Chrome VI Testing
Chrome VI is a kind of poison harmful to human and environment. It is easily absorbed by human through assimilation, respiratory tract, skin and mucosa. It will lead to raucity, nasal mucosa atrophy, especially perforation of nasal septum and bronchiectasis by air, disgorge and stomachache by assimilation, peltry and eczema by skin. The most serious damage is carcinogenesis .
Cr plays an important role in tanning leather, and makes it flexible. In electricity, metal processing, electroplating industries, the solvent contains Cr(Ⅵ). The residual Cr(Ⅵ) in leather will be absorbed by skin and respiratory tract, and damage to stomach, liver, kidney, and eyes, retinal hemorrhage and optic atrophy appearing.
Chrome tanned leather is an extremely useful and valuable commodity for most industries because of its flexibility. The naturally occurring chrome III, which is used as the tanning agent, is perfectly safe if the leather is produced under the correct conditions and must not be confused with chrome VI. There are many advantages of using chrome tanned leather and this is why it is preferred for most leather products.
In leather production there are three ways in which chrome III could oxidise into chrome VI:
During the tanning process –If the temperature or pH is too high then chrome III has the propensity to oxidise to chrome VI.
Chemicals used –If chrome powder is sourced from a non-reputable supply then there is a possibility that it may contain chrome VI.
Finished leather –After the leather has been made, there is a small chance of chrome III oxidising into chrome VI at high temperatures. This is why chrome tanned leather should never be incinerated.
The test method to detect chrome VI has recently been revised and published as EN ISO 17075:2007. This method has a detection limit of 3ppm and for a leather to pass; chrome VI must be none detected.
What is chrome VI?
Hexavalent chromium VI is the hazardous form of the naturally occurring chromium element and the safe trivalent form of chromium used in tanning. Chromium III tanned leather can form traces of chromium VI under certain environmental conditions. The conversion from Chromium III to Chromium VI is an oxidation process and can be facilitated by the factors like heat, UV radiation, changes in pH, presence of unsaturated organic compounds (e.g. natural fats), oxidizing agents and many other factors. Often several of these factors need to be present at the same time.
The formation of Chromium VI from Chromium III can be slow which means that articles not containing Chromium VI directly after production of the leather may develop some Chromium VI during transport and storage, especially where there is a propensity for chrome VI to form due to the conditions outlined.
Under well managed production conditions, chrome tanned leather should pose a very low risk of containing chrome VI. Poor process control, poor quality chrome powder and adverse storage conditions can however, cause the formation of the harmful hexavalent form of chromium.
The risks
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.
Why carry out chrome VI testing?
The new legislation on chrome VI will come into force on May 1st 2015; the forthcoming restriction will state that leather articles and articles containing leather parts that come into contact with the skin cannot contain 3 mg/kg or more of chromium VI by weight of the total dry weight of that leather part. This means all such articles that come into contact with the skin are within the scope, regardless of the length of time of the contact.
Examples of products that are within the restriction scope include:
Footwear
Gloves
Clothing
Accessories e.g. hats
Belts and braces
Watch straps
Purses and wallets
Bags
Horse riding gear
Dog leashes
Automotive seats
Covers for car steering wheels
Furniture
