Bronopol, a preservative marketed as a formaldehyde releaser, doesn't actually work the way we thought. Researchers found it releases very little formaldehyde but instead breaks down into other reactive molecules (like 2-bromoethanol) that trigger immune responses in skin cells at much lower concentrations than formaldehyde alone would. This means bronopol can cause allergic reactions through its own chemical activity, not just from the formaldehyde it releases.

Scientists tested bronopol's chemical reactivity by mixing it with amino acids and analyzing what compounds formed. They also exposed human immune cells (dendritic cells and monocytes) to bronopol at various concentrations and measured inflammatory markers to see how the cells responded.

Funding not disclosed in abstract