Fixing exposure limits for toxic chemicals in the UK--some case studies

The former Director of the Health and Safety Executive in Britain describes the process by which limits are fixed for exposure of workers to toxic chemicals. Four examples of the process are analysed in detail, examining the controls introduced since 1975 for asbestos, man-made mineral fibres, styrene, and MbOCA. The toxicity assessments available to the decision makers are summarised, as are also the estimates of the additional costs to industry of stricter limits, and the possible economic effects on production and jobs. The author then draws some general conclusions based on British experience since 1975. These include: that decision taking was possible on the basis of uncertainty about the precise effects on humans of particular levels of exposure; that the decisions could be seen to be sensibly related to the toxicity assessments; and that the precise limit fixed was dependent as much on the costs and practicability of tighter limits as on the nature of the health effects.