Mednotes

L1 Public Health Occupational Medicine

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aliasesL1 Public Health Occupational Medicine

22 min read

Overview

An introduction to occupational health as a branch of public health: what occupational and environmental medicine cover, the two-way relationship between work and health, the New Zealand legal framework under the Health and Safety at Work Act 2015, how hazards and risks are identified and controlled, how exposure and health are monitored, the scale of work-related death and harm in New Zealand, and how a clinician should recognise, act on and support recovery from work-related disease and injury.

Defining occupational and environmental medicine

  • Occupational medicine takes a preventative approach to health and safety in the workplace by looking at how a work environment can affect a person’s health, and how a person’s health can affect their work.
  • Environmental medicine is primarily concerned with the human health impacts of industrial practices on the broader environment outside of the industrial site.
  • Source for both definitions: Australasian Faculty of Occupational and Environmental Medicine (racp.edu.au).

WHO definition: occupational health is an area of work in public health to promote and maintain the highest degree of physical, mental and social well-being of workers in all occupations. Its objectives are:

  1. Maintenance and promotion of workers’ health and working capacity.
  2. Improvement of working conditions and the working environment so they become conducive to safety and health.
  3. Development of work organisation and working cultures that reflect the essential value systems adopted by the undertaking concerned, including effective managerial systems, personnel policy, principles for participation, and voluntary quality-related management practices to improve occupational safety and health.

The science and practice of occupational health involves several disciplines: occupational medicine, nursing, ergonomics, psychology, hygiene, safety and others.

The two-way relationship between work and health

Work and health act on each other in both directions.

Effects of health on work, grouped into four risk categories:

  • Impairment risks
  • Incapacity risks
  • Sensory risks
  • Mobility risks

Effects of work on health, grouped into five risk categories:

  • Biological risk
  • Chemical risk
  • Psychosocial risk
  • Physical risk
  • Ergonomic risk

History of occupational medicine

  • Agricola (1494 to 1555) and Paracelsus (1493 to 1541) formally recorded risks to employed medieval artisans.
  • Ramazzini, professor of medicine in Italy, is recognised as the father of occupational medicine, around 1700. He wrote that “it is right and proper that the art of medicine should furnish some sort of protection for these workers whose labour is so necessary in every way”.
  • Ramazzini also proposed that, in addition to the questions of Hippocrates, one further question be asked: “Quas atres exerceant?”, meaning “What is your job?” He added that “I find that attention is hardly ever paid to this matter, or if the doctor knows it without asking, he gives little heed to it: though for effective treatment, evidence of this sort has utmost weight.” The lecture stresses that these words, written nearly 300 years ago, remain true today.

New Zealand figures:

  • Dr Bill Glass, Senior New Zealander of the Year 2019. Associated work cited: neuropsychological symptoms in workers handling cargo from shipping containers and export logs (May 2022); solvent neurotoxicity in vehicle collision repair workers in New Zealand (October 2016).
  • New Zealand’s Regional Industrial Medical Officers of the Tom Garland era, 1945 to 1954: Francis King, Tom Garland, Alan Bell and Stan Hickling.

The Health and Safety at Work Act 2015 (HSWA) provides a balanced framework to secure the health and safety of workers and workplaces. The Work Health and Safety Regulatory System has three linked parts.

Law, as a pyramid from mandatory at the top to broader guidance at the bottom:

  1. Health and Safety at Work Act
  2. Regulations
  3. Safe work instruments
  4. Approved codes of practice
  5. Guidance, standards and information

The pyramid can be read in court as evidence of compliance.

