Potential fragrance allergens used in daily products should have a concentration limited to levels that are at, or below, acceptable exposure levels based on the quantitative risk assessment for the induction of dermal sensitization. To date, there are insufficient data to discern any quantitative relationship between induction and elicitation concentrations for fragrance ingredients that have a potential for dermal sensitization. When available, these data should be used to confirm the effectiveness of quantitative risk assessment–based risk management procedures.
In this study, the relationship between the allergen concentration and the time to elicit allergic contact dermatitis in eugenol-sensitized patients was studied. The products used to elicit allergic contact dermatitis had a concentration of eugenol that was equal to, or below, the International Fragrance Association standard.
Volunteers with and without known sensitization to eugenol were patch tested with various concentrations of eugenol (dilution series) and also underwent repeated open application tests (ROATs). This study model has previously been successfully used with stronger sensitizers.
In this study, allergic contact dermatitis, as evidenced by a positive ROAT, could not be elicited by any of the concentrations studied, including in those patients where the patch tests were positive.
When tested in a 3-week ROAT at, or below, its current International Fragrance Association Standard, eugenol did not induce reactions even in those known to be sensitized. Whether this represents a false-negative result for a weak allergen is unknown.