The court granted the annulment, finding that the requirement to base the classification of a carcinogenic substance on reliable and acceptable studies was not satisfied. Specifically, when verifying the degree of lung overload of titanium dioxide particles in order to assess carcinogenicity, ECHA did not take into account all the relevant factors (e.g. relevant density value of the tested substance) in order to calculate the lung overload.

Additionally, the court found that the Commission’s classification and labeling of titanium dioxide as carcinogenic was not compliant with Regulation 1272/2008, which states such classifications may only be based on the intrinsic properties of the substance which determine its intrinsic capacity to cause cancer. The ECHA Opinion classified the carcinogenic hazard of titanium dioxide as “non-intrinsic in a classical sense,” as the carcinogenicity hazard is linked solely to breathable titanium dioxide particles, when they are present in a certain form, physical state, size, and quantity, only occurring in lung overload conditions, and corresponding to particle toxicity.

The ruling by EU judges did not affect the EU-wide ban on titanium dioxide, which went into effect on August 7 2022, after a transition period of 6 months. This was following the assessment of EFSA in 2021, which could not exclude genotoxicity concerns after consumption of titanium dioxide particles. Earlier in 2022, food safety regulators in the UK, US, and Canada declared TiO2 to be safe for ingestion. According to the US Department of Agriculture (USDA), the 2021 opinion „reflects a hazard assessment of titanium dioxide nanomaterials but does not reflect human exposure to titanium dioxide and is not relevant as such to demonstrate its use as a food additive.”

In its statement regarding the EFSA opinion, the FDA remarked that in some genotoxicity tests, a test substance was used that was not representative of the food color additive, and in some studies there were intake routes not relevant to human dietary exposure. They also highlighted that the EFSA opinion did not confirm general and organ toxicity, as well as reproductive and developmental toxicity. The FDA still allows the use of TiO2 as a color additive up to 1% (by weight).

The Canadian health officials explained that numerous studies have raised concerns regarding the safety of using TiO2. Some forms of the substance have different properties than food-grade TiO2. Several non-dietary investigations revealed harmful consequences, however, food-grade TiO2 did not provide the same outcomes.

Recently, new publications relevant for the risk assessment of titanium dioxide have also been published. French researchers investigated the absorption of titanium dioxide through the buccal cavity in pigs, which is very similar to humans, in addition to in vitro testing in human buccal cavity cell cultures. Rapid absorption of nanoparticles was demonstrated in both approaches. After absorption, they damage the DNA of cells through oxidative stress, affecting their survival and the renewal of the oral epithelium. The results highlight the importance of considering direct exposure through the buccal cavity when assessing human risks.

In a study published in June 2023, knowledge gaps in the human digestive tract fate and agglomeration behavior of the food-grade TIO2 were addressed under in vitro conditions. During thorough physico-chemical characterization using several methods, it was established that the TIO2 particles were resistant to gastrointestinal dissolution, and thus their stability in lysosomal fluid was studied. The biopersistence of the substance in the lysosomal fluid highlighted its potential for bioaccumulation. The researchers showed that under conditions simulated in the small intestine, in the range of human exposure levels, E171 is present with a similar degree of dispersion as in water obtained by means of high-energy sonication.

According to current EU regulation, despite no feasible alternative exist at the moment, the use of TiO₂ is prohibited in food additives. The chemical provisionally remains on the Union list as the requirement to replace it would almost certainly cause significant medicines shortages on the European market.

TiO₂ (E171) was primarily used as a white coating colorant in food and medicinal products.