Gut 1993; 34:1641-1645

SPECIAL REPORT

Aldehyde disinfectants and health in endoscopy units

The report of a working party of the British Society of Gastroenterology Endoscopy Committee

R E Cowan, A P Manning, G A J Ayliffe, A T R Axon, J S Causton, N F Cripps, R Hall,P J V Hanson, J Harrison, R J Leicester, C Neumann, J Wicks

British Society ofGastroenterology,Endoscopy Committeeworking party, StAndrews Place, LondonR E CowanA P ManningG A J AyliffeA T R AxonJ S CaustonN F CrippsR HallP J V HansonJ HarrisonR J LeicesterC NeumannJ WicksCorrespondence to:Dr R E Cowan, ColchesterGeneral Hospital, TurnerRoad, Colchester, EssexC04 5YJ.Request for reprints to:Ms D Wilford, Group ProductManager, AstraPharmaceuticals Ltd, HomePark, King's Langley, HertsWD4 3DH.

Accepted for publication6 August 1993

Summary of main recommendations(1) Glutaraldehyde, used in most endoscopyunits in the United Kingdom for the disinfec-tion of flexible gastrointestinal endoscopes, isa toxic substance being an irritant and asensitiser; symptoms associated with glutaral-dehyde exposure are common among staffworking in endoscopy units.(2) The Control of Substances Hazardous toHealth Regulations 1988 (COSHH) obliges theemployer to make a systematic assessment ofrisk to staff of exposure to glutaraldehyde andinstitute measures to deal effectively withexposure.(3) At present glutaraldehyde remains the firstline agent for the disinfection offlexible gastro-intestinal endoscopes. Other agents are beingdeveloped; a standard means ofassessment forflexible endoscope disinfectants should bedevised.(4) Equipment and accessories that are heatstable should be sterilised by autoclaving;disposable accessories should be usedwherever possible.(5) Flexible gastrointestinal endoscopesshould be disinfected within automatedwasher/disinfectors; trays, bowls or bucketsfor this purpose are unacceptable.(6) Local exhaust ventilation must be used tocontrol glutaraldehyde vapour. Extracted airmay be discharged direct to the atmosphereor passed over special absorbent filters andrecirculated. Such control measures must beregularly tested and records retained.(7) Endoscope cleaning and disinfectionshould be carried out in a room dedicated tothe purpose, equipped with control measuresto maintain the concentration of glutaralde-hyde vapour at a level certainly below thecurrent occupational exposure standard of 0-2ppm and preferably below the commonly usedworking limit of 0.1 ppm. Sites other than theendoscopy unit where endoscopy is regularlyperformed, such as the radiology department,should have their own fully equipped cleaningand disinfection room.(8) COSHH limits the use of personal protec-tive equipment to those situations where othermeasures cannot adequately control exposure.Such equipment includes nitrile rubber gloves,apron, chemical grade eye protection, andrespiratory protective equipment for organicvapours.

(9) Monitoring of atmospheric levels ofglutaraldehyde should be performed by a com-petent person such as an occupational hygien-ist; the currently preferred method ofsamplinguses a filtration technique, the commerciallyavailable meters being less reliable.(10) Health surveillance of staff is mandatory;occupational health records must be retainedfor 30 years.(11) Endoscopy staff must be informed of therisks ofexposure to glutaraldehyde and trainedin safe methods of its control. Only staff whohave completed such an education and trainingprogramme should be allowed to disinfectendoscopes.(12) The unsafe use of glutaraldehyde hassignificant health and legal consequences; thesafe use of glutaraldehyde may have revenueconsequences that contribute significantly tothe cost of gastrointestinal endoscopy.

IntroductionIn 1988, a working party of this Society recom-mended aldehyde preparations (2% activatedglutaraldehyde and related products) as first lineanti-bacterial and anti-viral disinfectants for flex-ible gastrointestinal endoscopes.' On the basis ofthis, glutaraldehyde is the most commonly useddisinfectant in endoscopy units. In that report,reference was made to health hazards to stafffrom the use of glutaraldehyde and suggestionswere made as to their reduction. Anxiety regard-ing exposure to aldehyde disinfectants, however,continued to be expressed. Therefore, the Endo-scopy Section Committee of the BSG set up aworking party to formulate recommendationsregarding the use of aldehyde disinfectants andstaff health in endoscopy units.

