Inter-laboratory reproducibility of the hand disinfection reference procedure of EN 1500

Recent tests carried out using EN 1500 have suggested that most alcohol-based hand gels are significantly less effective than the reference alcohol [2-propanol, 60% (v/v)] whereas liquid alcohol-based hand rubs are not. However concerns about the accuracy and reproducibility of the test have been raised. We therefore analysed 41 experiments performed in four different laboratories using EN 1500 hand disinfection procedures with the reference alcohol, to analyse inter-laboratory reproducibility of the test. The mean reduction factors (difference of the log(10) of the pre-value and the post-value) from the four laboratories did not reveal a significant difference (P=0.059; analysis of variance), although the difference of the mean pre and post-values was highly significant (P<0.001). EN 1500 is a reproducible test method which leads to valid data.