Frequently Asked Questions
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Common questions on workplace biological monitoring scope, methodology, ethics, timing and interpretation — for UK H&S managers, occupational hygienists and compliance teams.
Programme scope
Most UK programmes are commissioned to demonstrate adequate control under COSHH regulation 7 for skin-notated substances, or to discharge a statutory duty under CLAW 2002 for lead. Some sites also run discretionary programmes for substances of internal concern.
Frequently asked questions
What is biological monitoring?
It is the measurement of a workplace substance or its metabolite inside the worker — usually in urine — to estimate the absorbed dose from all routes of exposure.
Is biological monitoring mandatory in the UK?
It is mandatory only under the Control of Lead at Work Regulations 2002 for lead. Under COSHH it is the recognised way to demonstrate adequate control for substances with skin notation or HSE BMGVs.
What is the difference between a BMGV and a BEI?
BMGVs are HSE Biological Monitoring Guidance Values (UK). BEIs are ACGIH Biological Exposure Indices (US). Both are advisory, expressed in similar units, and used by UK occupational hygienists to interpret results.
When during the shift should samples be collected?
It depends on biomarker half-life. Most solvent metabolites are end-of-shift; inorganic mercury is pre-shift next morning; chromium and cadmium are end-of-shift end-of-week.
Do workers have to consent?
Yes. Workers must be informed of the purpose, the substance and biomarker, how results will be used, and who will see them. Individual results are confidential occupational health data.
Who sees individual results?
Only the worker, the occupational health professional and (where consent is given) the worker's GP. Employers receive only de-identified group statistics.
How often should a programme be repeated?
Routine verification is typically annual or biennial; quarterly during a process change or after a control failure; more frequently for high-hazard substances such as MDI or hexavalent chromium.
Can biological monitoring replace air monitoring?
No. The two are complementary — air monitoring evaluates control performance at source; biological monitoring evaluates the worker's whole-body absorbed dose.
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