Bronopol Dårligst Preservative No known benefits Bronopol at a glance Used as a preservative in numerous commercial applications Has broad-spectrum antimicrobial activity Can cause allergic contact dermatitis White crystals in its raw form Bronopol description Bronopol, also known as bronosol, is an organic compound first synthesized in 1897. It is used as a preservative in numerous commercial applications thanks to its broad-spectrum antimicrobial activities. The ingredient name you’ll see on the label is 2-bromo-2-nitropropane-1,3-diol. While it does an exemplary job of preventing bacterial growth (which is always a good thing, as some cosmetics without preservatives would be prone to rapid microbial growth) in both rinse-off and leave-on products, it is also known to cause allergic contact dermatitis. There are several other, equally effective preservatives that do not present this potential for side effects. In its raw form, bronopol appears as white crystals. Use levels in cosmetics range from 0.02–0.05%, a testament to this preservative’s potency. Related ingredients: Formaldehyde-Releasing Preservative