THE UNCERTAINTY FACTOR IN THE SETTING OF OCCUPATIONAL EXPOSURE STANDARDS

Abstract

In recent years new programmes have appeared within the EC and OECD involving risk assessment of chemicals in relation to their potential health effects on various sections of the human population, including workers. As an element of such programmes judgements are required to be made about the acceptability of occupational exposure to chemicals at particular levels, taking into account the toxicological data available. Some of these programmes seek to establish ‘health-based’ occupational exposure limits. Uncertainty Factors have a significant influence in such considerations. There is a notable absence of published information in relation to the quantitative aspects of decision-making in this area. This paper discusses the current situation regarding Uncertainty Factors involved in deriving a ‘health-based’ occupational exposure limit, the Occupational Exposure Standard (OES) in the U.K. The Uncertainty Factors involved in the proposals of the WATCH (Working Group on the Assessment of Toxic Chemicals) panel of the Health and Safety Commission's Advisory Committee on Toxic Substances, for OES values for substances considered in the period 1990–1993 have been analysed.