13.2 Occupational health and safety

Occupational Health and Safety Fundamentals

Occupational health and safety (OHS) focuses on protecting workers from job-related harm, including injuries, illnesses, and fatalities. Since working adults make up such a large portion of the population, OHS has a massive ripple effect: it reduces healthcare costs, increases productivity, and improves quality of life for workers and their families.

Epidemiology is central to this effort. Through study designs like cohort and case-control studies, along with surveillance systems and exposure assessments, researchers can identify workplace hazards and develop evidence-based strategies to prevent harm.

Definition of occupational health

OHS is the field dedicated to preventing work-related injuries, illnesses, and deaths by identifying hazards and implementing controls. It operates within both legal and ethical frameworks:

• Employer responsibility: Employers are legally required to provide a safe work environment (enforced through agencies like OSHA in the U.S.).
• Worker rights: Workers have the right to know about hazards they face and can refuse work they reasonably believe is unsafe.

Common occupational health hazards

Workplace hazards fall into four broad categories. Each type can lead to distinct health outcomes, and many workers face multiple categories simultaneously.

Physical hazards involve energy sources that can damage the body:

• Noise exposure leading to hearing loss
• Radiation exposure increasing cancer risk
• Ergonomic issues causing musculoskeletal disorders (e.g., carpal tunnel syndrome from repetitive hand motions)

Chemical hazards involve harmful substances workers inhale, absorb, or ingest:

• Toxic dusts and fibers causing respiratory diseases (e.g., asbestosis from asbestos exposure)
• Irritants causing skin disorders like contact dermatitis
• Carcinogens leading to cancers (e.g., benzene exposure linked to leukemia)

Biological hazards involve exposure to living organisms or their products:

• Infectious agents causing zoonotic diseases (e.g., brucellosis in agricultural workers)
• Bloodborne pathogens like hepatitis B affecting healthcare workers

Psychosocial hazards stem from how work is organized and experienced:

• Chronic workplace stress contributing to depression and anxiety
• Shift work disrupting sleep patterns and increasing cardiovascular risk (e.g., hypertension)

Epidemiology in occupational health

Several study designs and tools are used to investigate occupational hazards. Each serves a different purpose.

• Surveillance systems track work-related injuries and illnesses over time using standardized databases (e.g., OSHA 300 logs, which employers use to record workplace injuries).
• Cohort studies follow groups of workers over time to assess exposure-outcome relationships. A classic example: following asbestos workers for decades to measure their lung cancer incidence compared to unexposed workers.
• Case-control studies start with workers who have a disease and compare their past exposures to those of healthy controls. This design was key in linking mesothelioma to asbestos exposure.
• Cross-sectional studies measure the prevalence of a health outcome in a worker population at a single point in time, such as surveying office workers for carpal tunnel syndrome rates.
• Mortality studies analyze causes of death among worker populations to identify occupational risk factors. Coal miners and black lung disease (pneumoconiosis) are a well-known example.

Researchers also rely on specific exposure assessment techniques:

• Air sampling measures airborne contaminant levels in the workplace.
• Biomonitoring analyzes biological markers in workers' bodies (e.g., blood lead levels in battery manufacturing workers).
• Job-exposure matrices link job titles to potential exposures, allowing researchers to estimate cumulative exposure over an entire career, even when direct measurements aren't available.

Prevention of occupational hazards

Prevention strategies follow the hierarchy of controls, which ranks interventions from most to least effective:

1. Elimination — Remove the hazard entirely (e.g., stop using a toxic chemical).
2. Substitution — Replace the hazard with something safer (e.g., use a less toxic solvent).
3. Engineering controls — Isolate workers from the hazard through physical changes (e.g., install ventilation systems to remove airborne contaminants).
4. Administrative controls — Change how work is done (e.g., job rotation to limit any single worker's exposure time).
5. Personal protective equipment (PPE) — Provide respirators, gloves, or ear protection as a last line of defense.

The hierarchy matters because controls at the top protect workers without relying on individual behavior, while PPE at the bottom depends entirely on workers using it correctly every time.

Beyond the hierarchy, several other prevention approaches work together:

• Regulatory enforcement: Agencies like OSHA establish safety standards and enforce compliance through workplace inspections and penalties.
• Risk assessment: Systematic identification and prioritization of hazards, sometimes using hazard mapping to visualize where risks concentrate in a facility.
• Training and education: Teaching workers proper techniques (e.g., safe lifting) and building a safety culture through management leadership programs.
• Ergonomic interventions: Redesigning workstations (e.g., adjustable chairs, monitor height) and implementing task rotation to reduce repetitive strain injuries.
• Medical surveillance: Pre-employment screenings and periodic health exams (e.g., annual hearing tests for noise-exposed workers) to catch problems early.
• Workplace health promotion: Wellness initiatives like fitness programs and health education workshops that address overall worker well-being beyond just hazard prevention.