Chromic acid solutions
The classification of chromic acid solutions has been under debate in the UK and EU for some time. This is of particular concern to companies in the surface treatment industry, who use it as part of electroplating processes, as the CLP classification impacts on the COMAH classification.
Briefly, although chromic acid solutions can be made from chromium trioxide dissolved in water, it is not necessarily accurate to classify the solution on the basis of chromium trioxide, as there are different ionic species in equilibrium in solution (which vary according to concentration and pH), and it would be an over-classification for acute toxicity hazards to classify on this basis.
The HSE issued guidance on this issue under CHIP, stating that, for COMAH purposes, chromic acid solutions should be classified according to the Harmonised Classification for chromic acid, which does not include health hazards. However, a similar decision has not been made under CLP, meaning that the COMAH category for chromic acid solutions is open to debate. (The situation is further complicated by the fact that animal testing has already been carried out, so new animal tests can be carried out. Also, it would be very problematic to ensure that the ionic species you were trying to test was actually present in solution).
TT Environmental have produced a discussion document on this topic, which has been issued to the Environment Agency for them to take a decision (as the HSE have said that it is up to the EA), see Review of status of CLP classification for Chromium Trioxide and Chromic Acid solutions for COMAH .
At the time of writing, July 2017, we are still awaiting a decision on the classification of chromic acid solutions under CLP for COMAH purposes.