Titanium dioxide as a pollutant

Although originally classified as biologically inert, there is a growing body of evidence on the toxicity of titanium dioxide to humans and non-target organisms. The compound is widely used in paints, foodstuffs and textiles.

Titanium dioxide’s carcinogenicity when inhaled is well-known from occupational settings during the production of titanium dioxide (TiO2) powders or in the manufacture of products containing the substance and reported in animal studies involving inhalation of titanium dioxide particles. 

The International Agency for Research on Cancer classifies titanium dioxide as a Group 2B carcinogen.

The State of California regulates titanium dioxide in the form of airborne particles measuring 10 micrometers or less, stating: "...titanium dioxide (airborne, unbound particles of respirable size) is on the Proposition 65 list because it can cause cancer. Exposure to titanium dioxide may increase the risk of cancer."

Titanium dioxide is used as a pigment in paints. The production procedure is highly polluting because of the large quantities of wastes which are often thrown into the sea where, by chemical reaction, they can be transformed into 'red mud'. These wastes destroy living organisms such as plankton and they can also impregnate the flesh of fish used for human consumption.

It is used in face mask textiles to improve stability to ultraviolet light and  as a white colorant and matting agent. Nanofibers containing titanium dioxide are used to make antimicrobial filters, often in combination with silver and graphene, while titanium dioxide nanoparticle coatings may also be applied to cotton fabric to enhance a mask's antibacterial properties. In a study of 12 face masks, every mask contained titanium dioxide (TiO2) particles in at least one layer, at levels that exceeded the acceptable exposure level.  

Titanium dioxide is approved by the US FDA as a color additive and is often used in foods such as salad dressings, bread, and cheese to give products a white appearance.  In contrast, titanium dioxide was deemed unacceptable for food products by the European Food Safety Authority (EFSA) in May 2021 because scientists “couldn’t exclude genotoxicity concerns.