***This book was highly commended in the Public Health category of the British Medical Association's 2013 annual Medical Book Competition.*** Volume 100 of the IARC Monographs, A Review of Human Carcinogens, covers all agents previously classified by IARC as "carcinogenic to humans (Group 1)" and was developed by six separate Working Groups: Pharmaceuticals; Biological agents; Arsenic, Metals, Fibres, and Dusts; Radiation; Personal Habits and Indoor Combustions; Chemical Agents and Related Occupations. This Volume 100A covers Pharmaceuticals, specifically Busulfan, Chlorambucil, Methyl-CCNU, Cyclophosphamide, Etoposide in combination with Cisplatin and Bleomycin, Melphalan, MOPP, Tamoxifen, Thiotepa, Treosulfan, Diethylstilbestrol, Estrogen-only Menopausal Therapy, Combined Estrogen-Progestogen Menopausal Therapy, Combined Estrogen-Progestogen Contraceptives, Azathioprine, Chlornaphazine, Ciclosporin, Plants containing Aristolochic Acid, Methoxsalen plus Ultraviolet A Radiation, and Phenacetin. Because the scope of Volume 100 is so broad, its Monographs are focused on key information. Each Monograph presents a description of a carcinogenic agent and how people are exposed, critical overviews of the epidemiological studies and animal cancer bioassays, and a concise review of the agent's toxicokinetics, plausible mechanisms of carcinogenesis, and potentially susceptible populations, and life-stages. Details of the design and results of individual epidemiological studies and animal cancer bioassays are summarized in tables. Short tables that highlight key results are printed in Volume 100, and more extensive tables that include all studies appear on the Monographs programme website (http://monographs.iarc.fr). It is hoped that this volume, by compiling the knowledge accumulated through several decades of cancer research, will stimulate cancer prevention activities worldwide, and will be a valued resource for future research to identify other agents suspected of causing cancer in humans.