Contact urticaria with anaphylactic reactions caused by occupational exposure to iridium salt.

This paper presents the case of a non-smoking and non-atopic male, exposed to iridium chloride at work, who developed respiratory tract symptoms and contact urticaria. Application of iridium salt to normal skin caused contact urticaria. An iridium chloride prick test showed a positive reaction and a scratch test produced anaphylactoid reactions. Platinum salt allergy was excluded through prick testing with hexachloroplatinate solution. There is no previous report describing a case where an individual has a positive prick test reaction to iridium salts and simultaneously a negative one to platinum salts. The results are interpreted as immediate-type hypersensitivity (Type I allergy?) to iridium salt. The route of sensitization was probably through the airways. Further testing showed that iridium salt allergy could persist for at least 18 months after exposure ceases. 14 employees at the same factory were prick tested with iridium and platinum salts with negative results. Prick testing is recommended as a method of first choice when investigating a person with suspected iridium salt allergy.