Biological Agents and Agriculture

Introduction
Legislation
Risk assessment
Preventing and controlling risks
Zoonoses
Non-infectious biological factors
Further information

Introduction

Biological agents are found in many sectors. As they are rarely visible, the risks they pose are not always appreciated. They include bacteria, viruses, fungi (yeasts and moulds) and parasites.

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Legislation

‘Biological agents’ refers mainly to three groups of micro-organisms:

bacteria,
fungi (yeasts, moulds, etc.) and
viruses.

Biological agents in the European Directive 2000/54/EC on the protection of workers from risks related to exposure to biological agents at work also include:

genetically modified microorganisms,
cell cultures and
human endoparasites.

Biological agents are classified in the directive into four risk groups according to their level of risk or infection emanating from them and the possibililites of prevention and treatment.

Risk group 1: Biological agents which are unlikely to cause human disease
Risk group 2: Biological agents that can cause human disease and may be a hazard for workers; they are unlikely to spread to the community; there is usually effective prophylaxis or treatment available
Risk group 3: Biological agents which may cause severe human disease and are a serious hazard to workers; they may present a risk of spreading to the community but there is usually effective prophylaxis or treatment available
Risk group 4: Biological agents which cause severe human disease and are a serious hazard to workers; they may present a high risk of spreading to the community; there is usually no effective prophylaxis or treatment available

European legislation aims to minimise the health risks from biological agents in the workplace. The list of biological agents provides indications of allergenic potential and toxic effects. Measures proposed include containment categories for laboratory work and industrial processes.

The Directive also lays down requirements for notification of selected activities to authorities. For workers likely to be exposed to certain biological agents, employers have to keep records including information about exposure and health surveillance. Workers have to be provided with access to their personal data.

These requirements are minimum requirements and have been implemented into national legislation. Some Member States have introduced Codes of Practice and guidelines for safe handling of biological agents including selected sectors and occupations. It is therefore important to refer to the relevant national regulations related to biohazards at workplaces.

It is advisable to consult national legislation about handling biological agents in the workplace which should include classification tables of hazardous biological agents (microorganisms and parasites) related to risk level, a basis for risk assessment and preventive measures to take when using these substances.

The Directive requires the employer to

assess the risks posed by biological agents, and
reduce the risk to the workers by
- elimination or substitution
- exposure prevention and control
- information and training of the workers, and
- provide health surveillance as appropriate.

Currently, no occupational exposure limits have been set for biological agents, although some Member States have set limits for their toxins. The essential difference between biological agents and other hazardous substances is their ability to reproduce. A small amount of a microorganism may grow considerably in a very short time under favourable conditions.

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Introduction

Risk assessment is a requirement under European legislation enacted in all Member States. Risk assessment means identifying what may cause harm so that preventive measures can be taken. Proper risk assessment is the basis for successful risk management.

When a work activity involves the deliberate, intentional use of biological agents, such as cultivating a micro-organism in a microbiological laboratory or using it in food production, the biological agent will be known, can be monitored more easily and prevention measures can be tailored to the risk posed by the organism. Information about the nature and effects of the biological agent used should then be included in the inventory of hazardous substances.

When the occurrence of the biological agents is an unintentional consequence of the work, as is often the case in agriculture, the assessment of risks that workers are exposed to, will be more difficult. Nevertheless, for some of the activities involved, information on exposures and protection measures is available.

A four-step approach to risk assessment

Make an inventory of the substances used in the processes in the workplace and those generated by the process such as aerosols of blood or urine. Assess substances used at work including any new substances introduced.
Collect information about these substances, i.e. the harm they can do and how this can happen.
Assess exposure to the identified dangerous substances, looking at the type, intensity, length, frequency and occurrence of exposure to workers,
Rank the severity of the established risks. This list can then be used to draw up an action plan to protect workers.

Consider whether existing measures in place give adequate protection and what more should be done to reduce risks. Is it possible to get rid of the risk altogether by using a different agent or process? If the exposure is not avoidable, it should be kept to a minimum by limiting the number of exposed workers and the exposure time. The control measures must be tailored to the working process, and the workers must be well trained to follow safe working practices.

