Book excerpt: Toxicity against tissue stem cells (TSCs) is a major problem in drug development and environmental health science. Despite their essential function in all human cellular tissues, the nature of tissue stem cells is not fully understood. The small fraction of stem cells in tissues and the lack of specific biomarkers for their quantification present a formidable challenge to developing tools for their study and assays that can identify stem cell-toxic agents. Human Stem Cell Toxicology reveals TSC toxicity as a biomedical reality that is now well under siege by newly emerging ideas and technologies, despite these challenges. Chapters consider stem cell toxicity by environmental agents, pharmaceutical drug candidates, and marketed therapeutic medicines with adverse side effects. New insights to cellular, molecular, biochemical and chemical mechanisms of human tissue stem cell toxicity are brought together. Experimental and theoretical treatments are of specific topics, including approaches to monitoring TSC function, newly discovered TSC types and TSC toxicity resistance mechanisms are covered by expert authors. This book informs and champions the continued development of innovative technologies to predict the TSC toxicity of compounds before their use, whether in patients or the environment, by addressing emerging new cell-based approaches and concepts for technical innovation. This publication will be a useful reference for postgraduate students and researchers working in toxicology, pharmaceutical science, tissue cell biology and stem cell biology.