Occupational Exposure Limits (OELs)

 In order to control toxic effects in workplaces the commonest strategy is to define Occupational Exposure Limits (OELs). OELs are based on the best available information from industrial experience, from experimental laboratory studies and from accidents.

Different kinds of OELs are applied in practice. The TLVs (Threshold Limit Values) which have been defined in Table 1 are published by the American Conference of Governmental Industrial Hygienists (amongst others) [http://www.acgih.org/home.htm]. They set a limit concentration below which it is believed that nearly all workers can be repeatedly exposed day after day without adverse effect [Refs. 6, 7]. Therefore, these may also be regarded as target airborne concentrations that should never be exceeded in a laboratory environment. The TLVs are regularly reviewed and corrected when new information becomes available.
Annexure 1 provides the latest Occupational Exposure Limits (termed alternatively as Workplace Exposure Limits) set by the UK Health and Safety Executive.

Almost all countries in the world today have adopted similar table of values of OELs for regulating personnel health at workplace (industry and laboratory). For detailed information on effects of various chemicals one may access the following website of International Program on Chemical Safety (a World Health Organization subsidiary): http://www.who.int/ipcs/publications/ehc/en/.