Percutaneous absorption of formaldehyde in rats

Area of Science:

• Dermal toxicology
• Cosmetic science
• Pharmacokinetics

Background:

• Formaldehyde is a common preservative in cosmetic products.
• Concerns exist regarding potential dermal absorption and systemic exposure.

Purpose of the Study:

• To investigate the dermal absorption of formaldehyde from an oil-in-water (O/W) cream formulation.
• To assess the percutaneous penetration and systemic distribution of formaldehyde in rats.

Main Methods:

• [14C]Formaldehyde was incorporated into an O/W cream at a 0.1% concentration.
• Dermal absorption was studied in rats over 48 hours, including under occlusive conditions.
• Excretion pathways and tissue distribution of radioactivity were analyzed.

Main Results:

• Approximately 5% of the applied radioactivity was absorbed percutaneously within 48 hours.
• Occlusive conditions did not significantly increase formaldehyde absorption.
• The majority of the absorbed formaldehyde was excreted in urine and exhaled air, with some found in the carcass.

Conclusions:

• Formaldehyde exhibits limited dermal absorption from O/W cream formulations in rats.
• The primary routes of systemic elimination are urine and exhaled air.
• Results provide a basis for estimating formaldehyde penetration in human skin from cosmetic applications.