APPENDIX V: SENATE TESTIMONY PREPARED BY DAVID LEWIS
Briefing on “Oversight on the State of Science and Potential Issues Associated with EPA’s Sewage Sludge Program”
September 11, 2008
TESTIMONY OF DAVID L. LEWIS, PhD1
Director, International Center for Research on Public Health and the Environment, www.researchcenter.uga.edu
Visiting Scientist, Department of Marine Sciences,
University of Georgia Athens, Georgia 30602, DavidL@uga.edu
Chairman Boxer, Ranking Member Inhofe, and honorable members of the committee, thank you for the privilege of testifying today about my research on sewage sludge at the U.S. Environmental Protection Agency.
OPENING STATEMENT OUTLINE
“EPA’s handling of the 503 sludge rule”
• EPA-ORD identified six scientific weaknesses, which have existed since EPA’s sludge program began
• EPA-OW reneged on its promise to fix these weaknesses
• OW/ORD silenced scientists who tried to fix these weaknesses
• Witness A. McElmurray and I would not be here today had OW worked with ORD to fix these weaknesses
• EPA needs to fix OW/ORD
• My written testimony answers twelve questions concerning how the US Environmental Protection Agency (EPA) has handled the sewage sludge issue.
Sewage sludge is the semi-solid material that settles out at municipal wastewater treatment plants when water containing effluent from municipal and industrial sources is purified. It consists mostly of human feces and contains a variety of chemical and biological contaminants, which enter municipal sewerage systems from various sources, including homes, businesses, hospitals, and factories. Some municipalities also direct stormwater runoff into sewer lines for treatment at wastewater treatment plants.
2. What are biosolids?
In 1978, John Walker at EPA’s Office of Water (OW) proposed to associate deputy assistant administrator Henry Longest that EPA support the use of sewage sludge as an inexpensive fertilizer for agriculture. Walker wrote, “The application of some low levels of toxic substances to land for food crop production should not be prohibited; rather, it should be controlled by proper rates of sludge/toxic application, soil management, etc.”2 Longest and his superiors supported the idea and EPA began developing guidelines for processing sewage sludge into fertilizer, which came to be known as “biosolids.”3
Based on levels of certain bacteria or viruses called “indicator” pathogens, which are used to indicate the presence of pathogens, processed sewage sludge is distributed as either Class A or Class B biosolids. (Testimony Appendix I)
3. Why did I conduct research on sewage sludge at EPA?
In 1996, I wrote a commentary for Nature titled “EPA Science: Casualty of Election Politics.4 In it, I discussed a number of areas where EPA regulations involve microbiological processes but fail to incorporate this area of science into the regulations. Relatively few microbiologists worked for EPA at the time.
When a local reporter with the Atlanta Journal-Constitution asked me for a worst-case example, I put the question to other scientists working at EPA research laboratories across the country. Their suggestion was the 503 sludge rule, in which EPA’s Office of Water had not done a risk assessment for pathogens (disease-causing microorganisms). The newspaper ran a full-page article about the commentary and focused on the sludge rule. I filed several successful complaints with the Department of Labor to fend off retaliations.
To settle one of the complaints in 1998, my top career EPA manager in the Office of Research & Development (ORD), Henry Longest, proposed that I be assigned to the University of Georgia (UGA) under the Intergovernmental Personnel Act (IPA) to continue earlier work that I had done concerning infection control in dentistry. As a member of the graduate faculty at UGA, I had collaborated with researchers at dental and medical schools in California and Missouri to investigate an outbreak of human immunodeficiency virus (HIV), the AIDS virus, in a Florida dental practice.
Working after hours with a dentist treating AIDS patients in Atlanta, we discovered that the AIDS virus could escape disinfection by hiding in lubricants in dental devices used for drilling and polishing teeth. Live HIV, we found, leaked back out in amounts that were high enough to readily infect human blood cells (lymphocytes) when the devices were reused. We published the work in Lancet and Nature Medicine, and our findings convinced public health organizations worldwide to issue new infection control guidelines for dentistry.5
For the IPA assignment Longest offered me, I proposed organizing an epidemiological study of endoscopy-related hepatitis C (HCV) cross-infections in Egypt where that virus is highly prevalent.6 Flexible endoscopes used in colorectal cancer screening and many other important diagnostic and therapeutic procedures are not designed with infection control in mind. Approximately 80 percent of these devices used in the United States and elsewhere contain internal air and water channels that are too narrow to brush out visible amounts of blood, tissue, and feces that collect inside them.
