Occupational hypersensitivity to metal salts, including platinum, in the secondary industry

Background: Exposure to platinum group elements (PGEs) - platinum (Pt), palladium (Pd), rhodium (Rh) and iridium (Ir) - may cause acute toxicity or hypersensitivity with respiratory symptoms, urticaria and (less frequently) contact dermatitis. Our aim was to determine the prevalence and the clinical characteristics of hypersensitivity to platinum salts and to other elements of the platinum group. Methods: A total of 153 subjects working in a catalyst manufacturing and recycling factory were examined. The examination consisted of a work exposure and medical questionnaire, physical examination, skin prick test for PGEs and other common aeroallergens, and patch tests for PGEs. Skin prick tests and patch tests were performed with H₂[PtCl₆], K₂[PtCl₄], Na₂[PtCl₆], IrCl ₃, RhCl₃, PdCl₂, aqueous solutions at different concentrations. Results: Positive prick test reactions to Pt-salts at various concentrations were found in 22 (14.4%) of 153 workers; eight had simultaneous reactions to all Pt-salts tested; seven had positive responses to H ₂[PtCl₆] only; four had simultaneous positive reactions to both H₂[PtCl₆] and K₂[PtCl₄]; three had positive reactions to H₂[PtCl₆] and Na ₂[PtCl₆]. Three of 22 had positive reactions to H ₂[PtCl₆] and IrCl₃ solutions, two of these had positive reactions to H₂[PtCl₆], IrCl₃ and RhCl₃ solutions. Positive patch test reactions to platinum salts at day 2 were seen in two of 153 subjects. Conclusions: The results of this study demonstrate that Pt-salts are important allergens in the catalyst industry and that the clinical manifestations involve both the respiratory system and the skin. Hexachloroplatinic acid should be considered the most important salt to use for skin prick tests.