After A Bridge Collapse, Questions About Engineering Safety

IRA FLATOW: This is Science Friday. I’m Ira Flatow. On Tuesday, a highway bridge collapsed in the city of Genoa, Italy. And at least 39 people died in the collapse and its aftermath. The failure of the bridge is making people take a second look at engineering safety across Europe and around the world.

And joining me now to talk about that and other selected short subjects in science, Sophie Bushwick, senior editor at Popular Science. Always good to see you, Sophie.

SOPHIE BUSHWICK: You too.

IRA FLATOW: Let’s talk about how much do investigators know about why this bridge collapsed.

SOPHIE BUSHWICK: So this bridge was concrete reinforced with steel. And right now, they’re not positive what caused the collapse. But it could have been steel inside the concrete, where they couldn’t look at it, corroding. Or it could have been the concrete itself wearing away.

There’s actually a twin of this bridge that had structural issues back in the ’60s when a tanker hit it. So there’s consideration about that.

IRA FLATOW: So this bridge, this design, is commonly used in other parts of the world?

SOPHIE BUSHWICK: Concrete with steel reinforcement is commonly used, yes, all over the place. And it’s kind of scary because a lot of these– when they build new bridges, they can build sensors into the structure itself, which can kind of give you an idea of how healthy that bridge is. But when you have older ones, you kind of have to put the sensors on the outside. And they’re not as good at giving that read.

IRA FLATOW: Right. So when the concrete– when the steel goes into the concrete, you lose track of the steel. You don’t know. It might be rusting or corroding.

SOPHIE BUSHWICK: Right, exactly.

IRA FLATOW: And on the new bridges, they actually can keep track of that better.

SOPHIE BUSHWICK: Right. Sensors are becoming a lot cheaper and easier to put into bridges.

IRA FLATOW: All right. Closer to home this week, federal judges ordered the EPA to ban a pesticide. I’m going to try to pronounce it, chlorpyrifos– chlor–

SOPHIE BUSHWICK: Chlorpyrifos.

IRA FLATOW: OK.

[LAUGHTER]

SOPHIE BUSHWICK: I’ve been working on that one.

IRA FLATOW: Chlorpyrifos.

SOPHIE BUSHWICK: Chlorpyrifos.

IRA FLATOW: And tell us the story on that one.

SOPHIE BUSHWICK: This is actually the latest step in an 11-year, epic battle basically. So chlorpyrifos is an insecticide. And it’s also a neurotoxin. In large enough amounts, it can cause muscle spasms and paralysis. And it can shut down the heart and lungs, which was primarily thought to be concern for people living in rural or agricultural areas.

But it turns out that exposure to trace amounts of chlorpyrifos over a long time can cause developmental problems in children. And so in 2007, environmental groups first sued the EPA to get them to ban this insecticide. And it went back and forth. And there were reviews.

And in 2016, the EPA concluded that, yes, there were trace amounts on the food that we’re eating that isn’t within safe levels. But then, they were within two days of a court-ordered ban in 2017. And they reversed course on it.

IRA FLATOW: The EPA reversed course?

SOPHIE BUSHWICK: The EPA reversed course. And they said they weren’t going to ban it. And so now, the latest thing is a federal court has said, look, you have 60 days to ban it. And if they– they do have another choice, which is to petition the Supreme Court to fight this decision. But if they don’t do that, then they have to ban it.

IRA FLATOW: Wow. Wow. The EPA has been overturning things. But the courts are getting involved in these things.

SOPHIE BUSHWICK: Right.

IRA FLATOW: In other regulatory news, the FDA has approved a contraceptive app.

SOPHIE BUSHWICK: That’s right.

IRA FLATOW: There’s an app for that now?

SOPHIE BUSHWICK: There’s an app. So there are apps that people have been using to track fertility and your period and ovulation cycle. But this is the first time the FDA has approved one of these apps as a form of contraception.

This isn’t a new method. People have been using this for at least hundreds of years to know what days you’re fertile and what days you’re not. But what’s different is that this one basically takes the calculations and puts it in the hands of the algorithm.

IRA FLATOW: So does it give you a little signal, today’s a good day? Is it keeping track?