IPA rules required that I apply my research on flexible endoscopes to EPA’s mission. There was widespread support among scientists within ORD to address the issue of pathogens in sewage sludge; therefore, local EPA managers agreed that I could apply my research on infection control in endoscopy to EPA’s mission by investigating risks posed by pathogens in sewage sludge. ORD’s concern was that exposing the US population to pathogens in municipal wastes could potentially provide an open door to emerging infectious diseases. So, I intended to fill in some of the gaps in scientific data that were missing as a result of EPA not having done a pathogens risk assessment for the 503 sludge rule.
To accomplish my research on sewage sludge, I assembled a team of scientists at the University of Georgia, including a professor of medical microbiology, to study anecdotal reports of illnesses and three deaths reported by residents living near land-application sites. We collaborated with a physician in California treating children exposed to sewage sludge, and I paid for all of the research out of my personal funds. Altogether, we studied ten land application sites in the United States and Canada.
We were interested in investigating these anecdotal cases even though they were insignificant in number compared with, for example, the numbers of deaths attributed to auto accidents, smoking, and other major public health issues. Whether these cases would turn out to indicate a significant public health problem depended on what the actual number of cases was and whether there were any indirect effects involving larger groups.
Dentistry is one example in which even a few documented cases may have been the proverbial tip of the iceberg. For reasons that are not yet fully understood, the hepatitis C epidemic in the United States began to precipitously collapse in 1988. The downturn in HCV cases, which occurred mostly among injection drug users, coincided with the first suspected case of HIV infection in dentistry. In response, the American Dental Association had undertaken a national campaign to improve infection control. Hepatitis B also dropped dramatically, while hepatitis A and other non-bloodborne infections did not.
Any reduction in sporadic cases of dental infections and the collapse of the HCV epidemic may be entirely coincidental. However, HCV is primarily transmitted by sharing blood-contaminated devices, and drug addicts did not suddenly stop sharing needles in 1988. Our research suggests that when inefficient mechanisms of transmission, e.g., those involving poorly disinfected dental devices, become commonplace, they may actually play an important role in driving major epidemics. The reason is that they could be moving infectious agents around within the general population and introducing them to high risk groups engaged in more efficient mechanisms, e.g., needle sharing.
4. How are biosolids applied to land, and what aspect of land application did I study at EPA?
Processed sewage sludge, or biosolids, is used as a fertilizer or soil conditioner in agriculture, forestry, mining reclamation, home gardens, and a variety of other uses. It is spread on the surface of land and incorporated in soil in liquid, semi-solid, and solid (e.g., pellet) forms. Liquid biosolids are also applied by sub-surface injection.
Some of my colleagues at ORD were concerned with aerosols generated when liquid sewage sludge is sprayed on land. By contrast, I focused on dry organic dusts picked up by winds. Such dusts can allow pathogens trapped inside to remain viable even while traveling great distances. (Testimony Appendix II)
5. What contaminants do biosolids contain, and which ones did I study at EPA?
EPA estimates that there may be trace amounts of as many as sixty thousand organic chemical contaminants in sewage sludge, including priority pollutants regulated under the federal Clean Water Act. Organic contaminants include, for example, pesticides, petroleum byproducts, antibiotics, and other pharmaceuticals. Biosolids also contain a wide variety of inorganic pollutants. These pollutants include heavy metals, such as mercury, cadmium, molybdenum, arsenic, lead, thallium, and chromium. Biosolids can also contain other inorganic pollutants, such as nitric, hydrofluoric, and sulfuric acids.
Generally speaking, any chemical contaminants present in wastewater originating from municipalities and local industries are also likely to be present in biosolids, and often at much higher concentrations. Biosolids also contain parasites and disease-causing bacteria, fungi, protozoa, and viruses. My research at EPA focused on chemical contaminants in sewage sludge dusts that could irritate the skin, eyes, mucous membranes, and respiratory tract and possibly lead to infections, especially staphylococcal infections.
