FS04.4 Decreased MDBGN conc. in a product is counteracted by increased exposure

Abstract

Background: Some types of cosmetic products such as creams and soaps are commonly used several times a day, especially in occupational use‐situations. Little is known about how the daily frequency of application of an allergen in a product influences the allergic response.Objectives: This study investigates the allergic responses elicited in pre‐sensitised individuals when exposed to a specific amount of allergen applied either in 1 application per day or distributed over 4 applications per day. As model allergen is used the cosmetic preservative methyldibromo glutaronitrile (MDBGN). Patients/Methods: 19 contact allergic individuals and 12 controls participated in a double‐blind, randomized repeated open application test (ROAT) using two coded aqua/ethanol (80:20) solutions preserved with 100 ppm and 400 ppm MDBGN, respectively. 12 cm2 areas on the lower arms were applied 2 drops either once daily of the 400 ppm solution or 4 times a day for the 100 ppm solution.Results: Most patients developed dermatitis following application of approximately equal amounts of MDBGN on both arms not distinguishing whether the allergen was applied as a 400 ppm solution once daily or a 100 ppm solution 4 times daily. Controls were negative.Conclusions: Applications with 400 ppm MDBGN once daily or 100 ppm MDBGN 4 times per day had, in a ROAT study, approximately equal capabilities of provoking allergic dermatitis in agreement with well‐known patch test data that dose per unit area is more important than concentration of allergen in the product. This may complicate risk assessment and regulation of cosmetic allergens. Further studies, however, are needed before more general conclusions can be made.