How effective are plastic bag bans? And a whole new way to do astronomy
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This podcast is supported by the Icahn School of Medicine at Mount Sinai, the academic arm of the Mount Sinai Health System in New York City, and one of America's leading research medical schools.

What are researchers on heart health working on to transform patient care and prolong lives? Find out in a special supplement to Science Magazine prepared by the Icahn School of Medicine at Mount Sinai in partnership with Science. Visit our website at www.science.org and search for Frontiers of Medical Research-Heart. The Icahn School of Medicine in Mount Sinai. We find a way.

This is the Science Podcast for June 19, 2025. I'm Sarah Crespi. First this week, the Vera Rubin Observatory is just coming online. Once fully operational, it will take a snapshot of the entire southern sky every three days.

Producer Megan Cantwell talks with staff writer Daniel Cleary about his trip to the site of the largest camera ever made for astronomy. Next on the show, probing the impact of plastic bag regulations. Environmental economist Anna Popp joins me to discuss her work quantifying litter collected by shore cleanup efforts before and after the onset of plastic bag rules.

And in a sponsored segment from our Custom Publishing office, Director of Custom Publishing, Erica Berg, talks with Deepak Bhat and Philip Swirsky about advances in the science of heart health.

This year, the Vera Rubin Observatory will start its 10-year probe into the universe. I'm Megan Cantwell, a producer at Science, and I learned from our staff writer Daniel Cleary all about how this telescope could transform the field of astronomy. In the past, almost all telescopes would be made with aiming to zero in on something really little and look at it in great detail.

In recent years people have got more interested in surveys, collecting big populations of similar sort of objects. The idea behind the Rubin Observatory is to take in a huge amount of sky with a very large telescope so it collects a lot of light so it can see things that are very distant and very dim. It'll take a 30 second exposure, close the shutter, move to another part of the sky, take another one

It'll do that all night long. It's going to discover something like 10 times more objects in our own solar system than we know about already. New asteroids and moons, planets, objects in the outer solar system. So many galaxies, billions and billions of them. It's a very intense way of doing astronomy. It's almost like industrial scale because they're just pumping out data and data all night long. So...

It needs a lot of infrastructure to keep that going smoothly. Daniel made the journey from England to central Chile to visit the observatory and see what it will take to keep this massive operation running. It's a two-hour drive from La Serena up to the observatory. Every so often, as you wind around various hills, you see these little glimpses of white telescopes at the tops of some of these peaks.

Eventually you get up to the summit and there is this enormous building perched on the top of a mountain, which seems quite extraordinary. That site was chosen because the air is very dry and it's very stable. The sky is exceptionally clear. This was...

Upgrading the site because one, it was accessible. There were already a lot of like ranchers and some roadways to get out here. Alyssa Shugart is the deputy manager for the observing specialists team. She's been on the ground at the Rubin Observatory since 2020, watching the site transform from a construction project to a bustling center with many scientists and staff.

It's such a different way of observing with Ruben. It must be like you're having to invent the process over again. Yeah, no, we are very much building the ship as we're sailing it.

The building the telescope is housed in is made up of several levels, from a clean room where they can coat the telescope's mirrors to offices for staff. You go in at ground level and immediately go upstairs where there's a sort of office level. And they have the control room of the telescope, which looks a bit like something you would have for a space mission. They have this enormous display on the wall when it's operating.

which has 24 graphs showing the sort of temperatures and pressures and heat flows at various places, because there are objects in there that generate heat. And there's potential for that heat to damage the sensors. A lot of things that they're now doing manually, they will learn how it's done, and then they'll teach an AI system to do them.

You can imagine the observing specialist more like an airline pilot. If things are going well, 90% of our night will be very smooth, but there's that 1-10% of time that you really want us there. I entered the dome itself where the telescope is. It fills the room much more than other telescopes I've seen. It's so short and squat, isn't it? It's big and fat and I love it.

