Sewage sludge (also known as ‘biosolids’) refers to the semi-solids left over from municipal waste water treatment. Current legal disposal options include incineration, landfill, and land application to agricultural land, rangeland, or forests.
The resources on this page provide a scientific overview of health impacts from land application. Risk assessment is complex because Sludge Contains Highly Varied Amounts of Organic Chemicals, Toxic Metals, Chemical Irritants, and Pathogens. Furthermore, the effects of their interactions, long-term build-up in soils, leaching into waterways, and uptake into crops and the food system have not been well-studied. Thus, little is known about the long term human heath and Ecological Consequences of Sludge Application. There is, however, clear scientific documentation of the sometimes deadly Direct Human Health Consequences of Land Application. Furthermore, by bringing together and concentrating varied pathogens and antibiotics, Wastewater Treatment Selects Antibiotic Resistant Bacteria, a health problem worldwide.
The paucity of scientific research is not accidental. Journalists and researchers have chronicled how the EPA’s Conflicts of Interest and those of other institutions, including the NAS, USDA, municipalities, and universities, obstruct sludge research and further undermine risk assessment and regulation.
EPA’s Sludge Regulation fails to incorporate existing scientific information and to protect the public. Yet while many scientific experts recommend a total ban on sludge application to land, EPA and others continue to promote it. Sludge is sold to the public as nutrient-rich garden compost and portrayed to farmers as a valuable fertilizer.
Even ending land application, however, is only a partial solution. Alternatives, incineration and landfill, are also hazardous. Ensuring ecosystem and human health requires Reformulating the Problem with the explicit goal of preventing sludge formation. This will require organic wastes and industrial wastes be kept separate and treated at their source.
For an illuminating non-technical introduction to the origins of sewerage systems and the creation and disposal of toxic sludge see: Civilization & Sludge: Notes on the History of the Management of Human Excreta by Abby A. Rockefeller.