CommentaryHexavalent and trivalent chromium in leather: What should be done?

- Small amounts of CrVI can be released from Cr-tanned leather.
- CrVI concentration on the skin is generally not sufficient to elicit skin reaction.
- CrIII, released in larger amounts, is a much less potent sensitiser than CrVI.
- Proper tanning methods will avoid most skin reactions to either CrVI or CrIII.
- Adequate use of leather goods reduces the risk in sensitised subjects.

Trivalent chromium compounds are used for leather tanning, and chromium may be released during use of leather goods. In certain instances, small amounts of hexavalent chromium can be formed and released. Both trivalent and hexavalent chromium can elicit allergic skin reaction in chromium sensitised subjects, the latter being significantly more potent. Induction of sensitisation only occurs after exposure to hexavalent chromium. A minority of subjects are sensitised to chromium, and in a fraction of these subjects allergic skin reaction have been described after wearing leather shoes or, less frequently, other leather goods. The evidence that in all these cases the reaction is related to hexavalent chromium is not always strong. The content of hexavalent chromium in leather is regulated in European Union, but rate of release rather than content is relevant for allergic skin reaction. The role of trivalent chromium appear much less relevant if at all. Modern tanning procedure do not pose significant risk due to either hexavalent or trivalent chromium. Dismissing bad quality and worn-off leather goods is relevant in reducing or eliminating the skin reaction. It should also be pointed out that shoe components or substances other than chromium in leather may cause allergic/irritative skin reactions.