Human hair is the subject of a remarkably wide range of scientific investigations. Its chemical and physical properties are of importance to the cosmetics industry, forensic scientists, and to biomedical researchers. The fourth edition of this book confirms its position as the definitive monograph on the subject. Previous editions of this book were recognized as "concise and thorough". Features of the Fourth Edition: - New information on chemical damage from permanent waving, bleaching and sunlight and how to minimize or prevent this damage. - A new view of the cause of dandruff is presented with new supporting data. This view suggests new approaches for both treatment and for marketing of scalp care products. - The latest information on the science of hair growth and hair growth stimulating agents is provided, including Propecia. - A new section has been added on skin and eye irritation and skin sensitization from ingredients used in hair care, and a model has been provided to predict relative skin irritation of shampoos. - New micrographs on "normal hair fiber shape variations" and how fiber shape can influence chemical and physical interactions of hair fibers will be covered. - Additional material is now included on hair straightening.