Hazardous substances represent a potential health risk for employees in many industries. In order to keep the risk to humans as low as possible, the basic principle in occupational safety and health is to avoid the use of hazardous substances, substitute them with non-hazardous chemicals, or if this is not possible, reduce exposure to the lowest possible level. For this reason, it is important to define limit values up to which a hazardous substance poses no risk to human health according to current knowledge.
For a long time, the industrialized nations have set occupational exposure limits (OELs) for a range of hazardous substances. For some chemical agents, the European Union specifies OELs. These must be met in the European countries, but the individual countries can also set lower OELs.
To provide a basis for the derivation of occupational exposure limits, knowledge available to date is compiled. The hazard potential of a chemical agent can be assessed and a quantifiable risk for this substance can be derived. Here, the scientific summary of animal and human studies poses a challenge.
In an international comparison, limit values for a hazardous substance can differ substantially. There are many reasons for this: the legislation differs between the countries and the scientific evaluation of studies does not necessarily follow a uniform methodology. The derivation of limit values is therefore usually a two-step procedure. In the first step, the scientific findings are summarized, and in the second step, they are adjusted with respect to country-specific norms and feasibility, such as the level of tolerable risk or socio-economic aspects, respectively. Variation could therefore be reduced if at least the scientific part of the derivation of limit values were performed according to a uniform methodology, independently of the legal situation in the different countries.
Against this background, PEROSH, a European network of 14 national occupational safety and health research institutes, initiated a project with the aim of developing a best-practice solution for the scientific derivation of a dose-response relationship of hazardous substances. Based on the broad experience of the project group, a method paper was developed to define a procedure for the individual steps that is as uniform and scientifically validated as possible (comprehensive literature searches, qualitative selection and evaluation of the study results, systematic analysis of the data, derivation of a dose-response relationship, comparison of animal- and human-related results). 1,3-butadiene was chosen as an example substance according to this scheme, since it is widely used and a large number of toxicological and epidemiological studies of it have been published.
With this report, the author group hopes to contribute to a consensus-based and harmonized procedure for the derivation of dose-response relationships of hazardous substances that enjoys broad consensus and application.
The report can be found and downloaded here.