Editing Titanium dioxide (section)

===Sunscreen and UV blocking pigments===
In cosmetic and skin care products, titanium dioxide is used as a pigment, sunscreen and a thickener. As a sunscreen, ultrafine TiO<sub>2</sub> is used, which is notable in that combined with [[Zinc oxide nanoparticle|ultrafine zinc oxide]], it is considered to be an effective sunscreen that lowers the incidence of [[Sunburn|sun burns]] and minimizes the premature [[photoaging]], [[photocarcinogenesis]] and [[immunosuppression]] associated with long term excess sun exposure.<ref>{{Citation|last1=Gabros|first1=Sarah|title=Sunscreens And Photoprotection|date=2021|url=http://www.ncbi.nlm.nih.gov/books/NBK537164/|work=StatPearls|place=Treasure Island (FL)|publisher=StatPearls Publishing|pmid=30725849|access-date=2021-03-06|last2=Nessel|first2=Trevor A.|last3=Zito|first3=Patrick M.}}</ref> Sometimes these UV blockers are combined with iron oxide pigments in sunscreen to increase visible light protection.<ref>{{Cite journal|last1=Dumbuya|first1=Hawasatu|last2=Grimes|first2=Pearl E.|last3=Lynch|first3=Stephen|last4=Ji|first4=Kaili|last5=Brahmachary|first5=Manisha|last6=Zheng|first6=Qian|last7=Bouez|first7=Charbel|last8=Wangari-Talbot|first8=Janet|date=2020-07-01|title=Impact of Iron-Oxide Containing Formulations Against Visible Light-Induced Skin Pigmentation in Skin of Color Individuals|journal=Journal of Drugs in Dermatology |volume=19|issue=7|pages=712–717|doi=10.36849/JDD.2020.5032|issn=1545-9616|pmid=32726103|doi-access=free}}</ref>

Titanium dioxide and zinc oxide are generally considered to be less harmful to [[coral reef]]s than sunscreens that include chemicals such as [[oxybenzone]], [[octocrylene]] and [[octyl methoxycinnamate|octinoxate]].<ref>{{Cite web|title=US Virgin Islands bans sunscreens harming coral reefs|url=https://www.downtoearth.org.in/news/wildlife-biodiversity/us-virgin-islands-bans-sunscreens-harming-coral-reefs-70158|access-date=2021-03-06|website=www.downtoearth.org.in|date=April 2020 |language=en}}</ref>

Nanosized titanium dioxide is found in the majority of physical sunscreens because of its strong UV light absorbing capabilities and its resistance to discolouration under [[ultraviolet]] light. This advantage enhances its stability and ability to protect the skin from ultraviolet light. Nano-scaled (particle size of 20–40&nbsp;nm)<ref>Dan, Yongbo et al. [https://www.perkinelmer.com/CMSResources/Images/44-171045APP_011990_01-NexION-350D-TiO2-NPs-in-Sunscreen.pdf Measurement of Titanium Dioxide Nanoparticles in Sunscreen using Single Particle ICP-MS] {{Webarchive|url=https://web.archive.org/web/20211206180608/https://www.perkinelmer.com/CMSResources/Images/44-171045APP_011990_01-NexION-350D-TiO2-NPs-in-Sunscreen.pdf |date=6 December 2021 }}. perkinelmer.com</ref> titanium dioxide particles are primarily used in sunscreen lotion because they scatter visible light much less than titanium dioxide pigments, and can give UV protection.<ref name="Nano-scaled titania"/> Sunscreens designed for infants or people with [[sensitive skin]] are often based on titanium dioxide and/or [[zinc oxide]], as these mineral UV blockers are believed to cause less skin irritation than other UV absorbing chemicals. Nano-TiO<sub>2</sub>, which blocks both UV-A and UV-B radiation, is used in sunscreens and other cosmetic products.

