Oxford Handbook of Occupational Health (2 edn)
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Human tissue and body fluids
Sources of exposure/industries
See Table 3.1 for routes of exposure.
| Route | Examples |
|---|---|
Through non-intact skin or intact mucous membranes (blood-borne transmission) | • Blood-borne viruses (BBV) • hepatitis B (HBV) • hepatitis C (HCV) • human immunodeficiency virus (HIV) • hepatitis D (HDV) • viral haemorrhagic fevers • Malaria |
Inhalation (respiratory transmission) | • Tuberculosis • Influenza • SARS |
Ingestion (faecal–oral transmission) | • Enteroviruses • Typhoid |
| Route | Examples |
|---|---|
Through non-intact skin or intact mucous membranes (blood-borne transmission) | • Blood-borne viruses (BBV) • hepatitis B (HBV) • hepatitis C (HCV) • human immunodeficiency virus (HIV) • hepatitis D (HDV) • viral haemorrhagic fevers • Malaria |
Inhalation (respiratory transmission) | • Tuberculosis • Influenza • SARS |
Ingestion (faecal–oral transmission) | • Enteroviruses • Typhoid |
Respiratory infections
Those who undertake aerosol-generating procedures, e.g. post-mortem staff, physiotherapists (suction and expectoration), bronchoscopy staff.
Faecal–oral infections
Sewage workers, laboratory staff.
Factors affecting exposure and risk assessment
The risk of transmission is determined by:
Dose or level of exposure depends on the details of the incident including route of exposure and body fluid involved
Source infectivity.
Risk assessment for BBV exposure is described in detail on 
p.
816, Management of needlestick and contamination incidents.
Health effects
Risk controls
Adherence to standard infection control procedures, including hand hygiene, use of PPE (gloves for procedures that involve a risk of contamination, double gloves for surgical procedures on patients known to be infected with BBV). Aprons, goggles, and mask are required where there is a risk of splashing, boots or overshoes if floor is contaminated. Other risk controls include:
use of safer sharps devices, avoidance of re-sheathing needles
correct disposal of sharps and infected waste
correct transport of specimens
filtering respiratory masks for aerosol-generating procedures
immunization against HBV, TB, influenza
appropriate decontamination procedures for spills
Prompt management of sharps and contamination incidents ( p.
816, Management of needlestick and contamination incidents).
Relevant legislation
An EU Directive aimed at preventing sharps injuries in healthcare was issued in 2010. Member states must implement the directive by May 2013. HSE are currently considering the implication for UK law. For more information see 
http://www.nhsemployers.org/EmploymentPolicyAndPractice/European_Employment_policy/Pages/Initiatives-On-Needlestick-Injuries.aspx
Blood
Blood-stained fluid
Pleural fluid
Pericardial fluid
Peritoneal fluid
Cerebrospinal fluid
Synovial fluid
Amniotic fluid
Breast milk
Semen
Vaginal secretion
Unfixed tissues and organs
Health care workers (HCWs), in particular:
surgeons, theatre nurses
dentists
midwives
dialysis technicians
ambulance technicians
mortuary technicians
laboratory workers
chiropodists
acupuncturists
Police and firefighters
Prison workers
Social workers
Military personnel
There is a lower, but significant, risk among:
Embalmers and crematorium workers
Cleaners
Specific guidance and further information
Guidance for clinical health care workers
Protection against infection with blood-borne
viruses. http://www.dh.gov.uk/
Guidance on risk controls in hospitals and laboratory environments
HSE (2005). Biological agents: Managing the risks in laboratories and healthcare premises. Available at: http://www.hse.gov.uk/biosafety/biologagents.pdf
Controlling the risks of infection at work from human remains: a guide for those involved in funeral services (including embalmers) and those involved in exhumation. http://www.hse.gov.uk/pubns/web01.pdf
Safe working and the prevention of infection in the mortuary and post-mortem room. http://www.hse.gov.uk/pubns/priced/mortuary-infection.pdf; http://www.hpa.org.uk; http://www.hse.gov.uk/biosafety/infection.htm
Microbial pathogens (in laboratory settings)
Common sources
Exposure to dangerous pathogens through work occurs almost exclusively in the experimental or clinical laboratory setting, often in health care or veterinary science (see Table 3.2).
