Work Related Health Issues

Introduction

Occupational medicine is a crucial component of the MCCQE1 and the Public Health curriculum. It bridges clinical medicine with legal, social, and preventative aspects of healthcare. In the Canadian context, understanding the relationship between work and health is essential for the Health Advocate role within the CanMEDS framework.

Work-related health issues encompass occupational diseases (caused directly by work) and work-related diseases (aggravated by work conditions).

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CanMEDS Focus: As a Health Advocate, a Canadian physician must identify determinants of health, including employment conditions, and facilitate the patient’s safe return to work (RTW) whenever possible.

The Occupational History

The most critical skill for the MCCQE1 regarding occupational health is the ability to take a thorough exposure history. A missed occupational history leads to missed diagnoses and missed opportunities for prevention.

The “CHOPD” Mnemonic

Use this mnemonic to screen for occupational etiology:

C: Community (Home environment, hobbies, waste sites)
H: Home (Heating, age of home, renovations)
O: Occupation (Current and past jobs, specific tasks)
P: Personal Habits (Smoking, diet)
D: Diet/Drugs/Drinking

Detailed Occupational History Taking Steps

Step 1: Current Job Description

Do not rely on the job title. Ask: “What do you actually do?” and “What materials do you handle?”

Step 2: Exposure Assessment

Ask about specific hazards: dusts, fumes, chemicals, noise, radiation, biological agents, and psychological stress.

Step 3: Timing of Symptoms

Is there a temporal relationship?

Do symptoms improve on weekends or holidays? (Typical for occupational asthma or dermatitis)
Do co-workers have similar symptoms?

Step 4: Past Occupational History

Chronological list of all previous jobs. This is vital for diseases with long latency periods (e.g., Mesothelioma).

Step 5: Protective Measures

Does the patient use Personal Protective Equipment (PPE)? Is there proper ventilation?

Common Occupational Hazards and Conditions

Occupational hazards are generally categorized into five groups. Understanding these is vital for MCCQE1 preparation.

Physical

Physical Hazards:

Noise: Causes Noise-Induced Hearing Loss (NIHL). Characterized by a sensorineural dip at 4000 Hz on the audiogram.
Radiation: Ionizing (cancer risk) and Non-ionizing (cataracts, burns).
Temperature: Heat stroke, frostbite.
Vibration: Hand-Arm Vibration Syndrome (HAVS), Raynaud’s phenomenon.

Occupational Lung Diseases (Pneumoconioses)

This is a high-yield topic for the MCCQE1. You must be able to differentiate between the major pneumoconioses based on history and radiographic findings.

Condition	Exposure Source	Latency	Clinical/Radiographic Features
Asbestosis	Insulation, shipbuilding, brake linings, construction (pre-1980s).	15-20+ years	Lower lobe fibrosis. Pleural plaques (calcified). Increased risk of bronchogenic carcinoma and mesothelioma.
Silicosis	Mining, sandblasting, quarrying, glass making.	10-20 years	Upper lobe nodular opacities. “Eggshell” calcification of hilar lymph nodes. Increased risk of TB.
Coal Worker’s Pneumoconiosis	Coal mining.	10-20 years	Upper lobe opacities. Black sputum (melanoptysis). Caplan syndrome (with RA).
Occupational Asthma	Isocyanates (paint), flour (bakers), animals (vets), cedar dust.	Weeks to years	Symptoms improve away from work. Use peak flow monitoring at work vs. home to diagnose.

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Important Distinction: Asbestos exposure increases the risk of Bronchogenic Carcinoma (lung cancer) significantly more than it causes Mesothelioma, although Mesothelioma is almost exclusively caused by asbestos. Smoking acts synergistically with asbestos for lung cancer risk but not for mesothelioma.

The Canadian Workers’ Compensation System

In Canada, Workers’ Compensation is a provincial responsibility (e.g., WSIB in Ontario, WorkSafeBC). It is based on the “Historic Compromise”: workers gave up the right to sue employers in exchange for a no-fault insurance system.

Principles of the System

No-Fault: Compensation is paid regardless of who was to blame for the accident.
Collective Liability: Employers fund the system.
Security of Payment: Injured workers are guaranteed payment.
Exclusive Jurisdiction: The compensation board is the final decision-maker.

The Physician’s Role

Physicians in Canada have specific legal and ethical obligations regarding work-related health.