SOPHIE BUSHWICK: Yeah. It’s got a red light, green light signal.

IRA FLATOW: [LAUGHS] It does.

SOPHIE BUSHWICK: It does. The problem is that in general, fertility tracking is considered by the CDC to have about a 76% effective rate. Now, the people who manufacture this app say they’ve got a 93% effectiveness.

IRA FLATOW: Wow.

SOPHIE BUSHWICK: But some critics have said that with the study that they used, they recruited people who already use the app. And the critics say, well, if somebody accidentally got pregnant while they were using the app, they wouldn’t keep using it. And they wouldn’t want to participate in a study about how effective it is. So you might have a sort of self-selecting group that could be giving you a higher rate of efficiency.

IRA FLATOW: Well, I’m sure there’ll be more apps coming out.

SOPHIE BUSHWICK: Yes. I’m sure this is not the only one that the FDA will be looking at.

IRA FLATOW: You have a story about the health effects of an ingredient in marijuana that seems kind of intriguing. Because we’re seeing marijuana being used now for more and more health problems.

SOPHIE BUSHWICK: Right. So this is a case of it being used with inflammatory bowel disease. So a lot of people who have Crohn’s disease or ulcerative colitis have been taking cannabis to treat it. And anecdotally, they say it feels better.

But scientists didn’t know what the mechanism was until they kind of stumbled on it accidentally. So researchers were looking at mice. And they were looking at the epithelial cells in their gut. This is sort of like a passageway between the body and the white blood cells in the immune system versus the kind of microbial zoo living in your gut.

And there’s all these chemical pathways that mediate whether your immune system can get into your gut and how many of these cells can. And they found that one of the chemicals that regulates this pathway is an endocannabinoid. And cannabinoids found in marijuana could substitute for it.

IRA FLATOW: So it’s sort of identical to cannabis?

SOPHIE BUSHWICK: It can bind to the same receptors, yes.

IRA FLATOW: So that would then explain why some people say, hey, this works when I–

SOPHIE BUSHWICK: Right, exactly. If the same thing that happens in mice is also happening in humans, then that could definitely be it.

IRA FLATOW: Yeah. So much more we don’t know about.

SOPHIE BUSHWICK: Absolutely. It’s tough when you’re studying it in animals and then trying to apply it out to us.

IRA FLATOW: And finally, Sophie, there’s a new pterosaur in town? What’s a pterosaur? And where is it?

SOPHIE BUSHWICK: A pterosaur–

IRA FLATOW: I don’t see it around here.

SOPHIE BUSHWICK: You might have heard of it as a pterodactyl.

IRA FLATOW: There you go.

SOPHIE BUSHWICK: But, yeah, this is a flying dinosaur. The latest species is called Caelestiventus hanseni. Caelestiventus means heavenly wind. So this is a pterosaur from the Triassic. So that’s the period from 200 to 250 million years ago.

And it was actually– we don’t have a ton of pterosaur remains from that long ago. Because a lot of them– they have hollow bones like birds. And their bones just got– their remains just got crushed as marine sediment landed on them. But this fossil was found in the desert in Utah at the Saints and Sinners Quarry.

And so it was relatively intact. They got part of the face, the skull, the jaw. They even have a bit of the wing. They think it had a five-foot wingspan. And they found details, like they think that it had a flap of skin hanging under its chin. Maybe it used it to hold food like a pelican beak. Or maybe it was just decoration, like a bird’s plumage.

IRA FLATOW: And these are pretty rare, right, having something like this?

SOPHIE BUSHWICK: Yes. They’ve only found about 30 remains of pterosaurs from this period. And they’ve got a lot more from more recent ones. So in, say, more like 66 million years ago, a lot more recent, these animals got up to– they could have a 30-foot wingspan.

They could be enormous. But back in the day, we have fewer remains of what they were like during the Triassic. And we know they were a little smaller and a little waddlier, I guess.

IRA FLATOW: Well, we’ll now have to go see if we can see it somewhere on exhibit.

SOPHIE BUSHWICK: I hope so.

IRA FLATOW: Thank you, Sophie. Sophie Bushwick, senior editor at Popular Science.

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