Prevention Of Allergy To Laboratory Animals, Plants And Other Organic Matter

Prevention of Laboratory Animal Allergy

Because of the large size of the population exposed, the high risk of disease, and the potential severity of the consequences, laboratory animal allergy remains one of the most serious occupational disease risks for the University's staff and students. This University policy revises and updates the existing policy and incorporates new guidance issued in 2002 by the Health and Safety Executive (HSE).

In line with the HSE guidance, this policy places more emphasis on:

management of general health and safety issues

risk assessment
non-employees, such as students
use of individually-ventilated cages and isolators
respiratory protective equipment
health surveillance
audit of prevention measures

Departments and individuals are required to follow this University policy in order to comply with the law. Following this policy will reduce exposure to animal allergens and will ensure that new cases are detected at an early stage, thus reducing both the risk of new cases of disease and the risk of severe symptoms in affected staff or students. This policy does not deal with other health and safety issues in animal facilities, for example management of infection risks, which are covered in other University policy documents.

THIS STATEMENT FORMS PART OF THE UNIVERSITY SAFETY POLICY. APPENDIX 11 OF UNIVERSITY GUIDANCE NOTE S1/95 IS WITHDRAWN. PLEASE AMEND THE INDEX.

University Occupational Health - Service February 2003

University Safety Office - February 2003

1. Introduction

(a) General

This policy on the prevention of laboratory animal allergy (LAA) is intended to protect the health of all University staff and students, visiting academics and students, agency staff and contractors, and all other visitors. LAA is not confined to staff working in animal facilities. Furthermore, the policy extends beyond work regulated by the Animals (Scientific Procedures) Act (1986) (ASPA) to cover any work with the potential for exposure to animal allergens.

(b) Laboratory Animal Allergy

Many animals, including mammals, birds, fish, crustaceans, insects, amphibians, and their larval or egg forms, can cause allergy in man. Allergens are excreted in animal urine and are present in serum, saliva and other secretions. Animal grooming and other activity spreads allergen on to fur, skin and bedding. Levels of allergen may be high even in apparently clean and dust-free environments. Exposure occurs by inhalation and by contact with skin (including bites and scratches) or mucous membranes. LAA is a well-recognised and preventable occupational disease. Those who develop its more severe forms may need to seek a change of career; it also has the potential to lead to loss of employment, and/or long-term ill-health. Although symptoms usually develop in the first few months or years of exposure, they can develop at any time. The most common forms of laboratory animal allergy are rhinitis and conjunctivitis (similar to hay fever). Surveys have shown that around a third of people working with rats or mice may have rhinitis or conjunctivitis. Some people have urticaria (similar to nettlerash, or hives). Asthma is less common but, in some cases, can be severe and potentially life threatening. Anaphylactic shock is immediately life threatening but occurs rarely, usually after an animal bite or other puncture wound in a person with known LAA. The biological mechanism for LAA is thought to be allergic sensitisation, although it is not possible to detect the relevant antibodies in every case. Surveys have shown that the number of people who are sensitised outnumbers the number of people with symptoms. Once sensitisation has occurred, it is a permanent state and any symptoms will recur on re-exposure, sometimes at very low levels of exposure. Once a diagnosis of LAA has been made, prompt cessation of exposure is recommended to minimise the risk that symptoms will continue in the future after animal work has stopped. If the problem is recognised early and managed well, many people with mild symptoms can continue to work with animals and expect to have only minimal interference with work or home life.

2. Management of health and safety

Where staff are under the control of the Director of Biomedical Services (BMS), then the Director is responsible for their health and safety. Where staff are under departmental control, then the relevant head of department bears that responsibility. The Buildings and Estates Sub-Committee's "Grey Book" sets out the responsibilities of heads of departments with respect to building safety and to items of large, fixed equipment. The Director of BMS is responsible for ensuring that risk assessments are produced and implemented for activities carried out under his/her control. Where departmental staff (i.e. non BMS staff) students, or visitors carry out activities (e.g. animal procedures) where there may be exposure to animal allergens, either in the animal facility or in other areas, then the relevant head of department is responsible for ensuring that risk assessments are carried out and implemented.

