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Food Safety and Toxicology
Realistic Evaluation of Titanium Dioxide Nanoparticle Exposure in Chewing Gums Fabio Fiordaliso, Claudia Foray, Monica Salio, Mario Salmona, and Luisa Diomede J. Agric. Food Chem., Just Accepted Manuscript • Publication Date (Web): 07 Jun 2018 Downloaded from http://pubs.acs.org on June 7, 2018
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Journal of Agricultural and Food Chemistry
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Realistic Evaluation of Titanium Dioxide Nanoparticle Exposure
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in Chewing Gums
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Fabio Fiordaliso1*, Claudia Foray1, Monica Salio1, Mario Salmona2, Luisa Diomede2
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Ricerche Farmacologiche “Mario Negri”, 20156 Milan, Italy.
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2
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Farmacologiche “Mario Negri”, 20156 Milan, Italy.
Unit of Bio-imaging, Department of Cardiovascular Research, IRCCS- Istituto di
Department of Molecular Biochemistry and Pharmacology, IRCCS- Istituto di Ricerche
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*
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Cardiovascular Research, IRCCS-Istituto di Ricerche Farmacologiche “Mario Negri”,
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Via G. La Masa 19, 20156 Milan, Italy. e-mail:
[email protected]. Phone:
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+39-02-39014513, Fax: +39-02-33200049
Correspondence
to: Fabio
Fiordaliso,
Unit
of
Bio-Imaging,
Department
of
1 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
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ABSTRACT
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There is growing concern about the presence of nanoparticles (NPs) in titanium dioxide
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(TiO2) as food additive (E171). To realistically estimate the number and the amount of
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TiO2 NPs ingested with food we applied a transmission electron microscopy method
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combined with inductively coupled plasma optical emission spectrometry. Different
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percentages of TiO2 NPs (6-18%) were detected in E171 from various suppliers. In the
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eight chewing gums analyzed as food prototypes, TiO2 NPs were absent in one sample
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and ranged 0.01-0.66 mg/gum, corresponding to 7-568 billion NPs/gum, in the other
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seven. We estimated that the mass-based TiO2 NPs ingested with chewing gums by
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European population ranged 0.28-112.40 µg/kg b.w./day and children ingested more
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nanosized titanium than adolescents and adults. Although this level may appear negligible
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it corresponds to 0.1-84 billion TiO2 NPs/kg b.w/day, raising important questions on their
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potential accumulation in the body, possibly causing long-term effects on consumers’
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health.
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Keywords: Nanoparticles, titanium dioxide, E171, food, chewing gum
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1. Introduction
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Titanium dioxide, with its whitening and brightening properties, is the most widespread
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pigment used in food products, cosmetics, paints and pigments as well as pharmaceuticals
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(w/w)2 and in Europe as E171 3 to a quantum satis level 4. The presence of nanoparticles
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(NPs) in E171, defined as nano-objects with all external dimensions in the nanoscale
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range (500 nm), presumably of CaCO3, together with TiO2 particles similar to those in the
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other gums (Fig. 5E). These cuboid crystals completely disappeared after acid treatment
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(Fig. 5F), while TiO2 was still present with 15% of particles with diameter below 100 nm
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and 76% between 100 and 200 nm (Supplementary Figure S2).
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We also examined an additional chewing gum (gum #8) which did not list E171 among
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its ingredients, but had a white coating similar in appearance to the other TiO2-containing
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coated gums. TEM analysis did not detect any TiO2 particles in the coating, even with the
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double number of gums (from 5 to 10) dissolved in 50 mL water (Supplementary Figure
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S3).
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3.3 Quantification of TiO2 and TiO2 NPs in chewing gums
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ICP-OES analysis was carried out on each gum to quantify titanium and calculate the
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concentration of TiO2, expressed as mg/g of chewing gum and mg/piece of gum (Table
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1). A great variability in the amount of TiO2 per chewing gum was found, ranging from
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the largest content of 15.25 mg/gum of gums #2 to 0.35 mg/gum of gum #7, in which
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CaCO3 was used as coating agent (Table 1). ICP-OES analysis did not reveal the presence
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of TiO2 in gum #8. These differences in TiO2 content among the chewing gums arise from
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the different amounts of E171 employed by the manufacturers, which ranged from a
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minimum of 0.03 % (w/w) to a maximum of 0.75% (w/w) of the weight of the gum
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(Table 1). 10 ACS Paragon Plus Environment
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To quantify the TiO2 NPs in chewing gums, from the average diameter provided by TEM,
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we calculated at first the volume (as a sphere) for each TiO2 particle, and then from the
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volume, we computed the mass (considering anatase density 3.895 g/cm3). The sum of
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the weights of particles with diameter