The EU Scientific Committee on Consumer Safety considered nano sized titanium dioxide to be safe for skin applications, in concentrations of up to 25 percent based on animal testing.<ref>{{Cite web|url=https://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_136.pdf|title=Health_scientific_committees}}</ref> The risk assessment of different titanium dioxide nanomaterials in sunscreen is currently evolving since nano-sized TiO<sub>2</sub> is different from the well-known micronized form.<ref name=":2">{{Cite journal|date=2010|title=Sunscreens with Titanium Dioxide (TiO<sub>2</sub>) Nano-Particles: A Societal Experiment|journal=Nanoethics|pmc=2933802|last1=Jacobs|first1=J. F.|last2=Van De Poel|first2=I.|last3=Osseweijer|first3=P.|volume=4|issue=2|pages=103–113|doi=10.1007/s11569-010-0090-y|pmid=20835397}}</ref> The rutile form is generally used in cosmetic and sunscreen products due to it not possessing any observed ability to damage the skin under normal conditions<ref>{{Cite web|last=cosmeticsdesign-europe.com|title=Scientists encourage 'safer' rutile form of TiO<sub>2</sub> in cosmetics|url=https://www.cosmeticsdesign-europe.com/Article/2013/09/26/Scientists-encourage-safer-rutile-form-of-TiO2-in-cosmetics|access-date=2021-03-06|website=cosmeticsdesign-europe.com|date=25 September 2013 |language=en-GB}}</ref> and having a higher [[UV protection|UV absorption]].<ref name=":3">{{Cite journal|date=29 March 2006|title=Characteristics of silica-coated TiO<sub>2</sub> and its UV absorption for sunscreen cosmetic applications|url=https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/abs/10.1002/sia.2313|journal=Wiley Analytical Science|doi=10.1002/sia.2313|via=Wiley Online Library|last1=Jaroenworaluck|first1=A.|last2=Sunsaneeyametha|first2=W.|last3=Kosachan|first3=N.|last4=Stevens|first4=R.|volume=38|issue=4|pages=473–477|s2cid=97137064 |url-access=subscription}}</ref> In 2016 Scientific Committee on Consumer Safety (SCCS) tests concluded that the use of nano titanium dioxide (95–100% rutile, ≦5% anatase) as a UV filter can be considered to not pose any risk of adverse effects in humans post-application on healthy skin,<ref name="Eur Acad Dermatol Venereol">{{Cite journal |last1=Dréno |first1=B. |last2=Alexis |first2=A. |last3=Chuberre |first3=B. |last4=Marinovich |first4=M. |date=2019 |title=Safety of titanium dioxide nanoparticles in cosmetics |journal=Journal of the European Academy of Dermatology and Venereology |language=en |volume=33 |issue=S7 |pages=34–46 |doi=10.1111/jdv.15943 |issn=0926-9959 |pmid=31588611 |s2cid=203849903 |doi-access=free |hdl-access=free |hdl=2434/705700}}</ref> except in the case the application method would lead to substantial risk of inhalation (ie; powder or spray formulations). This safety opinion applied to nano TiO<sub>2</sub> in concentrations of up to 25%.<ref name=":4">{{Cite journal|date=7 November 2016|title=OPINION ON additional coatings for Titanium Dioxide (nano form) as UV-filter in dermally applied cosmetic products|url=https://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_202.pdf|journal=Scientific Committee on Consumer Safety|publisher=European Commission|via=ec.europa.eu}}</ref>

Initial studies indicated that nano-TiO<sub>2</sub> particles could penetrate the skin, causing concern over its use. These studies were later refuted, when it was discovered that the testing methodology couldn't differentiate between penetrated particles and particles simply trapped in hair follicles and that having a diseased or physically damaged dermis could be the true cause of insufficient barrier protection.<ref name=":2" />

SCCS research found that when nanoparticles had certain photostable coatings (e.g., [[alumina]], [[Silicon dioxide|silica]], cetyl phosphate<!--Q27292009-->, [[Silicone#Personal care|triethoxycaprylylsilane]], [[manganese dioxide]]), the photocatalytic activity was attenuated and no notable skin penetration was observed; the sunscreen in this research was applied at amounts of 10&nbsp;mg/cm2 for exposure periods of 24 hours.<ref name=":4" /> Coating TiO<sub>2</sub> with alumina, silica, [[zircon]] or various [[polymer]]s can minimize [[avobenzone]] degradation<ref>{{Cite journal|title=Preparation of rutile TiO<sub>2</sub>@avobenzone composites for the further enhancement of sunscreen performance|url=https://pubs.rsc.org/en/content/articlelanding/2016/ra/c6ra23282e#!divRelatedContent&articles|journal=RSC Advances|bibcode=2016RSCAd...6k1865W|via=Royal society of chemistry|last1=Wang|first1=Can|last2=Zuo|first2=Shixiang|last3=Liu|first3=Wenjie|last4=Yao|first4=Chao|last5=Li|first5=Xiazhang|last6=Li|first6=Zhongyu|year=2016|volume=6|issue=113|page=111865|doi=10.1039/C6RA23282E|url-access=subscription}}</ref> and enhance UV absorption by adding an additional light diffraction mechanism.<ref name=":3" />

{{Chem|Ti|O|2}} is used extensively in plastics and other applications as a white pigment or an opacifier and for its UV resistant properties where the powder disperses light – unlike organic UV absorbers – and reduces UV damage, due mostly to the particle's high refractive index.<ref>[http://www2.dupont.com/Titanium_Technologies/en_US/tech_info/literature/Plastics/PL_B_Polymers_Light_Science.pdf Polymers, Light and the Science of TiO<sub>2</sub>] {{Webarchive|url=https://web.archive.org/web/20170329071755/http://www2.dupont.com/Titanium_Technologies/en_US/tech_info/literature/Plastics/PL_B_Polymers_Light_Science.pdf |date=29 March 2017 }}, DuPont, pp. 1–2</ref>