Percutaneous absorption of formaldehyde in rats

As formaldehyde is used as a preservative in cosmetic products, its dermal absorption from an O/W-cream was studied using rats. [14C]Formaldehyde as a tracer, together with non-labelled formaldehyde, was incorporated into a cream at a total concentration of 0.1%. Approx. 5% of the applied radioactivity was absorbed percutaneously within 48 h. Higher values were not found under occlusive conditions. The labelled substance was excreted primarily in urine and exhaled air. Further radioactivity was found in the carcass. Based on these results, a rough approximation was attempted of the amount of formaldehyde which could penetrate human skin after the application of a formaldehyde-containing cosmetic.