Duty holders, four categories:

  • PCBU (for example a business or organisation)
  • Workers (employees, volunteers)
  • Officers (for example a director or chief executive)
  • Others at a workplace (for example visitors)

Regulatory functions:

  • Ministry of Business, Innovation and Employment (MBIE)
  • Regulators: WorkSafe New Zealand, Civil Aviation Authority, Maritime New Zealand
  • Third parties (for example compliance certifiers, inspection bodies)

Key terms:

  • Hazard: includes a person’s behaviour where that behaviour has the potential to cause death, injury or illness to a person, whether or not that behaviour results from physical or mental fatigue, drugs, alcohol, traumatic shock, or another temporary condition that affects a person’s behaviour.
  • Risk: arises from people being exposed to a hazard, a hazard being a source of harm.
  • PCBU responsibility: a person conducting a business or undertaking who manages or controls a workplace must ensure, so far as is reasonably practicable, that the workplace, the means of entering and exiting it, and anything arising from it are without risks to the health and safety of any person.

Worker engagement and participation is presented as a four-step cycle: ask questions, share information, identify risks, suggest ideas. Supporting WorkSafe guidance includes the Introduction to the Health and Safety at Work Act 2015 guide (February 2019, 2nd edition) and General risk and workplace management parts 1 and 2, covering the Health and Safety at Work (General Risk and Workplace Management) Regulations 2016 (November 2022).

Hazards, risks and occupational disease

Health NZ’s seven critical risks:

  1. Violence and aggression at work: workers being abused, threatened or assaulted in circumstances arising out of, or during the course of, their work.
  2. Moving and handling: harm from activities requiring a worker to use any part of their muscles or skeletal system to lift, lower, push, pull, carry, throw, hold or restrain. In Health NZ, moving and handling concerns people in care, whereas manual handling relates to inanimate objects.
  3. Hazardous substances: harm from hazardous substances throughout the lifecycle, due to improper management during procurement, transport, use, storage and disposal.
  4. Biological exposures: harm from biological hazards, that is disease-producing agents such as bacteria, viruses and fungi. Harm includes acute and chronic conditions arising from work or the workplace.
  5. Physical site works: risks relating to buildings, structures or utilities, for example construction or infrastructure risks. Owned by the Infrastructure and Investment Group.
  6. Psychosocial risks: physical or psychological harm from work-related psychological trauma, poor work design, social factors and the context of work.
  7. Safe movement of people and vehicles: harm to workers and others from movement of vehicles and pedestrians at workplaces or where work is carried out, and work-related driving.

Six broader occupational hazard/risk categories: work-related injuries; psychosocial; carcinogens and airborne; musculoskeletal; work organisational (fatigue and shiftwork related); environmental.

Examples of occupational diseases, by source:

  • Biological: hepatitis; HIV/AIDS; tuberculosis; Legionnaires; leptospirosis; campylobacter. Ask whether the person has travelled for work.
  • Exposures: asthma; skin disorders; lead poisoning; isocyanate exposure; welding fumes; chemical sensitivities; cancers; radiation; silicosis.
  • Environment: fatigue; stress; hearing loss; musculoskeletal disorders; heat exposure; injuries; asthma; skin disorders; lead poisoning.

“New diseases” in chronological order:

  • Ebola and Marburg viruses, haemorrhagic fever, 1976
  • Legionnaire’s disease, 1976 (Philadelphia)
  • HIV, 1981
  • Helicobacter pylori, 1982
  • Bird flu (H1N5), 1990
  • Popcorn workers lung (bronchiolitis obliterans), 2002
  • SARS-CoV, severe acute respiratory syndrome, 2003
  • Peripheral inflammatory neuritis (pork slaughtermen), 2008
  • Nanotechnology, 2008
  • Swine flu, 2009
  • MERS-CoV, 2012
  • Zika virus, 2014
  • Covid, 2020
  • Nipah virus
  • Disease X

Managing risk

Risks must be managed so far as is reasonably practicable. Weighing what is reasonably practicable, the factors are ranked:

  • Most important to consider: likelihood of the risk; consequence of the risk; knowledge about the risk and the means of mitigating it.
  • Less important to consider: availability of means of mitigating the risk; costs.

The hierarchy of control measures, most effective at the top to least effective at the bottom:

  1. First try elimination: eliminate risks (elimination).
  2. If elimination is not reasonably practicable: substitute, isolate, or apply engineering control measures (minimisation).
  3. If there is still risk: apply administrative control measures (minimisation).
  4. If risk still remains: use personal protective equipment (PPE), the last line of defence (minimisation).

