Biological Monitoring

Many jobs involve using chemicals which can harm health if they are not properly handled. Under the Control of Substances Hazardous to Health Regulations 1994 (COSHH) employers have to look for the risks to employees health from chemicals in the workplace. Employers must make sure that exposure to chemicals is either prevented, or properly controlled.

How do Chemicals enter the human body?

The main ways that chemicals can enter your body are:

by breathing them in;
by absorbing them through the skin; or
by swallowing them. This can happen if your hands become contaminated at work and you do not wash them before eating, drinking or smoking.

If you are exposed to chemicals in the job you do, the most common way of finding out how much you are exposed to is to measure how much of the chemical is present in the air you breathe in. However, this does not tell you how much of the chemical has actually entered your body. In particular, it does not measure how much has entered your body through the skin or by swallowing. This is why we sometimes recommend biological monitoring for certain chemicals.

How can the amount of chemicals in the body be measured?

Biological monitoring can be used to indicate how much of a chemical has entered your body. It involves measuring the chemical you are exposed to at work (or what it breaks down into) in a sample of your breath, urine or blood. Which of these three samples is used depends on how the chemical you are exposed to is processed by your body. Biological monitoring is often used together with air monitoring.

Biological monitoring is especially useful when:

there is likely significant absorption through the skin; and
control of your exposure depends on personal protective equipment and your employer needs to check it is protecting you.

What does it mean if the results show high traces of chemical exposure?

If your result is high it does not necessarily mean that you will become ill, but it does indicate that your exposure may not be properly controlled. Under these circumstances your employer will probably need to look at how the chemical is being handled to see how exposure can be reduced.