JECFA previously assessed titanium dioxide at its 13^th meeting, at which time the expert committee assigned a “not specified” ADI for the additive due to an absence of significant absorption and a lack of toxicological effects in the available experimental animal and human studies. Since its original evaluation by JECFA, titanium dioxide has become a public point of contention, with its ban being introduced (and then subsequently withdrawn) in California legislation in 2023, a legal battle playing out in the EU over the additive’s ban and classification as a carcinogen in 2022, and the European Food Safety Authority (EFSA) calling titanium dioxide unsafe. However, supporters of titanium dioxide say that claims about its dangers are founded in unreliable studies, and some recent research has supported its safety as a food additive.

Total zinc and barium sulphate

Zhu et al. were the first to provide evidence that TiO₂ NPs (21 nm) can transfer from daphnia to zebrafish by dietary exposure. Hence, dietary intake could be a major route of exposure to NPs for high trophic level aquatic organisms. Ecological research should therefore focus, not only on the concentration of NPs in the environment, but also on its bioconcentration, bioaccumulation and biomagnification. In addition it has been shown that TiO₂ NPs can increase accumulation of other environmental toxicants: enhanced accumulation of cadmium (Cd) and arsenic (As) was found in carp in the presence of TiO₂ NPs. The strong adsorption capacity for Cd and As was explained by the large specific surface area and strong electrostatic attraction of TiO₂ NPs that contribute to facilitated transport into different organs.

In a study published in 2022 in the journal Particle and Fibre Technology, researchers examined the impact of maternal exposure to titanium dioxide nanoparticles in newborn offspring mice. They found that “a chronic exposure to TiO2 NPs during pregnancy alters the respiratory activity of offspring, characterized by an abnormally elevated rate of breathing.” Breathing was also shown to be “significantly and abnormally accelerated,” and the ability for neural circuitry to effectively adjust breathing rates was impaired. The researchers concluded: “Our findings thus demonstrate that a maternal exposure to TiO2 NPs during pregnancy affects the normal development and operation of the respiratory centers in progeny.”