Detection of human carcinogens

Compounds are tested to determine if they are carcinogenic (cancer causing) to humans by exposing rodents to the maximum dose tolerated, and observing if cancer develops in the rodents' lifetime. These tests are slow and expensive. Compounds exist that directly cause changes, or mutations, in the DNA, the genetic information of cells, leading to cancer development. Other compounds directly cause mutations, but also cause more frequent cell division, which increases the chance that a mutation will occur. Some compounds do not directly cause mutations, but at the maximum tolerated dose, increase the frequency of cell division, which may lead to cancer development; these compounds may not be harmful at lower doses. Some compounds cause mutations in rodent DNA, but not in human DNA. Therefore, testing the maximum tolerated dose in rodents is not an effective way to determine carcinogenicity. Another strategy for testing is presented. Rodents can be used for short-term testing of the possible carcinogenic effects of compounds, but other tests should be done in tissue culture (outside of the body) to further examine the effects. (Consumer Summary produced by Reliance Medical Information, Inc.)