Review and revise your assessment where necessary, when there are significant changes in materials, equipment, work methods, location or people involved and if there are accidents or complaints associated with the work

Biological hazards in agriculture

In agriculture, forestry, horticulture, and animal food and fodder production, workers are at risk from:

bacteria, fungi, mites, and viruses transmitted from animals, parasites and ticks (zoonoses);
respiratory problems due to microorganisms and mites in organic dusts of grain, milk powder, flour, spices; and
Specific allergic diseases like farmer’s lung and bird breeder’s lung.

Workers in agriculture are at risk of being exposed to sensitisers (substances producing an allergic reaction).

Common skin sensitisers in agriculture include:

animal proteins from urine and dander;
flour; and
some vegetables, plants, and spices.

Workers in agriculture may be exposed to respiratory sensitisers:

animal epithelia and urine;
decorative plants;
some foodstuff, plants and vegetables (e.g. coffee bean dust, egg proteins, flour and grain dust, fruits, vegetables, fish, seafood, soybean dust, spices);
storage mites;
moulds;
some wood dusts incl. composite boards; and
textile fibres (e.g. silk during sericulture)

Who might be harmed

If you have identified an activity where workers may be exposed to biological agents, collect information about these exposures. Think about the people directly involved and also others who might be affected such as cleaning personnel. Look at how the work is actually done, rather than how it should be done or how you think it’s done.

People are at risk of being exposed to biological agents whenever they are in contact at work with:

natural or organic materials like soil, clay, plant materials (hay, straw, cotton, etc.);
substances of animal origin (wool, hair, etc.);
food;
organic dust (e.g. flour, paper dust, animal dander);
waste, wastewater;
blood and other body fluids.

Health effects

Biological agents can cause three types of disease:

infections caused by parasites, viruses or bacteria,
allergies initiated by exposure to mould organic dusts like flour dust and animal dander, enzymes and mites, and
poisoning or toxic effects.

Some biohazards have the potential to cause cancer or foetal harm. Microorganisms can enter the human body via damaged skin or mucous membranes. They can be inhaled or swallowed, leading to infections of the upper respiratory tract or the digestive system. Exposure also occurs accidentally by animal bites or needle stick injuries.

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Prevention

Introduction
Elimination and substitution
Control
Monitoring and review
Training
Information for workers

Introduction

European legislation provides a hierarchy of measures to prevent or reduce the exposure of workers to dangerous substances.

Elimination
the best way to reduce the risks connected with dangerous substances is to remove the need to use those substances by changing the process or product in which the substance is used.
Substitution
if elimination is not possible, then the substitution, or replacement, of the hazardous substance or the process with one less dangerous under its condition of use is the next best option.
Control
where the risks to workers are not prevented, control measures should be implemented to remove or reduce the risks to workers’ health.

In some cases, where a disease can be prevented by vaccination, this should be provided to workers on a voluntary basis.

Elimination and substitution

Any avoidable exposure to dangerous substances should be eliminated. This may not be easy for many of the biological hazards faced in agriculture. Changing from one substance to another is a three-stage process:

Identify the alternatives (process or substance change).
Compare the alternatives: carry out a risk assessment of all the alternatives, including the substance or process used, and compare your findings. Check relevant national legislation on occupational safety and health, as well as environmental and product safety legislation to ensure that the options are legal and compatible, and ascertain the minimum standards that you have to achieve.
Make the decision: take the decision based on the regulatory needs, technological possibilities, potential implications for the quality of the products, costs, including the required investment, and training for use of the new product.

Control

If elimination or substitution is not possible, the following control hierarchy should be followed when elimination and substitution is not possible:

Design work processes and controls, and use adequate equipment and materials to reduce the release of dangerous substances, for example by enclosure of the emitting process or providing local exhaust ventilation (LEV).
Apply collective protection measures at the source of the risk, such as ventilation and appropriate organisational measures such as minimising the number of exposed workers and the duration and intensiveness of the exposure;
Apply individual protection measures including personal protective equipment where exposure cannot be prevented by other means.

Minimise the exposure concentration, time, frequency and number of workers exposed. Decide whether existing precautions are adequate or if more should be done. Investigate whether model instructions and guidelines are available. If work practices are changed, changes of exposure should be evaluated.

