You could be flushing important information about your health right down the toilet—quite literally. Pee and poop can tell you a lot about your health, so what if your waste…didn’t go to waste? What if, instead, it could tell you more about your health? Like number one, it can catch a condition like diabetes early. Or number two, check out what’s going on in your gut microbiome.

That’s the goal of the smart toilet—a device that gets all up in your business to tell you more about your health. Ira talks with the inventor of the PH Smart Toilet, Dr. Seung-min Park, instructor of urology at Stanford’s School of Medicine in California, about how the toilet works, how it can be used to catch diseases early on, and the ethical implications of such a device.

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Dr. Seung-min Park is an instructor of urology at the Stanford University School of Medicine in Stanford, California.

IRA FLATOW: This is Science Friday. I’m Ira Flatow.

Later in the hour, happy 50th birthday to CITES, the agreement that regulates the trade of wildlife and plants. We’re going to check in on how much progress has been made these last 50 years. Plus, a breakthrough in material science. Get this– a soft robot that can heal itself. We’ll talk about what we can learn from these more skin-like bots. And no, they are not as creepy as they may sound. Trust me.

But before we get into that, I want to bring on a guest who is doing his duty to literally do his duty. He’s developing a toilet that analyzes your waste, and might be able to help diagnose an illness from sampling it. In other words, you could be flushing important information about your health right down the toilet. And I mean that literally.

But what if your waste didn’t go to waste? What if, instead, it could tell you more about your health? Like, number one, checking on your number one and catching a condition like diabetes early. Or, number two, checking out number two to see what’s going on in your gut. Maybe your microbiome needs some attention.

That’s the goal of the smart toilet, a device that gets all up in your business to tell you more about your business, so to speak. Conditions like urinary tract or kidney infections, even cancer, can be detected by what gets dumped into a toilet. And as cool as it may sound, it does bring up concerns about privacy and ethics. For example, the toilet keeps track of who is using it by taking fingerprints of your fingers and, well, of your rear end– even photos of your butt.

So how do we keep that very personal stuff out of the wrong hands? Just a brief heads-up– we’re going to get a bit graphic, in the interest of science of course, all the way to the end, if you know what I mean.

Joining me is the inventor of the PH Smart Toilet, Dr. Seung-min Park, instructor of urology at Stanford University School of Medicine, in Stanford, California. Welcome to Science Friday.

SEUNG-MIN PARK: Yeah, thank you for having me today.

IRA FLATOW: How does the toilet learn about me?

SEUNG-MIN PARK: Even if you are a super human, you cannot avoid the number one and number two processes because it’s very natural. It is always called nature’s call. So what we are trying to do is trying to glean biomarkers from human excretion. Because we believe that human excretion is a wealthy resource for your health tracker. So we’re collecting data, such as a digital biomarker. That’s physiological, biochemical, and behavioral data collected by smart sensors in the toilets.

IRA FLATOW: So you have sensors and probes in the toilets. So walk me through this. I go to the toilet. I do my business.

IRA FLATOW: Then, do I flush it, or does it collect it before the flush? What happens?

SEUNG-MIN PARK: Yes. We are trying to make it as passive as possible. Which means you don’t have to do a single thing. So naturally, you do your natural behavior. Then all the procedure will be performed by the smart toilet itself. So you don’t have to do a thing.

SEUNG-MIN PARK: So we have sensors which detect the user sitting, sensors that detect the user’s end of defecation or urination. We have sensors to collect data from the excreted specimen.

IRA FLATOW: So how does it know if it’s me or someone else on the toilet?

SEUNG-MIN PARK: Yes, it’s a very important question. Because your toilet will be shared by a roommate or family members. It’s also for personalized health care. So we’re trying to provide as personalized as possible. So we tried to put the fingerprint scanner at the flush lever. So whenever you flush it, we’re trying to capture your fingerprint scan so that we can match the result that’s collected by the smart toilet. So that’s one way to identify a person.

And a second way is we’re utilizing the human anus as a biometric identifier. Which is a very unusual case. But I collaborated with a colorectal surgeon for the last five years. And they already knew that it can be used as a biometric identifier because it’s so unique for a person. So we utilize that as a biometric identifier. And we proved that it’s more than 95% accuracy that identify a person.

IRA FLATOW: Let me just see if I understand this. Are you saying that my anus is unique like a fingerprint?

SEUNG-MIN PARK: Yes, that’s correct.

IRA FLATOW: Wow. Have you tested this toilet on yourself?

SEUNG-MIN PARK: Yes, I did. Not for the anal print stuff. But I installed the first prototype that was collaborated with the industrial partner. And it is installed in my house. And I tested it almost 87 days consecutively. There were 800 defecation and urination events combined. It is literally called the stool and voiding diary.