6. How are biosolids regulated, and which regulations did my research at EPA involve?
Sewage sludge, or biosolids, is regulated under 40 CFR, Part 503 (the “sludge rule” or “503 rule”). The 503 rule sets limits on levels of indicator pathogens and certain inorganic chemicals, including nine heavy metals (arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium, and zinc) and certain nutrients, e.g., nitrates. If processed sewage sludge fails to meet Part 503 criteria, Toxicity Characteristic Leaching Procedure (TCLP) tests must be performed to determine whether the waste is hazardous. If so, it must be disposed of accordingly under the Resource Conservation and Recovery Act (RCRA). My research related most directly to the 503 sludge rule.
7. What are the scientific weaknesses in EPA’s sludge rule, and which ones did I address in my EPA research?
When the 503 rule was promulgated in 1993, ORD identified six areas in which research was lacking: (1) monitoring of surface and groundwater to understand how sewage sludge pollutants are transported and chemically transformed in the environment; (2) characterizing the variability of land application practices in actual practice; (3) determining the bioavailability of sewage sludge pollutants for uptake by plants and animals; (4) assessing the ecological effects of chemicals and pathogens in sewage sludge on wildlife and other plant and animal communities; (5) determining the distribution and variability in the concentrations of sewage sludge pollutants and their capacities to remain bound to the sludge; and (6) understanding long-term changes at land application sites, including, for example, changes in soil pH, land use, and the capacity for sewage sludge to bind chemical contaminants.
Upon investigating a complaint that I filed regarding OW’s failure to address the six scientific weaknesses identified by ORD, EPA’s Office of Inspector General (OIG) audited the program and issued a report in 2002.7 The Inspector General found that OW failed to follow through with the research support it promised, and, as a result, EPA could not assure the public that land application is safe. The National Academy of Sciences also determined other scientific weaknesses in the 503 rule in 1996 and 2002, such as EPA’s lack of a risk assessment for pathogens, a lack of epidemiological studies, and a lack of any understanding concerning how contaminants in sewage sludge may interact.
My work at EPA specifically addressed weaknesses number 1, 3, 4, 5, and 6 above, which were identified by ORD in the preamble to the 503 rule. My work also involved issues addressed by the NAS, such as investigating anecdotal cases of residents and workers reporting adverse health effects, and studying the interactions of chemicals and pathogens in sewage sludge.
8. What were the main areas of scientific controversy, and how did my research relate to them?
• Organic pollutants: EPA does not regulate organic chemicals, including priority pollutants, in biosolids. Land application proponents argue that all potentially harmful organic chemicals in biosolids, such as pesticides, petroleum byproducts, and pharmaceuticals, are present only at very low levels and are unavailable for uptake by plants and humans. They also argue that a number of chemicals that were of concern, e.g., chlordane, have now been banned or restricted and should no longer present a problem.
• Heavy metals: EPA excludes some potentially toxic heavy metals occasionally found in sewage sludge, including, for example, thallium, antimony, and chromium.
• Pathogens: Disease-causing organisms found in sewage sludge include parasites and many kinds of bacteria, viruses, fungi, and protozoa. These organisms exhibit different levels of resistance to treatment processes designed to reduce their numbers, and the effectiveness of different treatment processes is uncertain.
In my EPA research, my coworkers and I studied residents living near land application sites. We included both affected and unaffected residents, that is, those who reported symptoms and those who did not. Based on dose-response curves and other data, we found an association between gastrointestinal, respiratory, and skin-related complaints and dusts blowing from land application sites. (Testimony Appendix III)
9. Did my research at EPA, or any other research, ever determine whether biosolids are safe?
No. Without knowing which potentially harmful contaminants are present, and at what concentrations, and how they interact as mixtures, and without performing any toxicity tests, epidemiological studies, or carefully designed cause-and-effect studies, it is impossible to know whether any particular batch of biosolids presents any significant risk to public health or the environment.
10. Did my research at EPA, or any other research, ever prove that sewage sludge applied under the 503 rule has harmed public health or the environment?
