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Biosolids are solid wastes produced and treated by wastewater treatment plants that are applied to land as a soil supplement. This material is a combination of solids flushed down toilets and disposed through household drains, as well as industrial wastes disposed of through public sewage systems (1). These source materials may contain chemical compounds, heavy metals, and pathogens (23).

Until the 1980s, solid wastes from wastewater treatment plants were routinely discarded in the oceans. At that time, scientific evidence demonstrated that this practice was killing marine life, which led congress to pass the Ocean Dumping Ban Act of 1988 (4). Municipalities were faced with the challenge of where to put the waste, and the practice of spraying treated biosolids on farmland as fertilizer increased greatly in ensuing years. By 2002, 60% of the 5.6 million tons of dry sewage sludge/biosolids produced in the United States was applied to land (1).

EPA adopted the “503 rule” in 1993 to regulate the land application of biosolids. The rule established maximum permissible levels of nine heavy metals and mandated a treatment process to reduce the level of pathogens. Based on the 503 rule, Class A biosolids are intended to have no detectable levels of pathogenic microbes, while Class B biosolids may contain detectable levels (1).

The 503 rule has been criticized by activists and some researchers for its failure to address a broader range of possible contaminants and the lack of enforcement of practices that it does regulate (5). Additionally, some research suggests that regrowth of pathogens may be occuring in the treated biosolids (26). A growing number of residents in areas where land application of biosolids is practiced have complained of respiratory problems, skin irritation, and other ailments that they attribute to the use of biosolids (278). To date, few scientific studies have examined the possible health effects of this practice.

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Real People – Real Stories about this issue.

Protocol for documenting and investigating symptoms reported near Biosolids land application sites

This protocol was designed with funding from the Water Environment Research Foundation (WERF) to assist environmental and public health officials in responding to residents who report symptoms that residents attribute to land application of biosolids. Community members may wish to recommend the protocol to their state and local environmental and public health officials to consider using as a systematic way of responding to and investigating reports of symptoms near biosolids land application sites.

Download entire protocol or select chapters:

Full protocol- Version 9/2/2008


Decision Tree

Step 1: Health Questionnaire

Step 2: Site Identification Source Report

Step 3: Biosolids Generator Questionnaire

Step 4: Biosolids Applier Questionnaire

Step 5: Site Follow Up Report


Government agencies
Environmental Protection Agency (EPA)
National Academy of Sciences report

University-affiliated groups 
Cornell Waste Management Institute

Organizations supporting land application of biosolids
National Biosolids Partnership (NBP)
North East Biosolids and Residuals Association (NEBRA)

Community groups & environmental not-for-profit organizations
The Watchers
Loudoun Neighbors Against Toxic Sludge
Citizens for Sludge-Free Land
Resource Institute for Low Entropy Systems
Sierra Club


1 Committee on Toxicants and Pathogens in Biosolids Applied to Land, National Research Council (NRC). (July, 2002). Biosolids Applied to Land: Advancing Standards and Practices. Washington, D.C.: National Academy Press.

2 Gattie, D.K, & Lewis, D.L. (2004). A high-level disinfection standard for land-applied sewage sludges (biosolids). Environmental Health Perspectives, 112(2): 126-131.

3 National Institute for Occupational Health and Safety (NIOSH). (July, 2002). Guidance for Controlling Potential Risks to Workers Exposed to Class B Biosolids. Cincinatti: NIOSH – Publications Dissemination.

4 Committee on Science, U.S. House of Representatives. (2000). EPA’s Sludge Rule: Closed Minds or Open Debate? Retrieved June 19, 2006 from

5 Harrison, E.Z., McBride, M.B., & Bouldin, D.R. (1999). Land application of sewage sludges: An appraisal of U.S. regulations. International Journal of Environment and Pollution, 11(1): 1-36.

6 Gibbs, R.A., Hu, C.J., Ho, G.E., & Unkovich, I. (1997). Regrowth of faecal coliforms and salmonellae in stored biosolids and soil amended with biosolids. Water Science and Technology, 35(11-12): 267-275.

7 Lewis, D.L., Gattie, D.K., Novak, M.E., Sanchez, S., & Pumphrey, C. (2002). Interactions of pathogens and irritant chemicals in land-applied sewage sludges (biosolids). BMC Public Health, 2(11).

8 Shields, H. (2001). Sludge Victims