Advantages of VHP biocides described

Recognition of the need to reduce bioburden, or ‘kill bugs’, can be dated back to Dr John Snow in his pioneering work of 1854, says Howorth Air Technology. What followed was the dawning understanding that certain chemicals, such as formaldehyde, are ‘very efficient bug killers’, and can mitigate spread of disease. Unfortunately, however, as the company points out, ‘they are also very good at killing people, with guidelines being applied in recent years to minimise danger’. Here business development manager – Pharma, Chris Smith, discusses how the advent of vapourising hydrogen peroxide as a high efficacy biocide over the past 30 years has ‘simplified and de-risked bioburden reduction’. 

Biocides are dangerous reagents; the clue, as they say, is in the title. Biocides kill biological entities – bacteria, fungals, plant life, and of course, animals. Essential when making an area aseptic, they are damaging or lethal to humans if not properly broken down to safe levels once the task is complete. There are many biocides for various applications. Formaldehyde, which has been used as a fumigant for well over a century, is the ‘classic’ biocide, and personifies all that can be wrong in these reagents – highly toxic, carcinogenic, and mutagenic, it leaves toxic residues of repolymerised formaldehyde when decomposed. Clean-up is as hazardous as the initial decontamination. Other biocides, such as chlorine dioxide, ethylene oxide, and peracetic acid, also have challenges associated with post-decontamination clean-up. 

These biocides typically require high relative humidity to operate, necessitating, in most cases, preconditioning of the area to be decontaminated. Decontamination cycle times, particularly when formaldehyde is used, can be very long when incorporating this pre-conditioning with clean-up. When using gaseous biocide agents, stringent safety precautions need to be implemented to avoid leakage into occupied areas. It is also necessary to remove electronics and equipment when using these biocides: this is not only inconvenient, but has the implication that any contamination on or in equipment will re-introduce bioburden into the room, so secondary, spray and wipe treatment will be required.