Managing emissions at the source

Managing emissions at source is the best way to control exposure. Include systematic dust and aerosol prevention by:

modifying the working process. Avoid work procedures producing dusts, aerosols or vapours
using substances in a less hazardous form e.g. as pellets or pastes instead of powders or liquids
using closed systems for filling and transferring e.g. powdery substances or fibres
controlling exposure with effective encapsulations, local exhaust ventilation(LEV), fume hoods, general ventilation, splash guards, screens, and other workplace arrangements;
drawing up a maintenance and cleaning plan including intervals, cleaning methods and devices. Use wet methods or vacuum cleaners instead of brooms.

Controlling risk by good animal husbandry

In some cases the risks to humans can be controlled if you follow good husbandry practices to help prevent animals carrying or excreting large numbers of the disease-causing organisms. These practices include the following:

ensure good standards of hygiene in young-stock housing;
avoid contaminating animal drinking water with dung;
keep animals, especially young, as stress-free as possible - particularly important on farms that open to the public;
have regular stock health checks by a vet.

In some cases it is possible to reduce the risk of contracting a zoonosis by controlling the disease in the animal, for example, vaccinating cattle against Leptospira hardjo or using salmonella-free feed for pigs and poultry. This has the added benefit of not only protecting workers, but also having economic benefits of improved animal health.

Control by work practices

The steps needed to remove or reduce the risks to workers will depend upon the particular biohazard, but there are a number of common actions that can be applied:

Many biological agents are communicated via air, such as exhaled bacteria or toxins of mouldy grain. Avoid the formation of aerosols and dusts. Ensure that this is also taken into account when cleaning or during maintenance operations.
Good housekeeping, hygienic working procedures and use of relevant warning signs are key elements of safe and healthy working conditions.
Many microorganisms have developed mechanisms to survive or resist heat, dehydration or radiation, for example by producing spores. Include decontamination measures for waste, equipment and clothing and appropriate hygienic measures for workers. Include instructions for safe disposal of waste, emergency procedures, and first aid.

Consider the following:

avoid or minimise the use of equipment or tools likely to cause cuts, abrasions or puncture wounds, and use safe working practices and PPE where appropriate;
when taking blood samples, use vacuum tubes rather than syringes and put all used needles into a sharps box of an appropriate standard. Label and dispose of the box safely, but not in your domestic waste;
do not use mouth-to-mouth resuscitation on newborn animals – use traditional husbandry methods of resuscitation such as massaging or clearing nostrils with straw;
avoid handling birth fluids or afterbirths with bare hands and bury or burn them;
control or eliminate rats, and use a fork or shovel, or wear gloves, to move dead rats.

Personal Protective Equipment

Personal respiratory protective devices should be used in addition to other practicable control measures if exposure cannot be otherwise prevented. It has to comply with EU regulations.

Select the most suitable protective device for each work task or exposure. Refer to the producer’s guidance for appropriate choice
Respirators should only be used by one worker and not be shared.
In regular use, the device should be kept in good condition, cleaned after use, filters changed as appropriate and the device checked for technical or other damage.
Make sure equipment for personal use, such as gloves, is carefully selected, worn, maintained and replaced.
General selection guides for gloves and clothing are available.
Protective gloves and boots can cause allergies themselves, especially when made of latex rubber or leather tanned with chromium-containing substances. Avoid their use.
Lay down written procedures for regular cleaning, disinfecting, storing, inspection, repairing, discarding and maintaining respirators.

The use of personal protective equipment should be a last resort when all other means of preventing or controlling the risk are insufficient. Times when it may be necessary include:

When helping animals to give birth, handling afterbirths, working with obviously infected stock (e.g. with orf or ringworm), examining mouths or during rectal examinations. Suitable PPE will include a waterproof apron or parturition gown, obstetric gauntlets for calving/lambing etc and plastic or synthetic rubber gloves for oral or rectal examinations;
When there is a risk of splashing from urine or placental fluids. Use face protection (for eyes and mouth).

Personal hygiene

Any work with animals inevitably involves contact with dung and urine, which contain disease-causing organisms. Personal hygiene is therefore vitally important. If you are an employer, provide washing facilities wherever staff or visitors work with animals (at least, clean running water and paper towels). Make sure that you and your staff:

wash cuts and grazes immediately with soap and running water;
cover new and existing wounds with a waterproof dressing before beginning work - some organisms enter the body through open wounds. Consider whether you or your staff need first-aid training;
wash hands and arms before eating, drinking or smoking after contacting animals, or working in areas with animal dung.

