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

Important considerations in biological exposure monitoring
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31.Biological exposure indices (BEIs) are reference values intended as guidelines for the evaluation of potential health hazards in the practice of industrial hygiene. BEIs must not be used as statutory reference values.

 

32. A BEI represents in theory the level of an HCA or metabolite most likely to be observed in a specimen collected from a healthy worker who has been exposed to an HCA to the same extent as a worker with inhalation exposure to an OEL-TWA. BEIs do not represent a sharp distinction between hazardous and non-hazardous exposures. For example, owing to biological variability, it is possible that an individual’s measurements can exceed the BEI without incurring an increased health risk. Conversely, there may be some susceptible individuals who may be harmed at levels below the BEI.

 

33. If measurements in specimens obtained from a worker on different occasions persistently exceed the BEI, or if the majority of measurements in specimens obtained from a group of workers at the same workplace exceed the BEI, the cause of the excessive values must be investigated and proper action be taken to reduce the exposure.

 

34. BEIs apply to eight-hour exposures, five days a week. However, BEIs for differing work schedules may be extrapolated on toxicokinetic grounds. BEIs should not be applied, either directly or through a conversion factor, in the determination of safe levels for non-occupational exposure to air and water pollutants, or food contaminants. The BEIs are not intended for use as a measure of adverse effects or for diagnosis of occupational disease.

 

35. Actual exposures can be determined using some of the above methods, but it is important to understand the limitations of results. The level of a hazardous chemical or its metabolites in the body does not necessarily correlate with exposure to the hazardous chemicals, symptoms or damage to health.