Here - PFI Group
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24<br />
Newsletter<br />
Joint <strong>PFI</strong> and LGR Research Project<br />
The pronounced toxicity of chromium(VI) and the introduction<br />
of a limit value for chromium(VI) in leather<br />
articles of daily use have made elucidation of the<br />
mechanisms of chromium(VI) formation in leather a<br />
matter of prime concern. In a joint research project,<br />
the Test and Research Institute Pirmasens (Prüf- und<br />
Forschungsinstitut Pirmasens, <strong>PFI</strong>) and the Tanning<br />
School Leather Institute Reutlingen (Lederinstitut<br />
Gerberschule Reutlingen, LGR) have investigated<br />
how total chromium, soluble total chromium, and the<br />
substances naturally present in hides are interrelated<br />
with chromium(VI) formation in leather und leather<br />
goods.<br />
CHEMISTRY<br />
How is Chromium(VI) Formed<br />
in Leather and Leather Goods?<br />
Tests for contaminants in footwear and leather goods<br />
repeatedly reveal the presence of highly hazardous<br />
chromium(VI). In a recent laboratory study on<br />
60 shoes of various kinds, some of which contained<br />
several different kinds of leather, six were found to<br />
contain high levels of chromium(VI). Among the other<br />
54 shoes without conspicuous initial chromium(VI) values,<br />
chromium(VI) could be detected in 11 after they<br />
had been subjected to an ageing process in which the<br />
leathers were incubated for 24 hours at 80 °C. The<br />
German Federal Institute for Risk Assessment had<br />
long recommended a ban on leather goods with a<br />
chromium(VI) content exceeding 3 mg/kg. The eighteenth<br />
amendment to the German Consumer Goods<br />
Ordinance of 3 August 2010 therefore includes a provision<br />
for chromium(VI). Consumer goods exceeding<br />
the chromium(VI) limit value may no longer be placed<br />
on the market and must be removed from the market.<br />
This can mean serious economic damage for manufacturers<br />
and the trade.<br />
Chromium as Tanning Agent<br />
Tanning with chromium(III) salts is the principal<br />
method of leather tanning. Chrome-tanned leather<br />
is characteristically strong and supple. Its properties<br />
make it suitable for use in numerous products: for<br />
footwear and apparel, and also for furniture and<br />
car interiors.<br />
What is the Function<br />
of Chromium in Tanning?<br />
Leather is a product derived from animal hides preserved<br />
by tanning. During the tanning process the<br />
tanning agent chromium binds to the collagen in the
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