The problemGlutaraldehyde is the agent used in most unitsfor the disinfection of flexible gastrointestinalendoscopes (unpublished data). In common withother aldehydes, glutaraldehyde is toxic,irritant, and allergenic. Problems may arise fromcontact with liquid glutaraldehyde or its vapour.

Glutaraldehyde as an irritant - direct contactwith liquid may cause an irritant dermatitis aswell as exacerbate existing eczema; vapour mayirritate mucous membranes of nose, throat andeyes, and also affect the respiratory tract causing

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cough and bronchospasm, especially in the asth-matic. Irritation is related to length and level ofexposure.

Glutaraldehyde as an allergic sensitiser - a trueallergic asthma in the previously non-asthmaticmay follow glutaraldehyde exposure. This maybe severe and persistent even if further exposureto aldehyde is avoided. It may also cause a trueallergic dermatitis. Sensitisation usually relatesto short term high peaks of exposure.

Glutaraldehyde may also cause other miscellane-ous effects - these include headache, dizziness,nausea, metallic taste, yellow discolouration ofskin.

Surveys suggest that the prevalence of symp-toms associated with glutaraldehyde exposure ishigh among staff working in endoscopy units. In1981 it was reported that staff in 16 of 48 units(33%) had experienced problems with exposure.2Similar results were published in 1990 with 35%of units suspecting glutaraldehyde toxicity and

'363% 'harmful or potentially harmful problems'.Another survey reported a prevalence of symp-toms of 65%4 and again a recent study suggestedthat 79% ofunits had at least one member of staffaffected.5

COSHH and endoscopyThe Health and Safety at Work Act 1974requires employers to ensure, so far as is reason-ably practicable, the health, safety, and welfareat work of all their employees. The Act alsorequires employees to comply with the precau-tions established to ensure safe working. TheControl of Substances Hazardous to HealthRegulations 1988 (COSHH)6 require employersto assess the risks to the health of staff ofexposure to hazardous chemicals such asglutaraldehyde, to avoid such exposure wherethis is reasonably practicable, and otherwise toensure adequate control. Engineering means ofcontrol must be used in preference to personalprotective equipment. Failure to comply withCOSHH, in addition to exposing staff to risk,constitutes an offence and renders the em-ployer liable to penalties under the Health andSafety at Work Act 1974. The Health and SafetyExecutive (HSE) who enforce COSHH hasadopted a 10 minute time weighted averageoccupational exposure standard for glutaralde-hyde of 0-2 ppm (0 7 mg/M3).7 Such standardsare reviewed annually and may in the future berevised downwards. The odour threshhold forglutaraldehyde is reported to be 0 04 ppm.COSHH obliges the employer to make a

systematic assessment of risk to staff of exposureto glutaraldehyde and to institute measures todeal effectively with exposure. The HSE advisesthe following:

(1) Remove the hazardous substance by sub-stituting a safer substance or changing theprocess; or, where this is not practicable;

(2) Control exposure by - enclosing the pro-cess, using extraction and ventilation equip-ment, and adopting safer working and handlingprocesses (COSHH limits the use of personalprotective equipment as the means of protectionto those situations where other measures cannotadequately control exposure);

(3) Ensure that control measures are properlyused, maintained, and tested;

(4) Monitor staff exposure and performappropriate health surveillance;

(5) Educate staff on the risks and appropriateprecautions to be taken.

Remove the hazardous substance:glutaraldehyde - the case for its continued useGastrointestinal endoscopy entails intubationthrough areas that are not sterile. It is importantthat infectious agents are not transferred fromone patient to another as a consequence of usingcontaminated equipment.

