REGULATORY 13/12/13 - O-Opinion on Bismuth citrate

The chemical Bismuth Citrate (CAS 813-93-4) (EC 212-390-1) is a new substance used in hair dye.

First submission was received by the end of January 2009. It includes a complete dossier and the applicant ask for its safety evaluation when used in progressive hair dye formulation at a concentration up to 2.0% in the finished cosmetic product. 

Progressive hair dyes work gradually, with colour build-up over a period of two to three weeks of daily application. With such application, the hair gradually darkens until the required shade is achieved. Thereafter, colour is maintained by up to 3 applications per week. The product is intended for use by middle-aged and older people, principally men.

According to the current US Code of Federal Regulation, bismuth citrate may be safely used in cosmetics intended for colouring hair on the scalp, subject to the following restrictions:- the amount of bismuth citrate in the cosmetic shall not be in excess of 0.5% (w/v); - the cosmetic may not be used for colouring eyelashes, eyebrows or hair on parts of the body other than the scalp. 

SCCS was asked to evaluate if bismuth citrate, used in hair dye at a maximum concentration of 2.0%, could be safe for consumers, but inadequate information has been provided by the applicant, and therefore SCCS concluded that the safety of bismuth citrate cannot be assessed.     

In fact, the quality of the dossier was poor and contains the following major shortcomings:- Although a concentration of 2% of bismuth citrate in cosmetic formulations is applied for, all of the studies submitted for local toxicity testing were performed with a concentration of 0.5%. In addition, supporting data for the concentration claimed was not provided. - Data on identity and/or characterization of bismuth citrate in batches, lots, and formulations was often missing or inadequate. - Data on solubility and/or stability of bismuth citrate in solvents was missing, partly conflicting or inadequate. - The list of references was poorly sorted, titles of the pdf files were partly misleading and several copies were only partly legible. - The only certificate of analysis (CoA) provided was only partly legible.

In order to proceed with the evaluation of the product safety, a complete and adequate physico-chemical characterisation of Bismuth citrate is needed.

Skin and eye irritation studies are required at the concentration of 2% as applied for by the applicant.

The mutagenicity of bismuth citrate can presently not be assessed given the studies provided. A complete set of in vitro studies according to the current Notes of Guidance is required.