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Health surveillance and biological monitoring
Environmental monitoring measures the agent in the air, biological monitoring measures the agent or its metabolite in the worker's body, and medical surveillance looks for an early health effect – three complementary tools that aim to detect exposure before disease develops.
Why it matters in the exam
Exam questions ask you to distinguish environmental monitoring, biological monitoring and medical surveillance, to choose the correct biological index for a given agent (blood lead, urinary mercury, cholinesterase for organophosphates) and to time the sample – end of shift, end of the working week or at any time. The Israeli framework is also asked: pre-placement and periodic examinations under the regulations, performed by an occupational physician, with a duty to remove a worker whose results exceed the permitted value. It is a broad topic with many short questions, so the table is worth memorising. The logic is simple: air monitoring shows what is in the environment but not how much actually enters the body, for example when gloves are not worn or food is eaten in the work area.
Key points
- Environmental monitoring measures air, biological monitoring measures the body, medical surveillance looks for effect.
- Biological monitoring reflects all routes of exposure, including skin and ingestion.
- Sampling time follows the half-life of the agent or metabolite.
- In Israel: pre-placement and periodic examinations under the regulations, by an occupational physician.
- An excess requires removal and review of the plant's controls.
Summary table
| Agent | Biological index | Sampling time | Note |
|---|---|---|---|
| Lead | Blood lead | Any time (cumulative) | The main index of occupational exposure |
| Inorganic mercury | Urinary mercury | Before shift, timing not critical | Reflects cumulative body burden |
| Organophosphates | Red-cell cholinesterase activity | Compared with the worker's baseline | The fall from baseline matters more than the absolute value |
| n-Hexane | Urinary 2,5-hexanedione | End of shift at end of the working week | The neurotoxic metabolite |
| Benzene | Urinary S-phenylmercapturic acid | End of shift | Sensitive index at low exposure |
| Carbon monoxide | Carboxyhaemoglobin | End of shift | Short half-life, sample promptly |
In the full version for subscribers
- A simple algorithm
- Memory aid
- Exam traps
- 5 review cards
- Enough for IMLE
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Sources
- Israel Labour Inspection Organization Regulations (environmental and biological monitoring of workers exposed to harmful agents), 2011 — Medical examinations and biological monitoring
- ACGIH, TLVs and BEIs, 2024 — Introduction to the Biological Exposure Indices
- LaDou & Harrison, CURRENT Diagnosis & Treatment: Occupational & Environmental Medicine, 6th ed., 2021 — Medical surveillance and biological monitoring
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.