Health-based occupational exposure limits for high molecular weight sensitizers: How long is the road we must travel?

In this paper pitfalls in risk assessment for high molecular weight allergens, which can cause typical Type L/IgE-mediated respiratory allergy, are discussed. The major pitfalls seem to be that no agreement exists on the preferential end point that should be used in risk assessment. As a result, it is unclear which exposure-response relationship should be considered. In addition, there is a lack of data on health risks for non-occupationally exposed reference populations, so the baseline risk is often not known and little is known about the shape of exposure-response relationships and the existence of exposure thresholds. The good news is that more and more groups have published exposure-response relationships for several allergens. The possibilities for risk assessment approaches that should lead to occupational exposure standards are explored. Specific consideration is given to situations in which data on exposure-response relationships for humans are available. Considerable progress has been made in this area by use of advanced statistical techniques for exposure-response modelling. The major practical constraint at this moment seems to be the absence of well-standardized measurement techniques (immunoassays) for the evaluation of allergen exposure in the field.