IRA FLATOW: And the data that it collects, where does the data go?

SEUNG-MIN PARK: Yeah, all the data will be stored in the cloud system. So we want to connect it to a local hospital or a local health care system so that the physician can routinely analyze or access the data. So that they want to find out if anything happened before the user fell ill or something.

IRA FLATOW: Some people might be uncomfortable listening to us talking or our conversation. But as you say, everyone poops and pees. It’s nature’s call.

IRA FLATOW: How does that affect the advancement of smart toilets among scientists and the industry?

SEUNG-MIN PARK: Yes, there are a huge amount of pressure actually. Because there is criticism of our system being too much about– it sounds like or it resembles Big Brother in 1984. Because we’re tracking almost like a very private event of human being, right?

SEUNG-MIN PARK: Because human excreta has been taboo in almost every culture. And there’s a lot of different things associated with human excretion, such as menstruation or–

IRA FLATOW: Well, couldn’t that be threatening to some people, certainly in this age that we live in, about knowing if someone is pregnant or not?

SEUNG-MIN PARK: Yes, this is one of the biggest challenges for us because our system may track the pregnancy record. If it is revealed to another agency, then they may track the abortion. So it’s a very sensitive subject. So we want to protect our system’s data as much as possible. So we’re just regarding all the generated data from our system as a PHI, Patient Health Information.

IRA FLATOW: What about people like astronauts?

IRA FLATOW: There are no doctors up there. Maybe you can detect things.

SEUNG-MIN PARK: Yes. I think one of the best application of our system is for the Deep Space Mission. Because NASA is trying to send people to Mars in the next 10 years. But one of the biggest problem for sending people to Mars is the travel time. Because it will take at least six months to 12 months. And the space crew member will be exposed to very hostile working environments, including radiation, including confinement, the distance from the Earth, et cetera, et cetera. So we’re trying to protect the astronaut as much as possible, and proactively.

So we’re trying to utilize our system to monitor the immune system by analyzing the microbiome in the feces.

IRA FLATOW: Right. I imagine when you came up with this idea, the first thing scientists do is say, how can I get this funded, right?

IRA FLATOW: Did you have any trouble finding people who would like to invest in your research?

SEUNG-MIN PARK: Yes. Honestly, I submitted this proposal to the National Science Foundation in 2021. And I thought it was a good fit for that request for proposal because the request for proposal was titled Smart Connected Health. But even though I was able to address all the issues about the smart toilet, but the reviewers actually believe that there’s a glitch in our approach. Because there’s going to be a lot of ethical consideration, privacy issues, and the consideration for female participants, and all the issues.

It is a well known subject in the field, but people still have some barriers or some obstacles to adopt this system as a routine monitoring system.

IRA FLATOW: Right. Well, I mean, just in privacy issues, no one wants incriminating photos of their rear end getting out.

SEUNG-MIN PARK: That’s true. So we’re trying to replace the sensors– a little bit less invasive manner. So I think we’re utilizing a sensor, which we call the optical sensor, but, a.k.a., it’s a camera, basically. So we’re trying to make it as less invasive as possible, such as we can use an IR camera instead of a photographic camera or some other, like the LiDAR sensors, which measures the distance between the point. So we’re trying to replace it so that the people will not have some feeling about the invasive nature of this smart toilet system.

IRA FLATOW: Right. Part of your goal is getting this really in-depth individual data– sort of an information dump, if you will. This is part of a growing idea about precision health and personalized medicine, right?

SEUNG-MIN PARK: That’s correct. Even before a person is born, prenatal genetic screening can be done. Which means the precision health can be starting with conception. So we’re trying to protect people or trying to maintain people as healthy as possible by continuous monitoring of their health signatures.

IRA FLATOW: Do you have a special name for your toilet that would make it more fun to sit on, instead of threatening?

SEUNG-MIN PARK: Yeah, we call it a Precision Health Toilet, but it’s not that funny at all.

IRA FLATOW: Well, I was thinking more like the Tush Toilet or something like that.

SEUNG-MIN PARK: We have a motto actually. The motto is Don’t Waste the Waste. That’s the motto that tells about, even though it’s waste, there’s a wealth of biological information that we can glean.

IRA FLATOW: Well, you’re right, when people who need the help that the toilet might offer them. It’s very serious business– speaking of business.

IRA FLATOW: Dr. Park, thank you for taking time to be with us today. And good luck.

SEUNG-MIN PARK: Thank you so much for having me today. It’s my great honor and pleasure.

IRA FLATOW: Dr. Seung-min Park, instructor of urology at Stanford School of Medicine.

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Rasha Aridi is a producer for Science Friday. She loves stories about weird critters, science adventures, and the intersection of science and history.

Ira Flatow is the host and executive producer of Science Friday. His green thumb has revived many an office plant at death’s door.

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