Reflections in Mutation ResearchReflections on a career and on the history of genetic toxicity testing in the National Toxicology Program

One of the highly visible aspects of the U.S. National Toxicology Program (NTP) has been its genetic toxicity testing program, which has been responsible for testing, and making publicly available, in vitro and in vivo test data on thousands of chemicals since 1979. What is less well known, however, is that this NTP program had its origin in two separate testing programs that were initiated independently at the National Cancer Institute (NCI) and the National Institute of Environmental Health Sciences (NIEHS) before the NTP was established. The NCI program was in response to the 1971 National Cancer Act which dramatically increased the NCI budget. In contrast, the NIEHS testing program can be traced back to a publication by Bruce Ames, not the one describing the mutagenicity assay he developed that became known as the Ames test, but because in 1975 he published an article showing that hair dyes were mutagenic. The protocols developed for these NCI contracts became the basis for the NTP Salmonella testing contracts that were awarded a few years later. These protocols, with their supporting NTP data, strongly influenced the initial in vitro OECD Test Guidelines. The background and evolution of the NTP genetic toxicity testing program is described, along with some of the more significant milestone discoveries and accomplishments from this program.