Titanium dioxide (TiO₂) is considered as an inert and safe material and has been used in many applications for decades. However, with the development of nanotechnologies TiO₂ nanoparticles, with numerous novel and useful properties, are increasingly manufactured and used. Therefore increased human and environmental exposure can be expected, which has put TiO₂ nanoparticles under toxicological scrutiny. Mechanistic toxicological studies show that TiO₂ nanoparticles predominantly cause adverse effects via induction of oxidative stress resulting in cell damage, genotoxicity, inflammation, immune response etc. The extent and type of damage strongly depends on physical and chemical characteristics of TiO₂ nanoparticles, which govern their bioavailability and reactivity. Based on the experimental evidence from animal inhalation studies TiO₂ nanoparticles are classified as “possible carcinogenic to humans” by the International Agency for Research on Cancer and as occupational carcinogen by the National Institute for Occupational Safety and Health. The studies on dermal exposure to TiO₂ nanoparticles, which is in humans substantial through the use of sunscreens, generally indicate negligible transdermal penetration; however data are needed on long-term exposure and potential adverse effects of photo-oxidation products. Although TiO₂ is permitted as an additive (E171) in food and pharmaceutical products we do not have reliable data on its absorption, distribution, excretion and toxicity on oral exposure. TiO₂ may also enter environment, and while it exerts low acute toxicity to aquatic organisms, upon long-term exposure it induces a range of sub-lethal effects.

Lithopone has therefore traditionally been used in stoppers and putties, jointing compounds and sealing compounds, primers and undercoats and in road-marking paints.

Titanium dioxide, or TiO2, will be listed on product labels, but companies are not required to list ingredient size or structure. When it is used in sunscreens to block UV light, titanium dioxide is considered an active ingredient, which means the concentration must also be listed.

French researchers studied how and where E171 nanoparticles enter the bloodstream, first studying the route through pigs and then in vitro with human buccal cells, for a 2023 study published in the journal Nanotoxicology. The research showed that the nanoparticles absorbed quickly through the mouth and then into the bloodstream, before damaging DNA and hindering cell regeneration.

In 2021, the European Food Safety Authority concluded that titanium dioxide is no longer safe in foods due to the same concerns over nanoparticles. As a result, titanium dioxide is now banned as a food additive in the EU. Although studies have shown that the absorption of ingested titanium dioxide is low, evidence suggests that titanium dioxide nanoparticles can accumulate in the body over time. Health Canada deemed it safe in 2022 but noted concerns. Unlike their European counterparts, Canadian officials did not consider studies performed with titanium dioxide nanoparticles alone. 

No acute effects of nano-sized TiO₂ were observed in Danio rerio (zebrafish) embryos. Exposure of rainbow trout to TiO₂ NPs triggered lipid peroxidation, influence on the respiratory tract, disturbance in the metabolism of Cu and Zn, induction of intestinal erosion  and accumulation in kidney tissue. Linhua et al. exposed juvenile carp to 100 and 200 mg/ml of particles and TiO₂ observed no mortality. However, the fish suffered from oxidative stress and pathological changes in gill and liver. In the infaunal species Arenicola marina, exposure to TiO₂ NPs in sediment caused sub-lethal effects including decrease in casting rate and increase in cellular and DNA damage. Aggregated particles were visible in the lumen of the gut, but no uptake through the gut or the skin was observed.

While the FDA maintains that the regulated use of titanium dioxide is safe, the European Food Safety Authority and some other experts warn of potential, serious health risks.

A legal additive in the United States, titanium dioxide is used in everything from food to consumer goods and the U.S. Food and Drug Administration says regulated use of the product as a color additive in food is safe within certain restrictions.

The MBR9668 coating offers a range of advantages for manufacturers in the coatings industry. Primarily, its high hiding power allows for the efficient application of thinner layers, reducing material consumption and operational costs. This cost efficiency does not come at the expense of quality; the coating ensures a uniform finish with excellent opacity and gloss. Furthermore, the durability imparted by MBR9668 means that coatings will not only maintain their aesthetic appeal but also resist environmental stresses such as weathering, moisture, and chemical exposure.

Lithopone or sulphide of zinc white has been in general use for twenty years or more in many industries where a white pigment of considerable body or hiding power is required that is not subject to change like lead carbonate and has not the brittle character of zinc oxide, besides being sold at a lower figure than either of these. Nevertheless it is still comparatively new to the general painting trade. Because of our tariff protection its manufacture in this country has made great progress. Yet in spite of this and the duty imposed on it, the imports are still in excess of the quantity manufactured here. A short history of its origin will no doubt prove of interest to our readers.

While lithopone and anatase titanium white gained traction between the 1920s and 1950s, by the advent of the First World War, rutile titanium white had started to overshadow them. Their significance in the artist’s palette has since dwindled, and their use as an artist’s pigment is currently nearly obsolete.

Asia-Pacific accounted for the largest revenue share in 2019. China and India are the key markets in the region that have a growing paint and plastics industry, owing to rise in urbanization and industrial developments such as in automotive and construction domains. 

This article reviews the uses, benefits, and safety of titanium dioxide.