No. There are only two cases proving that land-applied sewage sludge has harmed public health or the environment. These are the McElmurray and Boyce cases, in which cattle on two dairy farms in Georgia were poisoned by high concentrations of cadmium, molybdenum, arsenic, thallium, chlordane, and other hazardous wastes in sewage sludge produced by the City of Augusta. None of the sewage sludge applied in those cases ever complied with EPA’s applicable guidelines, including 40 CFR, Part 503, and its predecessor, 40 CFR, Part 257.
The peer-reviewed scientific literature contains three studies concerning the potential effects of sewage sludge on residents living near land application sites. (Testimony Appendix III) One is the 1985 Dorn study in Ohio, which found no adverse health effects. Another is our 2002 study of residents living near ten land-application sites in the US and Canada. We found a dose-response association between gastrointestinal, respiratory, and skin-related diseases and the distances residents lived from fields treated with sewage sludge. The third study, which was conducted in Ohio and published in 2007, supported our results. However, none of these studies are conclusive.
The 2002 National Academy of Sciences report, “Biosolids Applied to Land: Advancing Standards and Practices,” concluded that there is no documented evidence that biosolids applied under EPA’s 503 sludge rule has ever harmed public health or the environment. Our peer-reviewed studies were deleted from the final version of this report without the approval of the NAS panel.8 Also, the Augusta cattle cases were dismissed in the report based on data that EPA’s Office of Water provided to the panel, which US District Judge Anthony Alaimo recently ruled were “fudged,” “fabricated,” and “invented.”9
While I believe that our EPA-approved, peer-reviewed scientific research provided credible evidence, which should not have been deleted from the NAS report, I do not believe that our research proved that sewage sludge applied under EPA’s 503 rule has caused gastrointestinal, respiratory, and skin-related diseases. Nature accurately described our research findings in a recent editorial as having established “an association between these factors” and that “recent research underscores those findings.”10
11. How did EPA respond to my research findings concerning land application of sewage sludge?
Local EPA managers in Athens, Georgia, fully supported my research on sewage sludge and approved all of my research plans. Nevertheless, Henry Longest and other senior EPA officials involved with the agency’s policies on sewage sludge alleged that my writings in Nature and elsewhere violated government ethics rules. They also required special procedures for my promotion and other favorable personnel actions to be approved.
I filed a number of complaints with EPA’s Office of Inspector General and the US Department of Labor. Both organizations investigated and found that OW officials and others had retaliated and/or acted improperly concerning the content of my peer-reviewed research articles and other scholarly writings. The Committee on Science in the House of Representatives held two hearings into these retaliations in 2000.11 As a result, Congress passed the No Fear Act signed by President Bush in 2002.12
Then, after failing to get local EPA managers in Athens to “muzzle” me,13 Longest offered me an opportunity to take the IPA assignment to study infection control issues at the University of Georgia. The only catch was that I had to agree to resign my EPA position as soon as I was eligible to retire. Longest had dead-ended my career at EPA, and, when UGA offered to pursue a tenured faculty position for me, I accepted his offer. Just three weeks after I signed the agreement proposed by Henry Longest, John Walker, Longest’s former employee at OW, contacted land application specialist Julia Gaskin and others at UGA and offered Gaskin a research grant to conduct a study dealing with the cattle cases in Augusta.
While Walker pushed his project forward at UGA, Longest began applying the brakes to my UGA research. For example, Longest required that all actions involving my research at UGA be approved by EPA headquarters. Headquarters officials wasted no time prohibiting me from using a sophisticated mathematical model developed at UGA, which I needed to predict the complex interactions of pollutants contained in sewage sludge. They also prohibited me from collaborating with other EPA scientists who wanted to help with the research.
While my research papers were undergoing internal peer review at EPA, Walker met on two occasions with an industry representative and requested information that he could use in EPA’s internal peer-review process to stop my sludge research from being published. The industry representative later emailed Walker allegations that my sludge research had never passed peer review and that my research at the University of Georgia was not approved by EPA.
Of course, only someone working at EPA would know whether EPA had approved my research plans and internally peer-reviewed my research. The industry representative was only a conduit for false information that Walker or other EPA officials provided. The head of EPA’s peer-review panel, who later testified in my Labor case, called Walker’s actions “disgusting” and stated that my research articles were fully approved.
