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Absorption of lawsone through human skin
Margaret E K Kraeling1, Robert L Bronaugh, Connie T Jung
1Office of Cosmetics and Colors, US Food and Drug Administration, College Park, MD 20740, USA. margaret.kraeling@fda.hhs.gov
Cutaneous and Ocular Toxicology
|April 28, 2007
Summary
Lawsone, the active ingredient in henna hair dye, showed minimal skin absorption in studies. Most lawsone remained on the skin surface, indicating low percutaneous absorption potential for henna hair products.
Area of Science:
- Cosmetic Science
- Dermatology
- Toxicology
Background:
- Lawsone, the primary colorant in henna, is approved by the FDA for hair coloring but deemed mutagenic by the EU's SCCNFP.
- Concerns regarding lawsone's safety prompted investigations into its skin absorption from henna-based hair products.
Purpose of the Study:
- To quantify the extent of lawsone absorption through human skin from henna hair coloring and shampoo products.
- To assess the potential for percutaneous absorption of lawsone following topical application.
Main Methods:
- Radiolabeled [(14)C]-lawsone was added to commercial henna products.
- Products were applied to human skin explants in flow-through diffusion cells.
- Lawsone absorption and retention in skin were measured over 24 and 72 hours.
Main Results:
- For hair paste, 0.3-1.3% of lawsone was absorbed into receptor fluid within 24 hours, with 2.2-4.0% remaining in skin.
- For shampoos, 0.3% was absorbed, with 3.6-6.8% remaining in skin.
- The majority of applied lawsone was washed off, and extended studies showed minimal increase in absorption over 72 hours.
Conclusions:
- Lawsone exhibits low percutaneous absorption from henna hair products.
- Receptor fluid measurements provide a reliable estimate of lawsone exposure.
- The findings suggest limited systemic exposure risk from topical henna applications.
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