Cr(III) reactivity and foot dermatitis in Cr(VI) positive patients.

Chromium allergy has become synonymous with Cr(VI) allergy. However, real exposure to chromium from leather products may include both Cr(III) and Cr(VI). In this study, we investigate the reactivity to both Cr(VI) and Cr(III) in consecutive patients to analyse the relation between foot eczema/leather exposure and reactivity to Cr(III). From March 2002 to December 2004, 2211 consecutive patients with suspected allergic contact dermatitis were patch tested with 0.5% potassium dichromate (Cr(VI)) and 13% chromium trichloride (Cr(III)). A total of 71 (3.2%) patients had a positive reaction to Cr(VI), of which 31 also had a positive Cr(III) reaction. No Cr(VI) negative patients had a positive reaction to Cr(III). An increased risk of foot dermatitis was found in Cr(VI) positive patients with a concomitant positive or doubtful reaction to Cr(III) compared with Cr(VI) positive patients with no reactions to Cr(III). The increased risk was not due to a higher degree of sensitivity to Cr(VI). Leather was reported most frequently as the suspected cause of chromium dermatitis (54%). However, Cr(VI) allergics having foot eczema and positive or doubtful Cr(III) reactions often had positive reactions to other shoe allergens. Thus, Cr(III) allergy is part of a multiple shoe allergy pattern.