An applied example given is the Covid public health message: wash your hands, wear a face covering, keep your distance.

Exposure and health monitoring

Questions to ask about occupational exposure:

  • Exposure and frequency: how much, and how often?
  • Other factors that make exposure worse, such as enclosed spaces, heat, workers’ health, workforce age, hours worked.
  • Known information and its health effects on workers, for example substance type, workplace exposure standards (WES), the WorkSafe website, and other industry information.
  • Where to go for information.

Exposure monitoring measures what you are being exposed to at work:

  • Levels of noise and dust exposure
  • The amount of harmful substance
  • What is in the substance
  • Whether there are other factors it reacts to
  • Exposure limits (WES)

It is carried out by someone with the right knowledge, skills, training and experience, such as an occupational hygienist. WorkSafe resources: “Exposure monitoring and health monitoring, guidance for businesses” and “Workplace exposure standards and biological exposure indices”.

Health monitoring is health being checked because of exposures:

  • Hearing tests for noise
  • Lung function for lung exposures
  • Drug testing
  • Workplace assessments
  • Lead levels, often from Public Health
  • Vision

It requires written records and must be carried out by qualified, trained and experienced health practitioners, for example an occupational health nurse, with referral to another health practitioner for medical assessment or formal diagnosis. Record requirements are 30 to 40 years. Relevant bodies: NZOHNA and the HASANZ Register.

What is not health monitoring:

  • Well-being programmes measuring blood pressure, blood sugar, cholesterol, gout
  • Employment pre-screening
  • Fitness-to-work examinations

Headline estimates (WorkSafe, work-related health estimates 2019):

  • Work-related health deaths: 750 to 900 per year (revised estimate).
  • Work-related ill-health hospitalisations: 5,000 to 6,000 per year (revised estimate).
  • A worker is 15 times more likely to die from a work-related disease than from a workplace accident.
  • $2 billion each year.

Breakdown of the estimated 750 deaths (all percentages are of the lower estimates of 750 deaths and 5,000 hospitalisations):

  • Approximately 50% caused by cancers.
  • Approximately 250 deaths from lung cancer, about half of these attributed to asbestos-related lung cancer; other important causes are silica dust and diesel engine exhaust.
  • Approximately 90 deaths from mesothelioma, an asbestos-related cancer of the lining of the lungs and other organs.
  • Approximately 25 deaths from breast cancer, from exposure to shift work.
  • Main non-cancer causes: approximately 200 deaths from COPD (exposure to vapours, dust, gases and fumes); approximately 80 deaths from ischaemic heart disease (mostly from low job control and second-hand smoke); approximately 30 deaths from asbestosis. The infographic also states that one third of deaths are caused by cancer and two thirds are non-cancer.

Breakdown of the estimated 5,000 to 6,000 hospitalisations:

  • Approximately 20% non-melanoma skin cancer
  • Approximately 10% lung cancer
  • Approximately 30% respiratory COPD
  • Approximately 15% ischaemic heart disease
  • Approximately 5% asthma
  • Approximately 5% depressive episode
  • Approximately 2% anxiety disorders

International comparison (State of a Thriving Nation, Business Health and Safety Leaders Forum): New Zealand’s workplace fatality rate is higher than that of two-thirds of OECD countries, and sits noticeably higher than the United Kingdom and Australia.

Warning

The OECD fatality bar chart carries no printed numeric values per country; the ordering and bar heights were read visually from the chart, so exact rates are not available from the slide.

ACC injury claims:

  • 2025 year-to-date injury cost, being the cost of all active claims: $939,482,650.
  • Top industries for new work-related claims, highest to lowest: construction (highest, approximately 32,000 in 2023), manufacturing, agriculture/forestry/fishing, retail trade, health care and social assistance, education and training, transport/postage and warehousing, accommodation and food services, administrative and support services, wholesale trade, other. Each industry shows a declining trend from 2023 to 2025 year to date.

