Isoeugenol: a survey of consumer patch-test sensitization.

The potential of isoeugenol, an important fragrance and flavour ingredient, to induce delayed contact hypersensitivity or to elicit pre-existing sensitization reactions in man was evaluated by analysing patch-test data from dermatitic and non-dermatitic subjects. Results from a total of 6512 patch tests (involving approximately 5850 subjects) on isoeugenol alone and on various consumer products and fragrance blends containing isoeugenol, were collected from fragrance and formulator companies. Hypersensitivity induced by isoeugenol was concentration dependent. All but two of the reactions occurring in this survey were at exposure concentrations greater than or equal to 0.8% isoeugenol. No induced reactions occurred in the 1004 patch tests reported at isoeugenol concentrations between 0.03 and 0.5%. One induced reaction in 32 patch tests was attributable to isoeugenol at a concentration of 0.02% while another induced reaction in 23 patch tests conducted at the same concentration was resolved to an isoeugenol-eugenol mixture. One elicited reaction at an isoeugenol concentration of 0.04% occurred in the 6512 patch tests reported in this survey. This single elicitation was resolved to an isoeugenol-eugenol mixture, but the specific causative agent was not identified. The results of this survey indicate that isoeugenol has a very low potential for either eliciting pre-existing sensitization reactions ('elicited' reactions) or inducing hypersensitivity ('induced' reactions) in subjects exposed to consumer products containing this ingredient.