IARC evaluations: how are they conducted and what suggestions are derived therefrom?

The IARC Monographs on the Evaluation of Carcinogenic Risks to Humans are considered by several Institutions a point of reference for the prevention of adverse effects (namely cancer) of occupational exposures. The conclusions which lead to the Classification of a substance or an industrial process are the results of a vote within a Working Group of experts and are expressed in terms of “evidence” based on both epidemiological and experimental data or “other relevant data”. Several points are discussed which include the methods of identification of the experts, the criteria of evaluation of the available data, the meaning of some definitions and finally the impact of IARC conclusions and Classification on Public Health regulations and secondarily on compensation procedures or trial decisions. Three recent examples regarding the Classification of Free Crystalline Silica, Shift-Work and Vinyl Chloride Monomer, which cannot be accepted as such without some criticism, are reported. In conclusion the Authors appreciate the effort of the IARC to provide a source of information which “may assist national and international authorities in making risk assessments and in formulating decisions concerning any necessary preventive measures”. However, they suggest that the IARC “overall evaluation” should not be taken as confidently as if no doubt at all would exist on the final statement and the consequent Classification. Some suggestions as to the solution of the question are also provided.