3. COSHH assessment

Animal allergens are substances hazardous to health as defined by the COSHH regulations and the provisions of University Policy Statement S2/00 apply. An assessment of the risks to health created by any work involving animal allergens must be set out in writing, be readily accessible, and provided to individual workers or exposed visitors. The assessment must be reviewed:

annually
whenever a new case of LAA occurs
whenever control measures need review for other reasons (e.g. after a breakdown in room ventilation systems).

Appendix 1 lists the factors to be taken into account in the assessment. This can usefully form the basis of a set of local rules that set out the safe working practices to be adopted in the work. Appendix 2 lists items that should be included in the local rules.

4. Prevention and control of exposure

(a) General

A reduction in the use of animals will reduce the number of new cases of LAA and departments already consider alternatives to the use of animals as part of the Ethical Review Process. Restricting the number of people exposed, and the number of times each person is exposed, will also reduce the number of new cases of LAA. Departments must restrict entry to areas with animal allergen exposure to essential workers and, preferably, link entry to security systems for access.For those who must work with animals, it is often not possible to prevent exposure to animal allergens. Exposure must therefore be reduced to as low a level as reasonably practicable, using a combination of ventilation systems, systems of work, respiratory protective equipment (RPE), and personal protective equipment (PPE). No simple standardised method for measuring animal allergens is available and there is no occupational exposure limit against which to measure the efficiency of control measures.

Departments must ensure they have systems in place to prevent unnecessary exposure to those who do not need to work with animals. These systems include restrictions on access to animal areas, the use of filter-top cages for transportation of animals outside of these areas and measures for preventing the spread of animal allergens to clean areas on footwear and clothing. Further details are given below.

(b) Animal facility ventilation

For most laboratory animals, their welfare requirements or health status will determine their housing requirements. Most often, this involves the use of open cages in ventilated rooms. In the case of mice and rats, the use of individually ventilated cages (IVCs) and isolator units is increasing and these can provide better control of workers' exposure to allergens. The use of these systems is recommended, wherever possible, in preference to open caging.

Open cages in ventilated rooms

The environment provided in these rooms is primarily intended to comply with the animal welfare standards set out in ASPA. Generally, between 10 and 20 air changes per hour (depending on species) will provide suitable air quality for the animals. Careful design and position of air inlets and outlets can also provide a degree of control of exposure to animal allergens for workers. For example, supplying air at or near ceiling level and exhausting it at low level avoids contaminated airflow in a worker's breathing zone.

However, the nature of open caging means that there will always be a relatively high level of animal allergens in the room air. Suitable RPE/PPE may therefore be needed in this environment, even when animals are not being handled.

Containment of allergens within the animal holding rooms is best achieved by keeping the rooms at negative pressure relative to corridors and by keeping the facility as a whole at negative pressure relative to its surroundings. Doors to animal rooms should be kept closed as far as possible, so that ventilation systems can operate at their design efficiency.

In some cases (e.g. in order to maintain pathogen-free status), users may seek to positively pressurise animal holding rooms. This jeopardises the control of allergens outside the room and it is preferable to identify some other means of achieving the desired result (e.g. using flexible film isolators). If the use of positively pressurised rooms cannot be avoided, then the manager of the animal facility must inform both the Safety Office and the Occupational Health Service.

Individually ventilated cages and isolators

IVCs and isolators can be an effective way of reducing exposure to animal allergens, provided that they are sealed systems and the animals are not being handled outside of the containment. These types of enclosed caging systems can reduce the likelihood of transfer of allergens from cage to room. The use of RPE will not therefore normally be needed, unless animals are being handled outside of the containment or dirty bedding is being removed from cages.

IVCs or isolators may be operated at negative or at positive pressure. In the latter case, this is done to protect the health status of the animals. Air may only be returned to the room from positive pressure IVCs or isolators if it first passes through a HEPA filter.

