Evaluation of the content of TiO₂ nanoparticles in the coatings of chewing gums

Abstract

Titanium dioxide is a metal oxide used as a white pigment in many food categories, including confectionery. Due to differences in the mass fraction of nanoparticles contained in TiO, the estimated intakes of TiO nanoparticles differ by a factor of 10 in the literature. To resolve this problem, a better estimation of the mass of nanoparticles present in food products is needed. In this study, we focused our efforts on chewing gum, which is one of the food products contributing most to the intake of TiO. The coatings of four kinds of chewing gum, where the presence of TiO was confirmed by Raman spectroscopy, were extracted in aqueous phases. The extracts were analysed by transmission electron microscopy (TEM), X-ray diffraction, Fourier Transform Raman spectroscopy, and inductively coupled plasma atomic emission spectroscopy (ICP-AES) to establish their chemical composition, crystallinity and size distribution. The coatings of the four chewing gums differ chemically from each other, and more specifically the amount of TiO varies from one coating to another. TiO particles constitute the entire coating of some chewing gums, whereas for others, TiO particles are embedded in an organic matrix and/or mixed with minerals like calcium carbonate, talc, or magnesium silicate. We found 1.1 ± 0.3 to 17.3 ± 0.9 mg TiO particles per piece of chewing gum, with a mean diameter of 135 ± 42 nm. TiO nanoparticles account for 19 ± 4% of all particles, which represents a mass fraction of 4.2 ± 0.1% on average. The intake of nanoparticles is thus highly dependent on the kind of chewing gum, with an estimated range extending from 0.04 ± 0.01 to 0.81 ± 0.04 mg of nano-TiO per piece of chewing gum. These data should serve to refine the exposure scenario.

Physicochemical Characterization of the Pristine E171 Food Additive by Standardized and Validated Methods

“…In turn, this ensured representative sampling and avoided biased measurements due to agglomeration and particle overlap. It resulted in higher fractions of nanosized particles (<100 nm) than those reported in several publications [6,7,9,42,43,53,56,57], where these factors were less well controlled. Geiss et al consider such optimization as essential for the development of validated and harmonized sample preparation protocols [55].…”

“…In addition to the EFSA opinion, several studies characterized commercially available pristine E171 materials and food products containing E171 [6,7,9,42,43,52,[56][57][58]. In general, mean particle sizes between 106 and 145 nm and size distributions ranging from 30 nm to 400 nm were reported for electron microscopy (EM) analyses [6,9,42,43,[56][57][58]. One study showed a size distribution ranging from 30 to 600 nm for scanning electron microscopy (SEM) and 20 to 400 nm for asymmetric flow field-flow fractionation coupled with inductively coupled plasma mass spectrometry (AF4-ICP-MS) [7].…”

“…One study showed a size distribution ranging from 30 to 600 nm for scanning electron microscopy (SEM) and 20 to 400 nm for asymmetric flow field-flow fractionation coupled with inductively coupled plasma mass spectrometry (AF4-ICP-MS) [7]. In these studies, the fraction of nanoparticles (<100 nm) ranged from 10% to 54% [6,7,9,42,43,56,57]. Geiss et al were able to characterize E171 contained in finished and semi-finished confectionery products, along with exactly those pristine E171 samples used in each of the products, allowing a direct comparison of the particle size distribution in the pristine and extracted materials.…”

Critical review of the safety assessment of titanium dioxide additives in food

“…The ANS Panel at the European Food Safety Authority (EFSA) proposes to use a proportion of 3.2% by mass to estimate the nano-sized fraction of E 171 for risk assessment considerations [ 13 ]. TEM analyses of TiO 2 particles in the coatings of chewing gums revealed a nano-sized mass fraction of 4.2% on the average [ 45 , 46 ]. This review only includes studies where TiO 2 test materials have been characterized with respect to their size preferably with indications on the primary particle diameter.…”

Development of a novel chlamydia growth-monitoring method and its application for screening anti- and pro-chlamydial compounds

“…The ROS can then synergistically act by attacking polyunsaturated phospholipids in bacteria and catalyzed site-specific DNA damage via generation of H 2 O 2 [61]. TiO 2 nanoparticles have been used as whitening agent, food additive (E171) and a drug delivery vehicle [62,63]. TiO 2 nanotubes are potential to be used as a drug vehicle in the area of nanomedicine, like for bone regeneration or cancer therapy [64].…”