Changes in the pattern of sensitization to common contact allergens in Denmark between 1985-86 and 1997-98, with a special view to the effect of preventive strategies

The objective of the present study is to describe any changes in the prevalence of sensitization to common contact allergens in patch-tested patients over a 12-year period, Attention is given to possible effects of preventive strategics introduced in Denmark regarding nickel and chromate sensitization during that period, and particular areas of concern are identified. Members of the Danish Contact Dermatitis Group collected patch-test results from consecutive eczema patients as well as information about exposures and demographic variables over a 6-month period in 1985-86. The investigation was repeated in 1997-98 in the same clinics, at the same time of year, using identical methods and patch-test substances, including nickel sulphate 5%, potassium dichromate 0.5% and fragrance mix 8%. Nickel was the most common contact allergen in both study periods, followed by the fragrance mix. In children 0-18 years of age, the frequency of nickel allergy decreased from 24.8% in the first study period to 9.2% in the second study period (P < 0.0008), Fragrance mix allergy doubled in frequency from 4.1% in 1985-86 to 9.9% in 1997-98, an increase that affected all age groups. Contact allergy to potassium dichromate decreased significantly from 3.0% in the first period to 1.2% in the second period (P = 0.001). The decrease was seen in both sexes and was most pronounced among those of working age, No other significant changes were found in the frequency of sensitization to common allergens over the 12-year observation period.