Health and Science

Around the world, the management of biosolids to ensure safety and health has been the focus of hundreds of scientific research studies for many decades. The results of these studies have consistently shown that responsibly managed biosolids are both safe and beneficial. According to EPA, "because of the strict federal and state standards, the treated residuals from wastewater treatment (biosolids) can be safely recycled." ("Biosolids") The U.S. Environmental Protection Agency (EPA) has found no documented case of illness or disease resulting from biosolids exposure.

To ensure comprehensive federal oversight of responsible biosolids management in the United States, EPA issued the 40 CFR Part 503 Biosolids Rule (Part 503 rule) of 1993. The process EPA used in developing the rule was based on a combination of best available technology and limiting health and environmental risks. Further reviews and studies of the rule have been conducted by the National Academy of Sciences (NAS), the National Institute for Occupational Safety and Health (NIOSH) and EPA's Office of Inspector General (OIG). Many other studies attest to the safety and efficacy of biosolids recycling.

• The 40 CFR Part 503 Biosolids Rule
• National Academy of Sciences review
• NIOSH study
• OIG Report
• Other studies

The 40 CFR Part 503 Biosolids Rule
On Feb. 19, 1993, EPA published the 40 CFR (Title 40, Code of Federal Regulations) Part 503 Biosolids Rule governing the use and disposal of municipal sewage sludge pursuant to Sections 405(d) and (e) of the Clean Water Act. (Standards for the Use or Disposal of Sewage Sludge 40 CFR 503) Part 503 requirements are based on results of a comprehensive multimedia risk assessment that began in the mid-1970s and was more extensive than any previous federal rulemaking effort for biosolids. EPA's publication, A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule, shows the many steps followed to develop the scientifically defensible, safe set of rules.

Building on existing state and federal regulations, the Part 503 rule sets forth a clear set of standards to reduce risks and increase quality for the use and disposal of biosolids. The rule contains numerical limits for chemical pollutants and pathogens applicable to the land application of biosolids. The Part 503 rule has helped biosolids managers to identify beneficial use options such as "Exceptional Quality" biosolids. These biosolids meet Class A pathogen reduction requirements, the most stringent metals limits (pollutant concentrations) and vector control requirements. Exceptional Quality biosolids can then be used in the same manner as other fertilizer products.

There have been several revisions to the Part 503 rule. Most recently, EPA has been reassessing current standards for dioxin and dioxin-like compounds in land-applied biosolids as part of an ongoing agency-wide dioxin reassessment. On June 12, 2002, EPA published a Federal Register notice of data availability for the Round 2 Part 503 sewage sludge regulations. This document summarizes the new sewage sludge data and risk assessment for dioxin. Based on a revised risk assessment, EPA estimates that land-applied biosolids present a very low health risk even to the most highly exposed populations.

National Academy of Sciences review
In mid-1993, at the request of EPA, the Water Science and Technology Board of the National Research Council (NRC)/NAS undertook an extensive review of the Part 503 rule, including an evaluation of public health concerns, current biosolids management practices and regulations, and implementation issues. Sponsors of the study included EPA; U.S. Department of Agriculture; Food and Drug Administration; Bureau of Reclamation; Water Environment Research Foundation; Association of Metropolitan Sewerage Agencies; National Water Research Institute; and the National Food Processors Association, as well as several water and wastewater authorities and private companies.

In 1996, NAS released "Use of Reclaimed Water and Sludge in Food Crop Production." This extensive peer review concluded that "the use of these materials in the production of crops for human consumption, when practiced in accordance with federal guidelines and regulations, presents negligible risk to the consumer, to crop production and to the environment."

In 2000, EPA again asked NAS to review the science and methodology underlying the agency's current health and environmental standards for biosolids. On July 2, 2002, the panel released the results of its 266-page study, "Biosolids Applied to Land: Advancing Standards and Practices," which largely confirms the findings of the 1996 NAS study. Its overarching finding is that "there is no documented scientific evidence that the Part 503 rule has failed to protect health," and it does not call for any restrictions on land application of biosolids. According to the report, "a causal association between biosolids exposure and adverse health outcomes has not been documented." It further states that the panel recognized that the land application of biosolids is a widely used, practical option for managing the large volume of sewage sludge generated at wastewater treatment plants. Furthermore, the report refutes claims by David Lewis, an EPA microbiologist, and others of the presence of Staphylococcus aureus in biosolids. "There are no publications documenting S. aureus in biosolids." The fact remains that S. aureus has never been found in biosolids.

NIOSH study
In 1997, NIOSH, a division of the U.S. Centers for Disease Control, conducted a three-year Hazard Evaluation at a Class B biosolids operation located in LeSourdsville, Ohio. The NIOSH Hazard ID (HID-10) report, issued July 2000, addressed complaints of gastroenteritis by five wastewater treatment plant workers whose symptoms were similar to those associated with infections caused by common bacteria such as Shigella, Salmonella and enteropathogenic E. Coli species. Given the common nature of most of the diseases and the ubiquitous presence of microorganisms in the environment, the question of causation between a microbial pathogen in biosolids and an illness is an important one.

The hazard ID was withdrawn in the spring 2002 after a review recognized shortcomings in the evaluation and its findings. In the end, the Centers for Disease Control and NIOSH concluded that failure to practice good personal hygiene and use personal protective equipment were the probable cause of the workers' health complaints

OIG report
In March 2002, EPA's Office of Inspector General released a status report prepared in response to a series of allegations by the National Whistleblower Center (NWC) in March 2001 concerning EPA's regulation of biosolids. The document responded to claims leveled against the agency by the NWC and EPA microbiologist David Lewis, long associated with the NWC. Lewis and NWC brought a series of actions against EPA and is a well-known opponent of the agency's biosolids policy.

The report reiterates a series of inadequacies in biosolids program oversight first reported by the OIG more than two years ago. The report discredits the allegations of the NWC and David Lewis on investigations, grants and risk assessment. The OIG report also clearly states that the beneficial use of biosolids is "low-risk" to public health and the environment and, therefore, is a "low priority."

The OIG report also incorrectly suggests that because a risk assessment was not conducted on pathogens, EPA has no understanding of risks associated with pathogens in sludge. After the best scientific review EPA could technically conduct in establishing its Part 503 rule, the agency did not consider human pathogen exposure a risk, a fact supported by the agency's years of experience with biosolids. Importantly, the report reiterates EPA's support of biosolids recycling.

Other studies
Numerous additional studies and other literature address the safety and efficacy of biosolids. For example, a substantial body of literature examining the role of chemicals in biosolids supports the lack of groundwater contamination and exposure to humans and animals, either directly or through crops.

Other literature addresses the occurrence and survivability of pathogens in various types of biosolids, as well as the relationship of biosolids, odor and health. Other literature also is available that looks at the health effects of biosolids as demonstrated by epidemiologic and toxilogic studies.

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