Evaluating reproductive and developmental effects of TiO ₂ : how data gaps on chemistry, use and exposure, hinder risk assessment by authorities

Titanium dioxide (TiO₂) is available on the market in a wide range of combinations of physico-chemical properties, including variations in crystallinity, size, purity, and surface coating. Each form is associated with specific applications, leading to distinct exposure route(s). Concerns regarding the reproductive and developmental toxicity of TiO₂ nanoparticles (TiO₂-NPs) have been raised. Therefore, a review of both regulatory data and of the scientific literature was conducted to identify potential discrepancies. This review highlighted that reported effects are primarily related to anatase form via the oral route, largely due to the lack of studies on other nanoforms. By comparing available data with regulatory requirements and, in light of the identified concern, it becomes evident that additional data are needed to ensure the safe use of TiO₂ and emphasizes the need for further research. Ultimately, the robustness of the existing evidence should be reevaluated to determine whether classification and labeling under the European CLP Regulation is warranted.