Disinfection - eradication of vegetativebacteria and viruses - rather than sterilisation -the eradication of spores as well as vegetativeforms - has been regarded as adequate forroutine gastrointestinal endoscopy. Flexibleendoscopes are damaged by heat and are, there-fore, not autoclavable. Cold disinfection by achemical agent that does not damage their consti-tuent parts is necessary. In a busy endoscopy listwhere time constraints are usually pressing ashort contact time between endoscope and dis-infectant is desirable.While the transfer of any infection should be

avoided, in the context of gastrointestinal endo-scopy some agents have particular importance.Any disinfectant should have wide activity,particularly against intestinal bacteria, pseudo-monas aeruginosa, mycobacterium tuberculosis,human immunodeficiency virus (HIV), hepatitisB and C virus (HBV HCV), and enteric viruses.An earlier working party report emphasised theimportance of thorough cleaning of the endo-scope before disinfection'; it recommended 2%glutaraldehyde and related products as the firstline disinfectants, a four minute soak beingsufficient to inactivate vegetative bacteria andviruses, including HIV and HBV. A longercontact time of 20 minutes was advised if myco-bacterium tuberculosis was strongly suspected.Any alternative first line agent should match

glutaraldehyde effectiveness within a shortcontact time and must not damage endoscopicequipment. This working party has carefullyconsidered a variety of potential alternatives.The earlier report had suggested the use of 8%dettox (Dettol ED) plus 70% ethyl alcohol as asecond line combination. This has drawbacks: itis a two stage process; some endoscope compo-nents may show deterioration with alcohol; con-centrated alcohol is a fire hazard. Again, thiscombination cannot be regarded as a first lineregimen.

Virkon, a preparation containing peroxygencompounds, has been the subject of much dis-cussion. It is attractive in terms of its apparentlack of toxicity. Although many data, however,on its microbiological effectiveness are, atpresent, preliminary, unpublished, and thus notsubjected to peer review, available informationdoes suggest that Virkon has low activity againstmycobacterium tuberculosis' and polio virus.'Doubts have also been expressed regarding thecompatibility of Virkon with some endoscopicequipment; endoscope manufacturers have not,at present, sanctioned the use of Virkon to

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disinfect flexible endoscopes. In the light ofcurrent information, therefore, Virkon cannotbe recommended as a suitable disinfecting agentfor flexible endoscopes. This view may beadjusted, however, in the light of further infor-mation.A system based on peracetic acid (Steris)

results in apparent sterilisation using dedicatedequipment. It has precise plumbing require-ments, and a long cycle time of 30 minutes, afterthorough manual cleaning. Peracetic acid is itselfa toxic substance that could pose health risks tostaff, which the Steris system is designed tominimise. If used in most endoscopy units itwould entail the purchase of multiple sterilisingsystems and additional endoscopes. It cannot berecommended as a first line agent under normalcircumstances but may be suitable for some sites,particularly where sterility is important such asin operating theatres.The working party is aware that industry is

active in the development ofnew products andthat several disinfecting agents are currentlyreceiving microbiological and equipment com-patibility trials. Performance standards need tobe developed by industry and microbiologistsso that the suitability of agents can be assessedand compared. It is hoped that in the futureglutaraldehyde maybe replaced byan agent thatmatches it for efficacy and material com-patibility but is not hazardous to staff. Until thathappens there is no first line alternative toglutaraldehyde for the disinfection of flexiblegastrointestinal endoscopes.

Remove the hazardous substance: changingthe processAlthough glutaraldehyde is the first linechemical disinfectant for flexible endoscopes, itis important to use an alternative process forendoscopic accessories wherever this is feasible,restricting glutaraldehyde to equipment thatmay only be disinfected by that means. Dispos-able accessories should be used whenever pos-sible; sterilisation either in CSSD or in benchtop autoclaves on the endoscopy unit should beused for equipment and accessories that arecompatible with this process.

Control exposure by - enclosing the processThe disinfection of flexible gastrointestinalendoscopes should be performed within auto-mated washer/disinfectors after thoroughmechanical cleaning including the brushing ofchannels. Automated machines standardise thewashing/disinfecting process, are more conveni-ent for endoscopy staff, and reduce the potentialfor splashing and skin contact with disinfect-ant." They do not avoid, however, the need formanual cleaning and their use can increaseglutaraldehyde vapour levels. Automatedmachines may themselves become contami-nated with micro-organisms either from endo-scopes or from mains rinse water. They must becapable of self disinfection and should use sterileor filtered (0 2-0 45 ,t) rinse water. The rinsecycle must be thorough so as to remove allglutaraldehyde traces from the endoscope before

its removal from the machine. The machineshould dump used disinfectant to waste withoutit having to be drained manually.The use of glutaraldehyde for the disinfec-

tion of flexible gastrointestinal endoscopesshould be confined to appropriate automatedwasher/disinfectors; the use of trays, bowls orbuckets, whether lidded or not, for this purposeis unacceptable.

