Safety cabinets, laboratory equipment and containment laboratories have historically been fumigated using formaldehyde. Methods have changed over the years but currently the process consists of boiling Formalin and water in purpose designed machine commonly known and a formalin vapouriser.
Formaldehyde has many advantages, it is highly mobile and penetrative, reaching all areas of safety cabinets and laboratories and has a wide spectrum of biocidal activity. It kills nasties in its path, making it hard to move away from even though it has some issues.
Problems associated with Formaldehyde arise from:
- excessive Formalin leading to deposition of paraformaldehyde
- leakage from the safety cabinet or room being fumigated
- re-entrainment (when exhausted vapours are pulled back into the original source environment) from poor discharge arrangements
- having to maintain critical environmental conditions
- it being a carcinogen!
Crowthorne Group’s policy is to avoid discharging formaldehyde after fumigation to remove the risk of re-entrainment or exposure of personnel in plant rooms. Chemical neutralisation also allows fumigation of recirculating cabinets and other laboratory equipment.
A commonly used alternative (when fumigating safety cabinets and other laboratory equipment) is Hydrogen Peroxide, developed for fumigation of isolators and cleanrooms where equipment can be placed throughout the area, is broken down into oxygen and water to avoid the need to discharge it. It is less mobile than formaldehyde, meaning leaks do not migrate as far, but presenting limitations in fumigation of containment laboratories. Its biggest disadvantages are costs and the need for more independent studies into its efficacy.
It is expected that formaldehyde will be banned within a few years pending that its use can continue with strict controls.
Formaldehyde fumigation of containment laboratories is less clear due to the limitations of alternative agents, especially under emergency fumigation conditions.
- Review fumigation protocols and training of laboratory staff ready for safety inspections
- New safety cabinets should include hydrogen peroxide capability to future proof them, even if they also have formalin vapourisers fitted
There are two schools of thought with respect to the type of equipment to use for hydrogen peroxide fumigation:
- Built in – a system that has been designed to be fitted to cabinets and is the closest to traditional vapourisers, allowing in-house fumigation but also needs a fan/catalyst unit to pull fumigant through the filters
- External equipment – the historic limited choice of providers is changing with new manufacturers coming into the market, some require specific adapters fitted
A complication is the EU Biocidal Products Regulations 2012, applying to all biocidal products, however the HSE have said ‘they are content’ for us to continue purchasing standard laboratory reagents for fumigation. This is not however a statement of law and is open to change.