Human data on exposure and adverse effects are the most appropriate for human risk assessment, and modern toxicology focuses on human pathway analysis and the development of human biomarkers. Human biomonitoring and human placental transport studies provide necessary information for human risk assessment, in accordance with the legislation on chemical, medicine and food safety. Toxicology studies based on human mechanistic and exposure information can replace animal studies. These animal-free approaches can be further supplemented by new in silico methods and chemical structure-activity relationships. The inclusion of replacement expertise in the international Three Rs centres, the ongoing exploration of alternatives to animal research, and the improvement of conditions for research animals, all imply the beginning of a paradigm shift in toxicology research toward the use of human data.