. Particulate TiO 2 anatase is allowed as a pigment/colorant in cosmetics including toothpaste as CI 77891 [2,27,30].…”

Review on a novel biosilica source for production of advanced silica‐based materials: Wheat husk

“…Silica is the third most common occurring biogenic mineral, after calcium carbonate and calcium phosphate . Silica is a frequently used material in many application areas including bioactive implants, catalysis, drug delivery systems, food additives, nanoelectronics, and sensory systems . The silica can be named as biosilica when it is found in natural living sources such as plants like horsetail, bagasse, corn, rice, and wheat, and also in aquatic living beings like diatoms, radiolaria, and siliceous sponges.…”

Titrimetric method determination of the content of the mass part of siliciumin feed additives

“…To prevent the negative impact of mycotoxins on the body of animals are widely used feed additives belonging to the category of additives and functional group -substances to reduce contamination of feed mycotoxins (substances that can restrain or reduce the absorption of mycotoxins, promote their excretion or modify their the mode of action) -Law of Ukraine "On feed safety and hygiene". Particular absorption properties of feed additives based on silicium dioxide due is to the nanodispersity of particles (nano-SiO 2 ) and the chemical activity of the surface (Guichard et al, 2016;Winkler et al, 2016;Fruijtier-Pölloth, 2016). At the same time, amorphous highly dispersed nano-silicium is not active, that is they do not excrete vitamins and trace elements from the body.…”