Describe the concepts of occupational health and the occupational health services.

Definition, Objectives and the Nature of Occupational Disease

• The five objectives of the joint ILO/WHO definition should be given, since each implies a different activity:
• 1. Promotion and maintenance of the well-being of workers
• 2. Prevention of ill health caused by working conditions
• 3. Protection of workers from risks arising from factors adverse to health
• 4. Placing and maintaining the worker in an occupational environment adapted to their physiological and psychological capabilities
• 5. Adaptation of work to man and of each man to his job
• The fourth and fifth objectives express the central principle of the discipline — the work must be adapted to the worker, rather than the worker being expected to endure the work
• Why occupational disease IS different from other disease, and this is worth arguing explicitly:
• The exposure is known and measurable, unlike most environmental exposures
• The population at risk is defined and enumerable
• The exposure occurs at a known place for known hours
• There is an identifiable employer with a legal duty and the means to control it
• Therefore occupational disease is, in principle, entirely preventable, and its occurrence represents a failure of the system rather than an accident of nature
• The classification of occupational hazards into five groups is the standard framework:
• Physical — heat and cold; noise; vibration; abnormal pressure; radiation, ionising and non-ionising; and poor lighting
• Chemical — dusts causing pneumoconiosis; gases and fumes; metals such as lead, mercury, cadmium, arsenic and manganese; solvents; pesticides; and acids and alkalis
• Biological — brucellosis, anthrax, leptospirosis, tetanus, tuberculosis, hepatitis B and C and HIV in health workers, and Q fever
• Mechanical — accidents and injury from machinery, falls, and manual handling, which account for a very large share of the total burden
• Psychosocial — job stress, long hours and shift work, monotony, job insecurity, poor interpersonal relations, harassment and bullying, and lack of control over one’s work
• The psychosocial group is the most neglected and the fastest growing, and lack of control over the pace and content of work is among the best-established occupational risk factors for cardiovascular disease and depression
• The diagnosis of an occupational disease turns on a single question that is routinely not asked — "what work DO you DO?"
• The features suggesting an occupational cause — symptoms improving away from work, at weekends or on holiday, and returning on resumption, which is close to diagnostic for occupational asthma and dermatitis; similar illness in CO-workers; a compatible latent period; and a disease occurring at an unusual age or in an unexpected group
• The occupational history should cover — all jobs held, not merely the current one, since latency may be decades; the processes and substances actually handled; the duration and intensity of exposure; the protective measures used; and the health of co-workers

Occupational Health Services and the Indian Situation

• The components of an occupational health service:
• 1. Pre-placement (pre-employment) examination — to establish a baseline, to place the worker in a job suited to their capacity, and to identify those with particular susceptibility
• Its purpose is placement, not rejection, and this distinction matters ethically — the examination should ask what work this person can safely do, not merely whether they should be excluded
• 2. Periodic examination — at intervals determined by the hazard, to detect early, pre-clinical effects while they are still reversible
• 3. Biological monitoring — measuring the agent or its metabolite or effect IN the worker (blood lead, urinary mercury, cholinesterase for organophosphates)
• The distinction between environmental and biological monitoring is examinable — environmental monitoring measures the agent in the workplace air and reflects potential exposure; biological monitoring measures what has actually entered the worker and reflects the total dose from all routes
• Biological monitoring therefore captures absorption through skin and ingestion and takes account of the actual use of protective equipment, which air sampling cannot
• 4. Medical care for illness and injury, including first aid and emergency services
• 5. Notification of occupational disease and maintenance of records
• 6. Supervision of the working environment, including walk-through surveys and environmental monitoring
• 7. Health education, training and counselling
• 8. Supervision of sanitation, canteen, water supply and welfare facilities
• 9. Rehabilitation and return to work
• 10. Research and epidemiological surveillance
• The walk-through survey deserves emphasis as the most useful single activity — the occupational physician walks the process from raw material to finished product, observing what is actually done rather than what the manual says
• It reveals what no examination of workers can — where dust is generated, whether extraction is switched on, whether protective equipment is worn in practice, and where the short-cuts occur
• The threshold limit value (TLV) or permissible exposure limit is the airborne concentration to which nearly all workers may be repeatedly exposed without adverse effect
• Its limitations must be stated — it protects most but not all workers, since hypersusceptible individuals exist; it assumes an 8-hour day and 40-hour week and does not apply to longer shifts; it takes no account of combined exposures, which may act additively or synergistically; and it is not a sharp line between safe and dangerous
• For carcinogens there is NO known safe threshold, so the aim is the lowest achievable exposure rather than compliance with a limit
• The INDIAN situation, stated honestly, is the crux of any answer on services:
• The overwhelming majority of Indian workers — well over 90% — are in the unorganised sector, in agriculture, construction, mining, small workshops, brick kilns, quarries, domestic work and home-based work
• Occupational health legislation and services apply chiefly to the organised sector, and therefore reach the small minority who are already the best protected
• That mismatch is the central problem of Indian occupational health, and every other weakness follows from it — no employer to hold responsible, no records, no notification, no compensation, and no medical surveillance
• The other weaknesses — severe shortage of trained occupational health physicians and hygienists; gross under-reporting of occupational disease; weak factory inspection; failure of clinicians to take an occupational history, so that disease is attributed to other causes; and the absence of any link between the general health services and the workplace
• The practical conclusion — occupational health in India cannot be delivered through factory-based services alone, and must be integrated into primary health care, so that the medical officer at a PHC in a mining or agricultural district recognises silicosis and pesticide poisoning for what they are
• Ask what work the patient does, which is the single question that makes occupational disease visible at all
• Symptoms better at weekends and worse on Monday are close to diagnostic of an occupational cause
• Over ninety per cent of Indian workers are unorganised, which is exactly where the law and the services do not reach
• Take a history of all jobs, not the current one, since latency for some diseases runs to decades
• Occupational disease is entirely preventable in principle, so its occurrence is a system failure rather than misfortune
• Adapt the work to the worker, which is the central principle and the fourth objective of the joint definition
• Pre-placement examination is for placement, not rejection, asking what this person can safely do rather than excluding them
• Biological monitoring captures all routes, including skin and ingestion, which air sampling cannot
• Environmental monitoring measures potential exposure while biological monitoring measures what actually entered the worker
• The walk-through survey shows what is actually done, rather than what the manual says should be done
• A TLV protects most but not all workers, and is not a sharp line between safe and dangerous
• There is no safe threshold for a carcinogen, so the aim is the lowest achievable exposure rather than compliance
• TLVs assume an eight-hour day, and do not apply unmodified to the longer shifts common in Indian industry
• Lack of control over work causes disease, being among the best established psychosocial risks for heart disease and depression
• Psychosocial hazards are the fastest growing and the most neglected of the five groups
• Similar illness in co-workers is a strong clue, and should be asked about specifically rather than waited for
• Occupational health must be integrated into primary care in India, since factory-based services reach almost nobody
• A PHC officer in a mining district should know silicosis, which is the practical form that integration takes
• Under-reporting of occupational disease is gross, and follows directly from clinicians not taking an occupational history
• Periodic examination detects pre-clinical change while it is still reversible, which is its whole purpose
• Accidents cause a large share of the burden, and are easily forgotten when the focus falls on exotic diseases
• Health workers face biological hazards, which places them squarely within occupational health rather than outside it