DMDM Hydantoin

DMDM Hydantoin is a formaldehyde-releasing preservative (biocide) used at trace concentrations (typically ≤ 0.003%) to prevent microbial growth in water-based formulas. It releases small amounts of formaldehyde as a byproduct of its antimicrobial mechanism. DMDM Hydantoin itself is not on the Prop 65 list (CAS 6440-58-0); formaldehyde (CAS 50-00-0) is listed separately but is only relevant at the concentrations where it is present — at ≤ 0.002% DMDM Hydantoin the released formaldehyde is far below any Prop 65 threshold. Not an asthmagen at these use concentrations; H334 respiratory sensitizer classification does not apply. At occupational concentrate levels (>0.1%) it can cause allergic skin reactions (H317 skin sensitizer) in sensitive individuals.