Why we don’t like leather straps
It has been demonstrated that contained of chromium VI in leather produces a problem for human health. Chromium VI compounds can induce new cases of sensitisation and elicit allergic response.
Chromium VI are formed in the industrial process called tanning, that consist for treating leather. With that is achieved a great improved in finishing of leather in special case of watches with leather straps. Chromium Vi emerges of other compound called Chromium III.
So, Chromium VI compounds can be formed in leather through the oxidation of Chromium III compounds, which are added in some tanning processes to cross- link the collagen subunits in order to increase leather’s dimensional stability.
The problem is that Chormium VI takes a sensitisation direct or indirect with a contact skin or not. In already sensitised people, such contacts may also elicit allergic response at lower concentrations than those needed for the induction of sensitisation.
The COMMISSION REGULATION (EU) No 301/2014 of 25 March 2014 has proposed a restriction should cover leather articles and articles containing leather parts used by consumers or workers, that under normal or reasonably foreseeable conditions of use come into contact with the skin. So, watches leather strap will be involved is this normative. The determination limit chromium VI content in the total dry weight of the leather would be of 3 mg/kg (0,0003 % by weight).
But we realized long time ago that watches leather strap produces allergic response with contact on skin. In Alicante we have a very good leather industry. Leather Workers works with it long time ago and they recognize important problems with leather tanned even they describe some case of cancer with handling chromium salts.
It is possible in short terme this problem is been solved but until such time we are going to wait to use leather straps in our office, although we have already done long time ago.