Description: Biosolids are a product of the wastewater treatment process. During wastewater treatment the liquids are separated from the solids. Those solids are then treated physically and chemically to produce a semisolid, nutrient-rich product known as biosolids. The terms ‘biosolids’ and ‘sewage sludge’ are often used interchangeably though biosolids typically means treated sewage sludge that meet federal and state requirements and are applied to land as a soil amendment. Section 405(d) of the Clean Water Act (CWA)  requires the United States Environmental Protection Agency (EPA) to (1) develop a regulation to establish pollutant limits and management practices to protect human health and the environment from any reasonably anticipated adverse effects of pollutants that might be present in sewage sludge; and (2) review sewage sludge regulations every two years to identify any additional pollutants that may occur in biosolids and to set regulations for pollutants identified in biosolids if sufficient scientific evidence shows they may harm human health or the environment. The regulation 40 CFR Part 503, Standards for the Use or Disposal of Sewage Sludge , was published on February 19, 1993 (58 FR 9248). Part 503 established pollutants limits for ten metals. Since 1993, EPA has conducted nine biennial reviews and three national sewage sludge surveys to identify additional pollutants found in biosolids. To date, 739 chemicals have been found in biosolids. You can learn more about the curation of the list of chemical pollutants through 2021 here: Concentration data is also available for 484 chemical pollutants detected in the three national sewage sludge surveys here: Supplementary Information Table 4 ( To view all the microbial pollutants found in biosolids see Appendix B, ‘Table B-3: Microbial Pollutants Identified in Biosolids’ in Biennial Report No.9 (Reporting Period 2020-2021). (Last Updated December 21st, 2022).

    Number of Chemicals: 739