The land application of biosolids is controversial because of the adverse effects of heavy metals and pathogens. This work reviews the subject, from an extensive discussion of heavy metals and pathogens to the fate and effects of organic compounds, describing the physical, chemical, and biological characteristics of biosolids and offering a science-based perspective on the benefits and risks of land application to human health and the environment. Consideration is given to crop removal of metals and organics, soil erosion, and leaching, as well as to differing approaches and regulations in the US, Europe, and Canada. Epstein is an environmental scientist in the private sector and professor of public health at Boston University.