CIR Safety Review: The CIR Expert Panel determined that the data provided in its report were sufficient to address the safety of the tested ingredients Potassium Silicate, Sodium Metasilicate and Sodium Silicate. The CIR Expert Panel recognized the irritation potential of these ingredients, especially in leave-on products. However, because these ingredients have limited dermal absorption and Sodium Metasilicate is a GRAS direct-food substance, the CIR Expert Panel deemed the ingredients safe as currently used when formulated to avoid irritation.

FDA: Link to the Code of Federal Regulations for Metasilicate and Sodium Silicate
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 Silicate, Sodium Metasilicate and Potassium Silicate may be used in cosmetics and personal care 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 established a limit for the Acceptable Daily Intake of Silicon dioxide and certain silicates except Magnesium Silicate and Talc. http://www.inchem.org/documents/jecfa/jecmono/v05je04.htm

Sodium Silicate is formed when metal cations (sodium) combine with silica. Sodium Silicate functions as a buffering agent, corrosion inhibitor and a pH adjuster in cosmetics. Buffering agents, commonly called buffers, are chemicals which have the property of maintaining the pH of an aqueous medium in a narrow range even if small amounts of acids or bases are added. Buffering agents and pH adjusters are used in cosmetics to alter and maintain a product's pH at the desired level.