It is not possible to get a 100 percent accurate picture of the prevalence of contact allergy in the general population, but population studies can give a good estimate of the extent.
In the years 1990, 1998 and 2006, the Research Centre for Prevention and Health (RCPH) in Glostrup conducted population surveys of the prevalence of contact allergy in the Capital Region.
Uncertainties of population studies
Contact allergy are diagnosed through patch tests, which is complicated and costly to implement in large population studies.
It is also not possible to test for all allergens. For instance, there are more than 100 allergenic fragrances, but Danish population studies have only tested six to eight of them so far. Prevalence of fragrance allergy may therefore be even higher than the population surveys indicate.
Allergy among eczema patients
Another way to assess and distinguish the level of contact allergy is to look at how many patients with symptoms of contact allergy, namely eczema, who are allergic to chemicals.
This is monitored by the National Allergy Research Centre through the National Database for Contact Allergy.