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 irritants (Sources: Dermatology
, 2002, volume 205, number 1, pages 98–102; Contact Dermatitis
, December 2001, pages 333–340; and Toxicology and Applied Pharmacology
, May 2001, pages 172–178).