Control exposure by - using extraction andventilation equipmentLocal exhaust ventilation must be used to controlglutaraldehyde vapour arising during its activa-tion and endoscope disinfection. This may beachieved by housing an automated washer/disinfector within an extraction cabinet;machines are now available that perform bothfunctions. Local exhaust ventilation systems caneither discharge direct to the atmosphere or theair stream can be passed over a special absorbentfilter before being returned to the workroom.Both systems have advantages and disadvantagesbut the HSE prefers the direct discharge ofvapour to a safe place outside the building. Thisrequires ducting to connect the extraction boothto a safe place outside the building. The dis-charge point should be away from openablewindows, closed courtyards, and intakes forventilation systems; it may be necessary to ductthe extracted air to above roof level. Ifa long ductis required, installation costs may be high andmore powerful extraction fans will be required toovercome duct losses. Once installed, however,maintenance costs should be less than forrecirculating systems. Recirculating systemshave advantages where direct discharge to out-side the building would entail long ducts ordifficulties with installation. Their main dis-advantage is the need to change the filtersregularly before they become inefficient. There-fore, an effective system needs to be operated todisclose the degree of filter saturation or time inuse so that filters may be changed at an appro-priate time.The effectiveness of local exhaust ventilation

must be checked often. COSHH specifies thatcontrol measures must function efficiently; theymust be tested and examined at least every 14months. Records of these tests must be kept forat least five years.

Control exposure by - adopting safer workingand handling processesDisinfection should be carried out in an arearemoved from other staff or members of thepublic to avoid any potential for their being incontact with glutaraldehyde or its vapour. Theprocess should be sited in a dedicated cleaningand disinfection room adjacent to the endoscopysuite but separated from it by a self closing door.The Cleaning and Disinfection Room should

be designed to protect staff from contact withglutaraldehyde and its vapour. The atmospherewithin the room would ideally contain noglutaraldehyde vapour but certainly less than thecurrent occupational exposure standard of 0-2

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ppm; a suggested working limit is 041 ppm(personal communication).

Activated glutaraldehyde should be confinedto automated washer/disinfectors incorporatingor housed in local exhaust ventilation cabinetswithin a dedicated cleaning and disinfectionroom. If endoscopy is carried out at other sitessuch as radiology departments these should beprovided with their own cleaning and disinfec-tion room with suitable enclosure and ventilationfacilities. A less suitable alternative is to providea sufficient number of endoscopes and acces-sories to permit their return for disinfection inthe dedicated facilities on the endoscopy unit.The use of mobile disinfection equipment forthese purposes is potentially hazardous andshould be discouraged.

The use of personal protective equipmentIt bears repeating that COSHH limits the use ofpersonal protective equipment to those situa-tions where other measures cannot adequatelycontrol exposure.Any potential contact with glutaraldehyde

liquid or vapour, not contained by engineeringmeans, necessitates the wearing of protectiveequipment. This should include longsleevedgloves such as Marigold 'Blue Nitrile' or 'BiogelD' surgical gloves - other latex surgical glovesare not suitable; impermeable plastic apron,chemical grade eye protection or face shield, andrespiratory protective equipment suitable forremoving toxic organic vapours." After usecontaminated aprons should be disposed of in acontainer with a tight fitting lid.

If accidental spillage occurs, protective equip-ment as described must be used. The affectedarea should be closed to all unprotected staff, thespill should be contained with inert spillagegranules or suitable absorbent material and theroom well ventilated. All cleaning material andcontaminated clothes should be disposed ofimmediately in a container with a tight fitting lid.Any splashes to eyes or skin should be irrigatedimmediately with copious cold water. Any areain which glutaraldehyde is used should be pro-vided with a sink with running water and sterilewater for decontamination.