(c) Design of animal facilities

Other aspects of animal facility design help in the control of exposure to animal allergens. The following points will be taken into account by the University Surveyor's Office in the design of any animal facility.

Adequate hand washing facilities must be provided. Floors, walls and ceilings should be impervious, continuous and without sharp corners, in order to facilitate cleaning. Facilities for washing, changing, eating, and drinking should be situated so as to prevent the spread of allergen contamination. These facilities should be conveniently accessible to the work areas, so that staff can wash and change before eating and drinking. Office facilities should be similarly situated so as to avoid their contamination with animal allergens.

(d) Systems of work

Departments should ensure that their working practices are designed to minimise the release of allergens into the atmosphere.

Stock density and type of animal

Stock density should be kept as low as practicable (the concentration of allergens increases linearly with stock density). In some species (e.g. rats, mice and ferrets) female and young animals have been shown to be considerably less allergenic than adult males. Researchers should consider their use whenever experimental considerations permit.

Room cleaning

Rooms must be kept as free as possible from dust and suitable cleaning methods should be used to achieve this. Dry sweeping generates significant airborne allergen concentrations and must not be used. Surfaces may be damped down before sweeping, or a wet method may be used. The use of HEPA-filtered vacuum cleaners is the most effective way of minimising airborne allergen concentrations. Noise disturbance, from audible or ultrasound, may be a significant animal welfare issue. Equipment should be suitably silenced, or fitted with extended hoses, to avoid this.

Cage emptying and cleaning of open cages

Cage emptying and cleaning presents a high risk of exposure to animal allergens. Significant exposures occur when transferring animals from dirty to clean cages, when removing dirty bedding, and when cleaning cages. Designated cleaning areas should be provided. Cage cleaning inside animal holding rooms should be avoided. It is especially important to avoid cage cleaning and subsequent allergen contamination in corridors. (Corridors are normally kept at higher relative pressure than animal-holding rooms and should therefore be areas of lower allergen concentration). While general ventilation systems give some control of allergen exposure during these operations, the use of RPE will also be required. Properly designed cage scraping and cage cleaning stations should be used whenever possible. These should be designed with an inward airflow of sufficient velocity (normally at least 1 metre/second) to draw airborne allergens away from the user into the extraction system. Effective allergen control with this equipment depends on correct design, installation, use, and maintenance, so the manufacturer's recommendations should be followed. In addition, an annual examination and test must be carried out to comply with the COSHH Regulations. As an alternative, HEPA-filtered vacuum cleaning systems may be used with cleaning tools designed to scrape and collect bedding. The cleaner will need to be large enough to deal with large volumes of bedding. It may need to be silenced or fitted with extended hoses. Care will be needed when emptying the contents of these cleaning systems. Those carrying out this task will need to use PPE and suitable RPE (e.g. a powered respirator).

Procedures on animals

Many procedures (e.g. shaving) can cause significant allergen exposures.

Fur residues from shaving must be cleaned up using a HEPA-filtered vacuum cleaner, or by a damp cleaning method. The use of hand-held vacuum cleaners for this purpose poses a significant risk of allergen spread and exposure, so these devices must not be used for this purpose. General ventilation in procedures rooms should follow the principles used in animal holding rooms. Rooms that are designated SEP (i.e. for sterile procedures) must be maintained at positive pressure to the corridor to protect the sterile environment. In this case, control of animal allergens must be achieved by maintaining the unit overall at negative pressure relative to its surroundings. The use of local exhaust ventilation (LEV), e.g. laminar downdraught cabinets with inward airflow, microbiological safety cabinets, or flexible film isolators, will help to control exposure, but if such controls are not available, then the use of RPE/PPE may be required.

Animal bedding

Careful choice of bedding can reduce dust levels and associated airborne allergen concentration. Various types of "dust-free" bedding are available, though they may become dusty when broken down by animal activity. However, the bedding chosen will need to take account of animal welfare requirements as well as the potential to reduce allergen levels.

