Chemical Testing

CHROME 6

Clearing the Chromium/Chrome Tanning Confusion

There is much inaccurate information in circulation regarding the use of chromium salts and their associated safety for the tanning of leather.
Approximately 80% of global leather production is tanned with safe chromium 3 salts. It is a highly effective tanning agent producing a leather with a flexible range of properties making it suitable for many end uses.
Chromium is a transition metal that can exist in a number of different oxidation states each with distinctive properties.

Metallic chromium

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 3 compounds occur naturally in the environment. They are found in rocks, soil, plants and volcanic emissions. Chromium salts are present in foodstuffs and are a necessary nutrient for the human body as trivalent chromium 3 is required for the normal metabolism of fats and sugars. Nutritional supplements are currently on sale containing chromium picolinate. Chromium 3 sulphate is considered safe to use in leather manufacture.

Hexavalent chromium – Chrome 6 – Cr 6 – Cr VI

Hexavalent chromium 6 is the hazardous form of this element. It can be formed when trivalent chromium is oxidised. This usually occurs in the presence of oxygen combined with other factors such as extremes in pH. The salts have a characteristic yellow colour and are classified as carcinogens. Chromium 6 is not used in the chrome tanning of leather.

What is Chrome VI?

Hexavalent chromium VI is the hazardous form of this element. It can be formed when trivalent chromium is
oxidised. This usually occurs in the presence of oxygen combined with other factors such as extremes in pH. The salts have a characteristic yellow colour and are classified as carcinogens. Chromium VI is not used in the tanning of leather.

What are the risks of Chrome VI?

Chrome VI is recognized as a human carcinogen when it is inhaled. Chronic inhalation of Chrome VI has been shown to increase risk of lung cancer and may also damage the small capillaries in kidneys and intestines. Other adverse health effects associated with Chrome VI exposure, according to the National Institute for Occupational Safety and Health (NIOSH), include skin irritation or ulceration and allergic contact dermatitis
What legislation relates to Chrome VI?

Following an EU proposal there will be a new requirement which prohibits the placing on the market of leather
articles and articles containing leather parts if the content of chromium VI is equal to or greater than 3 mg/kg of the total dry weight of leather in the leather article or the leather parts. The restriction will apply to leather parts that under normal or foreseeable use come into contact with the skin. The restriction, which is written in Annex XVII of REACH, becomes effective from 1st May 2015.

Six new SVHCs Added to the Candidate List

On 17th December 2014, six new Substances of Very High Concern (SVHCs) were added to the Candidate List bringing the total to 161 substances.

The legal obligations that companies may have resulting from the inclusion of substances in the Candidate List may apply to the listed substances on their own, in mixtures or in articles. Producers and importers of articles (containing any of the six substances included in the Candidate List on 17th December 2014) have six months to notify ECHA if the SVHC is present in articles in amounts that total more than one tonne per producer or importer per year and above a concentration of 0.1% weight by weight. There are exemptions from the notification obligation if the substance is already registered for the use or when exposure can be excluded.

Substances added to the Candidate List on 17.12.2014
1. 2-benzotriazol-2-yl-4,6-di-tert-butylphenol (UV-320) CAS # 3846-71-7 / 223-346-6
2. 2-(2H-benzotriazol-2-yl)-4,6-ditertpentylphenol (UV-328) CAS # 25973-55-1 / 247-384-8
3. 2-ethylhexyl 10-ethyl-4,4-dioctyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate (DOTE) CAS # 15571-58-1 / 239-622-4
4. Reaction mass of 2-ethylhexyl 10-ethyl-4,4-dioctyl-7-oxo- 8-oxa-3,5-dithia-4-stannatetradecanoate and 2-ethylhexyl 10-ethyl-4-[[2-[(2-ethylhexyl)oxy]-2-oxoethyl]thio]-4-octyl- 7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate (Reaction mass of DOTE and MOTE) MOTE: CAS Number 27107-89-7; EC Number 248-227-6
5. Cadmium fluoride CAS # 7790-79-6 / 232-222-0
6. Cadmium sulphate CAS # 10124-36-4; 31119-53-6 / 233-331-6
For the full list of SVHCs see: http://echa.europa.eu/candidate-list-table