Walker emailed the false allegations to an attorney defending Augusta against the McElmurray and Boyce cases. Then this attorney had Walker’s letter and the allegations presented at public hearings in Georgia attended by UGA faculty members. Gaskin then took the allegations up with my UGA department head and argued that my research should be shut down. Eventually, Walker’s distribution of these false allegations killed UGA’s interest in hiring me and made it impossible for me to continue our research on sewage sludge.
When my four years at UGA were up in 2002, I returned to EPA just six months short of being eligible for retirement. Local managers approved my requests to investigate health complaints reported by workers spreading hay fertilized with sewage sludge from Augusta, Georgia.
Senator James Inhofe, who chaired the Environment and Public Works Committee, and Senate finance chairman Charles Grassley sent a letter to EPA administrator Christine Todd Whitman asking her to intervene in my termination, partly on the basis of national security. After the 9/11 attacks, EPA headquarters included me on a list of national experts to be contacted in the event of a bioterrorism attack on the United States. Whitman never replied, and EPA headquarters terminated me in May of 2003.
In a peer-reviewed journal article published in the American Journal of Law and Medicine, Professor Robert Kuehn of the University of Alabama described the tactics EPA used to end my career as an environmental scientist.14 Earlier this year, US District Court Judge Anthony Alaimo devoted four pages of a Court Ruling to describing EPA’s efforts to discredit my work at UGA, in which EPA and UGA officials used “fudged,” “fabricated,” and “invented” data.15 When describing EPA’s actions against me, Judge Alaimo wrote, “Senior EPA officials took extraordinary steps to quash scientific dissent, and any questioning of the EPA’s biosolids program.”
After retiring in 2005, my local EPA laboratory director, Dr. Rosemarie Russo, provided the following statement for public release: “Dr. Lewis’ involuntary termination over his research articles was not supported by the local lab management in Athens. He was an excellent researcher and an asset to EPA science.”
12. Were it not for the opposition to my sewage sludge research, would I still be working in this area?
No. Global climate change remains my primary research interest. My 1999 research article in Nature concerning effects that climate change could have on risks posed by environmental pollutants only mentions sewage sludge as one example where risks associated with certain pollutants could either increase or decrease.16
CONCLUSIONS
In 1996, EPA officials dismissed my concerns published in Nature over the growing political control of EPA’s science. A recent survey, however, shows that the situation has grown much worse.17 A total of 492 EPA scientists (31 percent of survey respondents) said that they could not express concerns about EPA’s work to colleagues without fear of retaliation. Twice that many (60 percent) reported a personal experience of political interference. “The proportion of EPA scientists reporting interference,” according to the survey, “was highest in the agency’s offices with regulatory duties and at its headquarters, while it was lowest in the Office of Research and Development, the EPA’s main research arm.”
My recommendation to this committee is to focus on the problem that lies at the heart of why we are here today. The failure of senior EPA officials to properly manage the agency’s sewage sludge program is only one small symptom of an organization that lacks the leadership it needs to effectively integrate common sense and good science into its regulations and enforcement activities. Given the chance, EPA’s Office of Research & Development has the expertise to resolve the issues surrounding the 503 sludge rule and, I am confident, every other rule and regulation that the agency has promulgated.
Before 1993, EPA rules and regulations required the concurrence of each assistant administrator, including the assistant administrator for ORD, which was established by Congress to independently review the science behind EPA’s regulations. That balance between program offices, which develop regulations, and ORD, which reviews the science behind those regulations, needs to be restored.
My hope is that what the committee learns from this briefing will be used as a hammer to drive the next president of the United States to give EPA the kind of leadership it needs to adequately insulate the agency’s science from outside forces, no matter how powerful or well-meaning the individuals behind those forces may be. Perhaps our way of life could accommodate the kind of EPA we have had in the past. But we can no longer afford to preserve EPA in its present state, not when the very scientists we depend on to find solutions to problems that threaten our very existence are intimidated into silence or driven out whenever they disagree with the powers that be.
Appendix I. Class A and Class B Biosolids
Untreated sewage sludge contains large numbers of disease-causing microorganisms, called pathogens, which include many different kinds of bacteria, viruses, fungi, and protozoa. To produce biosolids, various treatment processes, including lime stabilization, anaerobic and aerobic digestion, composting, and heat pelletization, are used to reduce pathogen levels.
