Basic Principles of Chemical Carcinogenesis

Abstract

Classically, chemicals that have been demonstrated to “cause or induce malignant neoplasms in humans or animals are termed ‘carcinogens’.” The basis for determining whether a chemical causes or induces malignant neoplasms is a complete evaluation of the carcinogenesis experiment or toxicology experiments involving the chemical, including a detailed histopathology review and statistical analyses. The inherent limitations of the test and evaluation methods should be carefully reviewed prior to the time final conclusions are drawn. More recently, chemicals that are found to cause or induce benign and/or malignant neoplasms have been termed carcinogens. It has been shown that benign neoplasms often progress to malignant neoplasms in humans and animals, and also that what are benign neoplasms to one may well be malignant to another pathologist. Chemical carcinogens that cause benign or malignant tumors in animals thus may cause benign tumors that are life threatening in humans. And chemicals that are known to cause malignant tumors often cause benign tumors as well. No chemical has been shown to cause only benign tumors. For the purposes of this article, however, carcinogens shall be those chemicals that cause benign or malignant tumors in humans or animals (1–9).