Chemical structure of mutagens and carcinogens and the relationship with biological activity

Chemical carcinogenicity has been the target of numerous attempts to create predictive models alternative to the animal ones, ranging from short-term biological assays (e.g. mutagenicity tests) to theoretical models. Among the theoretical models, the application of the science of Structure-Activity Relationships (SAR) has earned special prominence. SAR has been applied both in a qualitative way (for example as simple recognition of suspected sub-structures or Structural Alerts), and in a quantitative way (Quantitative SAR, QSAR) to build mathematical models linking the physical chemical or structural properties of the molecules to the toxicological endpoints. This paper summarizes the contribution that the two approaches can provide in different situations. It concludes that the study of the structure of the chemicals generates predictions with limited reliability for the individual chemicals, however it has been demonstrated to be an extremely powerful tool for priority setting relative to large samples of chemicals.