Monitoring and review

Once a control measure has been implemented in the process, its effectiveness should be monitored. Regular evaluation of the situation is needed to detect slowly deteriorating situations (e.g. reduced effectiveness of ventilation systems) and changes in the work practices.

For workers likely to be exposed to certain biological agents , employers have to keep records including information about exposure and health surveillance. Workers have to be provided with access to their personal data. These regulations have to be transferred into national legislation.

Monitor exposure and health problems regularly and re-assess, especially if the working methods are changed. In case of respiratory symptoms that could be related to work, medical examinations should be performed. Record the findings. Any skin disorder which is suspected to be associated with work should be reported immediately and a medical examination performed. Fellow workers who do the same job may also have similar skin problems.

Training

Training workers on the basis of risk assessment for safe work practices is an important part of risk management. Trained workers can not only work more efficiently, but can also work safer and with less risk to their health. The risk posed by a substance is determined by two factors, the substance’s characteristics and the degree of exposure. By training workers they should be aware of what the risk of exposure is and what they need to do to control their exposure.

Information for workers

Workers should be informed of the risks they face and the preventive measures in place to control those risks. They need to know how to work safely and how to use protective equipment, where required.

The employers also have to ensure that the workers and/or their representatives are informed and trained on:

the hazardous properties of the chemical agents handled;
the level, type and duration of exposure and the circumstances of work involving such agents;
appropriate precautions to safeguard themselves and other workers at the workplaces;
the effect of risk-management procedures taken or to be taken;
relevant occupational exposure limit values or biological limit values;
and where available, the conclusions to be drawn from any health surveillance and exposure assessment already undertaken.
To whom potential health problems should be reported
How to check their skin if exposed to substance that may cause dermatitis or other skin problems.

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Zoonoses

Introduction
Common Zoonoses

Introduction

All farm animals naturally carry a range of diseases, some of which can also affect humans. These diseases are known as zoonoses, and if you work with animals your health may be at risk from them.

Diseases transmitted from animals to humans can also affect visitors to farms - especially children or the elderly, who are more vulnerable to infection. These illnesses include those resulting from infection with the organisms Escherichia coli O157 (E coli O157) and Cryptosporidium parvum. If you open your farm to the public you should take special precautions to make sure that they are not made ill by zoonoses.

The precautions to be taken to minimise the risk of an infection by a zoonoses are the same as with the any other hazardous biological agent:

managing the risk at source;
controlling the risk by good animal husbandry;
control by work practices
personal protective equipment
personal hygiene

If you think that you are ill because you have contracted a disease from an animal, you should consult a doctor quickly. Tell your doctor if you work in agriculture or come into contact with farm livestock.

Common zoonoses

Escherichia coli O157 (E coli O157)

E coli O157 is a bacterium that lives in the gut of animals, including cattle, sheep, deer and goats. It is also carried by pets and wild birds. Simply carrying the bacteria will not normally cause an animal any harm or illness. In humans, however, the toxins it produces can cause illness ranging from diarrhoea to kidney failure. In some cases the illness can be fatal.

E coli O157 is unusual in that very few individual organisms are needed to infect humans. Infection can be caused by contacting animal dung, and then putting hands or fingers in the mouth, or eating food without washing hands. It is vital that anyone who works with or touches animals thoroughly washes their hands and arms before eating, drinking or smoking. Workwear should be left at the workplace for cleaning so that the families of those working on the farm cannot contract the disease by contact with soiled clothing.

Cryptosporidiosis

This disease, which may cause diarrhoea and abdominal pain with ’flu-like symptoms for up to six weeks, especially in the young and the old, is caused by a protozoa called Cryptosporidium parvum. It is carried by calves, lambs, deer and goats and may be
transmitted to humans by contact with animal dung or drinking water contaminated with dung. Assume that all your cattle, sheep, deer and goats carry E coli O157 and cryptosporidium.

Leptospirosis

There are two main forms of leptospirosis that may affect those working in agriculture:

Weil’s disease, from the bacterium Leptospira icterohaemorrhagiae, and
Cattle-associated leptospirosis, from the bacterium Leptospira hardjo.

Weil’s disease is usually contracted from infected rat’s urine or watercourses contaminated with it. Most rats probably carry the bacteria at some point in their lives. It is most commonly passed to humans through cuts and grazes, especially on the hands. It may result in fever, headache, vomiting and muscle pain, and can lead to jaundice, meningitis and kidney failure. In rare cases it can be fatal.

