Biological Monitoring

Biological monitoring measures the levels of hazardous substances or their breakdown products in the body.
Common tests include blood lead levels, urinary cadmium, urinary mercury, and breath carbon monoxide.
Biological monitoring supplements air monitoring by confirming whether substances are actually being absorbed.
The COSHH Regulations 2002 require biological monitoring where health surveillance identifies a need.
Results are compared against Biological Monitoring Guidance Values (BMGVs) published by the HSE.
Exceeding BMGVs indicates that exposure controls are inadequate and must be improved immediately.
Lead workers are legally required to have blood lead level monitoring under the CLAW Regulations 2002.
Workers exposed to isocyanates, chromium, mercury, and organophosphates may also require biological monitoring.
Test results must be kept confidential and shared only with the occupational health provider and the individual.
Biological monitoring complements rather than replaces workplace exposure monitoring and air sampling.

Confirm actual exposure	Air monitoring measures what is in the air — biological monitoring confirms what has entered the body.
Legal requirement	COSHH 2002 and CLAW 2002 require biological monitoring for specific substances including lead and isocyanates.
Early detection	Rising biological levels trigger action before clinical symptoms appear, preventing irreversible health damage.

Do

Don't

Attend all scheduled biological monitoring appointments as required by your employer
Understand which substances you work with that require biological monitoring on your site
Provide samples honestly — wash hands before urine samples to avoid contamination
Review your results with the occupational health provider and understand what they mean
Report any concerns about rising biological levels to your supervisor and occupational health
Follow improved control measures if your results approach or exceed guidance values
Keep biological monitoring records for at least 40 years as required for certain substances
Ensure monitoring is carried out at the correct timing relative to exposure and shifts
Use biological monitoring results alongside air monitoring to verify exposure controls work
Ask your employer for biological monitoring if you regularly work with notifiable substances

DON'T skip biological monitoring appointments — they detect exposure before symptoms appear
DON'T contaminate samples with workplace substances on your hands when providing specimens
DON'T ignore results that show levels approaching the biological monitoring guidance value
DON'T share other workers' results — biological monitoring data is medically confidential
DON'T assume air monitoring alone proves you are safe — biological monitoring confirms absorption
DON'T wait for symptoms before seeking biological monitoring for lead or isocyanate exposure
DON'T continue working with the same controls if your biological levels are rising over time
DON'T treat biological monitoring as punishment — it exists to protect your long-term health
DON'T dispose of monitoring records prematurely — retention periods can be 40 years or more
DON'T refuse monitoring if your employer identifies it as necessary under COSHH assessment

See also: Health Surveillance Requirements | Lead Paint and Coatings

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