(e) Respiratory protective equipment (RPE) and personal protective equipment (PPE)

Although ventilation systems and other engineering control measures are the primary means of control of exposure to animal allergens, airborne levels can still be significant in some tasks and areas. RPE will often be needed as well in order to achieve adequate control of inhalation exposure and PPE will be needed to limit skin contact with allergens. PPE also serves to control their spread outside animal-using areas.

It is important to realise the limitations of RPE and PPE:

it must be carefully selected (it must fit and it should not restrict the wearer's ability to work safely)
it must be put on, worn, and removed properly
it only protects the wearer
it may limit the wearer's ability to communicate or to carry out normal tasks
it must be properly stored, cleaned and maintained
users must be properly trained and supervised.

RPE – use

RPE must be worn:

when cleaning cages
when transferring animals into clean cages
by individuals spending significant time in rooms with open caging (especially BMS staff, but some research staff may also fall into this category)
when carrying out procedures where the risk assessment suggests there will be significant exposure
when cleaning or maintaining RPE/PPE
by people with LAA, following the advice and under the medical supervision of the Occupational Health Service.

RPE should also be worn:

by inexperienced workers, e.g. students, when being trained
by individual workers on request where they wish to minimise their exposure to animal allergens, e.g. when working (even for short periods) in rooms with open caging.

RPE – selection

For effective control of exposure to animal allergens, RPE must be of a suitable type and standard, and must be correctly fitted and worn. A number of different types of RPE are available, e.g. disposable dust respirators, disposable half-mask dust respirators, half-mask dust respirators with disposable filters, and powered respirators with ventilated hoods, visors, or helmets. Appendix 3 gives more information on RPE.

As a minimum, disposable dust respirators with appropriate CE marking conforming to BS EN 149:2001 FFP2 must be provided. Powered respirators are especially recommended for high exposure procedures, such as scraping cages, emptying the contents of HEPA-filtered vacuum cleaners, or changing filters on room ventilation systems. Surgical masks and nuisance dust masks provide no protection against animal allergens and must not be worn for that purpose.

RPE - fitting and use

RPE is effective only if properly fitted and used. In the case of disposable dust respirators and half-mask respirators, their effectiveness depends on a good seal between the respirator and the face. Consequently, one make or size of respirator will not necessarily fit all sizes and shapes of faces and it may be necessary to trial and/or purchase a number of respirators in order to ensure a good fit for all users.

Disposable respirators and half-mask respirators will not be appropriate for those with beards or facial hair in the area of the seal. In this case, powered respirators with ventilated hoods, visors, or helmets must be used. Powered respirators may also be more suitable for those whose work requires significant manual effort. They can provide higher levels of protection and can sometimes be used by people with LAA. (This must only be on the advice and under the medical supervision of the Occupational Health Service).

RPE - pathogen-free facilities

In these facilities, workers must adopt stringent standards of hygiene and wear clothing that prevents them transmitting infectious agents to the animals. They will also need to be provided with suitable protection against animal allergens. For example, the use of surgical masks provides protection for the animals but none for the worker, whereas disposable respirators without exhalation valves provide protection for the worker as well as for the animals.

PPE – clothing

The best allergen control is achieved by a complete change of outer clothing and shoes, together with the use of a shower. On entering the facility, all personnel should either change into appropriate protective suits or, as a minimum precautionary measure, place laboratory coats, which are only for use in the animal facilityover their ordinary clothing. Protective suits and laboratory coats should preferably have side or back closures, be capable of being fastened up to the neck, and have close fitting cuffs on long sleeves. Animal facility clothing should be distinguished by colour to help ensure that allergen-contaminated clothing is not worn outside the facility.

PPE – footwear

Impervious boots or plastic overshoes are often used to protect the health status of the animals. They also have practical value in preventing the spread of allergens and should be put on when entering the facility and removed on leaving.

PPE – caps

Caps are used to protect the health status of the animals. They also protect the hair from contamination with animal allergen and should be worn to prevent transfer of allergen.

