Substances or mixtures can be stabilised for several reasons:
- to prevent polymerisation and exotherm leading to explosion or fire (e.g. liquid monomers)
- to prevent oxidation leading to fire (e.g. self-heating or self-reactive powders)
- to preserve the product shelf life (e.g. biocidal preservatives in an organic solution which would otherwise bio-degrade)
Stabilisers can therefore affect the CLP classification in two ways:
- by reducing or removing a CLP hazard (e.g. polymer inhibitors, anti-oxidants)
- by adding to the CLP hazards through their intrinsic properties (e.g. biocides, although this is rare – generally a preservative to lengthen product life is added at such low concentrations that it does not affect the CLP classification, although it can occur with some aquatic hazards)
Where a stabiliser can add to CLP hazards through its intrinsic properties, this can be calculated easily by including the stabiliser in the formulation and assessing its hazards along with the other components of the product.
Classifying, labelling and producing a Safety Data Sheet for a product containing a stabiliser which reduces or removes its CLP hazards is more tricky.
In theory, the classification is for the stabilised product alone, and in the event that this means that i a substance or mixture is not classified for CLP, there is no requirement to produce a CLP label for the product.
However, in this case, it is good practice to include label information to the effect that the product is stabilised, and include any instructions required to keep the product stabilised. For example, if the product needs to be continuously stirred, or kept above or below a particular temperature, this information should be provided on the label, whether it is a CLP label or not.
The best thing to do is to consider what might happen if the product became unstable – what could cause this, what might the consequences be – and ensure that the label contains enough information to prevent the product becoming unstable.
The information on keeping the product stable should also be reproduced on the SDS, e.g. in Section 2.2, labelling information. Further information on how the product should be handled can also be placed in other appropriate parts of the SDs, e.g. information on the stabiliser’s identity could be placed in Section 3, handling and storage information in Section 7 etc.
Where an SDS is not formally required for a stabilised product, it is recommended that you produce one voluntarily, as it is the best method for communicating the risks of the product should it become unstable.