Delving Into Sewage to Diagnose Public Health Problems

This team of researchers thinks data collected from treatment plant waste could be used to make swift public and environmental health decisions.
Delving Into Sewage to Diagnose Public Health Problems
Rolf Halden and his team conduct research that uses sewage and sludge samples from wastewater treatment plants in the United States and throughout the world to assess potential health threats and identify behavioral trends.

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Most people probably view wastewater treatment plants as an integral part of modern infrastructure. Rolf Halden and his colleagues see them as windows to our behavior and well-being. “If somebody would tell me today he or she is working at a wastewater treatment plant, I would respond that is partially true, but that they are also working at a human health observatory,” he says.

Halden, professor and director of the Biodesign Center for Environmental Security at Arizona State University’s Biodesign Institute, heads research that uses sewage and sludge samples from wastewater treatment plants in the United States and throughout the world to assess potential health threats and identify behavioral trends. He said treatment-plant samples provide a real-world glimpse into the exposure of populations to chemical and biological agents, including accumulations of potentially harmful chemicals in the human body, as well as information on the level of consumption of meat, alcohol, prescription drugs and other substances. That data could ultimately be used to make swift recommendations to improve public and environmental health.

“It’s pretty exciting because it can help us understand and manage in real time our health and the health of the ecosystems that support us,” he says.

Halden began his sludge research about 15 years ago while working with a team at Johns Hopkins University. Lured by the prospect of identifying important health hazards and undeterred by rejected research grant applications, the scientists began to study chemicals in samples from treatment plants. In 2004, the researchers discovered that an antimicrobial compound (triclocarban) commonly added to personal-care products such as bar soap persisted during passage through wastewater treatment plants on the East Coast and was causing pervasive contamination of the environment, including in all urban streams sampled and a river that flows into Chesapeake Bay.

“When we published this along with a prediction that the observed surface-water pollution likely was a nationwide phenomenon, critics were unconvinced, forcing our team to add more monitoring locations in places other than the East Coast,” he says.

Soon the researchers started an initiative to collect and archive sludge samples from treatment plants nationwide. The team acquired additional samples from the U.S. Environmental Protection Agency, thereby creating what today is known as the National Sewage Sludge Repository, a scientific resource used for an EPA Toxic Release Inventory project and various other scientific collaborations.

“That NSSR terminology had to be revised at some point because we were receiving samples from outside the United States,” Halden says. “So now, we have integrated the National Sewage Sludge Repository into what we call the Human Health Observatory, a much larger sample archive that also contains other environmental and human tissue specimens. We want to use the existing infrastructure of wastewater treatment plants to study what we’re doing to ourselves and to the environment, and how we can improve our health, the health of our planet and the sustainability of our society into the future.”

Currently, Halden’s team, which includes ASU students, receives samples from volunteers, donors and stakeholders at more than 180 monitoring locations in the United States and about another 200 from international locales.

“We have a good mix of urban and rural locations, so we have very large city plants representing millions of people and also smaller plants that serve communities of maybe starting at 25,000 to 100,000 people,” he says. “We really have a broad spectrum there in terms of the volume of wastewater flows processed and the types of treatment strategies employed.”

Participation is voluntary, Halden says. Typically, plants send samples to the Biodesign Center for analysis. Then, researchers provide results in various forms, depending on the wishes of clients and volunteer agencies. Halden’s team maintains strict confidentiality agreements with participants.

“With the knowledge oftentimes comes a responsibility,” Halden says. “We have various ways of dealing with the information we retrieve. First of all, our principal objective is to not compromise anybody and to find out beforehand what people do and don’t want to do with their data. So, in the extreme, we have facilities that give us materials voluntarily at their cost. We analyze them, and they give us free rein of doing with these results whatever we like. We can publish it, and we can identify the facility.”

On the other end of the spectrum, some facilities want to learn about the composition of wastewater and sludges, but not necessarily from specific plants, possibly because the respective agency doesn’t have the resources necessary to react to that information.

“They just provide samples, and we publish the resulting data as nationwide average values without revealing the various contributing municipalities,” Halden says. “In this way, they can use the information, but they also enjoy the anonymity of just being potentially one sample in a large set of up to 100 different plants across the nation.”

The study’s long-term aim is ambitious: the ability to make real-time diagnoses and to provide recommendations for how to improve human and ecosystem health.

“We use the wastewater treatment plant as a microcosm for the global environment; if a chemical does not degrade during optimized wastewater treatment, it likely will not degrade in the environment,” Halden says. “And if a chemical accumulates in treated sewage sludge, then there’s a good chance it will also become enriched in other places featuring a high carbon and fat content, and those, unfortunately, include us – so, human beings.

“The goal is to come up with a very inexpensive way of determining the identity of unsustainable chemicals we use and to accurately estimate the human exposure that’s incurred by the use of harmful chemicals. The wastewater treatment plants are real-world environments. They reflect what actually happens to chemicals. This is not an artificial lab environment. This is the real deal.”

And if Halden has anything to say about it, sewage sludge samples from those real deals might ultimately help us not only to purify water but also to achieve better health and environmental sustainability.

The concept has already proven successful. The polluting antimicrobial (triclocarban), first discovered by Halden’s team in 2004 on the East Coast, was banned from many consumer products in a decision announced in 2016 by the U.S. Food and Drug Administration.

“In our present age of population growth and resource scarcity, we have to strive to recycle not only wastewater itself but also the energy, nutrients and organic matter contained in municipal sludges produced around the nation by unsung public health heroes — also known as treatment plant operators.”

For more information, contact the Human Health Observatory at


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