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


Hazardous Chemical Substances Regulations, 1995

Annexure 1

Setting Occupational Exposure Limits





8) OEL-RL and OEL-CL are set by the chief inspector on recommendation of the Advisory Council for Occupational Health and Safety (the Advisory Council), following assessment by the Standing Committee No. 7 (TC7) of the Advisory Council for Occupational Health and Safety.


9) TC 7 must first consider what type of limit is appropriate, OEL-RL, or OEL-CL, and secondly, at what concentration the limit should be set. Setting an OEL-RL is the first option to be considered and TC 7 comes to a decision based on a scientific judgment of the available information on health effects. If, however, TC 7 decides that an OEL-CL is more appropriate, consideration of the level at which to set the limit passes to the Advisory Council, since it involves socio-economic judgments, balancing risk to health against the cost and effort of reducing exposure. Following public consultation, new OEL-CLs and OEL-RLs are listed in Table 1 and Table 2 of Annexure 1 respectively with the approval of the chief inspector.




10) An OEL-RL can be assigned to a substance, if all three of the following criteria are complied with:


There is a no-risk at the exposure limit

Criterion 1: The available scientific evidence allows for the identification, with reasonable certainty, of a concentration averaged over a reference period, at which there is no indication that the substance is likely to be injurious to employees if they are exposed by inhalation day after day to that concentration.


Likely excursions above the exposure limit are unlikely

Criterion 2: Exposure to concentrations higher than that derived under criterion 1 and which could reasonably occur in practice, is unlikely to produce serious short or long-term effects on health over the period of time it might reasonably be expected to take to identify and remedy the cause of excessive exposure.


Compliance is reasonably practicable

Criterion 3: The available evidence indicates that compliance with an OEL-RL, as derived under criterion 1, is reasonably practicable.


11) A substance which does not meet criteria 1, 2 and 3, can be assigned an OEL-CL and must meet either of the following criteria:

Criterion 4: The available evidence on the substance does not satisfy criterion 1 and/or 2 for an OEL-RL and exposure to the substance has, or is liable to have, serious health implications for workers; or

Criterion 5: Socio-economic factors indicate that although the substance meets criteria 1 and 2 for an OEL-RL, a numerically higher value is necessary if the controls associated with certain uses are to be regarded as reasonably practicable.




12) Criterion 1 sets out the fundamental basis for establishing such a limit: The existence of a threshold above which there may be evidence of significant effects on health but below which, on existing knowledge, there are thought to be no adverse effects.


13) Criterion 2 is necessary in order to take account of HCS Regulation 10 (1) of the HCS Regulations whereby exposures above an OEL-RL are allowed provided the employer identifies the reasons for exceeding the standard and takes steps to reduce exposure to that OEL-RL as soon as is reasonably practicable. Clearly, it is necessary to take account of the likelihood and probable extent of cases in deciding whether an OEL-RL is appropriate. The health effects to be taken into account include sensory and other effects such as the slowing of reflexes which might result in the impairment of safety.


14) Criterion 3 takes account of whether industry can reasonably comply with the exposure limit derived under the first criterion. There is no purpose in setting an OEL-RL which plainly cannot be achieved in practice. Note that industry's ability to comply, influences the decision of whether to set an OEL-RL, but does not influence the level at which that OEL-RL is set.




15) To be assigned an OEL-RL, a substance must meet all the first three criteria; if it does not, then it can be considered for an OEL-CL. To be assigned an OEL-CL, there should be serious implications for the health of workers exposed to the substance. Serious health implications include both the risk of serious health effects to a small population of workers and the risk of relatively minor health effects to a large population. In practice, an OEL-CL has been most often allocated to carcinogens and to other substances for which no threshold of effect can be identified and about which there is no doubt about the seriousness of the effects of exposure.


16) An OEL-CL and an OEL-RL, therefore, differ not only in their legal status, but also in the way in which they are set. For an OEL-RL the only consideration in setting the limits is the protection of the health of the employee; for an OEL-CL this is still the primary consideration but socio-economic factors are also taken into account.


17) The indicative criteria, than, provide the framework within which the discussions at the various stages of limit-setting can be conducted.