Cost of harm (State of a Thriving Nation, excluding inflation), covering injuries (ACC and private), workplace fatalities and ill health:

  • The harm of workplace injuries, illness and fatalities was $5.4b in 2024 and has trended higher over the last decade.
  • Totals by year: 2014 4.3b, 2016 4.8b, 2018 5.5b, 2020 4.9b, 2022 5.2b, 2024 4.3b to $5.4b with a peak in 2019.
  • The Statistical Value of Life used in these figures represents the amount individuals are collectively willing to pay for a reduction in the risk of death, often used to assess the benefits of safety improvements in areas like transportation, and is used in the Treasury’s Cost Benefit Analysis (CBAx) tool.

Encountering occupational health issues in practice

Settings where occupational health issues present:

  • Injury or accident in ED
  • Pre-employment medicals
  • Hospital patient with disease
  • Public health with disease
  • General practice disease, and return to work / stay at work injury

Clinical prompts the lecture poses: how many of these people will you see; what would make you suspect a presentation is work related; what questions would you ask to aid clinical reasoning; what is the importance of asking. [slide does not elaborate with model answers]

ACC Schedule 2 occupational diseases (examples given):

  • Leptospirosis, brucellosis, orf and streptococcus, diagnosed as caused by working with animals or their carcasses
  • Angiosarcoma of the liver or hepatocellular carcinoma, diagnosed as caused by vinyl chloride monomer
  • Sino-nasal carcinoma, diagnosed as caused by working with wood dust
  • Kidney cancer, diagnosed as caused by trichloroethylene
  • Ocular melanoma, diagnosed as caused by ultraviolet radiation exposure from work involving welding

Injury from work, questions to ask: what has happened; did they report it to their workplace; early treatment; what is work like for the person.

Important

Notify WorkSafe about four categories of notifiable event. Death: if there has been a death, call WorkSafe immediately on 0800 030 040 (24/7). Injury: notify if someone has been seriously injured as a result of work. Illness: notify if someone has become seriously ill as a result of work. Incident: notify if someone has a serious or immediate risk to their health and safety because of an unplanned or uncontrolled work incident.

After hours: business hours are Monday to Friday 8.30am to 5pm excluding public holidays. After hours, for a death or serious injury, illness or incident requiring immediate attention, call 0800 030 040 and select option 2 or option 3. For all other workplace health and safety matters, complete the relevant online form and the Notifications team will attend to it the next business day.

Enforcement and what it means to a workplace, illustrated by news coverage: WorkSafe Corrections investigations labelled “shocking” by a union; five guilty parties sentenced over the Whakaari/White Island volcano disaster; WorkSafe filing charges over a Hokitika child’s serious burns at a school camp (25 October 2024); and WorkSafe New Zealand being ordered to pay a company over $158,000 for a failed prosecution (23 August 2022).

Warning

On the enforcement slide the heading “What does this mean to a workplace” is partially obscured by the article collage in the layout, so some underlying text may not be fully legible.

Return to work, stay at work, and good work

Probability of returning to work declines sharply with time off:

  • 20 days off: 70% chance of returning to work
  • 45 days off: 50% chance of returning to work
  • 70 days off: 35% chance of returning to work

Employer-reported barriers to workers returning to work (Safe Work Australia, National Return to Work Survey). About one-fifth of employers (22.4%) said there were no barriers.

  • Finding the worker suitable work or duties 30.7%
  • Communication with healthcare providers, for example location and communication 27.1%
  • Injured workers being uncooperative 26.6%
  • Communication with insurers 26.3%
  • Suspected fraudulent compensation claims 22.2%
  • Getting the worker approved for duties 16.5%
  • Communication with the injured worker 14.9%
  • Limited business resources 14.8%
  • Inexperience with managing the claims process 11.0%
  • No barriers 22.4%
  • Other 4.0%; don’t know or prefer not to say 4.0%

Health Benefits of Good Work (HBGW) is an initiative from the Australasian Faculty of Occupational and Environmental Medicine (AFOEM) of the Royal Australasian College of Physicians (RACP). It is based on compelling Australasian and international evidence that good work is beneficial to people’s health and wellbeing, and that long-term work absence, work disability and unemployment generally have a negative impact on health and wellbeing. AFOEM policy documents include: Helping people return to work Position Statement (2010); Realising the Health Benefits of Work Consensus Statement (2022); Health Benefits of Work Evidence Update (2015); Improving workplace health and workplace productivity (2013); What is good work? Position Statement (2013); Health Benefits of Good Work Charter of Principles (2022).

