In short, the substitution process starts with identifying a chemical that needs to be removed, and understanding what function it has in the production process or properties it gives the product. In best case it may not be needed at all, or it could easily be swapped with only a slight modification of the process. It is also important to think of the aesthetic appearance and properties of the product. Is it possible to accept a slightly different nuance or a good enough property by using a less hazardous dyestuff or chemical as a substitute? Good relations with your supplier will make it easier to discuss these issues and obtain a good result. Often you need to get in touch with responsible persons in the production, who have the knowledge and further contacts to give you the information you are asking for. If you are thinking about substitution, you need to take extra care not to introduce other hazardous chemicals.
How substitution works – step by step
- Define the function, use and need of the substance you want to replace
- Define criteria for the alternative
- Search for available alternative solutions
- Evaluate and compare alternatives
- Test on a pilot scale
- Implement substitution
Define the function, use and need of the substance you want to replace
It is very useful to think about substitution using these different levels – function, use and need. Let’s look at the use of phthalates in PVC printing on textiles as an example
The function of the phthalate is to make the PVC plastic soft.
If you only consider the function you might find an alternative non-phthalate plasticiser.
You can also look at the use, which is PVC for textile printing. Bearing this in mind you might consider changing to another type of printing paste that does not require plasticisers: polyurethane or silicone for example.
The ultimate need is to produce textiles that are attractive. Perhaps this can also be achieved by other means, such as embroidery.
Depending on the question you ask, you might end up with several possible alternatives. Our recommendation is to take a broad perspective and look at all the possibilities so that you have as many solutions as possible at this stage.
Define criteria for the alternative
Before moving on to assessing and comparing alternatives it is important to think through what you want from an alternative. What would you like to achieve in terms of hazard profile and functionality: Is there a cost limit? How urgent is the substitution? Are there already legal requirements in place or do you have time to wait for an alternative that is currently at the research stage?
Search for available alternative solutions
You can find alternative solutions through the following channels:
- In-house knowledge
- Trade associations
- Networks of stakeholders (e.g. the ZDHC group)
- Reports from authorities (e.g. ECHA, US EPA, KEMI and others)
- Web-based resources (e.g. SUBSPORT, OECD and others)
- Your suppliers
- Chemical producers and formulators
Available online resources:
SUBSPORT is a web portal that provides lots of information linked to substitution. It also has a database containing hundreds of case stories of substitution from companies and organisations.
Lists available resources for substitution and assessment of alternatives, some containing examples or case stories.
We have rounded up a few good examples of succesful substitution cases on the next page. If you want to go straight there, click here.
Evaluate and compare alternatives
Assessing alternatives is about making sure you choose the best of the available alternatives, given the criteria you have set. The following aspects can be considered when assessing alternatives:
- Hazard assessment
- Functionality of alternatives
- Availability of alternatives
- Changes to processes
- Life-cycle considerations: energy, waste/discharge, carbon dioxide emissions, etc.
If the aim of substitution is to reduce hazardous chemicals, the hazard assessment is where you should start. Once you are sure you have one or more alternatives that are less hazardous than the substance you are substituting, you can look at all the other aspects.
Assessment of alternatives is widely discussed, and new and better methodologies are under development. Some regulations require that alternatives are assessed before hazardous chemicals can be routinely used, i.e. the European chemicals regulation REACH.
There are a number of available methods; some are simple and require only information from Material Safety Datasheets, while others require information from scientific publications or even re-testing of chemicals.
The OECD has worked with stakeholders to create a “toolbox” (also mentioned above) that is designed to help you choose a method of alternatives assessment that suits your competence and requirements.
The most comprehensive method for assessing alternatives is called the “GreenScreen for safer chemicals”. This was developed by the organisation Clean Production Action and provides a rigorous comparative hazard assessment based on 18 different hazardous endpoints. Chemicals are benchmarked on a scale of 1 to 4, which makes the comparison visible and easy. The GreenScreen is also a part of some US regulatory initiatives and standards for the building and electronics sector.
One common problem when assessing alternatives is the lack of data, especially for newer chemicals. For chemicals where little or no data is available, one can estimate hazardous properties based on chemical structure. The most popular methodology for this is called q-SAR, but this requires chemicals expertise and training. For use with the SIN List (one of the lists in our database of hazardous chemicals), ChemSec has developed a tool called SINimilarity. This gives you the opportunity to type in a chemical’s CAS number and find out if this chemical is structurally similar to any of the substances on the SIN List. If so, it is not unlikely that the chemical has similar problematic properties.
Test on a pilot scale
Even after thorough investigation of the feasibility of an alternative, there may be things that you could not foresee. It is therefore always wise to do a practical pilot test before implementing full-scale substitution.
Having come this far you can be very pleased. You could take this opportunity to pass on news of the substitution to your supply chain and perhaps even to consumers. However be aware that you may not yet have found the final and ultimate solution. Substitution is an ongoing process, since new scientific findings and regulations may turn up. Having done a proper alternative assessment though, you are prepared in the best possible way for this.