Airborne contact dermatitis from Ambrosia deltoidea (triangle-leaf bursage)

3 cases of contact dermatitis due to exposure to airborne allergens from Ambrosia deltoidea (triangle-leaf bursage) are presented. Although airborne plant dermatitis was suggested in each case by a history of aggravation of the rash by outdoor exposure and typical skin lesions, patch testing with an oleoresinous extract of A. deltoidea leaves identified the source of the sensitizer, not previously reported. As A. deltoidea is a ragweed that probably contains sesquiterpene lactones nearly identical to those of ragweeds widely prevalent in most of North America, the patients presented indicate the need for commercially available, standardized, plant extracts for patch testing in this country. The finding of positive patch tests with filters from an air sampler placed in 1 patient's domestic environment suggests a new avenue of investigation in airborne contact dermatitis.