TR 059 : Testing for Worker Protection | April 1994
A practical approach to risk assessment for occupational exposure standard setting and practical guidance on requirements for animal and human data are given in this report. The various types of OEL, the way in which health may be affected by exposure and the processes used by authorities and company specialists when setting OELs are explained. A step-wise process of data acquisition is described for deciding which substances may require an OEL, for developing OELs and for modifying these in the light of knowledge and experience to produce more definitive limits. In this document OELs initially set are termed ‘provisional’ while those which have been subject to review are termed ‘revised’ OELs. Development of OELs is a dynamic process; no OEL can be said to be a final, definitive standard.
While health risks need to be assessed from available animal and human data for each substance and preparation used in the workplace, an OEL will need to be set for a relatively small proportion of these, since many will not become airborne and adequate control of others will be achieved by control of the more major workplace contaminants. Chemical and physical properties are listed which, together with knowledge of the way substances are likely to be handled, stored, transported and disposed of, are of value in deciding if an OEL should be set.
Before studies are planned, any industrial experience with the substance or similar substances should be examined, as should structure-activity relationships for new substances. Information on the acute toxicity, irritancy, sensitising ability, genotoxic activity and short-term, repeated dose toxicity is required before setting a provisional OEL. This information may demonstrate that further toxicological studies are required before a provisional OEL can be set.
Since animal and other experimental studies can never guarantee freedom from adverse effects on health, workplace atmospheric monitoring and health monitoring are recommended when new materials are introduced into the workplace. The design of such studies would need to be determined on a case-by-case basis. Information so gained may confirm the adequacy of the provisional OEL or may indicate the need to set a revised OEL. The need for a revised OEL may also become apparent from data sought by competent EC authorities, from advances in medical knowledge and from workplace experience. Major changes in the use of a substance may also necessitate the setting of a revised OEL. This may necessitate the performance of further studies in animals and man.
The setting of OELs should be carried out on a case-by-case basis by professionally competent groups. Unnecessary standardisation of the process should be resisted. When completed, the data on which an OEL has been based and the considerations which have led to the actual figures should be made freely available.