Chromated steel and contact allergy. Recommendation concerning a "threshold limit value" for the release of hexavalent chromium.

Steel surfaces can be treated with zinc and chromates to prevent the steel from rusting. Cases of allergic contact dermatitis due to the release of hexavalent chromium (Cr64) from chromated surfaces have been reported. The main purpose of the present study was to develop a simple procedure for the determination of leachable Cr64 that could be used in industrial applications to check the quality of chromated products and to establish a "threshold limit value" for such products. Occlusive tests were performed in chromate-sensitive patients using chromated discs, and discs representing a release of 0.6 microgram/cm2 or more elicited positive results in all patients tested. It was proposed that the mean release of Cr64 from chromated parts should not exceed 0.3 microgram/cm2. Approximately 1 out of 4 yellow chromated parts, collected from a chromating plant and a car assembly plant, gave values above this limit. Today, several tests are performed to evaluate the technical quality of the chromate layers. It is suggested that the present method should be added to the test program in order to reduce the risk of causing chromate allergy.