| Hazard group | |
|---|---|
HG 1 | Unlikely to cause human disease |
HG 2 | Can cause human disease, and likely to be a hazard to employees, but unlikely to spread in the community and is treatable |
HG 3 | A hazard to employees, and also likely to spread to the community, but is treatable |
HG 4 | Can cause severe disease in humans, a hazard to employees and the community, and no treatment or prophylaxis available |
A full list of specific agents and their classification is published.1 | |
| Hazard group | |
|---|---|
HG 1 | Unlikely to cause human disease |
HG 2 | Can cause human disease, and likely to be a hazard to employees, but unlikely to spread in the community and is treatable |
HG 3 | A hazard to employees, and also likely to spread to the community, but is treatable |
HG 4 | Can cause severe disease in humans, a hazard to employees and the community, and no treatment or prophylaxis available |
A full list of specific agents and their classification is published.1 | |
Factors that affect the risk assessment
Consequence of infection (serious human disease)
Potential for transmission:
infect and harm employees
spread to the community
Amenability to treatment.
Risk controls
These are defined in detail in guidance from the Health and Safety Commission (HSC) and Advisory Committee on Dangerous Pathogens (ACDP). In summary, risk controls include the following.
Exposure controls
Containment: three levels of containment for Hazard Group 2–4 pathogens, including:
separation from other activities
–ve pressure ventilation
high-efficiency particulate absorption (HEPA) filtered air intake and output
restriction to authorized personnel (e.g. access controls)
safety cabinet
observation window to allow monitoring from outside.
Use of PPE including respiratory protective equipment
Emergency/incident planning (handling accidents)
Vector control (rats mainly)
Display biohazard warnings
Safe decontamination and disinfection procedures
Safe waste management
Safe transport of pathogens
Good hygiene: separation of eating areas for staff, hand washing routines.
Occupational health input
Immunization where available
Health surveillance: in practice this consists mainly of education to be vigilant and report symptoms, record of immunity
Advise on individual susceptibility, e.g. pregnancy, immunosuppression.
Specific legislation and guidance
Mainly outlined in general legislation (COSHH, MHSWR) but with additional guidance
Biological agents: managing the risks in laboratories and healthcare premises. http://www.hse.gov.uk/biosafety/biologagents.pdf
Safe working and the prevention of infection in clinical laboratories and similar facilities. http://www.hse.gov.uk/pubns/priced/clinical-laboratories.pdf
Immunization against infectious disease (The Green Book). Department of Health 2007.
• The Management, Design and Operation of Microbiological Containment Laboratories. HSC, ACDP, 2001
Vaccination of Laboratory Workers Handling Vaccinia and Related Poxviruses Infectious for Humans. HSC, ACDP, Advisory Committee on Genetic Modification, 1990.
Genetically modified organisms
Genetic modification (GM) is the term given to deliberate manipulation of the genetic material (DNA or RNA) of organisms in a way that does not occur in nature. The aim of GM is to introduce new or altered characteristics into plants, animals or, most commonly, micro-organisms (bacteria, viruses, and fungi). These modified attributes can be transferred subsequently between cells or organisms.
Common sources/specific industries
GM is carried out in laboratories, animal houses, and plant growth facilities (known as ‘contained use’).
Those at risk of occupational exposure include:
laboratory workers
animal house workers
horticulturalists in experimental facilities.
Health effects
These mainly relate to genetically modified micro-organisms (GMMs) and include specific infections.
Risk assessment and control
This is governed by primary legislation (The GMO (Contained Use) Regulations 2000 (with subsequent amendments, most recently in 2010). The regulations (see p.
111, References) give a framework for the usual principles of risk assessment, risk reduction, monitoring, and review, requiring:• Risk assessment of all activities involving gentetically modified organisms (GMOs)
A GM safety committee should be set up to advise on risk assessments
Notification of all premises to HSE before they are used for GM activities for the first time
Notification of individual activities of Class 2 to Class 4 to the Competent Authority (administered by HSE)
Maintenance of a public register of GM premises and certain activities.
