CIR Safety Review: The CIR Expert Panel found that Sodium Dehydroacetate, Dehydroacetic Acid, and cosmetics containing these ingredients were practically nonirritating, nonsensitizing, nonphotosensitizing, and nonphototoxic in numerous clinical tests. The CIR Expert Panel noted that Sodium Dehydroacetate and Dehydroacetic Acid are effective antimicrobials at low concentrations (less than and equal to 0.6%) against both bacteria and fungi and that Dehydroacetic Acid has an optimal pH range of 2 to 4. These ingredients are more likely to act by preventing the growth of microbes, rather than killing the microbes.

FDA: Link to Code of Federal Regulations for Dehydroacetic Acid and its sodium salt
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRS...
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRS...

Dehydroacetic Acid (3-Acetyl-6-methylpyran-2 4[3H]-dione) and its salts, including Sodium Dehydroacetate, are listed in Annex VI, Part 1 (preservative which cosmetic products may contain) of the Cosmetics Directive of the European Union and are authorized for use at a maximum concentration of 0.6%, expressed as the acid, and are prohibited only in aerosol dispensers (sprays).
Link to the EU Cosmetics Directive:
http://ec.europa.eu/consumers/sectors/cosmetics/documents/di...

Sodium Dehydroacetate is the sodium salt of Dehydroacetic Acid. These ingredients are used in cosmetics and personal care products as a preservative and antimicrobial agent. The use of preservatives in cosmetics and personal care products is required to prevent product damage caused by microorganisms and to protect the product from inadvertent contamination by the consumer during use.