Cattle-associated leptospirosis (CAL) is usually contracted after cattle urine has splashed into the eyes, nose or mouth, after urine or placental products have entered the body through broken skin, or after inhaling droplets of urine.

In humans the symptoms are ’flu-like with a severe and protracted headache. Without treatment they can persist for up to six weeks and in some cases meningitis, jaundice and kidney failure can occur.

The risk to human health is greater if a herd has recently been infected - consult your vet for information on this. If this is the case, consider wearing a face shield if your face or eyes are likely to be splashed with urine, or using a powered respirator to reduce the risk of inhaling any aerosol. Note that vaccinating cattle against CAL does not prevent them shedding the organism and possibly passing the disease on to humans.

Bovine tuberculosis

Bovine TB is most commonly carried by cattle, badgers and deer, and can infect humans by inhalation or hand to- mouth contact. People handling infected cattle are at risk, especially if they become contaminated with mucus from the respiratory tract (e.g. by holding the animal’s nose) and then do not follow the basic rules of good personal hygiene.

Salmonella

The salmonella bacterium may be carried by most types of farm animal, and can result in diarrhoea, fever and abdominal pains in humans. Occasionally more serious illness will result from contact with the organism.

Although salmonella is usually thought of as resulting from eating contaminated food, it may frequently result from contact with farm animal dung. Humans may be infected when the salmonella organism gets into the gut - usually when you put your hands contaminated with dung in or close to your mouth, e.g. during eating, drinking or smoking. Hand-to-hand contact is also an important source of infection.

Streptococcus suis (S suis)

S suis is a bacterial infection carried by pigs, often without any symptoms in the animal. It can be contracted by humans through cuts and grazes, or possibly by inhalation, and may result in meningitis or death. To control the risk follow the advice in the ‘Precautions’ section, and use good husbandry to eliminate the disease in stock.

Orf

Orf is caused by a virus carried by sheep and goats - lambs often show most symptoms - and may cause face, hand or arm ulcers if you contact lesions on animals or infected wool, fencing or hedges. Treatment is not usually needed as the lesions heal within six to eight weeks.

Ovine chlamydiosis (enzootic abortion of ewes - EAE)

EAE is caused by the organism Chlamydia psittaci, carried by sheep and possibly goats. In humans it may cause abortion or ’flu-like illnesses. It is normally passed to humans during handling or contact with an infected afterbirth, but may also be contracted by contact with soiled workwear that has been contaminated with afterbirths etc.

Psittacosis (Ornithosis)

This disease is also caused by the organism Chlamydia psittaci, often carried by ducks and other poultry (including turkeys) as well as caged, wild and exotic birds. In humans, a ’flu-like illness may lead to pneumonia and in severe cases endocarditis (inflammation of the heart chambers), hepatitis and death. It is usually transmitted to humans by inhaling dust or aerosol from dung or a nasal discharge from infected birds.

Q fever

This disease, caused by the Coxiella burnetii organism, is carried by sheep and cattle, and usually causes mild general illness, chill and headache in humans. In rare cases it can cause pneumonia, liver and heart valve damage or death. It is transmitted by contacting animals or their products, transferring raw milk to the mouth, e.g. on the hand, or inhaling dust contaminated with birth products, urine or dung.

Ringworm

Ringworm is a fungus which may infect cattle, pigs, sheep, horses and dogs. In humans, inflamed, swollen, crusty skin lesions form on the hands, forearms, head and neck. These are caused by fungal spores entering the skin through cuts and abrasions; spores may be transmitted to the skin from handling infected livestock or equipment such as gates etc that animals, especially cattle, have rubbed against.

Control the risk by:

preventing disease in animals by maintaining high standards of cleanliness in buildings, in particular calf pens, cattle crushes etc;
treating any infected cattle in accordance with veterinary advice.

Bovine spongiform encephalopathy (BSE)/variant Creutzfeldt Jacob Disease (vCJD)

Where there is a risk of exposure to the BSE agent as a result of work activities (e.g. slaughtering), then the relevant guidance should be followed from the Member State. Background and general occupational guidance will help you select the appropriate control measures. These control measures should include the sensible occupational hygiene precautions previously outlined.

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Non-infectious biological factors

The State of Occupational Safety and Health in the European Union – A Pilot Study identified that non-infectious biological substances were a hazard for the Agriculture sector. These include: