Let's talk dirty. A few years ago, oddly enough, I needed the bathroom, and I found one, a public bathroom, and I went into the stall, and I prepared to do what I'd done most of my life: use the toilet, flush the toilet, forget about the toilet. And for some reason that day, instead, I asked myself a question, and it was, where does this stuff go? And with that question, I found myself plunged into the world of sanitation -- there's more coming -- (Laughter) — sanitation, toilets and poop, and I have yet to emerge. And that's because it's such an enraging, yet engaging place to be.

To go back to that toilet, it wasn't a particularly fancy toilet, it wasn't as nice as this one from the World Toilet Organization. That's the other WTO. (Laughter) But it had a lockable door, it had privacy, it had water, it had soap so I could wash my hands, and I did because I'm a woman, and we do that.

(Laughter) (Applause)

But that day, when I asked that question, I learned something, and that was that I'd grown up thinking that a toilet like that was my right, when in fact it's a privilege. 2.5 billion people worldwide have no adequate toilet. They don't have a bucket or a box. Forty percent of the world with no adequate toilet. And they have to do what this little boy is doing by the side of the Mumbai Airport expressway, which is called open defecation, or poo-pooing in the open. And he does that every day, and every day, probably, that guy in the picture walks on by, because he sees that little boy, but he doesn't see him.

But he should, because the problem with all that poop lying around is that poop carries passengers. Fifty communicable diseases like to travel in human shit. All those things, the eggs, the cysts, the bacteria, the viruses, all those can travel in one gram of human feces. How? Well, that little boy will not have washed his hands. He's barefoot. He'll run back into his house, and he will contaminate his drinking water and his food and his environment with whatever diseases he may be carrying by fecal particles that are on his fingers and feet. In what I call the flushed-and-plumbed world that most of us in this room are lucky to live in, the most common symptoms associated with those diseases, diarrhea, is now a bit of a joke. It's the runs, the Hershey squirts, the squits. Where I come from, we call it Delhi belly, as a legacy of empire. But if you search for a stock photo of diarrhea in a leading photo image agency, this is the picture that you come up with. (Laughter) Still not sure about the bikini. And here's another image of diarrhea. This is Marie Saylee, nine months old. You can't see her, because she's buried under that green grass in a little village in Liberia, because she died in three days from diarrhea -- the Hershey squirts, the runs, a joke. And that's her dad. But she wasn't alone that day, because 4,000 other children died of diarrhea, and they do every day. Diarrhea is the second biggest killer of children worldwide, and you've probably been asked to care about things like HIV/AIDS or T.B. or measles, but diarrhea kills more children than all those three things put together. It's a very potent weapon of mass destruction. And the cost to the world is immense: 260 billion dollars lost every year on the losses to poor sanitation. These are cholera beds in Haiti. You'll have heard of cholera, but we don't hear about diarrhea. It gets a fraction of the attention and funding given to any of those other diseases.

But we know how to fix this. We know, because in the mid-19th century, wonderful Victorian engineers installed systems of sewers and wastewater treatment and the flush toilet, and disease dropped dramatically. Child mortality dropped by the most it had ever dropped in history. The flush toilet was voted the best medical advance of the last 200 years by the readers of the British Medical Journal, and they were choosing over the Pill, anesthesia, and surgery. It's a wonderful waste disposal device.

But I think that it's so good — it doesn't smell, we can put it in our house, we can lock it behind a door — and I think we've locked it out of conversation too. We don't have a neutral word for it. Poop's not particularly adequate. Shit offends people. Feces is too medical.

Because I can't explain otherwise, when I look at the figures, what's going on. We know how to solve diarrhea and sanitation, but if you look at the budgets of countries, developing and developed, you'll think there's something wrong with the math, because you'll expect absurdities like Pakistan spending 47 times more on its military than it does on water and sanitation, even though 150,000 children die of diarrhea in Pakistan every year. But then you look at that already minuscule water and sanitation budget, and 75 to 90 percent of it will go on clean water supply, which is great; we all need water. No one's going to refuse clean water. But the humble latrine, or flush toilet, reduces disease by twice as much as just putting in clean water. Think about it. That little boy who's running back into his house, he may have a nice, clean fresh water supply, but he's got dirty hands that he's going to contaminate his water supply with.

And I think that the real waste of human waste is that we are wasting it as a resource and as an incredible trigger for development, because these are a few things that toilets and poop itself can do for us. So a toilet can put a girl back in school. Twenty-five percent of girls in India drop out of school because they have no adequate sanitation. They've been used to sitting through lessons for years and years holding it in. We've all done that, but they do it every day, and when they hit puberty and they start menstruating, it just gets too much. And I understand that. Who can blame them? So if you met an educationalist and said, "I can improve education attendance rates by 25 percent with just one simple thing," you'd make a lot of friends in education.

