Health Canada's Food Directorate recently completed a “state of the science” report on titanium dioxide (TiO₂) as a food additive. Food-grade TiO₂ is a white powder made up of small particles that has been permitted in Canada and internationally for many years as a food additive to whiten or brighten foods. Food-grade TiO₂ has long been considered safe in Canada and in other countries when eaten as part of the diet.

Nano-sized TiO₂ generally shows low or no acute toxicity in both invertebrates and vertebrates. However, exposure of Daphnia magna to 20 ppm TiO₂ for 8 consecutive days was found to cause 40 % mortality. Zhu et al. showed minimal toxicity to D. magna after 48 h exposure, while upon chronic exposure for 21 days, D. magna suffered severe growth retardation and mortality. A significant amount of nano-sized TiO₂ was found also accumulated in the body of the animals. Similar findings with coated nano-sized TiO₂ (T-Lite™ SF, T-Lite™ SF-S and T-Lite™ MAX; BASF SE) were reported by Wiench et al. Biochemical measurements showed that exposure to TiO₂ NPs induces significant concentration-dependent antioxidant enzyme activities in D. magna. Lee et al. showed that 7 and 20 nm-sized TiO₂ induced no genotoxic effect in D. magna and in the larva of the aquatic midge Chironomus riparius.

The FDA is reviewing the safety of titanium dioxide in response to an April petition from EWG and other environmental and public health groups. This is the FDA’s first comprehensive review of titanium dioxide since 1973.