Abstract
A series of 230 patients with skin disease and 66 men with no skin disease were tested with a battery of nine common sensitizing substances. Among the patients the incidence of positive reactions was 36%, whereas in the control series it was 7·6%. The most common sensitizing agent was potassium dichromate. The incidence of chromate sensitivity was four times greater among assemblers than among men in other jobs. Hexavalent chromate was found on the surface of the nuts, bolts, screws, and washers used by the assemblers. The source of the chromate was a chromate dip which is used as a passivator in chromium plating and zinc coating. The process was modified in one department and the chromate dip omitted. Patch testing of 12 men who had developed dermatitis since the modification of the process revealed no further cases of chromate sensitivity. This cause of allergic dermatitis appears to have been eliminated from this department.