PPE – gloves

The use of disposable gloves and protective sleeving can afford protection against skin contact with animal allergens. They are particularly appropriate for protection against urine and contaminated bedding. Where worn, they should be of sufficient sensitivity to allow animals to be handled without distress. (As well as considerations of animal welfare, animals that are actively moving shed more allergen).

Where gloves cannot be worn, then particular attention must be paid to regular hand washing and the use of suitable moisturisers and emollient creams. Wearing gloves and/or regular hand-washing will also help reduce the spread of animal allergens outside the animal facility.

RPE and PPE - disposal of used or contaminated items

Suitable sealed containers (e.g. flip-top bins with lids) should be available for the disposal of used respirators, respirator cartridges, caps, overshoes, and gloves. Sealed containers for contaminated clothing should also be provided.

RPE and PPE – cleaning

Non-disposable RPE must be regularly cleaned in accordance with the manufacturer's instructions. To avoid exposure to animal allergens, this must be done using LEV, or by individuals wearing suitable RPE.

Facilities for laundering coats and overalls must be available, preferably situated within the animal facility. Contaminated cleaning must not be taken home for washing and must not be sent out of the animal facility for laundering without taking precautions against the spread of allergens (e.g. the use of water-soluble laundry bags). Note that RPE must be worn when handling contaminated RPE/PPE.

5. Maintenance, examination and testing of control measures

All equipment used as a control measure under COSHH must be properly maintained, and periodically examined and tested to ensure it remains in good working order. In addition, frequent visual checks will help in the early identification of potential problems.

(a) Ventilation systems

General ventilation systems, including room supply and extract systems, must be maintained in good working order. Room ventilation rates must be tested at least every two years. (The University Surveyor is responsible for ensuring that maintenance and testing is carried out). LEV (e.g. cage scraping and cage cleaning stations) must be thoroughly examined and tested annually by a competent person. Records must be kept for at least five years. In addition, visual checks should be made monthly on the airflows of animal rooms and LEV. This may be done simply by holding tell-tale streamers (e.g. strips of tissue paper) in the airflow and observing the direction and strength of movement, or by the use of smoke-generating tubes, anemometers, or micro-manometers. A record should be kept which should be retained for one year.

(b) RPE

Non-disposable RPE must be thoroughly examined, tested, and maintained at least monthly, according to the manufacturer's instructions. Departments should nominate an individual or individuals to do this. A simple record of these checks should be made for each item of non-disposable RPE, and this must be kept for at least five years. Care must be taken to ensure that RPE is stored in such a way as to prevent contamination with animal allergens and suitable facilities should be provided for this.

6. Use of control measures, including RPE/PPE

COSHH requires employees to make full and proper use of any control measure provided, including RPE/PPE, and the University requires that non-employees, such as students or visitors, follow the same rules. The Director of BMS and the relevant heads of departments are responsible for ensuring that their staff use the specified control measures. They should devise management systems to ensure that all their workers use control measures, including wearing RPE/PPE, wherever and whenever they are required.

7. Information, instruction and training

All those who are, or may be, exposed to animal allergens should receive relevant information, instruction, and training so that they are aware of the risks involved in their work and the precautions needed to control exposure. This should be part of the induction procedure for new animal facility staff, students, researchers, and academics. It should include:

the causes of LAA
the symptoms of LAA
how to use any control measures provided, including equipment, safe systems of work and RPE/PPE
where to obtain RPE/PPE
where and when to use RPE/PPE
details of health surveillance arrangements
where to seek confidential medical advice should symptoms develop.

8. Health surveillance and employment issues

Health surveillance is a legal requirement under COSHH, because it is currently not possible to completely control the risk of LAA by controlling exposure.

(a) Recording exposed jobs, projects and workers

The Director of the BMS and relevant heads of departments must maintain confidential records of workers with significant animal allergen exposure. Where names are not known (e.g. a new research group, or maintenance staff from the University Surveyor's department) the group should be included in the list. The system for generating the list should be linked to:

recruitment of staff
admission of students
acceptance of visiting researchers and students
registration in to health surveillance
induction process for new staff and students
card entry or other access control system.

