Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness

Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness

Threes G Smijs1–3, Stanislav Pavel4 1Faculty of Science, Open University in The Netherlands, Rotterdam, The Netherlands; 2University of Leiden, Leiden Amsterdam Center for Drug Research, Leiden, The Netherlands; 3Erasmus MC, Center for Optical Diagnostics and Therapy, Rotterdam, The Ne...

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Autores principales: Smijs TG, Pavel S
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Lenguaje:EN
Publicado: Dove Medical Press 2011
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Medical technology
R855-855.5
Chemical technology
TP1-1185
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spelling oai:doaj.org-article:fb143d632955486d8a10fb7a989edd922021-12-02T03:23:04ZTitanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness1177-8903https://doaj.org/article/fb143d632955486d8a10fb7a989edd922011-10-01T00:00:00Zhttp://www.dovepress.com/titanium-dioxide-and-zinc-oxide-nanoparticles-in-sunscreens-focus-on-t-a8465https://doaj.org/toc/1177-8903Threes G Smijs1–3, Stanislav Pavel4 1Faculty of Science, Open University in The Netherlands, Rotterdam, The Netherlands; 2University of Leiden, Leiden Amsterdam Center for Drug Research, Leiden, The Netherlands; 3Erasmus MC, Center for Optical Diagnostics and Therapy, Rotterdam, The Netherlands; 4Charles University, Faculty of Medicine, Department of Dermatology, Pilsen, Czech Republic Abstract: Sunscreens are used to provide protection against adverse effects of ultraviolet (UV)B (290–320 nm) and UVA (320–400 nm) radiation. According to the United States Food and Drug Administration, the protection factor against UVA should be at least one-third of the overall sun protection factor. Titanium dioxide (TiO2) and zinc oxide (ZnO) minerals are frequently employed in sunscreens as inorganic physical sun blockers. As TiO2 is more effective in UVB and ZnO in the UVA range, the combination of these particles assures a broad-band UV protection. However, to solve the cosmetic drawback of these opaque sunscreens, microsized TiO2 and ZnO have been increasingly replaced by TiO2 and ZnO nanoparticles (NPs) (<100 nm). This review focuses on significant effects on the UV attenuation of sunscreens when microsized TiO2 and ZnO particles are replaced by NPs and evaluates physicochemical aspects that affect effectiveness and safety of NP sunscreens. With the use of TiO2 and ZnO NPs, the undesired opaqueness disappears but the required balance between UVA and UVB protection can be altered. Utilization of mixtures of micro- and nanosized ZnO dispersions and nanosized TiO2 particles may improve this situation. Skin exposure to NP-containing sunscreens leads to incorporation of TiO2 and ZnO NPs in the stratum corneum, which can alter specific NP attenuation properties due to particle–particle, particle–skin, and skin–particle–light physicochemical interactions. Both sunscreen NPs induce (photo)cyto- and genotoxicity and have been sporadically observed in viable skin layers especially in case of long-term exposures and ZnO. Photocatalytic effects, the highest for anatase TiO2, cannot be completely prevented by coating of the particles, but silica-based coatings are most effective. Caution should still be exercised when new sunscreens are developed and research that includes sunscreen NP stabilization, chronic exposures, and reduction of NPs’ free-radical production should receive full attention. Keywords: skin barrier, TiO2, ZnO, nanoparticles, physicochemical, scattering, blue shift, UV-radiation, (photo) toxicity, cancerSmijs TGPavel SDove Medical PressarticleMedical technologyR855-855.5Chemical technologyTP1-1185ENNanotechnology, Science and Applications, Vol 2011, Iss default, Pp 95-112 (2011)
institution DOAJ
collection DOAJ
language EN
topic Medical technology
R855-855.5
Chemical technology
TP1-1185
spellingShingle Medical technology
R855-855.5
Chemical technology
TP1-1185
Smijs TG
Pavel S
Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness
description Threes G Smijs1–3, Stanislav Pavel4 1Faculty of Science, Open University in The Netherlands, Rotterdam, The Netherlands; 2University of Leiden, Leiden Amsterdam Center for Drug Research, Leiden, The Netherlands; 3Erasmus MC, Center for Optical Diagnostics and Therapy, Rotterdam, The Netherlands; 4Charles University, Faculty of Medicine, Department of Dermatology, Pilsen, Czech Republic Abstract: Sunscreens are used to provide protection against adverse effects of ultraviolet (UV)B (290–320 nm) and UVA (320–400 nm) radiation. According to the United States Food and Drug Administration, the protection factor against UVA should be at least one-third of the overall sun protection factor. Titanium dioxide (TiO2) and zinc oxide (ZnO) minerals are frequently employed in sunscreens as inorganic physical sun blockers. As TiO2 is more effective in UVB and ZnO in the UVA range, the combination of these particles assures a broad-band UV protection. However, to solve the cosmetic drawback of these opaque sunscreens, microsized TiO2 and ZnO have been increasingly replaced by TiO2 and ZnO nanoparticles (NPs) (<100 nm). This review focuses on significant effects on the UV attenuation of sunscreens when microsized TiO2 and ZnO particles are replaced by NPs and evaluates physicochemical aspects that affect effectiveness and safety of NP sunscreens. With the use of TiO2 and ZnO NPs, the undesired opaqueness disappears but the required balance between UVA and UVB protection can be altered. Utilization of mixtures of micro- and nanosized ZnO dispersions and nanosized TiO2 particles may improve this situation. Skin exposure to NP-containing sunscreens leads to incorporation of TiO2 and ZnO NPs in the stratum corneum, which can alter specific NP attenuation properties due to particle–particle, particle–skin, and skin–particle–light physicochemical interactions. Both sunscreen NPs induce (photo)cyto- and genotoxicity and have been sporadically observed in viable skin layers especially in case of long-term exposures and ZnO. Photocatalytic effects, the highest for anatase TiO2, cannot be completely prevented by coating of the particles, but silica-based coatings are most effective. Caution should still be exercised when new sunscreens are developed and research that includes sunscreen NP stabilization, chronic exposures, and reduction of NPs’ free-radical production should receive full attention. Keywords: skin barrier, TiO2, ZnO, nanoparticles, physicochemical, scattering, blue shift, UV-radiation, (photo) toxicity, cancer
format article
author Smijs TG
Pavel S
author_facet Smijs TG
Pavel S
author_sort Smijs TG
title Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness
title_short Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness
title_full Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness
title_fullStr Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness
title_full_unstemmed Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness
title_sort titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness
publisher Dove Medical Press
publishDate 2011
url https://doaj.org/article/fb143d632955486d8a10fb7a989edd92
work_keys_str_mv AT smijstg titaniumdioxideandzincoxidenanoparticlesinsunscreensfocusontheirsafetyandeffectiveness
AT pavels titaniumdioxideandzincoxidenanoparticlesinsunscreensfocusontheirsafetyandeffectiveness
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