Overview#
Hexavalent chromium is the Cr(VI) oxidation state of chromium, and it is carcinogenic when inhaled. Ordinary trivalent chromium, Cr(III), is much less harmful, so the restriction targets the hexavalent form specifically.
Where it's restricted#
RoHS caps hexavalent chromium at 0.1 percent by weight per homogeneous material. It is also restricted in vehicles under ELV.
Several chromium(VI) compounds, including chromium trioxide and dichromates, sit on the REACH Authorisation list, which means their use needs specific authorisation. See the REACH annexes reference for how authorisation works.
Typical uses#
Cr(VI) has been used for corrosion-resistant coatings and passivation layers, and in surface treatment of metals. Trivalent alternatives have replaced it in many of these processes.
Only the hexavalent form is restricted. A chromium plating or coating can be compliant if it uses Cr(III) chemistry rather than Cr(VI).