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Biological Monitoring

Biohazard Exposure The aim of biological monitoring is to detect hazardous substances in the body before adverse health effects occur. It is a preventative measure.

Biological monitoring is a form of Health Surveillance which can be used to assess the health risk of exposure to hazardous substances.



The legal basis for Biological Monitoring is set out in the Safety, Health and Welfare at Work (Chemical Agent) Regulations, 2001 and the Safety, Health and Welfare at Work Act, 2005.

The Law is mandatory for only one substance – Lead

For all other chemical exposure risks the requirement for biological monitoring is determined by risk assessment including environmental monitoring.

Health surveillance should be carried out as appropriate, based on the outcome of a risk assessment.

Health surveillance may be appropriate/required for employees when:

  • They work with substances that have been assigned a Biological Monitoring Guidance Value (BMGV).
  • The exposure of an employee to a hazardous chemical agent is such that an identifiable disease or adverse health effect is known to be related to the exposure.
  • There is a reasonable likelihood that the disease or effect may occur under the particular conditions of work.
Biological Monitoring (for Chemical Exposure)

Biological monitoring involves analysis of urine or blood samples collected from workers after routine exposure.

The measured exposure level of the specific substance can then be checked against the Biological Monitoring Guidance Value (BMGV) if such a guidance value has been set for the specific substance.

Biological Monitoring Guidance Values (BMGVs) are only available for a limited number of chemicals. BMGVs are used for assessing potential health hazards in the practice of occupational hygiene. They represent the limit of concentration of the particular chemical, its metabolite(s) or an indicator of effect in the appropriate biological medium. The BMGV represents the level most likely to be observed in specimens collected from healthy workers who have been exposed to the chemical through inhalation at the occupational exposure limit value (OELV).

The BMGV indicates a concentration below which nearly all workers should not experience adverse health effects. The BMGV is not intended for use as a measure of adverse effects or for the diagnosis of occupational illness. BMGVs are not an alternative or replacement for airborne OELVs. Biological Monitoring Guidance Values (BMGVs) are thus named to distinguish them from Biological Limit Values which are stated in the Safety, Health and Welfare at Work (Chemical Agents) Regulations 2001

As with other forms of Health surveillance, biological monitoring is not a substitute for control measures (such as reducing exposure, engineering control measures and PPE), but a measure of their effectiveness in controlling exposure to chemicals that are harmful to health. (Source H.S.A.)

Biological Monitoring Service

The employer has a duty of care to ensure that exposure to harmful chemicals is either prevented or properly controlled. The most common measure of determining exposure to chemicals is through environmental (air and surface swabs) monitoring of the workplace. However where there is a risk of skin absorption or ingestion of a chemical then biological monitoring for specific chemicals can provide more precise estimation of the total exposure.

MedWise can advise on all aspects of setting up and running the biological monitoring program, what to sampling plans, collection, analysis, interpretation of the results, records keeping, trending of the results.

MedWise can take samples from your site at defined sampling times (i.e. end of shift).

MedWise use the services of specialist biological testing labs the UK.

Please contact us for advice on setting up Biological Monitoring programs specific to your workplace requirements.