Potency and risk assessment of a skin-sensitizing disperse dye using the local lymph node assay

Disperse Blue 106 is an acknowledged skin-sensitization hazard. However, information about the relative sensitization potency of this chemical is lacking, and to provide this information was the purpose of the investigations described here. The approach taken was to measure dose-response relationships for C.I. Disperse Blue in the local lymph node assay, a method for the assessment of skin-sensitization potential in which activity is measured as a function of lymphocyte proliferative responses induced in draining lymph nodes. From these data, it was possible to derive EC3 values (such being the estimated concentration of chemical required to elicit a 3-fold increase in proliferation) that have been shown previously to reflect the relative sensitizing potency of contact allergens. These analyses revealed that Disperse Blue 106 had a relatively low EC3 value (0.01%), comparable to that measured concurrently for 2,4-dinitrochlorobenzene, a potent contact allergen. Collectively, these data reveal that Disperse Blue 106 represents a significant skin-sensitization hazard, and, in combination with information on dye migration and percutaneous penetration from various types of fabric and use conditions provide a basis for the development of effective and accurate risk assessments.