Occupational Health and Safety Act, 1993 (Act No. 85 of 1993)

Regulations

Regulations for Hazardous Chemical Agents, 2020

Annexures

Annexure 3 : Hazardous Chemical Agent Guidelines

Guidance on medical surveillance and biological monitoring

Biological monitoring

Distinction between biological monitoring, biological exposure monitoring and biological effect monitoring

Purchase

23.	In these regulations, biological exposure monitoring and biological effect monitoring are subsets of the overarching term, biological monitoring.

24.

Biological exposure monitoring is the measurement and assessment of chemicals or their metabolites (substances the body converts the chemical into, for purposes of elimination) in exposed workers. These measurements are made on samples of exhaled air, urine, blood or other biological materials, or any combination of these. Biological monitoring measurements reflect the total uptake of a chemical by an individual by all routes (inhalation, ingestion, through the skin or by a combination of these routes). Biological exposure monitoring, therefore, does not represent an adverse effect or an occupational disease – it only reflects exposure, but it is often incorrectly listed as a type of medical surveillance.

25.

Biological effect monitoring is the measurement and assessment of early non-adverse reversible subclinical physiological effects caused by absorption of chemicals (i.e. prior to established clinical disease). It typically involves measuring biochemical responses. For example, measuring plasma and erythrocyte cholinesterase activity in workers exposed to organophosphate pesticides; or measuring increases in urinary protein following exposure to cadmium; or changes in functioning of enzymes.

26.	Biological effect monitoring should be distinguished from medical testing for established clinical disease, which is also known as effect monitoring. For example, changes in blood cell counts following exposure to bone marrow toxins do not constitute biological effect monitoring.

27.

Biological effect monitoring responses may have potential health implications for the individual, and may also arise from causes other than occupational exposure. Consequently, biological effect monitoring should always be carried out with the close involvement of an occupational medicine practitioner.