When we saw it in motion, I didn't know what was moving, whether I was on a moving part or I was stationary, but it was very disconcerting. It was so smooth. The whole thing sits on a thin layer of oil between two flat surfaces. This is an enormous machine weighing 350 tons.

and when it turns around, it's silent. Eventually it'll be moving at four or five times the speed we saw it moving. So when we change positions from the telescope pointing from one part of the sky to the other, we want it to be able to move as quickly as possible, and once it's there, take the highest quality image as possible. On a normal telescope, it's quite hard to get accurate images right at the edge of your field of view. The images are often a bit distorted.

but by having three mirrors you can lessen that effect. So the light is essentially bounced back and forth between these three mirrors before it enters the camera. A mirror like that, which is a huge piece of glass 8.4 meters across, it gets warped by gravity as it moves. So on the back they have little motors that put pressure on the back of the mirror to make sure it stays in a perfect optical shape.

It's a big field of view and what we want to do is we want to maintain focus across that big field of view, right? So this is the only telescope that I think has a three mirror, three lens design. Really? Oh, okay.

The camera for Vera Rubin is the largest camera for astronomy that's ever been made. It's about the size of a small car. The sensor array is this big array of CCDs. CCDs are little camera chips. This has 189 of them and they're big.

So it's a huge amount of data in each image. The width of the image is about seven or eight full moons across. So the whole field of view is something like 40 full moons, which is huge compared to a normal professional telescope. You're getting this sort of snapshot of the entire southern sky out to a very great distance.

Once the observatory takes an image, the data begins its long but quick journey from Chile to California to be processed and reviewed by astronomers around the world. They are removing certain artifacts that are created by the telescope so that essentially all that scientists will see are the astronomical objects that they want to see.

The next thing they do is they compare that image to the same image taken three days earlier. It's going to be finding anything that changes, and that could be a quasar in the very distant universe, or it could be something in our solar system. That immediately generates an alert.

to different groups that have built things called alert brokers. And that's a software system that looks at each alert and tries to identify what it is. The alert system could generate millions of alerts a night for all sorts of objects, like asteroids, moons, and stars. Most won't require immediate attention, but some rare events will, like if two neutron stars collided with each other. A neutron star is what's left when...

A very large star ends its life, can't burn anymore, and it sort of collapses. Occasionally you'll get two of them that are orbiting each other, and they will gradually orbit closer and closer together and then merge.

In 2017, gravitational wave detectors sensed one and sent out an alert. Telescopes took ages trying to find it, about 11 hours or something like that. People are hoping that if we get another alert like that, Rubin will be able to pick up enough light to find it much quicker. And then you'll see that explosion from the very beginning.

Sometimes scientists will have set up automatic systems. They could, these bits of software themselves, send out a request to another telescope saying, "Please follow up this object." And they'll give its location and how bright it is. Scientists might wake up in the morning and find some amazing discovery has been made, but

that they have been sleeping and they've got follow-up observations and they've got characterization with a spectrum. I think many scientists think there aren't enough other telescopes to follow up all the things that Vera Rubin is going to find. As Rubin continues to harness light from the universe, its images will become sharper and more detailed, enabling all sorts of new analyses.

Our knowledge of how galaxies evolve is all based on the biggest, brightest ones that have been around for a long time. To understand how galaxies work, we need to know this much larger population of dwarf galaxies that at the moment we just can't see. They probably aren't just smaller versions of the big ones. They're irregular and lumpy and not a sort of fully formed shape.

Rubin is going to completely change that and find vast numbers of these things. Years into observation, researchers will be able to explore one of the main reasons the telescope was built in the first place, to understand dark energy. Dark energy is this mysterious force that is making the universe not just expand, but getting faster. The shape of a galaxy's image can be distorted because other matter in front of it acts as

acts as a lens, distorting the path of light. If you have a large number of them, you can do statistical comparisons and they'll be able to do very, very precise measurements of how this clumpiness has changed and what that means for the accelerating expansion of the universe.

