Dear Sir,

I wish to respond to the article in Leather international, September 2002, entitled ‘Chrome (VI) in consumer products’.

I was most concerned to read an article that was clearly written to shock and was based upon very limited evidence.

BLC Leather Technology Centre routinely test leather and leather products for chrome (VI) and rarely find positive results.

In fact, we have just completed a set of tests for over 100 commercial watchstrap leathers and found less than 3% indicating a positive result.

We also routinely test leathers for retail clients and, again, find only very rare instances of positive results for chrome (VI).

We do not recognise the level of 35% positive results quoted, based upon our routine testing data.

I would point out that the method used for determining chrome (VI) in leather is itself suspect1. The potential for determining false positive results is well documented.

Recent work1 on the test method shows that positive quantification for chrome (VI) can be obtained due to high pH, the presence of mimosa or oxidisable fats.

The review of the current analytical method for determining chrome (VI) through CEN TC 289 will indicate that the method is not reliable below determinations of 10mg/kg.

The current method claims an accuracy to 3mg/kg which is unlikely to be reliable. Failures that are close to the detection limit are very unreliable. The article makes no mention of the uncertainty of results quoted.

I also believe that the article attempts to use limited data to make sweeping statements. Two out of five watchstraps is hardly a significant sample!

To claim that the leather is next to the skin also demonstrates a significant lack of understanding of the construction of watchstraps.

Many leather watchstraps are constructed of three layers – a lining, a stiffener and an outer. Leather is often used as the outer and is not in contact with the skin.

Were these watchstrap leathers lining or outers? The level of chrome (VI) found was of the order 3.6 to 3.7mg/kg.

Once again this is so close to the limit that the consensus in the key technical committee is that this result is below the reliable detection limit.

The section on the testing of baby shoes again seems to use obscure criteria upon which to draw spurious conclusions.

Shoes are not toys, so why was the standard for toys quoted? Whilst one may see the logic of pointing out that baby shoes may be put into a babies’ mouth, does this mean that any object that may enter a babies’ mouth is to be judged a toy?

The article is titled chrome (VI). Table 2 identifies the data for chrome in leathers (370-980mg/kg) and provides the limit (60mg/kg) from EN 71.

ICP (the method of detection used) can only measure total chromium (ie chrome present as either III or VI). Table 2 does not identify that the column identifying chrome content includes chrome (III).

As the extraction system is acidic, I expect the chromium results reported to be totally chromium (III). Nowhere in the article is this clarified and yet the conclusion: ‘It can be seen that the samples do not comply with the stated safety requirements of the European Standard on safety of toys EN 71 Part 3’ is drawn.

The statement indicates that chrome (VI) is in some way implicated when the data is clearly related to chrome (III). The article recommends that ‘importers … should check the content of the dangerous chrome compounds’.

There are several possible chrome species but only two commonly found – chrome (III) and (VI). I am surprised that the term ‘compounds’ is used as this implies both species are ‘dangerous’ which is not the case.

There is no case for chrome (III) as a dangerous compound!

In fact, the Official Journal of the European Commission2 specifically allows the addition of chromium (III) sulfate as an additive to food supplements!

At BLC, we believe that tanners should take a responsible view to producing leather that is safe for the consumer and tested to be free from restricted substances.

However, articles such as this, which take a sensationalist view, based on an unreliable test method, limited evidence and dubious conclusions can only damage the reputation of the leather producing industry unnecessarily.

I trust that you will print this letter with equal prominence to the article.

C B Wood

Operations director, BLC Leather Technology Centre