(12)The substance Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, with the INCI name Trimethylbenzoyl diphenylphosphine oxide (TPO), is currently not included in the Annexes to Regulation (EC) No 1223/2009. TPO has been classified as a CMR substance of category 2 by Commission Regulation (EU) No 618/2012note. The classification became applicable on 1 December 2013. On 27 March 2014, the SCCS issued a scientific opinionnote which concluded that TPO is safe when used as a nail modelling product in a concentration of up to 5,0 % but that it is however a moderate skin sensitizer. Considering the skin sensitising properties of TPO and the high risk of exposure through skin contact in case of self-application of nail products, the use of TPO should be restricted to professionals only. In light of those elements, TPO should be added to the list of restricted substances in Annex III to Regulation (EC) No 1223/2009 for professional use in artificial nail systems with a maximum concentration of 5 %.