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The Science of Biosolids Recycling
The scientific process depends on critical peer review and debate. Biosolids recycling policy and practice rests on a body of scientific research conducted over 30 years and more. A large proportion of government and university scientists working with biosolids have come to believe that biosolids recycling in accordance with current laws and best management practices represents "negligible risk" (this is the finding of the 1996 National Research Council review of the federal biosolids program).
Still, there will be (and should be) robust discussion regarding new angles in the practice of recycling biosolids and other residuals. We at NEBRA believe that this robust scientific analysis and debate leads to better practice and policy.
Federal EPA regulation risk assessment and review
A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule
A U.S. Environmental Protection Agency guidance document describing the full risk assessment process that led to the final standards found in the federal 40 CFR Part 503 regulations ("the 503 rule") for the use and disposal of sewage sludge/biosolids: http://www.epa.gov/owm/bio/503rule/index.htm
Reviews of U.S. EPA risk assessment and 503 rule
1. National Research Council
The following projects involved panels of scientific experts, convened by this nation's most respected scientific body, the National Academy of Sciences, reviewing the science behind the federal regulation of biosolids/sewage sludge management:
Use of Reclaimed Water and Sludge in Food Crop Production (1996)
This is the first National Research Council expert panel review of the federal biosolids Part 503 regulatory program. It concluded…
"In summary, society produces large volumes of treated municipal wastewater and sewage sludge that must be either disposed of or reused. While no disposal or reuse option can guarantee complete safety, the use of these materials in the production of crops for human consumption, when practiced in accordance with existing federal guidelines and regulations, present negligible risk to the consumer, to crop production, and to the environment."
(National Research Council: "The Use of Reclaimed Water and Sludge in Food Crop Production," National Academy of Sciences, 1996, p.13.)
In 2000, the U.S. Environmental Protection Agency (EPA) asked the National Academy of Sciences to "review information on the land application of sludge and evaluate the methods used by the U.S. EPA to assess risks from chemical pollutants and pathogens in sludge." The Academy convened another National Research Council (NRC) panel that released its final report, Biosolids Applied to Land: Advancing Standards and Practices, in July, 2002. This report found:
"There is no documented scientific evidence that the Part 503 rule has failed to protect public health. However, additional scientific work is needed to reduce persistent uncertainty about the potential for adverse human health effects from exposure to biosolids. There have been anecdotal allegations of disease, and many scientific advances have occurred since the Part 503 rule was promulgated. To assure the public and to protect public health, there is a critical
need to update the scientific basis of the rule to (1) ensure that the chemical and pathogen standards are supported by current scientific data and risk-assessment methods, (2) demonstrate effective enforcement of the Part 503 rule, and (3) validate the effectiveness of biosolids management practices" (from Summary, page 3, prepublication copy).
In September, 2002, Dr. Thomas Burke, Chair of the panel that wrote the report, issued a statement clarifying the panel's findings. "First, we found no evidence of an urgent public health risk from exposure to land-applied biosolids, based on our review of the scientific literature. Currently, there are no studies documenting adverse health effects from land application of biosolids, even though land application has been practiced for years. But this finding was tempered by the fact that few studies are available on human exposure to biosolids, and that, even when they are investigated locally, there are no means of tracking health allegations nationally."
Dr. Burke's clarifying statement, along with the 12-page summary of the report, provides the clearest understanding of the NRC findings. To view the clarification statement, click here.
The NRC report can be downloaded here or it may be purchased in paperback book form from the National Academy of Sciences--order here (you can also read the report on-line at that webpage).
2. The Case for Caution
Cornell Waste Management Institute critique and responses
In 1997, the Cornell Waste Management Institute (CWMI) published a critique of the federal EPA risk assessment and the numerical standards contained in 40 CFR Part 503, "the 503" regulations. Soon afterward, New York State Department of Environmental Conservation, EPA, and U.S. Department of Agriculture staff responded to the CWMI paper. Despite these rebuttals, over subsequent years, The Case for Caution has been cited by many as reason for concern about biosolids recycling.
NEBRA takes an interest in presenting here The Case for Caution and responses to it because it contains information pertaining particularly to biosolids management practices in New England. New England biosolids managers and the public should be aware of those concerns and if and how they are addressed.
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