In addition, laboratories should follow good laboratory and containment practice.
Relevant legislation
The Genetically Modified Organisms (Contained Use) Regulations 2000. http://www.opsi.gov.uk/si/si2000/20002831.htm
• The Genetically Modified Organisms (Contained Use) (Amendment) Regulations 2002. http://www.legislation.gov.uk/uksi/2002/63/contents/made
The Genetically Modified Organisms (Contained Use) (Amendment) Regulations 2005. http://www.legislation.gov.uk/uksi/2005/2466/contents/made.
Further information and guidance
HSE Contained use of genetically modified organisms. http://www.hse.gov.uk/pubns/indg86.pdf
Animals and animal products
Common sources and industries
Any industry that involves direct contact with animals (live or dead), their excreta, or products:
Agriculture
Veterinary medicine
Meat processing (including abbatoirs), packing, and distribution.
Potential health effects
Zoonoses
These are a group of infections typically found in animals as the primary host, but which spread from animals to humans (see Table 3.3). Some can be transmitted from human to human. There are approximately 40 potential zoonoses in the UK and approximately 300,000 people in a variety of occupations are potentially exposed. Although most zoonoses are mild and self-limiting, some may cause long-term health effects.
| Zoonotic infection | Animal host |
|---|---|
Anthrax | Cows, sheep, others |
Glanders | Horses, cats, dogs |
Streptococcus suis | Pigs |
Brucellosis | Cows, sheep, goats, pigs |
Lyme disease | Deer |
Chlamydia infections | Poultry, exotic birds, sheep |
Q fever | Sheep, cows, goats |
Orf | Sheep |
The common zoonoses are covered in | |
| Zoonotic infection | Animal host |
|---|---|
Anthrax | Cows, sheep, others |
Glanders | Horses, cats, dogs |
Streptococcus suis | Pigs |
Brucellosis | Cows, sheep, goats, pigs |
Lyme disease | Deer |
Chlamydia infections | Poultry, exotic birds, sheep |
Q fever | Sheep, cows, goats |
Orf | Sheep |
The common zoonoses are covered in | |
Allergic (immune-mediated) disease
Some organic antigens are animal products (e.g. rat urine), or found in association with animal products (e.g. bloom on bird feathers) see 
p.
114, Organic dusts and mists.
Risk assessment
Route of exposure:high risk with skin contamination, inhalation of dusts and aerosols, and ingestion.
Prevention/exposure control
Good husbandry practices for livestock:
good standards of hygiene in young-stock housing
low stocking densities
avoid contaminating animal drinking water with dung
keep animals as stress-free as possible
Education and awareness of zoonoses:
warn employees and visitors about the risk of zoonoses and preventive measures
advise early consultation with a doctor and declaration of exposure to animals if suspicious symptoms occur
Identify those with individual susceptibility and restrict from exposure:
pregnant women (avoid pregnant sheep)
immune compromised people
Immunizing and treating livestock
Good occupational hygiene practices (Table 3.4).
Safe working practices | • Avoid tools that cause cuts and injuries • Safe use and disposal of sharps used to immunize/test animals • Avoid mouth-to-mouth resuscitation on newborn animals • Avoid handling birth fluids or placentae • Control or eliminate rats • Do not touch dead rats with unprotected skin |
Personal protective equipment (PPE) | • Essential for birthing, handling infected stock, mouth or rectal examinations: gauntlets/gloves, apron, boots • Use face protection (mask and goggles) if there is a risk of splashing • Use respirator if risk of exposure to aerosols (hosing down) or organic dust |
Personal hygiene | • Good washing facilities, separate eating areas • Wash hands and arms before eating or smoking • Cover wounds with waterproof dressing • Work wear should be retained and washed at the place of work (not taken home) |
Safe working practices | • Avoid tools that cause cuts and injuries • Safe use and disposal of sharps used to immunize/test animals • Avoid mouth-to-mouth resuscitation on newborn animals • Avoid handling birth fluids or placentae • Control or eliminate rats • Do not touch dead rats with unprotected skin |
Personal protective equipment (PPE) | • Essential for birthing, handling infected stock, mouth or rectal examinations: gauntlets/gloves, apron, boots • Use face protection (mask and goggles) if there is a risk of splashing • Use respirator if risk of exposure to aerosols (hosing down) or organic dust |
Personal hygiene | • Good washing facilities, separate eating areas • Wash hands and arms before eating or smoking • Cover wounds with waterproof dressing • Work wear should be retained and washed at the place of work (not taken home) |
Relevant legislation
Brucellosis, anthrax, bovine tuberculosis, and bovine spongiform encephalopathy (BSE) in animals are notifiable to the Divisional Veterinary Manager of the Department for Environment, Food, and Rural Affairs (DEFRA).