What is significant animal allergen exposure?

Everyone who is required to work with live animals for, broadly speaking, at least three hours a day, at least one day a week, for at least two months, should be included in the confidential record. If exposure is judged to be particularly intense, then a shorter time should be set. In addition, people who carry out in vitro work with significant exposure to animal allergens should be included. If in doubt, an Occupational Health Service risk assessment form should be completed and the Occupational Health Service will carry out an individual risk assessment.

(b) Recruitment and job descriptions

Job descriptions (and descriptions of course work, visitor programmes etc) must contain enough detail for people with pre-existing animal allergy to make an informed decision on whether to apply. It is also important to describe the requirements for RPE/PPE because some people may be unable to use the required equipment.

Where practicable, work with live animals should be restricted to experienced workers because this causes the minimum of disturbance, and hence animal allergen exposure. When it is necessary for an inexperienced worker, such as a student, to handle live animals, it should be under the supervision of a trained worker and with the use of appropriate RPE/PPE.

Job/course offers

It is potentially dangerous to expose people with pre-existing LAA to animal allergen. Therefore, job offers for staff who are required to work with animals (or the equivalent procedure for students or visitors) must be conditional on a satisfactory health clearance from the Occupational Health Service, even if the worker is transferring from one University post (or course) to another. Occasionally, the Occupational Physician may advise that animal work is not appropriate for an individual.

(c) Health surveillance

Health surveillance is mandatory under COSHH in order to detect the early signs of LAA and take action to reduce the risk of a severe allergic reaction and of long-term respiratory impairment. Workers with significant exposure must be registered with the Occupational Health Service. Line managers must allow workers time during the working day to attend appointments. Workers must attend health surveillance appointments.

Periodic health surveillance

After the initial health assessment, a questionnaire will be sent to the individual at his/her department at six weeks, three months and one year; and thereafter at yearly intervals, or intervals decided by the Occupational Health Service. Workers must return the completed questionnaires in confidence to the Occupational Health Service. Some workers, such as animal technicians, will be enrolled in enhanced health surveillance carried out by the Occupational Health Service staff. The Occupational Health Service will notify administrators and BMS administration about the worker's continuing fitness for work with animals but will not disclose personal medical information without permission from the worker. Symptoms that suggest possible LAA will be investigated further by the Occupational Health Service, which may advise a temporary suspension from animal work pending the results of tests.

(d) Procedures following a new case of LAA

A new case of LAA shows that allergen exposure is, or has been, sufficiently high to cause sensitisation. The working environment may cause further new cases, or lead to severe symptoms in workers whose LAA was previously well-controlled. The BMS and relevant departments must have written procedures for responding promptly to a new case of LAA after it has been confirmed by the Occupational Health Service. The procedures should include measures to:

protect the worker with LAA
review the COSHH assessment and control measures, in conjunction with the Safety Office and the Occupational Health Service
record this action.

Protection of the worker with LAA

Ideally, workers with LAA should avoid all exposure to animals and should, if possible, be redeployed elsewhere in the University. In practice, workers with milder forms of LAA can continue to work with animals if the problem is managed well. If an affected worker needs to continue such work, even on a temporary basis (for example to complete a research project), then this should only be considered by the department after consultation with the individual concerned and under the medical supervision of the Occupational Health Service. For the individual, there may be a personal conflict between protecting his/her health and continuing the project or job.

In addition to the general review of departmental working practices referred to above, the Occupational Health Service will undertake an individual review of controls, including the use of RPE/PPE and the use of medication, for the affected worker. The Occupational Health Service will make frequent health assessments of workers with LAA who are continuing in work and will notify the department of changes in fitness to work status, without disclosing confidential personal medical information.

Other issues in LAA

The Occupational Physician will also advise on various related matters and, if requested, will provide necessary medical reports. These matters include:

the need for reporting under the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (RIDDOR)
impairments and adjustments under the Disability Discrimination legislation
medical aspects of early retirement on grounds of ill-health
eligibility for industrial disease benefit through the UK social security system