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Titanium dioxide (TiO2), a widely used white pigment found in sunscreens, toothpastes, and paints, is no longer classified as carcinogenic in the EU following a landmark court ruling. The ruling overturns the European Commission’s 2019 move to list TiO2 as a suspected carcinogen and requires a fresh review of its classification.
Legal Reversal
The European Court of Justice (ECJ) annulled the European Commission’s 2019 classification, concluding that the EU Risk Assessment Committee (RAC) relied on insufficient scientific evidence for its classification. Upholding a 2022 judgement, the court removed the carcinogen label and instructed the Commission to reassess the hazard status of TiO2.
“It remains to be seen how this ruling will influence future hazard assessments by the RAC and the European Commission, as well as the CLP classification process,” confirmed Helge Kramberger-Kaplan, who holds a doctoral degree in engineering and serves as the managing director of Dr. Robert-Murjahn-Institut GmbH in Ober-Ramstadt, Germany. CLP refers to the EU’s Classification, Labelling and Packaging Regulations for Hazardous Chemicals.
Kramberger-Kaplan added, “Ideally, the arguments now confirmed by the ECJ after years of legal dispute would be considered from the outset in future reviews, avoiding further litigation and prolonged uncertainty.”
Animal Data vs Human Evidence
“The development of tumours following lung overload by ultrafine particles appears mainly in experiments with rats,” said Martin F. Wilks, MD, PhD, former director of the Swiss Centre for Applied Human Toxicology, University of Basel, Basel, Switzerland. “Epidemiological studies of workers involved in TiO2 production have so far shown no evidence of a dose-dependent increase in lung tumours.”
Despite the court’s decision, TiO2 has been banned in food products across the EU since 2022 because of its potential genotoxic effects. In 2021, the German Federal Institute for Risk Assessment warned that TiO2 particles could enter the cell nucleus and damage DNA and chromosomes.
A 2017 study by Gerhard Rogler, MD, PhD, head of the Department of Gastroenterology and Hepatology at the University Hospital Zurich and professor at the University of Zurich, both in Zurich, Switzerland, also reported risks: In mice with preexisting intestinal inflammation, TiO2 nanoparticles worsened symptoms. Rogler observed similar effects in patients with Crohn’s disease, where penetrating particles may weaken the intestinal barrier, trigger inflammatory flare-ups, and increase the risk for cancer over time.
Evidence Gap
“It’s notable that there is little new data to address the still controversial question of TiO2’s carcinogenicity,” said Thomas Backhaus, PhD, chair of Ecotoxicology and Environmental Risk Management at the RWTH Aachen University, Aachen, Germany. “None of the plaintiff companies appear to have provided evidence proving that TiO2 is not a lung carcinogen.”
Backhaus pointed to a recent study from Japan, which, even at higher particle loads comparable to those in the often-cited study by Uwe Heinrich, MD, PhD, professor emeritus at Hannover Medical School, and former executive director of the Fraunhofer Institute for Toxicology and Experimental Medicine, Hannover, Germany, found no evidence of lung carcinogenicity in rats. However, he noted that the overall data remained insufficient, as concluded in a recent review. “Why don’t TiO2 producers voluntarily conduct such studies?” he asked.
Low Public Risk
“I do not see a carcinogenic risk to the general population from inhalation,” Backhaus stated. “Exposure levels are far too low. The highest exposure is likely from hairsprays, which under current EU rules may contain up to 1.1% TiO2 for professional use and 1.4% for domestic use, according to Regulation (EU) 2021/850.”
Kramberger-Kaplan confirmed that “in everyday life, the long-term presence of dust concentrations high enough to cause such effects in human lungs is impossible. Even studies involving thousands of titanium dioxide production workers have found no evidence of harm.”
This story was translated from Medscape’s German edition.