Further information and guidance
Health protection agency. Zoonoses (infections acquired from
animals). 
http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/Zoonoses/
HSE Common zoonoses in agriculture, Agriculture information sheet No. 2 (revised) HSE http://www.hse.gov.uk/pubns/ais2.pdf
HSE/ACDP (1997). Working Safely with Research Animals. Available at: http://www.hse.gov.uk/pubns/priced/animal-research.pdf
Organic dusts and mists
These are a group of biological agents that have the potential to cause occupational disease, and are widespread in the workplace They are mainly high molecular weight proteins from plant and animal material and micro-organisms.
Common sources
Organic dusts
Animal proteins:
urine and dander from farm or laboratory animals (e.g. cows, rats)
Plant proteins:
natural rubber latex
grain dust
flour dust
wood dusts
colophony
Microbial:
moulds and spores that grow in vegetable matter (e.g. hay, mushroom compost)
enzymes.
Organic mists
Proteinaceous mists from washing fish products, and surfaces or equipment contaminated with fish/animal proteins
Bacterially infected metalworking fluids.
Specific industries
Health care industry
Rubber manufacturing
Laboratories and animal houses/care facilities
Farming
Baking and flour milling
Biological detergent manufacture
Fish processing
Engineering.
Health effects
Type I allergy (IgE-mediated):
occupational asthma
allergic rhinitis
contact urticaria
anaphylaxis
Hypersensitivity pneumonitis.
Factors affecting the risk assessment
Exposure
Potency of the specific allergen
Individual susceptibility (e.g. atopy, previous sensitization, cross-reactivity to similar allergens).
Risk controls
Minimize exposure: generic principles
good animal husbandry, including avoidance of overcrowding
good hygiene—regular cleaning of animal cages and housing, wood workshops, bakeries
general and local ventilation
dust abatement techniques: avoid dry sweeping or compressed air lines for cleaning; instead use an industrial vacuum cleaner or wet clean
Detailed guidance on the following specific biological allergens is available at http://www.hse.gov.uk/asthma/index.htm
flour dust
grain dust
laboratory animals
natural rubber latex
wood dust.
Use of PPE: can be used if a significant risk exists after appropriate efforts at exposure control, e.g. for intermittent dusty tasks.
Some advocate the use of respiratory protective equipment (RPE) as a last resort in sensitized workers whose livelihood depends on working in ‘at-risk’ situations (e.g. farmers). If this approach is advised, it must be with extreme caution, and then only after all possible efforts have been made to reduce exposure. The individual must be monitored closely (health surveillance) for signs of deterioration.
Health surveillance
All those who are exposed to a significant risk of allergic disease must have health surveillance as required by the Management of Health and Safety at Work Regulations.
Regular symptoms questionnaire and lung function
Follow-up positive symptoms with further investigation:
serial peak flow tests
skin prick tests
skin patch tests
total IgE and specific IgE for suspect agent (e.g. latex).
Exclude if exposure cannot be controlled adequately, or use PPE and monitor extremely closely.
Further information and guidance
Medical Aspects of Occupational Asthma. MS25, HSE ISBN 0717615472.
HSE (1994). Preventing asthma at work: how to control respiratory sensitisers. ISBN 0717606619.
HSE (1996). Controlling grain dust on farms, Agricultural information sheet No. 3. Available at: http://www.hse.gov.uk/pubns/ais3.pdf
HSE/ACDP (2004). The approved
list of biological agents. ACDP. Available at: http://www.hse.gov.uk/pubns/misc208.pdf
