ABSTRACT
As a sterilising agent, HPV has considerable benefits. It is highly sporicidal even at very low concentrations; at high concentrations, it can give very fast log reductions. Whilst the 8-hour OEL is given as 1 ppm, it is relatively nontoxic to humans, and it is also relatively noncorrosive to materials. A major benefit in these days of environmental concern is the fact that it is effectively unstable and breaks down more or less quickly to water and oxygen. It is not, however, a panacea to all the problems and issues of isolator sterilisation, and users should be aware of the following considerations:
• HPV is fully stable, in bulk, up to 300˚C (Schumb et al. 1956). However, the breakdown to water and oxygen is catalysed by a wide variety of material surfaces, especially heavy metals and organics. The speed of this reaction is governed not only by the composition of the surface, but also by its nature. Thus, the surface finish of, for
instance, a sheet of stainless steel may produce a varying breakdown of the HPV, depending on the degree of polish.
