Can exposure limitations for well-known contact allergens be simplified? An analysis of dose-response patch test data

Background. Allergic contact dermatitis is triggered by chemicals in the environment. Primary prevention is aimed at minimizing the risk of induction, whereas secondary and tertiary prevention are aimed at reducing elicitation. Objectives. To identify the elicitation doses that will elicit an allergic reaction in 10% of allergic individuals under patch test conditions (ED(10) patch test) for different allergens, and to compare the results with those for different allergens and with animal data indicating sensitizing potency from the literature. Materials and methods. The literature was searched for patch test elicitation studies that fulfilled six selected criteria. The elicitation doses were calculated, and fitted dose-response curves were drawn. Results. Sixteen studies with eight different allergens-methylchloroisothiazolinone/ methylisothiazolinone, formaldehyde, nickel, cobalt, chromium, isoeugenol, hydroxyiso hexyl 3-cyclohexene carboxaldehyde, and methyldibromo glutaronitrile-were selected. The median ED(10) value was 0.835 mu g/cm2. The ED(10) patch test values were all within a factor of 7 from the lowest to the highest value, leaving out three outliers. No obvious patterns between the sensitization and elicitation doses for the allergens were found. Conclusions. We found a rather small variation in the ED(10) patch test between the allergens, and no clear relationship between induction potency and elicitation threshold of a range of allergens. This knowledge may stimulate thoughts on introducing a generic approach for limitations in exposure to well-known allergens.