One or a blend of volatile and/or fragrant plant oils (or synthetically derived oils) that impart aroma and odor to products. These are often skin sensitizers because they are composed of hundreds of individual chemical components. Fragrance is a leading source of sensitivity to cosmetics.

References for this information:

Biochimica and Biophysica Acta, May 2012, pages 1,410-1,419

Aging, March 2012, pages 166-175

Chemical Immunology and Allergy, March 2012, pages 77-80

Experimental Dermatology, October 2009, pages 821-832

International Journal of Toxicology, Volume 27, 2008, Supplement pages 1-43

Food and Chemical Toxicology, February 2008, pages 446Š—”475

Skin Pharmacology and Physiology, 2008, issue 4, pages 191-202

American Journal of Clinical Dermatology, 2003, issue 11, pages 789-798

Skin Pharmacology and Physiology, 2008, issue 4, pages 191-202