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How to substitute?

Substituting substances is not necessarily a simple replacement of one chemical with another. You need to do your homework and there is no "one size fits all". Methods that work in one company may not work for your product or process. One approach you can use to address your substitution challenge is functional substitution, where you consider the specific function of the substance and how it could be met by alternatives in a broad sense – covering not only the substance itself but also aspects such as production techniques and product design. You may also need to try several alternatives before you find the best one. In your assessment, beyond the consideration of the hazard, exposure, technical performance and economic aspects, it is important to also look at wider effects, where these are relevant, such as energy and resource use, waste, recycling and socio-economic impacts. If you choose to develop a brand new product, consider an approach that takes into account safety and sustainability across its entire lifecycle. 


Once you have a shortlist of alternatives compiled, continue by comparing the options and decide which one would be the most promising for your use. You will need to carry out the following assessments:

  • Hazard and risk assessment.
  • Performance assessment.
  • Economic viability assessment.
  • Assessment of other impacts.

When comparing, you should also consider wider effects such as energy and resource use, waste, recycling or social impact.

Keep in mind that a substitution project is best approached in a stepwise and iterative process. You need to prioritise which elements you will assess first and in which level of detail – deciding this upfront when setting the scope for the substitution project.

After a first high-level analysis, come back to the criteria that appear to be key for the decision-making and carry out a more thorough analysis.

For chemical alternatives, make sure you evaluate their risks (hazard and exposure). Check whether ECHA or the EU Member States have them on a list for closer examination – they may be subject to future regulatory measures and you would not want to substitute to a substance that may soon become flagged as of concern. Use different toxicology databases and exposure models to make sure you get the full picture.

In addition to assessing the hazards and risks associated with the use of the alternative substances, it is also important that you assess performance and economic viability. You may want to make use of experimental design methods, which allow you to study several variables simultaneously. Finally, taking a lifecycle perspective, you might need to consider potential trade-offs between the different alternatives options (e.g. hazard vs greenhouse gas emissions).


Related methods, tools and materials for comparative hazard assessment
  • GreenScreen® for Safer Chemicals: A comparative hazard assessment tool developed by Clean Production Action. It helps evaluate alternatives to chemicals of concern based on 18 hazard endpoints.
  • The Quick Chemical Assessment Tool (QCAT): A simplified version of the GreenScreen® for Safer Chemicals hazard assessment methodology, to allow SMEs to perform a quick alternatives assessment for chemicals of concern. QCAT also provides detailed information on where to find data and how to interpret the data needed to complete a hazard assessment using the tool.
  • GHS Column Model: On the basis of just a small amount of information on the products in question, substitute substances can be assessed with the aid of this table.
  • Pollution Prevention Options Analysis System (P2OASys): The tool was designed by the Toxic Use Reduction Institute of Massachusetts (TURI). It aims to help companies conduct a comparative analysis of the hazard profile of alternatives. It can be used to analyse technological processes, individual chemicals or chemical mixtures. The tool requires certain expertise which may render it unsuitable for SMEs.


Related tools and resources for assessing economic viability


Related tools and resources for assessing other impacts

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