Substituting a substance of very high concern (SVHC) is not easy. There are lots of things to take into account when looking for suitable alternatives. The quickest solution may not be the best in the long term. ECHA Newsletter spoke with Dr Chris Howick, REACH Manager at INEOS ChlorVinyls, who has a long experience of substituting plasticisers. Even though there are no universal recipes for substitution, some basic rules apply in all cases. “First of all, you need to start substitution by evaluating the hazard and classification of the potential alternatives,” Dr Howick says and continues, “it is pointless to substitute a substance with another SVHC or a substance that has the potential to become one.” A good way to get started is to make a thorough search for the considered alternatives on different toxicology databases. “You can also check the classification. If it shows that the alternative is not hazardous, carcinogenic, mutagenic or toxic to reproduction (CMR) or persistent, bioaccumulative or toxic (PBT) then you know that you could have found a potential successful candidate,” he points out. However, not finding a classification does not necessarily mean that the substance is safe. This is very important to remember. “You also have to make sure that the substance is not classified simply because there is no data available. That is the danger here,” he reminds. Many of the tests, for example on reprotoxicity, are very expensive and they are required only for high volume substances. Therefore, it is often the case that there are data gaps in this area. “If you are substituting something that is carcinogenic with something that has not had any carcinogenicity assessment carried out, you might easily waste a lot of time on a substance that in the end cannot be used,” Dr Howick emphasises.
Start from the basics
The first step of every successful substitution process is to really understand the substance that you are dealing with. It must be clear what the substance does for your formulation or manufactured product. “It is very easy to say that you need a substance exactly like the one you currently use, but it might not be the answer. You should look for the effect that the SVHC is giving you and understand which chemical properties are key to the success of your product,” Dr Howick emphasises. Depending on the application, the challenges for substitution may look very different. “One of the key issues is to make a distinction between processing and product performance. In some cases, there may be an alternative that performs very well in the final article but it may be near impossible to process the article under industrial conditions. In other cases, an additive that is easily processed may not stand up well to product testing,” Dr Howick says. Therefore, you need to understand if the product or process has been developed around the additive that needs to be substituted. Otherwise, the result might be that the manufactured product is fine but, for example, the speed of production may only be half of what it used to be. Sometimes substituting one additive can also result in needing to substitute other ingredients to increase or keep the same level of productivity as before. This can result in a chain reaction, which makes the substitution process lengthier. “Therefore, my advice is that, if you plan a major substitution of, for example, DEHP or another SVHC, you should take the opportunity to review the whole formulation at the same time,” Dr Howick points out.
Give yourself time
In some cases, substitution can be done relatively quickly. An example of this would be moving from DEHP to one of the higher chain length phthalate esters, where the properties are very similar. However, in many cases, substitution takes much more time and effort. As an example, Dr Howick mentions applications with a lifetime guarantee that may need to undergo extended tests, sometimes in hostile environments. This means that, even if the alternative was reasonably easy to find, it requires long-term testing to prove that it really works. The same applies for example, to some substances in the automotive and aerospace industries that are critical from a security point of view. For these, finding alternatives and testing them carefully can take years, or even decades. Parameters such as reaction to fire, overall carbon foot prints, overall environmental performance and general product liability should not be compromised in these critical areas. “You might also need to seek an authorisation to continue to use your SVHC if the available alternatives do not produce the desired effects. It is not a surprise to see several companies seek DEHP authorisations for example,” Dr Howick points out and continues, “a lot of these substances were under the spotlight already before REACH, but REACH has certainly accelerated the substitution process. However, there are still companies that simply cannot find alternatives that work to the same degree of quality.” Still, Dr Howick is confident that for most of the hazardous substances it is possible to find a safer alternative, but we need to accept that it may take a long time if safety parameters not directly covered by REACH are involved. There is therefore a clear need for the authorisation process.
Dr Howick recommends that anyone planning to substitute should get in touch with the supplier of their SVHC and ask if they have a non-SVHC alternative. “Suppliers will have access to more data and can give an opinion on whether potential alternatives will succeed,” he says. He also advises companies to make use of ECHA’s website where they can search for toxicity data. It is, however, crucial to use the correct formal chemical name or CAS/EINECS number when carrying out the search – instead of using the public name of the substance that may have been used when it was bought, otherwise, you may miss important results on the website. Finally, Dr Howick reminds you to use the experience you have on your product and trust your own judgement. “You are the expert on your product. Don’t necessarily believe everything that a consultant or some other company may tell you.”
Make use of experimental design methods
Dr Howick recommends companies to familiarise themselves with experimental design methods as part of the substitution process. These methods can save time in the long run by carrying out a few simple tests. They make it possible to study several variables simultaneously, resulting in fewer tests being required. “The experimental designs will give you the minimum number of experiments that you need in order to get statistically significant results. It is a way of getting very good information quickly because several variables can be changed simultaneously,” he explains. According to Dr Howick, sometimes the results of the experimental design can even show that a certain ingredient in a formulation is unnecessary and can be removed from the formulation. This allows formulations to be simplified. “The Japanese statistician Mr Taguchi was the first one to develop these methods. However, now you can choose between several software packages that will design your experiment for you,” Dr Howick concludes.