B. M. Hausen

A Compositae plant mixture consisting of short ether extracts of arnica, German chamomile, feverfew, tansy, and yarrow has been included in the standard series for several years (1985 to 1990) to study the frequency of allergic reactions to Compositae (Asteraceae) species. One hundred eighteen of 3,851 tested individuals gave a positive response (3.1%). Further tests with the single species of the mixture and some additionally tested extracts of chrysanthemums and laurel oil (bay leaf; Lauraceae) revealed a high percentage of reactions to feverfew (70.1%) and lower responses to chrysanthemums (63.6%), tansy (60.8%), chamomile (56.5%), arnica (51.8%), yarrow (51.8%), and the cross-reacting laurel oil (50.5%). Ten of 85 reacted to arnica alone. The results show that it is important to test Compositae extracts in patients with allergic contact dermatitis because these contain (in contrast to a mixture of pure sesquiterpene lactones) other constituents (e.g., polyacetylenes, thiophenes) that may also contribute to the acquired hypersensitivity. Unrevealed sources of hand and face eczema (including airborne contact dermatitis) might be diagnosed more frequently.

8 alkyl gallates, including the widely used antioxidants propyl, octyl, and dodecyl (= lauryl) gallate, have been subjected to experimental sensitization in guinea pigs. Using a modern sensitization procedure, the results showed that all gallates are moderate to strong contact sensitizers: dodecyl (= lauryl) gallate was found to be the strongest. A characteristic correlation between side chain length and mean response was observed, giving a maximum of sensitization at a length of 12 carbon atoms (dodecyl gallate). A literature review revealed that the frequency of reports of allergic contact dermatitis from antioxidants of the gallate type has increased in the last 4 years. In most cases, the moderate sensitizer propyl gallate was the source of sensitization.

25 patients known or suspected to be allergic to different Compositae plants were tested epicutaneously with ether extracts of different Compositae species. 14 persons revealed a chrysanthemum hypersensitivity, 2 were allergic to arnica and 2 to camomile. In 1 patient a positive reaction to tansy was obtained. In the case of the chrysanthemum allergy, this was induced occupationally. All other patients had sensitized themselves by non-occupational contact. Cross-reactions were seen to tansy [14], yarrow [11], camomile [10], arnica and sunflower [5]. The components which are responsible for the sensitization as well as for the crossreactions are sesquiterpene lactones.

The results of patch tests with colophony in the standard series between 1983 and 1987 were analyzed. 5521 patients were tested in the Department of Dermatology, Hamburg, while 354 were tested in other clinics and private practices. Colophony was positive in 2.4% and 11.9%, respectively. Out of 62 patients in the 1st group and 75 in a 2nd group tested subsequently with 6 unmodified types of colophony and 12 types of modified-colophony products, 17 did not react to the unmodified material. However, most of them responded to 1 or more of the modified products. In the enlarged group (n = 75), reactions to Abitol and the maleic-modified products were the most frequently obtained. As the authors are convinced that the actual incidence of allergic reactions to modified-colophony products is underestimated, they propose to test a mixture of 3 materials: Chinese colophony (today 50% of the world market) and 2 derivatives (modified colophony), instead of the 60% mix of unmodified colophony, in the standard series.

An outbreak of dermatitis in a joinery shop is reported. The condition affected four out of five persons sanding a Brazilian rosewood substitute, Machaerium scleroxylum Tul. The features and extent of the rash are described, with illustration of the most severely affected individual who also developed erythema multiforme-like lesions in some areas. Patch testing with the wood has confirmed it to be the cause. The importance of positive identification of the wood is stressed, particularly as the workers and suppliers of the wood were under the impression that it was genuine Brazilian rosewood (Dalbergia nigra All.). Further patch testing with a series of dalbergiones has confirmed previous observations that R-3,4-dimethoxydalbergione is the sensitizer. The reason for the associated cross-reactions with other dalbergiones is discussed. The strong sensitizing potential of R-3,4-dimethoxydalbergione is highlighted.