TiO₂ NPs appeared to be more toxic to nematode Caenorhabditis elegans than submicron-sized TiO_2.  At a concentration of 1 mg/l, 7 nm particles affected its fertility and survival rate and were more toxic than 20 nm anatase particles. Similarly, Hu et al. showed that rutile particles (10–20 nm), at concentrations above 1 g/kg soil, can be bio-accumulated in earthworms, where they induce oxidative stress, inhibit the activity of cellulase and induce DNA and mitochondrial damage.

Stability and darkening[edit]

Because of its ability to absorb UV light, it's particularly useful as an ingredient in sunscreens — while its light-scattering properties are great for applications that require white opacity and brightness, such as in paint and paper.

A 2012 study published in the journal Environmental Science & Technology noted that children are especially exposed to titanium dioxide because of the food that contains the food additive and is particularly marketed to children, including candy and cakes.

Food additive or carcinogen? The growing list of chemicals banned in EU but used in US, by Mikaela Conley, The Guardian, June 23, 2022

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.

The leading Chinese TiO2 exporter in value and quantity has been Sichuan Lomon, followed by Henan Billions and Gansu CNNC Huayuan. However, Sichuan Lomon exported a value of titanium dioxide by USD100,000,000 more than the second rank Henan Billions. Henan Billions, on the other hand, exported over USD70,000,000 more TiO2 than Gansu CNNC Huayuan. This demonstrates the huge monopole-like position of the newly merged company Henan Lomon, which can determine the market development for TiO2 in China nearly all alone.

Titanium dioxide is produced in two main forms. The primary form, comprising over 98 percent of total production, is pigment grade titanium dioxide. The pigmentary form makes use of titanium dioxide’s excellent light-scattering properties in applications that require white opacity and brightness.

The availability of other white pigments poses a major challenge for the Lithopone market during the forecast period. Other alternatives to Lithopone include Zinc White, Titanium Dioxide, Calcium Carbonate, Blanc Fixe, and Barytes. The use of TiO2 has reduced the commercial significance of the Lithopone in the pigments industry.

Lithopone is an inorganic white pigment, obtained from co-precipitation of Zinc sulfide (ZnS) and Barium sulfate (BaSO4). Titanium Dioxide (TiO2) has replaced Lithopone as a white pigment in majority applications as TiO2 is more durable. However, it is much cheaper than TiO2 and has advantages such as low binder requirement and good dispensability. As a white pigment, it can improve the substrate's weather resistance, and improve the fungicidal properties of paint formulations. Some of the major applications of Lithopone include manufacturing of paint pigments, plastic & rubber products, paper, printing inks, cosmetics, and leather & linoleum products. It is commercially available under names such as pigment white 5, Barium zinc sulfate sulfide, Becton White, C.I. 77115, Charlton White, Enamel White, and Zincolith. On the basis of content of ZnS, Lithopone is available at 28%-30% Lithopone and 60% Lithopone.