Allergic contact dermatitis due to a herbicide (barban).

Canadian farmers are using increasing amounts of herbicides. Often they do not use adequate skin protection. Two cases of severe allergic contact dermatitis due to the herbicide barban are described. Patch testing with various substances, including barban, confirmed the diagnosis. Sensitization studies in guinea pigs and in one of the authors showed that barban is a potent sensitizer. It is recommended that if skin contact with barban occurs the skin be washed immediately with soap and water.     

Allergic contact dermatitis and its relationship to carcinogenicity

The relationship between allergic contact dermatitis (ACD) and carcinogenicity was investigated using a recently developed and validated simulation approach. The analyses indicated that while there are electrophilic and non-electrophilic components to ACD, these were not identical to those operating in carcinogenicity. Accordingly, with respect to carcinogenicity prediction, the results of ACD do not improve the results based upon mutagenicity testing alone, the latter being a surrogate for potential electrophilicity.     

Mechanisms of drug-induced allergic contact dermatitis

Allergic contact dermatitis is induced by a wide variety of drugs that trigger specific immune responses following topical exposure. Identified chemical stuctures involved in such reactions include the mercuric and thiosalicylic acid groups of thimerosal, the diphenylketone group of the anti-inflammatory drug ketoprofen, the amide or ester structure of local anesthetics, and the side-chain and thiazolidine ring of -lactams. The T cell responses to such compounds involve CD4+ and CD8+ + T lymphocytes and also CD4–/CD8– + T cells. Although "T helper 2" cytokine production by drug-specific human T cells from patients with allergic contact dermatitis has been described, T helper 1-like and T cytotoxic 1-like responses clearly play key roles in this cutaneous reaction.     

Allergic contact dermatitis caused by mushrooms

The first author is allergic to skin contact with mushrooms of Suillus americanus, S. granulatus, S. grevillei, S. luteus, or S. neoalbidipes. Symptoms develop between one and two days after contact and last for approximately a week, disappearing completely without treatment. Symptoms consist of reddening, swelling, and itching, at the sites of contact with pileus cuticle mucilage of all five species. Pore layer tissues (tested for S. americanus and S. luteus) also produced strong reactions, as did pileus trama (tested for S. luteus). Spores from spore prints (tested for S. americanus and S. luteus) produced no reaction. The reaction can be avoided by wearing gloves when handling allergenic species and by washing hands promptly after working with these species. Similar cases, reported from North America, Europe, and Russia, involve Agaricus, Boletus, Lactarius, Paxillus, Ramaria, and Suillus species. Several cases involve allergy to multiple species or genera. Symptom severity varies, presumably with intensity of exposure. In one case, symptoms were renewed following ingestion. Most cases demonstrate delayed allergic contact sensitivity.