Amidst the high hopes for all the science that the telescope could enable, there are concerns that the increase in low-Earth orbit satellites could obscure the observatory's view. These satellites can leave massive trails across images. And because Vera Rubin is looking at such a large part of the sky, it's really hard to avoid them. Right now, the trails from the satellites affect 1% of orbit.

all the images that they take, all the sky area that they cover. By the end of the survey, they may have much less usable data than they do at the beginning. Scientists are working with the satellite companies to hopefully lessen the impact, but in the meantime, the telescope is soon going to start operating at full capacity. The people that are studying the solar system, they think they're going to start seeing things in the first year because they're picking out things that are moving

and they'll be really obvious straight away. Whereas looking for the very subtle effects of dark energy, which involves analyzing huge number of galaxies, it may not be until right until towards the end of the survey that they'll be able to really make a firm conclusion. Almost every area of astronomy will

use it in some way. So they're still doing a lot of preparation to make sure they're ready for that enormous cinematic production that they're going to start towards the end of the year or early next year. Daniel Cleary is a staff writer for Science. You can find a link to his story at science.org slash podcasts. Stay tuned for a chat about the impact of plastic bag regulations on reductions in marine litter.

Around the world, 2 to 5% of plastic waste ends up in the ocean. Considering how much plastic we throw out every year, this is a sizable mass that enters marine ecosystems. The damage from animal and plant life to tourism is costly. Many efforts to combat plastic litter have centered on these thin plastic grocery bags

either banning them altogether or taxing them, charging a fee if you want to take one home. So this week in science, Ana Pop and colleagues wrote about measuring the impact of bag regulations on marine litter using citizen science. Hi, Ana. Welcome to the Science Podcast. Hello. Thank you so much for having me.

Oh, sure. You know, I always thought plastic bag bans had to do with this, you know, buildup of waste in the environment more generally, but I never really connected it to oceans and marine life. You know, how tightly related are they? You know, how do plastic bags that I'm here in Indiana that I get at the Kroger, how do they end up in rivers, streams, oceans, that kind of thing?

Something that makes plastic bags especially potentially harmful and easy to spread is that they're so light and easy to transport in the wind and water, et cetera. And so even something that starts in the middle of the country, far away from the oceans, can be blown by the wind, escaping, for example, can

a recycling truck or a trash truck end up near waterways, even in small streams that of course then eventually lead back to various aquatic ecosystems, whether that's lakes, rivers, and then eventually, of course, the oceans. Before this study that you did here, people were trying to measure impact of plastic bag

regulations on litter, but they weren't specifically looking at the marine impact. So what do we know kind of before going into this paper about how effective these regulations were? There's been a lot of great studies.

especially in the economics literature, for example, that are conducted at the store level. So this is using checkout data, for example. Some have shown reductions, some have shown substitutions between different types of bags. So from thin plastic bags to thicker plastic bags. And these have generally focused on only a couple or a handful of regulations.

And so what these haven't addressed, though, is then the direct impact on plastic litter in the environment, which is, of course, what motivates a lot of these policies to begin with because of their effects. So maybe just cutting down on how many get into people's hands doesn't necessarily impact

kind of how much end up in the environment, there could be various changes along that chain. Exactly. Like you could imagine that even if, for example, people substitute thin bags to thicker bags, then at the store checkout level, that may not show an effect. But let's say then people actually do end up reusing those thicker bags more.

or they are just more careful potentially about what they do with those thicker bags or the thicker bags are less likely to be blown away by the wind, then those might all eventually affect the actual amount of these bags that end up in the environment. Just as you described that kind of convoluted chain of events that have to occur here, it's really not easy to understand, to quantify a plastic bag getting picked up by a consumer and ending up

on the beach, on the shoreline. So can you kind of walk us through what you did to capture this potential change? Like how were you able to get data on plastic bags on the beach or on a riverbed? Yeah, exactly. I think you touched upon a big challenge of doing a lot of this research is the lack of sort of comprehensive data on plastic waste and plastics in general. And so what made this paper possible is this really great data from the Ocean Conservancy

So this is crowdsourced citizen science data. Essentially, when people go on all types of cleanups, so beach cleanups or river park cleanups, they enter, if they're doing the City to Ocean Conservancy's app, which is called Clean Swell, then they record a bunch of information on, for example, how many people are at this cleanup, and then also very detailed data.

categories of what types of items that they find. So there's over 60 different categories and, of course, then a big share of these in

include plastic items, including plastic bags. And so that's what made this study possible is the existence of this crowdsourced data. And so one thing that immediately stuck out to me was this is amazing, like that not only are they organizing cleanups, but they're also tracking that data in order to kind of show how policy change or even how the cleanups themselves are having an effect. It's such a smart idea. But then I

I immediately thought, OK, but when you do a beach cleanup, do you do it for a certain number of hours or do you do it until you have 10 pounds or 50 pounds or whatever? Are they going to if there's less litter, do they do less of it? Can you talk a little about kind of the hurdles there taking something that is not necessarily super clean, but still has that information you want and extracting it out?