Reporting: Physicians are legally required to report suspected work-related illnesses or injuries to the provincial board (e.g., submitting a Form 8). Consent is implied for this specific report, but prudent practice involves informing the patient.
Assessment: Document objective findings and functional limitations (not just symptoms).
Return to Work (RTW): The goal is early, safe return to work.
- Advocate for modified duties (light duty) rather than complete off-work status if medically safe.
- “Hurt does not equal Harm” – activity is often beneficial for recovery (especially MSK injuries).

Prevention and Control Strategies

When addressing occupational hazards, apply the Hierarchy of Controls. This is often tested in Public Health scenarios.

Elimination (Most Effective) Physically remove the hazard

Substitution Replace the hazard (e.g., water-based paint instead of solvent)

Engineering Controls Isolate people from the hazard (e.g., ventilation, noise enclosure)

Administrative Controls Change the way people work (e.g., job rotation, training)

PPE (Least Effective) Protect the worker with Personal Protective Equipment

Canadian Guidelines

WHMIS (Workplace Hazardous Materials Information System)

Canada’s national hazard communication standard.

Labels: On containers of hazardous products.
SDS (Safety Data Sheets): Detailed technical information.
Education: Worker training programs.

Canada Labour Code

Regulates occupational health and safety for federal worksites. Most other worksites are regulated by provincial Occupational Health and Safety Acts (OHSA).

Reportable Diseases

Many occupational diseases are also “Reportable Diseases” to Public Health (e.g., Anthrax, Brucellosis), distinct from reporting to the Workers’ Compensation Board.

Key Points to Remember for MCCQE1

History is King: Always ask “What do you do for a living?” and “Do symptoms improve on weekends?”
Silicosis vs. Asbestosis: Remember “Silica/Coal = High (Upper lobes)” and “Asbestos = Low (Lower lobes)”.
Reporting: It is mandatory for physicians to report work-related conditions to the compensation board.
RTW: Early return to modified work is the standard of care for most MSK injuries to prevent chronic disability.
Lead Poisoning: Look for microcytic anemia, basophilic stippling, abdominal pain (colic), and neuropathy (wrist drop).
Carbon Monoxide: Pulse oximetry is normal; order ABG with co-oximetry.

Sample Question

Question

A 58-year-old male presents to his family physician with a 6-month history of progressive dyspnea on exertion and a non-productive cough. He denies fever, chills, or weight loss. He has a 30-pack-year smoking history but quit 5 years ago. His occupational history reveals that he worked in building insulation and renovation for 25 years, retiring 3 years ago.

On physical examination, he is afebrile with a respiratory rate of 20/min. Auscultation reveals fine, end-inspiratory crackles at the lung bases. There is clubbing of the fingers. A chest X-ray demonstrates reticular opacities predominantly in the lower lobes and calcified plaques along the diaphragm.

Which one of the following is the most likely diagnosis?

Explanation

The correct answer is:

C. Asbestosis

Explanation: This clinical scenario is classic for Asbestosis.

Risk Factor: Long-term exposure to insulation (common source of asbestos pre-1980s).
Latency: Symptoms often appear 15–20+ years after initial exposure.
Physical Exam: Bibasilar fine crackles (“velcro crackles”) and digital clubbing are characteristic.
Radiology: The hallmark findings are lower lobe fibrosis (reticular opacities) and pleural plaques (often calcified, involving the diaphragm).

Why the distractors are incorrect:

A. Silicosis: Associated with mining or sandblasting. Radiographically, it affects the upper lobes and may show “eggshell calcification” of hilar nodes.
B. COPD: While he has a smoking history, the presence of digital clubbing and interstitial fibrosis (reticular opacities) strongly points away from pure COPD. Pleural plaques are specific to asbestos exposure.
D. Hypersensitivity Pneumonitis: Often related to organic dusts (moldy hay, birds). It can cause fibrosis but typically presents with upper/mid-zone predominance or ground-glass opacities, and pleural plaques are not a feature.
E. Coal Worker’s Pneumoconiosis: Associated with coal mining. Affects the upper lobes.

References

Medical Council of Canada. MCC Objectives for the Qualifying Examination Part I.
Canadian Centre for Occupational Health and Safety (CCOHS). WHMIS 2015 - General. Available at: https://www.ccohs.ca
Public Health Agency of Canada. Canadian Immunization Guide: Part 3 – Vaccination of Specific Populations.
Workplace Safety and Insurance Board (WSIB) Ontario. Physician’s Reference Guide.
Toronto Notes 2024. Public Health and Preventive Medicine Section.