Occupational limit values for the exposure assessment of chemicals based on environmental monitoring = I valori limite di esposizione utili alla valutazione del rischio chimico mediante monitoraggio ambientale

Occupational exposure limit values (OELs) are of fundamental importance in chemical risk assessment to take a decision on the acceptability of exposure levels measured in environmental monitoring campaigns, and for regulatory purposes as well. In the last five years, the issuing of European directives on dangerous substances, including some directives on carcinogens, mutagens and reprotoxic agents (CMR), has contributed to a rapid evolution in the availability of mandatory OELs. At present, the industrial hygienist must deal with various OELs, sometimes characterized by key differences in terms of type, applicability, derivation methods and number of chemical agents covered. Some scientific and socio-political issues, dictated for instance by the selection of the critical effect or the toxicological or epidemiological point of departure, the possibility of considering alternative data gained from in vitro or in silicotests, the rigidity of the derivation processes, the assessment of socio-economic and feasibility factors, can ultimately lead to the definition and proposal of different OELs for the same substance. The occupational hygienist must therefore take these aspects into account when choosing the most appropriate limit value for the assessment of occupational exposure to chemical agents and its compliance with OELs.