That's not the only thing it can do for you. Poop can cook your dinner. It's got nutrients in it. We ingest nutrients. We excrete nutrients as well. We don't keep them all. In Rwanda, they are now getting 75 percent of their cooking fuel in their prison system from the contents of prisoners' bowels. So these are a bunch of inmates in a prison in Butare. They're genocidal inmates, most of them, and they're stirring the contents of their own latrines, because if you put poop in a sealed environment, in a tank, pretty much like a stomach, then, pretty much like a stomach, it gives off gas, and you can cook with it. And you might think it's just good karma to see these guys stirring shit, but it's also good economic sense, because they're saving a million dollars a year. They're cutting down on deforestation, and they've found a fuel supply that is inexhaustible, infinite and free at the point of production.

It's not just in the poor world that poop can save lives. Here's a woman who's about to get a dose of the brown stuff in those syringes, which is what you think it is, except not quite, because it's actually donated. There is now a new career path called stool donor. It's like the new sperm donor. Because she has been suffering from a superbug called C. diff, and it's resistant to antibiotics in many cases. She's been suffering for years. She gets a dose of healthy human feces, and the cure rate for this procedure is 94 percent. It's astonishing, but hardly anyone is still doing it. Maybe it's the ick factor. That's okay, because there's a team of research scientists in Canada who have now created a stool sample, a fake stool sample which is called RePOOPulate.

So you'd be thinking by now, okay, the solution's simple, we give everyone a toilet. And this is where it gets really interesting, because it's not that simple, because we are not simple. So the really interesting, exciting work -- this is the engaging bit -- in sanitation is that we need to understand human psychology. We need to understand software as well as just giving someone hardware. They've found in many developing countries that governments have gone in and given out free latrines and gone back a few years later and found that they've got lots of new goat sheds or temples or spare rooms with their owners happily walking past them and going over to the open defecating ground.

So the idea is to manipulate human emotion. It's been done for decades. The soap companies did it in the early 20th century. They tried selling soap as healthy. No one bought it. They tried selling it as sexy. Everyone bought it. In India now there's a campaign which persuades young brides not to marry into families that don't have a toilet. It's called "No Loo, No I Do." (Laughter) And in case you think that poster's just propaganda, here's Priyanka, 23 years old. I met her last October in India, and she grew up in a conservative environment. She grew up in a rural village in a poor area of India, and she was engaged at 14, and then at 21 or so, she moved into her in-law's house. And she was horrified to get there and find that they didn't have a toilet. She'd grown up with a latrine. It was no big deal, but it was a latrine. And the first night she was there, she was told that at 4 o'clock in the morning -- her mother-in-law got her up, told her to go outside and go and do it in the dark in the open. And she was scared. She was scared of drunks hanging around. She was scared of snakes. She was scared of rape. After three days, she did an unthinkable thing. She left. And if you know anything about rural India, you'll know that's an unspeakably courageous thing to do. But not just that. She got her toilet, and now she goes around all the other villages in India persuading other women to do the same thing. It's what I call social contagion, and it's really powerful and really exciting.

Another version of this, another village in India near where Priyanka lives is this village, called Lakara, and about a year ago, it had no toilets whatsoever. Kids were dying of diarrhea and cholera. Some visitors came, using various behavioral change tricks like putting out a plate of food and a plate of shit and watching the flies go one to the other. Somehow, people who'd been thinking that what they were doing was not disgusting at all suddenly thought, "Oops." Not only that, but they were ingesting their neighbors' shit. That's what really made them change their behavior. So this woman, this boy's mother installed this latrine in a few hours. Her entire life, she'd been using the banana field behind, but she installed the latrine in a few hours. It cost nothing. It's going to save that boy's life.

So when I get despondent about the state of sanitation, even though these are pretty exciting times because we've got the Bill and Melinda Gates Foundation reinventing the toilet, which is great, we've got Matt Damon going on bathroom strike, which is great for humanity, very bad for his colon. But there are things to worry about. It's the most off-track Millennium Development Goal. It's about 50 or so years off track. We're not going to meet targets, providing people with sanitation at this rate. So when I get sad about sanitation, I think of Japan, because Japan 70 years ago was a nation of people who used pit latrines and wiped with sticks, and now it's a nation of what are called Woshurettos, washlet toilets. They have in-built bidet nozzles for a lovely, hands-free cleaning experience, and they have various other features like a heated seat and an automatic lid-raising device which is known as the "marriage-saver." (Laughter)

But most importantly, what they have done in Japan, which I find so inspirational, is they've brought the toilet out from behind the locked door. They've made it conversational. People go out and upgrade their toilet. They talk about it. They've sanitized it. I hope that we can do that. It's not a difficult thing to do. All we really need to do is look at this issue as the urgent, shameful issue that it is. And don't think that it's just in the poor world that things are wrong. Our sewers are crumbling. Things are going wrong here too. The solution to all of this is pretty easy. I'm going to make your lives easy this afternoon and just ask you to do one thing, and that's to go out, protest, speak about the unspeakable, and talk shit.

Thank you.

(Applause)