How to verify brushes are clean?

Q: We were recently audited and we were asked: how do you prove that the brushes you are using are not cross-contaminating the equipment surface with residues?

A: How do you prove brushes are clean, or for that matter, any cleaning device is itself clean, is an excellent question. This can apply to any reusable instrument, cloths, tube brushes, sponges, etc. These tools provide mechanical cleaning action which is a vital component in many manual cleaning activities.

If you are doing rinse water sampling for cleaning verification, a case is made that the brush residues on the shared brush are detected by the cleaning validation residue detection in the worst-case previous product.

If you are doing swab testing then a case can be made that you are directly swabbing areas that a brush will contaminate. In swab sampling, it is indeed harder to be certain that the brush contaminated area was swabbed.

Ideally, you should have dedicated brushes or at least worst case product grouped brushes. You can do an extraction from the brush after using it on a worst-case product residue to quantity how much potential cross-contamination could occur and then you need to calculate to show that it will still be well below acceptance criteria.

Still, another option is to consider disposable brushes.

Scrubbing is a vital tool that is used in pharma, biotech, laboratory, and medical device regulated facilities. And regulator questions on a specified process will require detailed answers for that particular application. We are of course happy to discuss your process any time!

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