A couple of thoughts on the Edinburgh Test Soil

This post is an elaborated version of my recent Linked In comment in the group HTM2030 and EN ISO 15883 Washer Disinfectors

I have been involved in countless tests of Cleaning Efficacy as every time a new WD is developed an optimum cycle must be determined. Edinburgh test soil is one of the “human fluids” resembling substance we have used due to the fact that it is later used to officially validate cycles in some areas.

In the cycle time wars where every manufacturer is looking to cut the time of the cycle to absolute minimum that takes it through validation the test soil and its use plays a critical role. Intuitively one can think of it’s amount, method of application and after the cycle testing it is already a lot. But what must be also taken into consideration are the less obvious variables.

1. Age of the test soil – in the situation where the cycle time is brought down to a borderline pass/fail the age of the soil can make a difference.
2. Soil drying time and conditions – depending on the thickness of the layer the drying time will differ and so will the performance of the machine unfortunately.
3. When the total amount of soil is predetermined the proportion of test soil applied to the chamber walls and the carrier versus the instruments themselves also matters – there are spots that are problematic to clean in the chamber and not always the obvious ones. Again as the cycle times are set to be shortest possible it becomes problematic.
4. Finally the test soil amount reference – whatever method is chosen here is a case of a judgement that may have a critical effect to the end result.

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About the author

Pawel de Sternberg Stojalowski

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Pawel de Sternberg Stojalowski MBA, MSc, BSc is a research and development specialist focusing on innovation within decontamination sciences. He’s been involved in R&D since 2007, designing equipment, processes and methodologies for cleaning, disinfection and sterilisation of surgical instruments as well as medical and laboratory equipment.