The U.S. Environmental Protection Agency established two classes of processed sewage sludge (biosolids), Class A and Class B. Class A biosolids have undetectable levels of “indicator” pathogens, such as Salmonella or E. coli, which are used to “indicate” the levels of pathogens. The most common type of biosolids, Class B, contains low levels of indicator bacteria.
The diagram above illustrates how common waste treatment processes, such as lime stabilization and composting, reduce the numbers of Salmonella and E. coli (boxes with “I”). However, some resistant pathogens, such as Listeria, Cryptosporidium, and Giardia, can still survive.18 During storage, organic nutrients in Class A biosolids can also cause Salmonella and certain other pathogens to re-grow. Class A and Class B refer only to levels of indicator pathogens. They can have the same levels of chemical pollutants.
APPENDIX II. Pathogens in Dusts
Bacteria and fungi, some with the potential to cause disease in plants or animals, may be finding their way from Africa to the Americas by hitchhiking on microscopic dust particles kicked up by storms in the Sahara.19 “This study presents evidence of early summer survival and transport of microorganisms from North Africa to a mid-Atlantic research site,” says Dale Griffin of the US Geological Survey in St. Petersburg, Florida, one of the researchers on the study.
Griffin and his colleagues tested air samples on a research ship in the middle of the Atlantic Ocean during May and June 2003 to determine if airborne, viable populations of bacteria and fungi could be detected and also to see if total population counts increased with the presence of airborne desert dust.
“The phenomenon known as desert-dust storms moves an estimated 2.2 billion metric tons of soil and dried sediment through the Earth’s atmosphere each year. The largest of these events is capable of dispersing large quantities of dust across oceans and continents. Because a gram of desert soil may contain as many as 1 billion bacterial cells, the presence of airborne dust should correspond with increased concentrations of airborne microorganisms,” says Griffin.
Microbes Hitchhike across the Atlantic on Desert Dust—From Sahara to North America
Viable bacterial and fungal populations were collected on twenty-four of forty sampling days. The three days where the highest populations were collected corresponded with the two highest periods of dust activity as determined by the US Navy’s Naval Aerosol Analysis and Prediction System Global Aerosol Model.
DNA analysis matched two of the isolates 100 percent to two dust-borne isolates previously collected from the atmosphere in Mali. One of them, a known human pathogen, has also been found in atmospheric samples in the US Virgin Islands when African desert dust was present. Additional analysis identified a number of bacteria and fungi capable of causing disease in animals and plants, including the cause of Florida Sycamore canker.20 “It is tempting to speculate that transatlantic transport of dust could be a vector to renew reservoirs of some plant and animal pathogens in North America and could also be the cause of new diseases,” says Griffin. Photo credit: NASA.
Appendix III. Selected Peer-Reviewed Scientific Articles by Lewis and Coworkers
Interactions of Pathogens and Irritant Chemicals in Land-Applied Sewage Sludges (biosolids)
By David L. Lewis, David K. Gattie, Marc E. Novak, Susan Sanchez, and Charles Pumphrey
June 28 2002
http://www.biomedcentral.com/1471-2458/2/11
Background
Fertilization of land with processed sewage sludges, which often contain low levels of pathogens, endotoxins, and trace amounts of industrial and household chemicals, has become common practice in Western Europe, the United States, and Canada. Local governments, however, are increasingly restricting or banning the practice in response to residents reporting adverse health effects. These self-reported illnesses have not been studied, and methods for assessing exposures of residential communities to contaminants from processed sewage sludges need to be developed.
Methods
To describe and document adverse effects reported by residents, forty-eight individuals at ten sites in the United States and Canada were questioned about their environmental exposures and symptoms. Information was obtained on five additional cases where an outbreak of staphylococcal infections occurred near a land application site in Robesonia, Pennsylvania. Medical records were reviewed in cases involving hospitalization or other medical treatment. Because most complaints were associated with airborne contaminants, an air dispersion model was used as a means for potentially ruling out exposure to sludge as the cause of adverse effects.
