[Relevance and role of guideline values for chemical risk assessment.]

Guideline values have been defined by the ad hoc S.I.M.L.I.I. Working Group as "the level of a risk factor, previously established for an environmental or biological context, to which the levels actually measured for/in the workers should be compared, in order to assess their degree of exposure".

Guideline values include limit values, action levels and reference values, and may refer to an environmental or biological matrix.

The present paper aims to discuss the methodologies currently used for the definition of the most relevant guideline and limit values at the national and international level, with a particular attention to those used in the European Union (OEL).

It is concluded that a correct use of guideline values represents a fundamental tool for both the assessment and the management of chemical risk in workers exposed to toxic and/or carcinogenic substances.