Relevance and role of guideline values for chemical risk assessment.

OBJECTIVES: 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". METHODS: Guideline values include limit values, action levels and reference values, and may refer to an environmental or biological matrix. RESULTS: 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). CONCLUSIONS: 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.