The International Agency for Research on Cancer (IARC) has listed titanium dioxide as a Group 2B carcinogen — an agent that may be carcinogenic but lacks sufficient animal and human research. This has caused concern for its safety in food products (11, 12).
Introduction
This cytotoxic effect was also reported before; i.e. Natarajan et al. conducted an experiment that found a strong oxidative stress, morphological changes in mitochondria and substantial loss in the fusion of primary hepatocytes exposed to P25TiO2NPs [52].
Titanium dioxide is an important chemical compound that is widely used in various applications, including paint, cosmetics, sunscreens, and food coloring. As the demand for this versatile substance continues to grow, the role of titanium dioxide manufacturers becomes crucial in ensuring a stable supply for industries around the world.
Recently, Yanagisawa et al. reported that the transdermal exposure (mimicking skin-barrier dysfunction or defect) of NC/Nga mice to TiO2 NPs (15, 50, or 100 nm), in combination with allergen, aggravated atopic dermatitis-like lesions through a T-helper type 2 (Th2) dominant immune response. The study also indicated that TiO2 NPs can play a role in the initiation and/or progression of skin diseases, since histamine was released, even in the absence of allergen.