Monitor - atmospheric levelsMonitoring of atmospheric levels can be used torecord the effectiveness of control measures. Anaccepted technique for air sampling is theOSHA64 method12 in which air is drawn throughtwo filters impregnated with 2'4 dinitrophenylhydrazine and phosphoric acid; the stableglutaraldehyde derivative is trapped on the filterand eluted to be analysed by high performanceliquid chromatography. Commercially availableglutaraldehyde meters are less reliable and sub-ject to interference from other vapours withinthe atmosphere such as alcohol, perfume, andaftershave.Atmospheric monitoring should only be

carried out by a person competent in the task;occupational hygienists are trained in themonitoring and the analysis of exposure data.Static sampling may be carried out to evaluate

the effectiveness of engineering controlmeasures; 'breathing zone' samples may becollected to detect peak exposure during theperformance of tasks at particular risk such asactivating or decanting glutaraldehyde. It shouldbe noted, however, that if effective engineeringcontrol were instituted such procedures wouldbe enclosed or performed under local exhaustventilation.

Traditionally, air sampling results have beencompared with the occupational exposurestandard, which is currently a 10 minute time-weighted-average level of 0-2 ppm. This valueshould not be assumed, however, to indicate a'safe' level. It is known that sensitisation is mostlikely to occur after short high level exposure andother adverse effects are experienced at levelsbelow the occupational exposure standard.'3

Monitor - staff: health surveillanceIt is not only good clinical practice but also aCOSHH requirement that employees who maybe exposed to glutaraldehyde receive regularhealth surveillance. Pre-employment healthsurveillance should include enquiry regardingasthma, skin, and mucosal symptoms such asthose of rhinitis and conjunctivits. Pre-employ-ment lung function testing by spirometry tomeasure forced expiratory volume, forced vitalcapacity, and peak expiratory flow rate shouldalso be carried out. 14 Employees should bereassessed annually by questionnaire for theoccurrence of symptoms; spirometry on aregular basis in the absence of symptoms prob-ably has little value. Records of occupationalhealth surveillance should be retained for 30years. Any symptoms occurring between regularchecks should be reported to the occupationalhealth department and investigated appropri-ately. If a diagnosis of occupational dermatitis oroccupational asthma were to be made furtherexposure to glutaraldehyde should be avoided. Ifthis is not possible the employee must be madefully aware of the risks of continuing exposure.In dermatitis, a rigorously adhered to skin careprogramme may permit an employee to workwhere glutaraldehyde is used; in asthma the useof B2 agonists and inhaled steroids may reducesymptoms but may mask the continuingpresence of airways hyper-reactivity. Furtherexposure to glutaraldehyde under these circum-stances may lead to the continuation of asthmaeven after exposure to glutaraldehyde hasceased. Occupational asthma and dermatitis dueto glutaraldehyde are both prescribed diseasesbut are not reportable to HSE under theReporting of Injuries, Diseases and DangerousOccurrences Regulations 1985 (RIDDOR).

Educate and inform staffIt is the responsibility of the employer to informstaff of the risks of exposure to glutaraldehydeand train them in the control measures thatshould be used. It is the duty of employees totake part in such programmes and to useglutaraldehyde in the safe manner in which theyare instructed.6 An education and training pro-gramme might include: COSHH requirements;

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risks of glutaraldehyde exposure includingpotential symptoms; local policies and pro-cedures; safe working methods; the role ofventilation; use of protective equipment andclothing; how to cope with spillage; healthsurveillance arrangements. It should entail anassessment of knowledge and practice andperiodic review. Safe working procedures,including the use of personal protective equip-ment and spillage procedures should be availablein written form and distributed to all staff takingpart. Only staff who have satisfactorily com-pleted such a training programme should beauthorised to use glutaraldehyde for endoscopedisinfection. Out of hours emergency endo-scopy should be carried out only if endoscopyassistants are available who have been properlytrained in the safe use of glutaraldehyde.

The working party acknowledges the advice of A J Chamings,Chairman of the British Occupational Hygiene Society SpecialInterest Group for the Health Service, Dr C C Harling, Chairmanof the Association of NHS Occupational Physicians, Mrs DCampbell, Gastrointestinal Endoscopy Sister, Telford, Dr J VCollins, British Thoracic Society, and the secretarial assistance ofMrs R Feather.

