Biological Monitoring
Lead Hazards
Exposure to lead at work, where lead dusts, fumes or vapours are created, can cause health problems. Biological monitoring can assess one’s exposure to lead dusts, fumes and vapours.
The body absorbs lead through:
- Inhalation – breathing in lead dust, fume or vapour,
- Ingestion – swallowing lead traces when eating, drinking, smoking or biting your nails, when hands and face are contaminated with lead,
- Absorption – only certain forms of lead (lead alkyls and lead naphthenate) can be absorbed through the skin. Cold metallic lead will not be absorbed through the skin.
Exposure to lead should be strictly controlled and monitored in accordance with the Control of Lead at Work Regulations 2002.
Symptoms
Lead which is absorbed into the body will circulate in the blood. Whilst the body will excrete a small amount of lead in the urine, however some will stay in the body, stored mainly in the bones.
Lead can be stored in the body for many years without the individual feeling ill. However, if the level of lead in the body gets too high it can cause:
- Headaches
- Tiredness
- Irritability
- Constipation
- Nausea
- Stomach pains
- Anaemia
- Weight loss
Continued uncontrolled exposure could cause:
- Kidney damage
- Brain and nerve damage
Exposure to lead during pregnancy, especially during the early weeks, can serious affect the unborn child.
Is Medical Surveillance required?
Medical surveillance is required where the risk assessment considers an employee’s exposure to lead to be ‘significant’.
Significant exposure is defined in the Control of Lead at Work Regulations 2002 ACOP and guidance where one of the following three conditions are satisfied:
- Exposure exceeds half the occupational exposure limit* for lead or
- There is a substantial risk of the employee ingesting lead or
- If there is a risk of an employee’s skin coming into contact with lead alkyls or any other substance containing lead in a form, e.g. lead naphthenate, which can also be absorbed through the skin.
If, as part of the assessment process, blood lead or urinary lead is measured and it is identified at a level equivalent to or greater than the levels below, the employee should be placed under medical surveillance:
- Blood-lead concentrations:
- Women of reproductive capacity – 20 microgrammes/dl or greater
- All other employees – 35 microgrammes/dl or greater.
- Urinary Lead concentrations
- Women of reproductive capacity – 25 microgrammes of Pb/g creatinine or greater
- All other employees – 40 microgrammes of Pb/g creatinine or greater.
Is it a legal requirement?
Exposure to lead and its compounds is subject to the Control of Lead at Work Regulations 2002. Medical surveillance is a legal requirement where exposure is ‘significant’.
What does the surveillance entail?
Annual Medical Surveillance with an Occupational Physician consists of:
- A full occupational and exposure history
- Past medical history
- Blood samples (biological monitoring) are taken for blood lead and where clinically appropriate ZPP and haemaglobin.
- Interpretation and explanation of the results to the employer and individual.
- Provision of HSE information leaflet ‘Lead and You’.
- Completion of relevant documentation for the Health and Safety Executive and Employer Records.
Biological Monitoring consists of:
- Blood samples (biological monitoring) being take for blood lead and where clinically appropriate ZPP and haemaglobin.
How long does it take?
Medical surveillance with the Occupational Physician takes around 30 minutes.
Biological Monitoring takes around 10 minutes.
How often should surveillance be done?
Biological monitoring is clinically indicated by exposure and previous results. The frequency of medical surveillance is determined by the blood lead levels, but it should be undertaken at least annually with an Occupational Physician. With women of reproductive capacity and young persons, the biological monitoring should be undertaken at least 3 monthly.
With all other categories the frequency is given below:
| Category | Blood0lead | Maximum interval between blood-lead measurements |
| A | Under 30 | 12 months |
| B | >20 and <40 | 6 months |
| C | >40 and <50 | 3 months |
| D | >50 and <60 | 3 months |
| E | 60 and over |
Want to Find Out More?
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Published date: 19th February 2018
Last revision: 17th July 2019