Carcinogenicity and mutagenicity testing, then and now

Cancer is a dread disease worldwide. Mortality of individuals suffering fro m cancer is high, despite the current improved methods of precocious detect ion, surgery and therapy. Prevention of cancer is the recognized goal of ma ny activities in cancer research. This aim was recognized early to involve, the bioassay of environmental chemicals or mixtures. The first such study involved application of coal tar to the ear of rabbits, and later on to the skin of mice. Subsequently, laboratory rats were introduced, and hamsters were utilized as a substitute for the unwieldy tests in rabbits. Investigat ors also became concerned with the mechanisms of carcinogenesis, and more d efinitive approaches to carcinogen bioassay in laboratory animals, as possi ble indicators of cancer risk in humans. These tests were expensive and len gthy, and did not serve the important purpose of accurately measuring risk of cancer to humans. Once it was realized that DNA and the genetic apparatu s might be a key target, rapid bioassays in bacterial and mammalian cell sy stems were introduced successfully. Thus, batteries of tests are now availa ble to detect effectively human cancer risks, and provide novel approaches to determine the underlying mechanisms, as a sound basis for cancer prevent ion. (C) 1999 Elsevier Science B.V. All rights reserved.