This working party report was accepted by the endoscopysection committee of the British Society of Gastroenterology andapproved by the Council of the British Society ofGastroenterologyin July 1993.

Members ofthe endoscopy committee working partyDr R E Cowan (chairman), Colchester General Hospital, Dr A PManning (secretary), Bradford Royal Infirmary, Professor G A JAyliffe, Hospital Infection Research Laboratory, Dudley RoadHospital, Birmingham, Dr A T R Axon, The General Infirmary,Leeds, Mr J S Causton, HM Inspector, HSE, Chelmsford, MrN F Cripps, Health Building Standards Manager, West MidlandsRHA, Birmingham, Mr R Hall, Derbyshire Royal Infirmary, DrP J V Hanson, Department of Gastroenterology, Guy's Hospital,London, Dr J Harrison, School of Health Care Sciences,University of Newcastde, Mr R J Leicester, St George's Hospital,London, Sister C Neumann, Gastroenterology Laboratory,Dudley Road Hospital, Birmingham, Sister J Wicks, EtidoscopyUnit, Scunthorpe General Hospital.

1 British Society of Gastroenterology. Cleaning and disinfectionofequipment for gastrointestinal flexible endoscopy: interimrecommendations of a Working Party. Gut 1988; 29: 1134-51.

2 Axon ATR, Banks J, Cockel R, Deverill CFA, Neumann C.Disinfection in upper digestive tract endoscopy in Britain.Lancet 1981; i: 1093-4.

3 French HM. Safe use of glutaraldehyde in endoscopy units inGreat Britain 1990. Gastroenterology Today 1991; 2: 48-9.

4 Calder IM, Wright LP, Grimstone D. Glutaraldehyde allergyin endoscopy units. Lancet 1992; 339: 433.

5 McAdam JG, Leicester RJ. Incidence of aldehyde sensitivityin endoscopy units. Gut 1992; 33: S52.

6 Control of substances hazardous to health regulations 1988:approved code of practice control of substances hazardous tohealth and approved code of practice control of carcinogenicsubstances. London: HM Stationery Office, 1988.

7 Health and Safety Executive. Guidance Note EH40/92.Occupational exposure limits. London: HM Stationery Office,1992.

8 Broadley SJ, Furr JR, Jenkins PA, Russell AD. Antimyco-bacterial activity of 'Virkon'.J Hosp Infect 1993; 23: 189-97.

9 Tyler R, Ayliffe GAJ, Bradley C. Virucidal activity of dis-infectants: studies with the polio virus. J Hosp Infect 1990;15: 339-45.

10 Babb JR, Bradley CR. The mechanics of endoscope disinfec-tion.I Hosp Infect 1991; 18A: 130-5.

11 Department of Health. Glutaraldehyde disinfectants: use andmanagement. SafetyAction Bulletin (92) 17; appendix 4.

12 US Department of Labor. Occupational Safety and HealthAdministration. Analytical methods manual. 1987: Method64.

13 Jachuck SJ, Bound CL, Steel J, Blain PG. Occupationalhazard in hospital staff exposed to 2 per cent glutaraldehydein an endoscopy unit.I Soc Occup Med 1989; 39: 69-71.

14 Aw TC, Barnes A. Occupational health and the use ofchemicaldisinfectants: what is needed under the COSHH regula-tions. Journal of the Institute of Sterile Service Management1990; 1:7-8.

Further readingHealth and Safety Executive. Introducing COSHH. Leaflet 5/90;IND (G) 65L.Health and Safety Executive. Glutaraldehyde and YOU. LeafletZ/92; IAC 64 (L).Health and Safety Executive. Respiratory sensitisers. Leaflet 9/90;IND (G) 95L.Draft Approved Code of Practice. Control ofrespiratory sensitisers -consultative document. Available from Sir Robert Jones MemorialWorkshops, Units 3 and 5-9, Grain Industrial Estate, HarlowStreet, Liverpool L8 4XY.Babbs JR, Bradley CR, Decontamination of flexible fibreopticendoscopy. Gastroenterology Today 1991; 1: 25-7.Campbell M, Cripps NF. Environmental control ofglutaraldehyde.Health Estatesj 1991; Nov: 2-6.

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