If You Want Tons of Public Health Data, Dive into the Sewer!

On a brisk fall morning near the MIT campus in Cambridge, Massachusetts, Luigi is among the throng going to work. His office, however, isn’t within one of the nearby engineering classrooms or state-of-the-art laboratories. Luigi is headed for a steaming manhole.

Luigi is a robot, and like his predecessor, Mario, he’ll be spending his day descending into the sewers around Boston and bringing back bottles full of you-know-what. With an exterior that looks like a tubular birdfeeder, he’s tricked out with an infrared receiver, motor, water-level sensor, temperature gauge, filter, and pump. To Luigi’s designers, a team of researchers at MIT, sewage is an untapped reservoir of knowledge. It’s Luigi’s job to help tell the city’s story—through the poop of its people.

From the food that nourishes us to the pollutants and pathogens that sicken us, “a lot of information gets imprinted on water as it flows in and out of our cities,” says Newsha Ghaeli, the leader of the Underworlds project at the university’s Senseable City Lab. “But we don’t look at it.” In a sense, our wastewater is going to waste. 

Underworlds is analyzing sewage for bacteria, viruses, and chemicals. Eventually the scientists could match these findings with demographic information about the neighborhood the sewer line serves. The hope is to create a “smart sewage platform” that monitors urban health patterns in real time.

For instance, if there’s lead swirling beneath the streets of Southie, officials can take quicker action. Identifying contagious disease outbreaks faster would give communities more time to mitigate their spread. And by teasing out biomarkers for obesity and diabetes, cities could improve their understanding of noncommunicable diseases too.

Carlo Ratti, director of the Senseable City Lab, explains that Underworlds samples everyone in the city, not just those who decide to, or can afford to, see a doctor. “We don’t need to rely on people to self-select as ill in order to get a snapshot of the health of our communities,” he says.

The wide range of internal and external forces acting on the human gut means the platform has an almost equally wide range of potential applications. Take antibiotics, for instance. Because of their overuse in both livestock and people, drug resistance is on the rise—the World Health Organization has even warned of an impending “post-antibiotic era.” Underworlds plans to pinpoint when and where genes for antibiotic resistance crop up.

The team also wants to monitor sewage for phthalates, those ubiquitous plasticizers found in everything from personal care products to food packaging to shower curtains. Phthalates are readily absorbed into the human body and known to leave through urine and feces. They also happen to be endocrine disruptors, and though the effects of exposure are still not fully understood, studies have linked these harmful chemicals to developmental and reproductive problems.

Congress has already banned the use of certain types of phthalates in children’s toys, but as the evidence against them mounts, more regulation could be on the way. And Luigi and his ilk could be there to gauge the response. By providing a quick and reliable method to measure a ban’s effectiveness, Underworlds, its creators envision, would not just passively record public health but actively inform and shape policies that promote it.

To prove its concept, the project has a three-year, $4 million grant from the Kuwait Foundation for the Advancement of Sciences. During that trial period, which began in November 2015, the team is sampling neighborhoods in Cambridge, Boston, and Kuwait. Eric Alm, co-principal investigator, is optimistic that the platform will expand to other cities by 2018. Even so, there are still a few kinks to work out before then.

For one, every time the researchers want to take a sample, they have to ask the city to come open the manhole; haul their equipment out to the street; don protective gloves, masks, and smocks; wait for Luigi to do his thing; and decontaminate the robot afterward. This process is hardly feasible on a large scale.

Luigi’s successor (who might be named Yoshi) is in the works. If all goes according to plan, this next iteration will be able to remain belowground and send back data remotely, giving the researchers live information without leaving the lab. Once they have the data, the researchers are still working out what they can—and should—hunt for. They can either broadly catalog all of the microbes or search through the sewage for specific genes or chemicals.

The Underworlds team also needs to know more about whose poop they’re examining. It’s important to note, says Alm, that none of the data can be traced back to a specific toilet, er, person. But in order to assess a particular sample’s statistical significance, the researchers need to know how many people contributed to it.

If they can overcome these hurdles, Underworlds could represent “a significant, seminal advancement” in public health monitoring, says Christian Daughton, a chemist with the U.S. Environmental Protection Agency.

As for the rest of us, it’s never been easier to make a donation to science.