Substances with certain hazardous properties can be of concern for human health and/or the environment. "Substitution" means replacing hazardous chemicals with safer alternatives - safer chemicals or techniques. Such substitution can bring substantial benefits for the company itself, the environment and the health of workers and consumers. In the workplace, substitution is at the top of the hierarchy of control measures applied to chemical substances.

We are facing a paradigm shift in regulatory risk assessment of chemicals pointing to hazard-based decision making with a compulsory substitution principle and a greater emphasis on strict obligations.

Increasing harmonisation between the different legal frameworks is necessary and efforts are made to achieve this. From a legal point of view, a hazard is thus defined by the CLP Regulation. Such substances therefore are mainly identified by their harmonised classification and labelling according to CLP which is based on their intrinsic hazardous properties, and therefore, a harmonised classification may trigger obligatory substitution provisions in downstream legislation.

Classification and labelling (C&L) itself already provides an incentive for voluntary substitution as the communication of the hazardous profile via the label allows informed choices of downstream users and consumers. Prioritisation of substitution activities of companies may be based on the C&L of their chemical products. Further criteria not included in the CLP regulation apply, in particular for PBT/vPvB substances, while further legislative changes are under discussion, e.g. on endocrine disruptors.

A common understanding of the most severe hazardous properties is reflected in the REACH SVHC criteria (while of course further non-legally binding criteria may be defined by authorities, dedicated expert bodies, or company policies in a certain context):

  • Carcinogenic (CLP classification in category 1A or 1B)
  • Mutagenic (CLP classification in category 1A or 1B)
  • Toxic to reproduction (CLP classification category 1A or 1B)
  • PBT/vPvB (according to criteria set out in Annex XIII REACH)
  • Endocrine disrupting compounds (interim criteria, may apply as legal criteria, are under development)
  • Respiratory sensitisers (according to CLP)

Substitution may be defined as: “the replacement or reduction of hazardous substances in products and processes by less hazardous or non-hazardous substances, or achieving an equivalent functionality via technological or organisational measures” (Lissner and Lohse, 2003). A key aspect of this working definition is the functional equivalence, i.e. the achievement of the same functionality by less hazardous means.

This can be either straight forward by another chemical or using a safer physical form, or other measure of technology or organisation. The substitution process is a step-wise process and the starting point is the identification of substitution needs and candidates for substitution within a company’s portfolio.

Potential alternative substances (technologies) need to fulfil various criteria. Meanwhile more and more tools and methodologies are available to support the finding and comparative assessment of alternatives based on hazardous properties and further decision supporting criteria, i.e. life cycle and sustainability considerations.

The OECD Substitution and Alternatives Assessment Toolbox (SAAT) provides a comprehensive compilation of resources relevant to chemical substitution and alternatives assessments. A very basic first indication, however, provides any existing restriction and ongoing regulatory scrutiny (“regulatory listing”) preventing a hazardous substance to be used on a sustained basis. Companies should therefore know their chemical portfolio and regularly screen for potential new constraints.

Anticipation of regulatory constraints is possible since regulatory procedures and steps are usually transparent and often take several years before they lead to regulatory risk management measures. Thorough understanding of the regulatory environment and the “cascade” is key to sustainable chemicals management and substitution.