Wood tars allergy, cross‐sensitization and coal tar

In a population of 1883 patients tested for allergic contact dermatitis (1985–1988), a prevalence of 5.4%(103 cases) was seen for wood tars (ICDRG allergen, 12% pet.) sensitization. In this group (n=103), retrospectively, a combined allergy was seen to wood tars and fragrance mix in 43% and to wood tars and balsam of Peru in 31%. A combined allergy to wood tars and coal tar was seen in 19 patients (18.5%); 14 to liquor carbonis detergens (LCD), 8 to lianthral and 3 to both LCD and lianthral. Within the group with wood tars allergy (n=103), a minority (n= 37) had a history of atopic dermatitis. Comparison of the test results in atopic and non‐atopic subgroups (within the group of 103) revealed a higher incidence of combined wood tars‐fragrance mix allergy in the atopic group (n= 37). In this group, a lower incidence of combined wood tars‐coal tar sensitization was seen in comparison with the non‐atopic group (n= 66). The authors believe that combined “wood tars‐coal tar” allergy could be the consequence of cross‐sensitization rather than due to long‐term previous topical treatment with tar derivatives. The high% of cross‐allergy between wood tars and fragrance mix emphasizes the role of wood tars as an important indicator allergen in perfume allergy.