CIR Safety Review: Concentrated solutions of Sodium Carbonate, but not Sodium Bicarbonate, are skin and eye irritants due to their alkaline nature. Highly concentrated solutions of Sodium Carbonate have a pH of greater than 11.

The cosmetic use of Sodium Carbonate at high concentrations is mainly limited to products designed to be diluted before use and in products where pH is buffered to near neutrality.

A review of the combined data from sensitization studies indicated that neither Sodium Carbonate nor Sodium Sesquicarbonate was a human sensitizer. The CIR Expert Panel did not consider testing for phototoxicity as warranted.

FDA: Link to Code of Federal Regulations for Sodium Carbonate
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRS...

FDA Link to Code of Federal Regulations for Sodium Sesquicarbonate
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRS...

FDA Links to Code of Federal Regulations for Sodium Bicarbonate
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRS...
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRS...
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRS...

Sodium Carbonate, Sodium Sesquicarbonate and Sodium Bicarbonate may be used in cosmetics products marketed in Europe according to the general provisions of the Cosmetics Directive of the European Union.
Link to the EU Cosmetics Directive:
http://ec.europa.eu/consumers/sectors/cosmetics/documents/di...

The Joint FAO/WHO Expert Committee on Food Additives has not restricted the daily intake of Sodium Carbonate. http://www.inchem.org/documents/jecfa/jeceval/jec_2137.htm

Sodium Carbonate, Sodium Sesquicarbonate and Sodium Bicarbonate are inorganic crystalline compounds that function as a pH adjusters in cosmetic formulations. pH Adjusters are chemicals (acids, bases, or buffering agents) which are used to control the pH of finished cosmetic products.