Affected residents lived within approximately one kilometer of land application sites and generally complained of irritation (e.g., skin rashes and burning of the eyes, throat, and lungs) after exposure to winds blowing from treated fields. A prevalence of Staphylococcus aureus infections of the skin and respiratory tract was found. Approximately one in four of fifty-four individuals were infected, including two mortalities (septicaemia, pneumonia). This result was consistent with the prevalence of S. aureus infections accompanying diaper rashes in which the organism, which is commonly found in the lower human colon, tends to invade irritated or inflamed tissue.
Conclusions
When assessing public health risks from applying sewage sludges in residential areas, potential interactions of chemical contaminants with low levels of pathogens should be considered. An increased risk of infection may occur when allergic and nonallergic reactions to endotoxins and other chemical components irritate skin and mucus membranes and thereby compromise normal barriers to infection.
Health Survey of Residents Living Near Farm Fields Permitted to Receive Biosolids
Archives of Environmental & Occupational Health
Vol. 62, No. 1, 2007
By Sadik Khuder, Ph.D.; Sheryl A. Milz, Ph.D.; Michael Bisesi, Ph.D.; Robert Vincent, Ph.D.; Wendy McNulty, M.S.; Kevin Czajkowski, Ph.D.
www.ohiowea.org/owea/residuals/HealthSurveyResidents08.pdf
Archives of Environmental & Occupational Health
Vol. 62, No. 1, 2007
Health Survey of Residents Living Near Farm Fields Permitted to Receive Biosolids
Sadik Khuder, Ph.D.; Sheryl A. Milz, Ph.D.; Michael Bisesi, Ph.D.; Robert Vincent, Ph.D.; Wendy McNulty, M.S.; Kevin Czajkowski, Ph.D.
The authors studied the health status of residents living in Wood County, Ohio, near farm fields that were permitted to receive biosolids. They mailed a health survey to 607 households and received completed surveys from 437 people exposed to biosolids (living on or within one mile of the fields where application was permitted) and from 176 people not exposed to biosolids (living more than one mile from the fields where application was permitted). The authors allowed for up to six surveys per household. Results revealed that some reported health-related symptoms were statistically significantly elevated among the exposed residents, including excessive secretion of tears, abdominal bloating, jaundice, skin ulcer, dehydration, weight loss, and general weakness. The frequency of reported occurrence of bronchitis, upper respiratory infection, and giardiasis were also statistically significantly elevated. The findings suggest an increased risk for certain respiratory, gastrointestinal, and other diseases among residents living near farm fields on which the use of biosolids was permitted. However, further studies are needed to address the limitations cited in this study.
Authors’ Comment
We observed an association between respiratory, gastrointestinal, and general symptoms linked with infectious diseases and residence in homes near farm fields permitted to receive Class B biosolids. Moreover, we found a significant dose-response relationship for excessive secretion of tears, abdominal bloating, and dehydration. These findings are in agreement with the findings of Lewis et al. 21 and studies on wastewater treatment workers. However, they contradict an earlier study from three areas in Ohio, in which researchers reported no significant differences in the risk of respiratory, gastrointestinal, and general symptoms between sludge-farm residents and control-farm residents. In the Ohio study, the biosolids application rates were low, and thus exposure levels may not have been comparable to those in this study. 22
Commentary
A High-Level Disinfection Standard for Land Applying Sewage Sludges (Biosolids)
David K. Gattie and David L. Lewis,
Environmental Health Perspectives Volume 112, No. 2, Feburary 2004
By David K. Gattie, David L. Lewis
Abstract
Complaints associated with land-applied sewage sludges primarily involve irritation of the skin, mucous membranes, and the respiratory tract accompanied by opportunistic infections. Volatile emissions and organic dusts appear to be the main source of irritation. Occasionally, chronic gastrointestinal problems are reported by affected residents who have private wells. To prevent acute health effects, we recommend that the current system of classifying sludges based on indicator pathogen levels (Class A and Class B) be replaced with a single high-level disinfection standard and that methods used to treat sludges be improved to reduce levels of irritant chemicals, especially endotoxins. A national opinion survey of individuals impacted by or concerned about the safety of land-application practices indicated that most did not consider the practice inherently unsafe but that they lacked confidence in research supported by federal and state agencies.