Professionalism/David Lewis and EPA

Dr. David Lewis was a senior-level research microbiologist for the US Environment Protection Agency's Office of Research & Development during the 1990s. He was awarded EPA’s Science Achievement Award for his research on the effects of global climate change on the breakdown of pesticides by bacteria [1]. However, once he began investigating illnesses and deaths linked to EPA programs that promoted the use of sewage sludge on agricultural lands, the EPA officials who developed the Agency’s sewage sludge regulations moved to shut down his research[2]. Although his research was shut down by the EPA, the incident provoked the Centers for Disease Control and Prevention to issue guidelines that would protect workers handling processed sewage sludge. Dr. David Lewis was ultimately fired from the EPA, and the debate on the safety of sewage sludge is still ongoing.

Sewage SludgeEdit

Sewage sludge is the residue that is generated during the treatment of domestic sewage. Domestic sewage first undergoes pretreatment by industry. Afterwards, it undergoes wastewater treatment where the byproduct becomes the sewage sludge. Because of its beneficial plant nutrients and soil conditioning properties, sewage sludge is often used as an organic soil conditioner and partial fertilizer in the United States and other countries. Finally sewage sludge gets treated by going through digestion, drying, composting, lime stabilization, and heat treatment among many others. After the sewage sludge is treated, it is ready for use in land application.[3] Some of the areas where sewage sludge is mainly applied are: agricultural land, disturbed areas such as mine lands and construction sites, plant nurseries, forests, recreational areas, cemeteries, highways, airport runway medians, and home lawns and gardens.

Application of treated sewage sludge is recommended by the EPA because of its beneficial plant nutrients and soil conditioning properties. However, the use of treated sewage sludge is often looked down upon because it may also contain pathogenic bacteria, viruses, parasites, and other microorganisms that can cause diseases.[4] Land application and surface disposal of untreated sewage sludge create a potential for human exposure to these pathogenic bacteria through direct and indirect contact that can cause harm.

Perspectives of Various Interest GroupsEdit

Support for SludgeEdit

Proponents use the term "Biosolids" while referring to treated sewage sludge. According to the EPA’s official website, “Only biosolids that meet the most stringent standards spelled out in the Federal and state rules can be approved for use as a fertilizer”.[5] The EPA maintains that well treated sewage sludge is safe enough to be considered a cheap and sustainable alternative to chemical fertilizers. Water Environment Federation (WEF), a non-profit organization representing water quality professionals, also endorses the use and recycling of biosolids.[6] The WEF conducts promotional campaigns in order to inform the public about various benefits of using biosolids. Water Environment Research Foundation and U.S. composting council are other notable advocates of biosolid usage.

Opposition to SludgeEdit

Less than 1% of all farmland in the U.S. use sewage sludge.[7] There is no EPA rule mandating the use of sludge, and farmers can usually have it delivered for free. Nonetheless, several interest groups have emerged to oppose the use of sewage sludge in America’s farmlands. Opponents of sludge have a strong online presence; a Google search of the term “sewage sluge” will return links to several sludge opposition groups on the very first page. United Sludge Free Alliance, a non-profit advocacy group, accuses the EPA of promoting the use of sludge despite being aware of its harmful effects on public health.[8] The group support stricter regulation of sludge usage, with the ultimate goal of ending the use of sludge as fertilizers. has compiled hundreds of testimonies by people claiming to have been victims of toxic sludge. In many of these cases, residents living next to sludge-treated lands reported having headaches, burning eyes, sore throat, nose bleeding, cough, and unexplainable lung diseases. There are numerous complaints about strong, unsettling odors. The website also contains scanned images of letters sent from concerned citizens to senators’ and local government officials, as well as news articles, some of which date back to 1995. Sewage Sludge Action Network,, and are also opposed to the use of sewage sludge.

Scientific Research on the effects of Sewage SludgeEdit

In 1996, National Research Council (NRC) published a report titled Use of Reclaimed Water and Sludge in Food Crop Production. The report concluded that “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, presents negligible risk to the consumer, to crop production, and to the environment”.[9] The materials that the paper is referring to are treated sewage sludge. The EPA also conducted its own study in late 1990s to determine whether dioxins present in treated sewage sludge pose a significant threat to public safety. The study focused on a high risk sample of farming families who use sewage sludge exclusively and eat from the crops grown on sludge applied land. The study found that only about .22 new cases of cancer could be expected to occur in a span 70 years.[10] As a result, the EPA declined to impose further regulation on the level of dioxins in treated sludge. In 2002, National Research Council published Biosolids Applied to Land, a report on the effectiveness of EPA rules regarding sewage sludge. The report did not find faults with EPA regulations, but it suggested that there are enough uncertainties regarding the adverse effects of sewage sludge to warrant more scientific research in that area.[11] They made about 60 recommendations to EPA for addressing public health concerns. But according to the EPA, the agency failed to implement most of those recommendations due to budget constraints.[12] EPA regulations regarding biosolids have largely stayed the same since then.

