The IARC classification system: Input, internal logic, output, and impact

Abstract

The IARC Monographs "Evaluation of Carcinogenic Risk of Chemicals to Man" elegantly condense and classify information on carcinogenic hazards. They serve as an invaluable basis for the regulation of carcinogenic exposures, yet the monographs are inadequate in several respects: 1. The monographs reflect only what is reported and published in peer-reviewed sources; they have not themselves generated support for studies on agents and processes for which information is lacking, partial, or inadequate. 2. There has been misuse of the output, which reflects varying levels of certainty as to human health hazards. Lack of absolute certainty on human carcinogenicity has been used as a basis for deferring regulations or other preventive action to restrict exposures. 3. The monographs ignore high-risk situations which may result from combined or interactive effects, because of the orientation mostly on specific agents. There is not adequate attention to frequently reported excesses of disease other than cancer in certain occupations with mixed exposures. Earlier recognition of more widespread and more reversible effects, other than cancer, needs to be emphasized to control exposures. 4. Control of carcinogenic exposures for workers has been less exacting and consistent than control of exposures for the community at large (water, air, food, and drugs). 5. The gap between knowledge of risks and action to control them is great and calls attention to the need for more aggressive professional input.