Health Effects of Treated Sewage Sludge/Biosolids

New research report released...

In mid March, 2013, the University of North Carolina reported on research purportedly linking health effects to treated sewage sludge/biosolids land application in the Southeast. Many public wastewater treatment utility professionals and others managing biosolids are concerned about sensationalized news reports of this study.

The UNC news release has been picked up by radio, print media, and online.  The study's abstract and a PDF of the full paper are available here.

Many public wastewater treatment utility professionals and others managing biosolids are concerned about sensationalized news reports of this study.  The conclusions stated in the media, driven by the UNC news release, create concern: "treated municipal sewage sludge....may be causing illness in people up to a mile from where the sludge is spread on land."

What are the actual research design & findings?

As sometimes happen, the actual published paper includes caveats that show how limited the study was - nothing more than a formal chance for people concerned about biosolids land application to tell their stories of how they think treated sewage sludge/biosolids affected them.

As the authors, Lowman et al. state:  "Our study was not designed to quantify the prevalence or incidence of reported symptoms, health impacts and other concerns in populations near land application sites."  It was a "qualitative" study, involving nothing more than interviews with 34 people who responded to an invitation from the study authors and the community groups with which they worked.  The design of the interviews was developed "from input from individuals living near sludge application sites and from a guide developed for previous research on air pollution from industrial hog operations in NC" (a guide which the same authors developed previously). 

The study included no sampling of soil or air or any other way of determining if the individuals interviewed were actually exposed to biosolids, if the environmental impacts they reported (e.g. biosolids runoff to water bodies) actually occurred, or if the symptoms they reported were related in time to land application events.  There was, apparently, not even any corroboration that what they thought they were experiencing was actually biosolids or something derived from biosolids.  The research only reports their stories, without any independent corroboration of any purported facts.  Lowman et al. admit to the likely bias of their respondents: "Although we did not ask for referrals to people who had problems with sludge, people with negative opinions of the practice may share local social networks, which could lead to their perspectives being overrepresented."

In addition, the study apparently involved no control group, even though the original study description provided to the National Institutes of Environmental Health Sciences said there would be: "We will recruit neighbors of sites permitted for sludge application in North Carolina and Virginia to participate in a one-year longitudinal study of environmental exposures, symptoms, physiological functioning, and health-related quality of life. Neighbors in two types of areas will participate: areas where permits have been issued but no land application has yet occurred; and areas where sludges have been recently applied."  According to the just-published paper, there was no "longitudinal study," just one-time interviews.  And there does not seem to have been any determination of whether respondents lived near sites that actually had land application or not; all that the authors report is that participants had to "live within one mile of a permitted sewage sludge land application site."  They report no effort to confirm if and when biosolids land application had actually occurred on those sites.  This is a significant flaw, because it is not uncommon for neighbors of farms where biosolids are used to assume that biosolids were the cause of malodors or other nuisances, when, upon independent investigation, other farming practices, such as manure management, were the issue.  Such independent investigation was not done for this study.

The Virginia Biosolids Council (VBC) learned of this proposed study in 2008 and expressed concern about its design in a letter to Dr. Steven Wing, the research lead at UNC.  For example, the VBC letter asked "In your previous research, you have stated that the location of such facilities as landfills and commercial hog farms is an environmental justice issue because the receiving population tends to be black and poor. In your description of the “Local Health Impacts” study, you indicated that you believe similar environmental justice issues affect the distribution of biosolids. We cannot find any research to support this thesis and it would appear that the “Local Health Impacts” research may be distorted through an inappropriate and biased environmental justice matrix, rather than revealing the objective truth on the ground." VBC reports receiving no reply to its letter.

The fact is, biosolids are used by farms requesting them, irregardless of neighborhood demographics.  In their recent paper, Lowman et al. report that "Interviewers observed that most participants lived in modest homes and neighborhoods that could be described as working or middle class, while a few lived in larger, newer homes that could be described as upper middle class."

In response to this week's publication of the study, Charles Hooks of the VBC notes: "Prof. Wing... has tried to fit land application into his environmental justice template, ignoring the fact that most farmers request biosolids. Biosolids are not imposed on farmers, they are highly desired by farmers. He ignores the lack of adverse health effects from the very people who live closest to biosolids – the farmers and their families. No attempt was made to verify the health and environmental claims of those who were interviewed. No acknowledgement is given to the vast amount of research showing no adverse health and environmental effects from biosolids."

There are some useful lessons

As noted above, there are many aspects of this study that make it no more than a telling of personal experiences that cannot be extrapolated to any other situation. 

However, what the authors report hearing from self-selected neighbors has some validity:  the land application of biosolids/treated sewage sludge and other common farming practices can sometimes generate offensive odors that can reduce quality of life for some people.

Offensive odors from a variety of sources can cause physiological symptoms in some individuals (e.g. Schiffman, 2005). As the Lowman et al. paper notes, "CAFO neighbors describe health impacts similar to those reported by neighbors of land applied sewage sludge."

Those working with biosolids strive to produce materials with low odors and to manage them to avoid odor impacts on neighbors.  "But we need to continue doing an even better job on this," says Ned Beecher of NEBRA.

"In addition," says Beecher, "the new Lowman et al. report notes that these upset neighbors claimed they had not been notified in advance.  Because of this, they expressed distrust of those managing and regulating biosolids.  Social science research has clearly shown that lack of information, the surprise of a sudden malodor, and other factors inherent to biosolids land application naturally trigger fear in some people.  We need to be ever more proactive in educating communities about biosolids and their use.  When biosolids managers respond with caring to neighbors' concerns, trust improves, as noted in the Lowman study:

"'A few respondents reported improvements in the land application practice over time and said officials and operators had responded to their concerns by respecting setback distances, using alternate driving routes, slowing down trucks hauling sludge, posting correct contact information on land application signs, and returning their phone calls requesting information.' 

"Pages 18 - 20 of the Lowman et al. paper provide feedback from those interviewed on how those managing biosolids can do better.  These are worth paying attention to, as is the final sentence: 'Residents’ documentation and ideas for improvements to land application offer a distinct perspective on the practice that industry and government officials lack. Meaningful involvement of community members in decision making about land application of sewage sludge will strengthen environmental health protections.'"