U.S. Environmental Protection Agency
Office of Water
Office of Science & Technology
... applying science & technology to protect water quality
Final Response to the National Research Council Report
Report on Biosolids Applied to Land and the Results of the Review of Existing Sewage
Sludge Regulations
December 2003; EPA-822-F-03-010
EPA is releasing a final action plan that explains the Agency's response to the recommendations
in the July 2002 National Research Council (NRC) report entitled "Biosolids Applied to Land:
Advancing Standards and Practices." The action plan is an important step in setting new
priorities for the sewage sludge (also known as biosolids) program. EPA is also announcing the
final results of its review of existing sewage sludge regulations to identify additional toxic
pollutants that may need to be regulated.
National Research Council (NRC) Report
Over the past decade, citizens and environmental organizations questioned the adequacy of the
chemical and pathogen standards for protecting human health. The Clean Water Act (CWA)
requires EPA to review the sewage sludge regulations every two years. To address these
concerns and fulfill its commitments under the CWA, the Agency commissioned the NRC of the
National Academy of Sciences to independently review the scientific basis of the regulations
governing the land application of sewage sludge.
The NRC published "Biosolids Applied to Land: Advancing Standards and Practices" in July
2002. They concluded that there is no documented scientific evidence that sewage sludge
regulations have failed to protect public health, but there is persistent uncertainty on possible
adverse health effects. The NRC noted that further research is needed and made about 60
recommendations for addressing public health concerns, scientific uncertainties, and data gaps in
the science underlying the sewage sludge standards.
In April 2003, the Agency released a preliminary multi-year strategy for public comment that
responded to the NRC report recommendations. Based on public comments and research
priorities from a Biosolids Research Summit held in July 2003 by the Water Environment
Research Foundation, EPA developed a final action plan that has four main objectives:
« Determine potential risks of select pollutants
« Measure pollutants of interest
• Characterize potential volatile chemicals and bioaerosols from land application sites
• Understand effectiveness of water/sludge treatment and risk management practices
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Due to budget constraints and competing priorities within the Agency, EPA is not able to
implement all of the NRC's recommendations. Thus, in its final action plan, the Agency
prioritized the recommendations based on public comment and criteria to help identify research
and regulatory measures that, when implemented, will maximize public health and
environmental protection.
The Agency expects to complete or begin activities, presented in the notice as "projects," within
the next two to three years, with the goal of strengthening the sewage sludge use and disposal
program. The sewage sludge program encompasses regulatory and non-regulatory components,
as described in the projects. Five examples of these projects include:
• Biennial Review under CWA §405(d)(2)(C)
* Methods development, optimization, and validation for microbial pollutants in sewage
sludge
• Sewage sludge field studies
« Targeted national survey of pollutants in sewage sludge
« Incident tracking workshop participation
Review of Existing Sewage Sludge Regulations
The CWA requires EPA to review the sewage sludge regulations every two years to identify
additional toxic pollutants in sewage sludge that may warrant regulation under section 405(d).
EPA conducted this review by evaluating publicly available information on the toxicity,
persistence, concentration, mobility, and potential for exposure of additional toxic pollutants in
sewage sludge. In April 2003, EPA published & Federal Register notice soliciting public
comment on the preliminary results of the review, which included a comprehensive list of
pollutants found in sewage sludge. At that time, EPA outlined the process it used for compiling
and analyzing the comprehensive list of pollutants, but did not identify any additional toxic
pollutants for possible regulatory action.
Since publishing the preliminary review results, EPA further analyzed the pollutants on the
comprehensive list to determine the sufficiency of available data for an exposure and hazard
assessment. EPA then conducted a human health and ecological exposure and hazard screening
assessment for those chemicals for which the requisite data was found.
Based on the results of the screening analyses, EPA has identified 15 chemicals for which it will
conduct a more refined risk assessment and risk characterization process. EPA will update the
concentration data on these chemicals by conducting a targeted sewage sludge survey. The new
concentration data and results will serve as a basis for determining whether to propose
amendments to the sewage sludge regulations for any of these chemicals. Today's Federal
Register Notice includes timeframes for taking action on these pollutants.
Additional Information
NRC report: Biosolids Applied to Land: Advancing Standards and Practices (PDF) (284 pp., 1.0)
(July 2002)
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