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Co-Formulant Testing in Preparation for Product Authorisation


What exactly constitutes a co-formulant? A co-formulant is any substance which is in a product besides the claimed active. Some raw materials however have their own biocidal effect and sit on approved actives lists but may not be active at the concentration present in the product, a common example of this is the use of caustic soda to stabilise household bleach.

Have you considered your requirements under BPR for Co-formulant testing? You may need to establish whether or not a co-formulant in your formulation is an active substance within the framework of the biocidal product regulation.

The requirement for evaluating co-formulants is detailed in the Guidance on the BPR: Volume II Parts B+C Version 3 April 2018 Section 4.2.2.1.

“If the co-formulants used potentially have biocidal activity, it is essential to demonstrate that the efficacy is due to the active substance and not to the co-formulants, e.g. a control should be performed with all co-formulants but without the active substance.”

For some products this can cause a major problem. If a co-formulant is able to achieve a reduction within 2lg of your finished product this is now classed as an active ingredient, or if your product without the co-formulant can’t produce a result within 1.5lg of the claimed reduction that co-formulant is an active ingredient. Testing these ingredients needs to be done to specific standards under potentially complex conditions and deducing whether or not a product complies with these restrictions can require several tests, as detailed in the ECHA technical Agreement for Biocides Nov 2018, and it will be a requirement of BPR registration.

As you apply for the authorisation of a microbiocidal product you will be required to provide your composition statement where your active substances are identified and so are the co-formulants, a Competent Authority can challenge these co-formulants regarding them as potential actives in the formulation. This can cause unnecessary delays which can be an issue when deadlines are already looming.

In cases where you think this may be an issue going forward or want to avoid the question before being asked, evidence is the best solution.

At MSL we can carry out co-formulant testing and give you the evidence and peace of mind, avoiding delays. We use the latest standards and guidance with our highly skill team to test your products and co-formulants quickly and affordably stopping a problem before it halts your authorisation process.

Contact our Projects Team for more information about this solution or any other testing needs for your Authorisation process.