Occupational relevance of positive standard patch-test results in employed persons with an initial report of an occupational skin disease

Objectives: It is commonly accepted that the standard screening tray is an essential diagnostic test in patch testing supporting the diagnosis of contact dermatitis, the most common type of occupational skin disease (OSD). In this study standard patch-test results of employed persons with an initial report of an OSD were analyzed within 24 occupational groups. Methods: An evaluation was made of employed persons recorded in the Register of Occupational Skin Diseases in Northern Bavaria (Berufskrankheitenregister Haut-Nordbayern; BKH-N) between 1990 and 1999, catering for those standard screening tray allergens tested over the 10-year period. Results: Nickel sulfate was the most common sensitizer (29.5%), showing occupational relevance in only 11% of the cases sensitized. Other common sensitizers were cobalt chloride (13.5%), p-phenylenediamine free base (10.7%), potassium dichromate (9.8%), fragrance mix (5.4%), thiuram mix (4.2%), balsam of Peru (4.0%), chloromethylisothiazolinone/methylisothiazolinone (4.0%), and formaldehyde (4.0%). The most occupationally relevant sensitizers were thiuram mix (71%), epoxy resin (67%), p-phenylenediamine free base (59%), p-phenylenediamine-black-rubber mix/N-isopropyl-N'-phenyl-p-phenylenediamine (53%), potassium dichromate (48%), formaldehyde (38%), chloromethylisothiazolinone/methylisothiazolinone (37%), and mercapto-mix/mercaptobenzothiazole (35%). Occupational groups at risk of acquiring delayed-type sensitization were, in particular, electroplaters, tile setters and terrazzo workers, construction and cement workers, solderers, wood processors, and leather and fur processors. Conclusions: The standard series contributes valuable information and asserts its position in clarifying the causes of OSDs. Based on the study results, the rate of occupationally relevant sensitization to each single allergen is demonstrated, and the difficulties in verifying the occupational relevance are discussed.