Careers in occupational medicine

To be a recognised specialist in New Zealand, 5 to 6 years of training is required:

  1. 2 years of general medical experience.
  2. A postgraduate course, at diploma level, in occupational and environmental medicine or a related field.
  3. 3 to 4 years of advanced training, which must include at least one academic year of full-time course work in occupational and environmental medicine, acquisition of a broad knowledge of the principles and practice of occupational and environmental medicine, achievement of a satisfactory level of clinical competence, passing the AFOEM exit examination, and participation in the AFOEM maintenance of professional standards programme.

On completing all examination and training requirements, the trainee is awarded the FAFOEM.

Students may join ANZSOM (Association of New Zealand Occupational and Environmental Medicine) as Associate Members for $90 per year. Eligible students are those interested in occupational health and studying medical, surgical or nursing, physiotherapy, occupational therapy, and psychology. ANZSOM advocates for universal access to occupational health services and represents members’ interests across the sector.

Other listed references: worksafe.govt.nz; How to manage work risks (WorkSafe); Accident Compensation Act 2001 No 49 (as at 27 November 2025) Schedule 2 Occupational diseases; anzsom.org.nz.

Self-test

  1. Distinguish occupational medicine from environmental medicine.
  2. State the three objectives of occupational health in the WHO definition.
  3. List the disciplines the WHO definition says are involved in the science and practice of occupational health.
  4. List the four categories under “effects of health on work” and the five categories under “effects of work on health”.
  5. Who is recognised as the father of occupational medicine, in what era, and what single additional question did he say should be added to the questions of Hippocrates?
  6. Describe the five tiers of the “Law” pyramid in the NZ Work Health and Safety Regulatory System, from most to least mandatory, and state what the pyramid can be used for in court.
  7. List the four categories of duty holder under the Health and Safety at Work Act 2015.
  8. Name the regulators and the government department that carry out regulatory functions in the NZ system.
  9. Define hazard and risk as the lecture defines them, and state the PCBU’s duty.
  10. List the seven critical risks used by Health NZ.
  11. Distinguish moving and handling from manual handling as Health NZ uses the terms.
  12. Describe the four tiers of the hierarchy of control measures in order, and say which are elimination and which are minimisation.
  13. When judging what is reasonably practicable, which three factors are most important to consider and which two are less important?
  14. Distinguish exposure monitoring from health monitoring, including who carries each out.
  15. List three things that are explicitly not health monitoring.
  16. How long must health monitoring records be kept?
  17. State the estimated annual number of work-related health deaths and hospitalisations in New Zealand, and how much more likely a worker is to die from work-related disease than from a workplace accident.
  18. Of the estimated 750 work-related health deaths, what proportion is caused by cancers, and give the approximate death counts for lung cancer, mesothelioma and breast cancer with their attributed exposures.
  19. Give the three leading non-cancer causes of work-related death with their approximate counts and attributed exposures.
  20. List four occupational diseases from ACC Schedule 2 with their causative exposures.
  21. What are the four categories of notifiable event that must be reported to WorkSafe, and what is the number to call for a death?
  22. State the probability of returning to work after 20, 45 and 70 days off work.
  23. Name the three most commonly reported employer barriers to a worker returning to work, with their percentages.
  24. What evidence base underpins the Health Benefits of Good Work initiative, and which body produced it?
  25. Outline the training pathway to becoming a recognised occupational physician in New Zealand and the fellowship awarded.
  26. A patient presents with new-onset asthma and a skin rash. Using the lecture’s framework, explain how you would establish whether the presentation is work related and what you would do next.

Answers

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