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Description of key information

Dermal absorption values of 7.2-9.5% is reported for urea.

Key value for chemical safety assessment

Absorption rate - dermal (%):
9.5

Additional information

Urea is present at appreciable levels in the human epidermis, where it may play a role as a humectant, maintaining hydration of the stratum corneum. At very high levels of exposure, urea may act as a denaturant and may enhance the dermal absorption of other compounds. Bronaugh et al (1982), report a dermal absorption value of 7.2%, based on the results of a study in the rat in vivo and comparable results in vitro.

The Cosmetic Ingredient Review (CIR) Expert Panel (2005) reviewed the available data on the dermal absorption of urea in vitro and vivo in various test systems and conclude that a value of 9.5% derived from a study in intact human skin in vitro is appropriate. The review also notes that the absorption of urea through abraded skin is considerably more extensive and that urea is known to enhance the dermal penetration of other substances.