Toxicology in the 21st Century (Tox21)

Throughout their lives, people are exposed to thousands of chemicals in food, household cleaning products, medicines and the environment. However, scientists know little about the potential for most of these substances to be hazardous to human health (i.e., their toxicity). In fact, more than 30 percent of promising pharmaceuticals have failed in human clinical trials because they are determined to be toxic, despite promising pre-clinical studies in animal models. New methods to assess chemical toxicity have the potential to improve how scientists evaluate environmental chemicals and develop new medicines. Learn more about the Tox21 program's focus on improving toxicity testing.