Another crucial property of TiO2 is that it can show photocatalytic activity under UV light. This makes it effective for environmental purification, for different kinds of protective coatings, sterilisation and anti-fogging surfaces, and even in cancer therapy.
Titanium dioxide has also been classified as a possible human carcinogen by the International Agency for Research on Cancer, which has caused concern about its use in food products. This classification, however, is currently based on limited evidence from animal studies that involved the inhalation of titanium dioxide particles that increased the risk of lung cancer.