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. 2022 Jul 30;19(15):9362.
doi: 10.3390/ijerph19159362.

Innovative In Vitro Strategy for Assessing Aluminum Bioavailability in Oral Care Cosmetics

Giorgia Allaria  1 , Giulia De Negri Atanasio  1 , Tommaso Filippini  2   3 , Federica Robino  4 , Lorenzo Dondero  1   5 , Francesco Soggia  6 , Francesca Rispo  1 , Francesca Tardanico  1 , Sara Ferrando  1 , Stefano Aicardi  1 , Ilaria Demori  1 , Jan Markus  7 , Katia Cortese  8 , Matteo Zanotti-Russo  4 , Elena Grasselli  1
Affiliations

Innovative In Vitro Strategy for Assessing Aluminum Bioavailability in Oral Care Cosmetics

Giorgia Allaria et al. Int J Environ Res Public Health. .

Abstract

Aluminum is an element found in nature and in cosmetic products. It can interfere with the metabolism of other cations, thus inducing gastrointestinal disorder. In cosmetics, aluminum is used in antiperspirants, lipsticks, and toothpastes. The aim of this work is to investigate aluminum bioavailability after accidental oral ingestion derived from the use of a toothpaste containing a greater amount of aluminum hydroxide than advised by the Scientific Committee on Consumer Safety (SCCS). To simulate in vitro toothpaste accidental ingestion, the INFOGEST model was employed, and the amount of aluminum was measured through the ICP-AES analysis. Tissue barrier integrity was analyzed by measuring transepithelial electric resistance, and the tissue architecture was checked through light microscopy. The margin of safety was also calculated. Overall, our results indicate that the acute exposure to aluminum accidentally ingested from toothpastes is safe for the final user, even in amounts higher than SCCS indications.

Keywords: aluminum; bioavailability; margin of safety; next-generation risk assessment; oral care cosmetics.

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Conflict of interest statement

The experiments were partially funded by Ludovico Martelli s.r.l. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1
Figure 1
Adverse effects of chronic overexposure to aluminum.
Figure 2
Figure 2
Schematic representation of Al3+ leach from toothpaste in a two-step model. The first step consists in INFOGEST COST model composed of oral, gastric, and intestinal phases of digestion. At each phase, the mixture was centrifuged and the supernatant was measured for Al3+ leach by ICP-AES. The second step consists in incubating several amounts of Al3+ (1,2,5,7,10,20,50 ppm) to assess its passage throughout the small intestine (SMI). The amount of Al3+ measured by ICP-AES in the side-B compartment corresponds to the amount of Al3+ into the bloodstream (BLOOD) and, ultimately, to Al3+ bioavailability.
Figure 3
Figure 3
Transepithelial electric resistance (TEER) measurement for assessing EpiIntestinal barrier integrity with Epithelial Voltohmmeter (EVOM). Diagram of electric circuit is also depicted. RTEER [Ω] = total electrical resistance of tissue; RM = resistance of buffer; RI = resistance of semipermeable filter insert; REMI = resistance of electrode medium interface.
Figure 4
Figure 4
Assessment of aluminum leached from toothpaste during the passage through the digestive tract. Starting amount of Al(OH)3 present in the toothpaste is indicated as gr of Al(OH)3. Al(OH)3 eventually ingested was assumed to be 5%.
Figure 5
Figure 5
Assessment of Al3+ bioavailability corresponding to the passage throughout intestinal mucosa (A) and TEER measure (B). Measures were performed in triplicate.
Figure 6
Figure 6
Histological sections of EpiIntestinal inserts exposed to different Al3+ treatments. (A) Hematoxylin-Eosin staining. The thickness of the insert and the general organization of cells do not show visible alterations compared with the control after Al3+ exposure. (B) Alcian-PAS staining for mucopolysaccharides. The staining is overall quite weak and does not show any increase in mucopolysaccharide synthesis or accumulation in Al3+-exposed inserts compared with the control. Asterisks: microporous membrane (pore size 4 µm) the tissue is cultured on.
Figure 7
Figure 7
The NGRA frame: tiered, interactive workflow with the aim to perform a safety assessment as final result (red).
See this image and copyright information in PMC

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