What is Biological Monitoring?
Biological Monitoring · Biological Monitoring overview
Biological monitoring is the measurement of a workplace chemical, its metabolite or a biological effect inside the worker — most commonly in urine — to estimate absorbed dose from all routes of exposure.
Definition
Biological monitoring (sometimes called biomonitoring) is the systematic and periodic measurement of an exposure biomarker in a biological matrix collected from a worker. Typical matrices include urine, whole blood, plasma, exhaled air and, occasionally, hair or nails. The aim is to characterise the dose that has actually entered the body, regardless of route — inhalation, dermal absorption or, exceptionally, ingestion.
Specific vs non-specific biomarkers
A specific biomarker is one that, once detected, can only have come from the substance of interest — for example urinary methylene dianiline (MDA) for methylene diphenyl diisocyanate (MDI) exposure. A non-specific biomarker is one shared with other sources, such as urinary hippuric acid, which arises from toluene exposure but is also present from dietary benzoate.
Programmes preferentially use specific biomarkers where validated methods exist. Where only non-specific biomarkers are available, background levels must be characterised and confounders documented.
Scope and limitations
Biological monitoring measures the internal dose; it does not, by itself, prove harm. It also cannot identify a single source when multiple workplace and lifestyle exposures share a metabolite. Half-life is the key constraint: a short-half-life substance must be sampled within a narrow window after exposure for the result to be meaningful.
Frequently asked questions
Is biological monitoring a medical test?
It is an occupational exposure measurement, not a diagnostic medical test. Results characterise dose, not disease.
Can biological monitoring detect past historical exposure?
Only for substances with very long biological half-lives (such as cadmium or PCBs). Short-half-life substances reflect only recent exposure.
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