Leather Working Group Information Sheet on Chromium
Leather manufacturing lifecycle analysis (LCA) has indicated that when comparing
chromium, vegetable and aldehyde based tannages, there is no clear environmentally
preferred tanning systemi.
It is therefore the perspective of the Leather Working Group (LWG)ii, that it is the effective
management and control of the leather manufacturing processes that yields the most
positive results in terms of appropriate environmental stewardship.
Currently, there is some potentially inaccurate information in circulation regarding the use of
chromium salts and their associated safety for the tanning of leather.
This text is designed to help those within the LWG that use chromium (III) as a tanning
material to better understand the scientific facts and therefore be able to give an informed
response to relevant questions.
It should be noted that approximately 80% of global leather production is tanned with
chromium III (trivalent) saltsiii. Trivalent chromium is a highly effective and efficient tanning
agent used to produce leather with a flexible range of properties making it suitable for many
end uses.
In at least one recent NGO publication, the use of chromium (III) tanning salts is described
as harmful to operators working within the leather manufacturing industryiv,v. While there are
a small number of historic studies, including a specific study on sensitizationvi there appears
to be little evidence to link chromium (III) to harmful or toxic effects in humansvii.
With regard to chromium (III) it appears without any risks as stated in REACH Annex XV
proposal of restrictionvii and within industry advisory documentsviii. Chromium (III) in
concentrations used in leather is not sensitizing, it is proven harmless and not classified as
CMR (Carcinogenic, Mutagenic or Toxic for Reproduction)ix.
The confusion around risk and toxicity appears to occur because chromium is a transition
metal that can exist in a number of different oxidation states each with distinctive properties.
Metallic chromium
Leather Working Group, The Pinnacle, 170 Midsummer Boulevard, Milton Keynes, Buckinghamshire MK9 1FE, UK
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This is a steel grey, hard metal found as chromite ore (it does not occur in the metallic state
naturally). It is used to harden steel, to manufacture stainless steel, and to form alloys. It is
also used in plating to produce a hard corrosion resistant surface.
Trivalent chromium – (Chrome 3 - Cr3 - Cr III)
Trivalent chromium compounds occur naturally in the environment. They are found in rocks,
soil, plants and volcanic emissions. Trivalent chromium salts are present in foodstuffs and
are a necessary nutrient for the normal metabolism of fats and sugarsx.Nutritional
supplements are currently on sale containing chromium picolinate. Chromium sulphate is
considered safe to use in leather manufacture.
Hexavalent chromium – (Chrome 6 - Cr 6 - Cr VI)
Hexavalent chromium (chromium VI) is the hazardous form of this element. It is formed
when trivalent chromium is oxidised. This usually occurs in the presence of oxygen
combined with other factors such as extremes in pH and in the presence of oxidising
chemistry. The salts have a characteristic yellow colour and are classified as toxic,
sensitising, carcinogenic and mutagenicxi. Chromium (VI) is not used during the processing
of leatherxii
Manufacturing leather without chromium VI
Through the use of best practice and the application of specific precautionary measures, it is
possible to minimise the risk of chromium (VI) formation and produce leather with nondetectable chromium (VI) levels which are compliant to current regulationsxiii using the ISO
17075 method for the detection of chromium (VI) in leather.xiv
These protocols are widely publicised and adopted by most good leather manufacturersxv.
Appropriate stewardship
It is recognised by the LWG that the unregulated disposal or dumping of leather making
waste (that may contain tanning materials) into the environmental is not acceptable. It is for
this reason that the LWG environmental audit protocol xvi contains a detailed review of waste
disposal mechanisms for both solid and liquid waste.
Leather Working Group, The Pinnacle, 170 Midsummer Boulevard, Milton Keynes, Buckinghamshire MK9 1FE, UK
Tel: +44 (0) 1604 679999 | Fax: +44 (0) 1604 679998 | Email: info@leatherworkinggroup.com |Website: www.leatherworkinggroup.com
Registered No: 08098331 (United Kingdom)
References
i
Ecobilan (member of Price Waterhouse Coopers) 2003. Environmental Analysis of Tanning
Processes. ESVPO5.
ii
Leather Working Group. www.leatherworkgroup.com
iii
Black et al (2013) Industrial Emissions Directive 2010/75/EU (Integrated Pollution
Prevention and Control) Best Available Techniques (BAT) Reference Document for
theTanning of Hides and Skins.
iv
Change your shoes campaign – EYD (2015) Starting point to and ethical and sustainable
shoe supply chain: http://changeyourshoes-bg.org
v
Change your shoes campaign Press Release 30 July 2015
vi
Jeanne Duus Johansen. Danish Ministry of the Environment, Environment Protection
Agency. Survey and health assessment (sensitisation only) of chromium in leather shoes
vii
ECHA RAC/SEAC Background document to the opinion on the Annex XV dossier
proposing restrictions on chromium VI in leather. ECHA/RAC/ RES-O-0000001412-8609/S1, ECHA/SEAC/RES-O-0000002419-71-02/S2
viii
Tetgemyer D and Kleban M (2013) IUR-1, Chromium and leather research. A balanced
view of scientific facts and figures.
ix
Langard S (1990), American Journal of Industrial Medicine, 17 (2), 189-215.
x
Institute of Medicine (2001). Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic,
Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon,
Vanadium, and Zinc. National Acadamy Press.
xi
Sax’s Dangerous properties of Industrial Materials.12 Edition. Richard J Lewis, Sr. October
2012.
xii
European Union Risk Assessment Report , chromium trioxide, sodium chromate, sodium
dichromate. ammonium dichromate, potassium dichromate. 3rd Priority List, Volume 53
xiii
COMMISSION REGULATION (EU) No 301/2014 of 25 March 2014 amending Annex XVII
to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the
Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) as regards
chromium
xiv
BSEN ISO 17075 (2007) Leather - chemical tests - Determination of Chromium VI.
xv
Christian Hauber (2000) United Nations Industrial Development Organisation (UNIDO).
Formation, Prevention and Determination of chrome VI in Leather.
xvi
Leather working audit protocol version 6.3, 2015
Leather Working Group, The Pinnacle, 170 Midsummer Boulevard, Milton Keynes, Buckinghamshire MK9 1FE, UK
Tel: +44 (0) 1604 679999 | Fax: +44 (0) 1604 679998 | Email: info@leatherworkinggroup.com |Website: www.leatherworkinggroup.com
Registered No: 08098331 (United Kingdom)