Biological monitoring is a way of assessing chemical exposures by measuring the chemical or its breakdown products in a biological sample (usually urine, blood or breath).

Biological monitoring is particularly useful where chemicals can be significantly absorbed through the skin and where controls rely upon the use of personal protective equipment, such as gloves and masks.

Biological monitoring has a number of roles in exposure assessment.  Our case studies illustrate some of the situations where it has been useful.

• To check that control measures are working
• To check that work practices are protective
• To check that training is understood and followed