Biosolids are carefully regulated at the federal, state and local level to protect the environment and to protect public health and safety.
The Federal 503 Rule
Under the authority of the Clean Water Act, the U.S. EPA established a comprehensive rule to protect public health and the environment from pollutants that might be present in treated biosolids. This regulation, called The Standards for the Use or Disposal of Biosolids (Title 40 of the Code of Federal Regulations, Part 503), is referred to as the Part 503 Rule.
The EPA conducted the most comprehensive risk assessment ever conducted by the agency in order to develop the 503 Rule. The Rule, which includes very conservative safety factors, applies to the producer, the land applier of biosolids and the landowner (or leaseholder). The Rule establishes best management standards that must be met to control potential disease-causing organisms and to protect public health. States may establish more stringent standards than those put in place by EPA.
More information about the 503 Rule and biosolids is available from the EPA here.