What does Cambridge sewage say about residents? MIT plans to find out
A new project aims to understand a city’s health and habits through its waste
Sometime in mid to late January, researchers from MIT plan to gather around a manhole on Portland Street in East Cambridge, dressed in plastic disposable biohazard coats and gloves. Each hour over the next 24, working in teams of two over four-hour shifts, they’ll sink a tube into the muck and pump one to two liters of sewage water into a plastic container. The container will be put into a cooler and taken to the nearby lab at MIT run by Eric Alm, a computational microbiologist. Alm’s lab will analyze all 24 of these sludgy samples to see what viruses and bacteria they hold; meanwhile, a vial of each sample will be sent to another lab to be analyzed for biomarkers (molecular or cellular flags for things like diseases and drugs, legal and illegal ).
These researchers—who include architects, computational biologists, designers, electrical and mechanical engineers, geneticists, and microbiologists—will be testing an idea that’s attracting interest around the world: namely, that sewage can tell us important things about the people who excrete it. Already, research has shown that sewage can reveal illicit drug usage, the presence of influenza, the poliovirus and other pathogens, and the state of community health. So far, however, none of this has been tested in our local waste systems, other than some proof-of-concept sampling done in Boston. That has led to this first formal effort by scientists and public health officials to get a sewage snapshot of the people of Cambridge.
Historically, public health officials have been stuck following their gut. “A problem in public health is we are plagued by not having good metrics,” says Sam Lipson, director of environmental health in the Cambridge Public Health Department, which is facilitating the research. An exception would be the well-documented health hazards of lead paint. But for many other substances, effects are unclear, and morally and logistically, city officials “can’t engage in controlled experiments,” Lipson says. He hopes the new research will lead to better data around issues like diet and wellness.
The MIT researchers have dubbed their project Underworlds, and it will run from 2015 through 2017, thanks to a $4 million grant through the Kuwait-MIT Center for Natural Resources and the Environment. Along with Alm, the research is being led by Carlo Ratti, an architect and engineer who is a professor at MIT and runs the Senseable Cities Lab, which studies how the physical and digital worlds blend. Yaniv J. Turgeman, an architect getting dual master’s degrees at MIT in design and computation and in environmental microbiology, is the research director, along with Mariana Matus, an MIT PhD candidate in computational biology. Students and professors at four other MIT labs will be involved in the project, as well as researchers from Kuwait University and the Kuwait Institute for Scientific Research.
“Sewage is really an unexploited source of rich information about human activities,” Alm says. And why not? Trash dumps provide treasure troves for archaeologists looking to find out how ordinary people lived. Our sewage, with chemical information that comes straight out of our own bodies, should be even more informative.
Matus says the Underworlds project will test for three main things. It will screen for viruses, like influenza, noroviruses, or enteroviruses such as polio or the nasty respiratory flu called D68; for bacterial pathogens like those that cause cholera or typhoid fever; and for biomarkers, or biochemical molecules, which include pharmaceutical drugs like antibiotics, illicit drugs such as cocaine or methamphetamines, and isoprostanes, which are compounds produced by the body and seen as a proxy for societal stress and disease levels. Data on such substances could predict epidemics or tell when they’re waning. They could also demonstrate the impact of shifts in regulations, such as bans on using trans fat in restaurants.
First, though, the researchers have to figure out what time of day sewage is at its best. Good sewage involves a maximum of toilet water and a minimum of detergents, soaps, and other things that scrub out information. “We want the time when we see the most human waste in the system, the most diverse hour for sewage,” says Newsha Ghaeli, an architect who came to MIT in 2014 as a research fellow and is the Underworlds project manager. (She concedes that she endures endless puns about her research.) Finding prime sewage time is the reason that they’ll spend that initial testing day taking samples once every hour, as well as some secondary samples at a nearby Cambridge manhole that draws sewage from the Portland Street neighborhood and a second, less residential neighborhood.
The data from these initial samples will be used to help develop the Underworlds software platform, which MIT is building to help analyze sewage information across a detailed map of Cambridge’s sewers, correlating the data with demographic information such as ethnic mix and average age. Then, in the second phase of the research, the team will take samples from 10 sites in Cambridge (six residential neighborhoods, two industrial neighborhoods, and at Harvard and MIT) over an eight- to twelve-month period. At this point, they will no longer have to gather sewage samples by hand. Instead, MIT researchers are building 4-foot-high robotic sewage samplers that can process and analyze the sewage, the data from which will feed directly into the software platform.
The Cambridge tests will lead to one in Kuwait City, which the team expects to launch in 2017. As in Cambridge, Kuwaiti officials want sewage tests to look for viral and bacterial presences and to measure the impact of public policy. They also want to be able to screen for biochemical threats.
What can be done with the data that will emerge? Public health officials might gain information that helps them fight disease, and doctors might be able to care for patients more effectively. Lipson says he’ll be curious to see if the tests find hazardous wastes, not so much from Cambridge’s vaunted biotech firms, whose discharges are closely regulated, but by other businesses, which are not.
One hindrance to integrating sewage sampling into public policy is the cost. The filters that are used to capture bacterial, viral, and molecular substances cost tens of thousands of dollars, meaning it will be expensive to test all the neighborhoods in a large city. MIT is building its own prototypes, which have to be waterproof and able to be remotely controlled. Eventually, such projects will be able to save money by testing for a narrower range of substances. Still, Alm thinks private companies will have to form in order to help achieve the necessary scale for sewage to shape public policy.
Another concern could be the extension of the surveillance state into the sewers. But it will not be easy to trace waste products, even those with legal implications (from illicit substances, for example), back to any individual toilet-flusher. The first test neighborhood in East Cambridge has just over 4,000 people in it, and none of the neighborhoods that will be tested will have fewer than 2,000 people. Turgeman, the research lead, said via e-mail there will be no way to link results to individual homes or buildings.
Someday, though, he hopes people have the option to buy smart toilets outfitted with sensors that measure what passes through them. Turgeman is working on making a certain porcelain god more omniscient. If we choose to connect a smart toilet to the Internet, we run a real risk of flushing our privacy. Until then, there are traces of all of us in the sewers—and those will tell a different, more collective story.
Michael Fitzgerald is a freelance journalist who writes from Cambridge.