Over the 20th century, several contact allergy epidemics arose in Western Europe. Today, industries use various assays to determine the sensitization potential of new ingredients and thereby prevent new contact allergy outbreaks. This study debates acceptable risk of sensitization in the general population by using a new epidemiological tool. The clinical epidemiology (CE) and drug utilization research (DUR) method recently estimated the 10-year contact allergy prevalence in the general population in Germany and Denmark based on patch test reading data in combination with an estimate of the number of persons eligible for patch testing each year based on patch test sales data. A reverse CE-DUR was performed to make delineations between the 10-year prevalence of contact allergy in the general population and the corresponding theoretical prevalences of contact allergy observed among patients with dermatitis in Denmark and Germany. Results indicated that if 1/100 subjects in the general population in Denmark and Germany had contact allergy; dermatologists would observe a prevalence of contact allergy among dermatitis patients was between 4.5-8.0% and 2.5-10.4%, respectively. The reverse CE-DUR approach can be used to alert public health authorities if the estimated number of sensitized persons in the general population is above a certain threshold.