Rule 503Edit

In 1993, the EPA introduced the Part 503 Rule under the Clean Water Act to stop uncontrolled ocean dumpings of municipal waste. The EPA stated in 'A Plain English Guide to the EPA Part 503 Biosolids Rule,' that "the Part 503 Rule provides comprehensive requirements for the management of biosolids generated during the process of treating municipal wastewater," and claimed that the rule "creates incentives for beneficial use of biosolids."[13]

According to the Part 503 Rule, biosolids are categorized into three groups for further applications. The standard that the EPA uses for this categorization includes pollutant concentration, treatment method and pollutant loading rates. The treated biosolids that meet the EPA standards are used for land application while the biosolids that does not meet the standards are either disposed or incinerated.[14]

There are two classes of biosolids for land application. Class A sludges are "pathogen-free, safe for contact", while class B sludges may have pathogen concentrations. The 503 Rule, however, does not directly regulate the use of Class B sludges; they are regulated by the states and the strictness of regulation differs from state to state. [15]

Whistleblowing and Firing of David LewisEdit

Dr. David Lewis published several articles stating on the potential health effects of using sewage sludge in which he claimed that the strictness of the 503 Rule was not satisfactory because the EPA never conducted an adequate pathogen risk investigation on the land application of sewage sludge. He also claimed that Class B sludges are most commonly used for agricultural uses, and listed several pathogen that are present in Class B sewage sludge that can cause illness. [16]

According to Dr. Lewis, the 503 Rule was not reviewed by his department, EPA's Office of Research and Development (ORD), even though the department recommended more scientific studies. Dr. David's article states that the federal court approved the 503 Rule even though many scientists from ORD were skeptical. [17]

Dr. Lewis and his research team argued that some illness have been stemming from the land application of biosolids. He claimed that "25% of 48 individuals living near land application sites who complained of chemical irritation had evidence of serious Staphylococcus aureus infections, which contributed to two deaths." He also listed Staphylococcus aureus as one bacteria that is found in Class B sewage sludge, which is not regulated at a national level under the 503 Rule.[18]

Dr. Lewis was not only involved in publishing articles that raised concerns for the EPA's policy but also participated in several public hearings as an expert witness and presented his research results.[19]

When the EPA fired him in 2003, he filed complaints to the Department of Labor claiming that the EPA did not treat him fairly because of his published articles that criticized the EPA. Dr.Lewis claimed that his articles were not fairly reviewed and were underestimated by the EPA. However, the Department of Labor dismissed his complaints and concluded that the EPA did not violate Dr.Lewis' employee rights.[20]

Ethical DilemmasEdit

David Lewis’s dilemma is similar to Frances Oldham Kelsey’s dilemma of approving Kevadon for the Food and Drug Administration. The approval of the drug would have been profitable, and even expected, at the time. But Kelsey, suspecting that the drug could lead to the births of thousands of kids without arms or legs, ultimately denied its approval. David Lewis took a similar stance, although unsuccessful, by continuing his investigation because he believed sewage sludge contained pathogenic bacteria and viruses that can cause diseases through direct and indirect contact.

Another similar situation is Dan Applegate and Convair. Applegate knew that the safety of the cargo door latching system had been compromised, and could have led to the deaths of hundreds of people. However, Applegate didn’t pursue the problem as Lewis did and only sent a memorandum to the program manager which was basically dismissed. Unlike Applegate, Lewis published his research outlining the harmful side effects of sewage sludge which ultimately got him fired from the EPA.

Although not yet vindicated by science, David Lewis should still be commended for trying to minimize the public health risks associated with sludge usage, even at the cost of his professional career.


  1. Dr. David Lewis, National Whistleblowers Center
  2. Dr. David Lewis, National Whistleblowers Center
  3. Control of Pathogens and Vector Attractions in Sewage Sludge, Environment Protection Agency: Environmental Regulations and Technology
  4. Control of Pathogens and Vector Attractions in Sewage Sludge, Environment Protection Agency: Environmental Regulations and Technology
  5. Water: Sewage Sludge (Biosolids) - Introduction, Environment Protection Agency
  6. Water Environment Federation Position Statement : Biosolids, The Water Environment Federation
  7. Water: Sewage Sludge (Biosolids) : Frequently Asked Questions, Environment Protection Agency
  8. Sludge and the EPA, United Sludge Free Alliance
  9. Use of Reclaimed Water and Sludge in Food Crop Production, The National Academies Press
  10. EPA Makes Final Decison on Dioxin In Sewage Sludge used in Land Applications, Environment Protection Agency
  11. Biosolids Applied to Land: Advancing Standards and Practices Biosolids Applied to Land: Advancing Standards and Practices, The National Academies Press
  12. Final Response to the National Research Council Report, Environment Protection Agency
  13. A Plain English Guide to the EPA Part 503 Biosolids Rule, Environment Protection Agency
  14. A Plain English Guide to the EPA Part 503 Biosolids Rule, Chapter 1, Environment Protection Agency
  15. Pathogen Risks From Applying Sewage Sludge to Land, David Lewis
  16. Pathogen Risks From Applying Sewage Sludge to Land, David Lewis
  17. Pathogen Risks From Applying Sewage Sludge to Land, David Lewis
  18. Pathogen Risks From Applying Sewage Sludge to Land, David Lewis
  19. Lewis v. U.S. Environmental Protection Agency, Department of Labor
  20. Lewis v. U.S. Environmental Protection Agency, Department of Labor