Is It Safe to Paint Your Wall White? A Case Study on Titanium Dioxide Classification

E. Elina Kahkonen*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review


Titanium dioxide (TiO2) is in the process of being classified as a suspected carcinogenic substance (Carc 2). The present case study probes the outcomes of this potential classification in terms of the reduction of hazardous exposure to TiO2 due to its classification. Furthermore, the case study examines the elements that are causing ambiguity during the classification process. This study was conducted by walking through the process from the present exposure to TiO2 to the hazard assessment associated with TiO2 exposure, to the regulatory classification process, and to practical outcomes affecting TiO2 usage. Finally, the impact of the classification on exposure, which was originally considered potentially hazardous, is evaluated. The case study shows that TiO2 classification as a carcinogen will not directly reduce respiratory exposure to TiO2, which was the original reason for the classification. Instead, the classification will lead to restrictions on recycling. Moreover, the classification will have an impact on certain solid artifacts and liquid mixtures for which hazardous exposure was not detected. Altogether, the present case raises questions concerning hazard communications associated with the Carc 2 classification; treatment of poorly soluble low toxicity (PSLT) particles and nanoparticles in the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) and the Classification, Labelling and Packaging (CLP) classifications; and use of human exposure studies for the purposes of chemical regulations. Based on the present study, the following recommendations are made: the final decision on the TiO2 classification should be reconsidered together with those of other PSLT particles and take into account extensive developments in the field of nanoscience. Furthermore, the European Chemicals Agency (ECHA) should develop state-of-the-art guidance on how to use the available human exposure data. Finally, the authorities that are in charge of European Union chemicals management are advised to further develop the regulatory network to utilize the information generated in REACH processes as efficiently as possible and to verify that the connections between the regulations result in the intended outcome. Integr Environ Assess Manag 2019;00:1-12. (c) 2019 SETAC

Original languageEnglish
Pages (from-to)1000-1011
Number of pages12
Issue number6
Early online date9 Jul 2019
Publication statusPublished - Nov 2019
MoE publication typeA1 Journal article-refereed


  • REACH regulation
  • CLP regulation
  • Titanium dioxide
  • Hazard assessment
  • Hazard communication
  • RISK


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