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Over the past few years, and again more recently I’ve seen a few cases of ‘exposures’ ( and near misses ) to formalin/formaldehyde and a couple involving gluteraldehyde. Most occurred in SBS departments/institutes or associated biomedical facilities. These have ended up requiring basic first aid for some of the workers involved, and in some cases precautionary hospital visits. Whilst I do not feel we have a serious issue here, I am writing to all Departments/Institutes across the School to raise the profile and to ask that you check procedures using these chemicals are justified in the first instance, and then appropriately risk assessed and controlled.
Controls will typically include:
- Use of suitable Local Exhaust Ventilation (LEV) systems e.g. ducted or carbon filtered recirculation fume cupboards, ducted or carbon filtered downflow ‘AFOS’ type benches, ducted MSCs, ventilated/filtered histology enclosures etc. LEV and any filters must all be tested at intervals not exceeding 14 months, and may require more frequent tests in some situations (e.g. filter saturation, re-testing LEV after major servicing etc). Operational checks must take place before using LEV – e.g. ensuring LEV working, fume cupboards not cluttered, downflow table surfaces not covered etc.
- Written SOPs for the more complex procedures must be in place – e.g. fumigation of MSCs, isolators etc
- Training of staff / students handling hazardous chemicals: University chemical safety awareness course as a minimum, and other training as identified through risk assessment. E.g. I would expect to see comprehensive training for fumigation procedures, perfusion activities etc.
- Provision and use of appropriate Personal Protective Equipment (PPE) for residual risk, and dealing with emergencies etc
- Emergency procedures understood/rehearsed – e.g. Major spillages and fumigant release.
Some of the examples that I have come across:
- Large numbers of students handling multiple culture dishes containing formalin on the open bench. Lab windows opened for ventilation during this activity. 1 student taken ill – possibly related to formalin exposure.
- Short exposure (~1 min) to sample in 4% formaldehyde under a dissection scope – eye pain, headache, nausea for several hours
- Gluteraldehyde ‘hidden’ in an RNAse inactivation agent used for wiping down equipment, surfaces etc .
- Formalin smells regularly reported around a carbon filtered downflow table used for infusion purposes in a biomed facility. Equipment performance problem.
- Splash to face / eyes of a gluteraldehyde solution used for infusion purposes. Worker was working over a carbon filtered downflow table. No eye protection. Filtration was not working well. Perfusion solution pooling on equipment. Perfusion table cluttered with poor draw of air. Research equipment replaced/modified to allow drainage of perfusate, filters replaced.
- Loss of formalin fumigant from a MSC into the lab: A trained worker removed the night door from an MSC that had held fumigant overnight – they had forgotten this was a recirculating unit – confused perhaps by the presence of a ducted cabinet next to it.
- Ducted downflow table in a biomedical facility periodically used for perfusions – had not been subject to any LEV checks since its installation although was subsequently shown to be performing normally.
- Histology – tissue fixation and fixed specimen store: Poor housekeeping/excess holdings/non-capped specimen pots/ ventilation issues. Smell of formalin throughout and complaints from workers.
- Dissolving paraformaldehyde outside of a fume cupboard, and on at least 1 occasion heated on a hotplate.
- Regular use of formalin in MSCs to deal with ‘dirty’ cabinets even at CL1– usually to try to deal with mycoplasma contamination. This practice is over the top and increases potential risk of exposure to workers. Focus should be to improve good micro/lab practices, aseptic culture technique, lab hygiene etc. Decision to fumigate must be risk based.
- Generation of formalin in huge excess within isolators using older methodology (formalin/permanganate kits); Inappropriate ventilation procedure. No exposures. Additional explosion/fire risk. Procedure scrapped.
So – a few reminders.
Gluteraldehyde (WEL 0.05 ppm both 15’ STEL & 8hr LTEL – 40x lower than formaldehyde). Toxic. Corrosive. Respiratory sensitiser – can cause asthma.
Was traditionally used as a chemical sterilising agent for non-autoclavable medical equipment (e.g. endoscopes) and in many surface disinfectants.
Rarely seen in use today ( for these applications ) because of well documented health risks. ‘Safer’ alternatives available.
Gluteraldehyde based disinfectants MUST NOT be used for disinfectant/sterilising purposes in the University.
Keep a check on new and emerging disinfectants to make sure Glut isn’t ‘hidden’ in them.
Gluteraldehyde is still used in many aspects of research e.g. some tissue fixation processes. Where used there must be a suitable and sufficient risk assessment and robust control measures adopted.
Formaldehyde (WEL 2ppm both 15’ STEL & 8hr LTEL). Toxic. Corrosive. Sensitising. Carcinogen.
Commonly used for tissue fixation/embalming procedures and as a disinfectant/biocide for fumigation of biologically contaminated safety cabinets, isolators etc.
Should only be used where it’s use is justified, and appropriate risk assessments and controls (physical e.g. LEV, and management e.g. SOPs, training etc) are employed.
Occupational health surveillance may be required where these chemicals are in use and not easy to control by engineering methods.
Mark Elsdon BSc(Hons) MISTR
School Safety Officer
University of Cambridge
School of the Biological Sciences
17 Mill Lane
Telephone: 01223 332797
Mobile: 07500 883497 (51497 on University network)
Fax: 01223 332355
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