So the short answer is that we tried to do a lot of things to make sure that we're comparing similar cleanups over time and over different places. In addition to checking, of course, the main outcome variable, which is the share of plastic bags collected in these cleanups. We did a lot of checks, for example, on the number of total items that people collect.

We did normalizations, controlling, for example, for the number of attendees, checking various types, whether there's kids there. Exactly. We thought, you know, maybe the types of cleanups that have a lot of kids are a little different than those that don't. And so we just try to control and check as many things about these cleanups that is possible. And not all of these bands are right next to the ocean. So did you include...

seaside as well as by a lake or by a river in the analysis you did? Yeah, a lot of them actually are not exactly next to the oceans. So these also happen in parks and lakes and rivers. In our overall analysis, all types of sort of aquatic cleanups are included. But we do, for example, break out, we check whether it's different at just the coastal, the ocean cleanups, the river cleanups and the lake cleanups. And

And another variable that you had to consider was what kind of regulation was applied in the area. So some places they charge you five cents to take a bag. Other places they say you are not allowed to give these out if you're a grocery store. Did you look into that as something that might affect what's going on on the shore? We mostly differentiated between three types. Compensations.

complete plastic bag bans. So that's self-explanatory. Any type of plastic bag is banned. And then partial bans, some of which allow for substitution to thicker recyclable bags. And then finally, taxes or fees, which are usually a couple of cents per bag. And in the United States, a lot of the earlier policies were bans. And so most of our results on the bans are more precise and

But it actually does seem like the taxes are in magnitude, especially effective in reducing or limiting plastic litter. But this again, because there's a lot less of these policies currently, it's a little bit noisier. So it's only suggestive. So let's talk a little bit about your results here. How many beach cleanups did you look at and how many places and how many laws? You know, can you kind of run us through the numbers? We compiled data on over 600 different policies.

policies. And then we have to overlap this with the cleanup data. And so essentially, the number of policies that we are evaluating is 182. And then over this time period from 2017 to 2023, we are using data on over 45,000 beach cleanups in the U.S. And what did you see when it came to this relationship between regulation of bags and how much litter

people saw on the beaches or what percentage of the litter was bags? We find in general, overall, that there is a reduction in the share of plastic bags that are found on beaches after these cleanups.

So basically, we're comparing not only before and after where these policies happen, but also places with policies to places without policies. So it's important to note that this is a relative decrease, but it does seem like overall these laws or these regulations are effective in at least limiting plastic bag litter. How strong of an effect did you see on

on the percentage of plastic bags? We found 25 to 47 percent decrease. And this is the decrease in the share of items that are plastic bags of all these items. So in magnitude, I think it's quite sizable effect. And in general, actually, we do see in the U.S. the share of plastic bags making up a larger percentage of items found. So this is limiting plastic pollution, but not eliminating it.

Are there some limitations here on like applying this more broadly to maybe other countries or places with different, I don't know, environments, number of amount of beaches? What are some of the kind of constraints? Definitely. I think in a lot of countries outside the United States, the actual share of bags, plastic bags as a percentage of litter might be even larger. There's of course also probably different dust behavior of a lot of consumers. And so

And so that's definitely in terms of generalizing the results, potential limitations. Also could think about, you know, if these results are suggestive for other types of plastic items, single use items. But again, different setting, but potentially. Even though we call them single use, of course, I take them home and hoard them and use them.

That's the thing, yes. Little wastebaskets and for kitty litter. And some people drink out of them. They sell drinks out of them. You know, like there's all kinds of behaviors that need to be accounted for when you think about changing something. Absolutely, yes. Everybody always talks about the, you know, under the sink, the buildup of plastic packs. Yeah. Yes. And I mean, I actually, just to be...

I do bring reusables every time and yet they still get in my house. I don't even know how anymore, but yeah, they still accumulate. Yeah. Well, it's better under the sink than on the ocean. What I want to emphasize is that, of course, this is studying one part of the entire plastic life cycle, which starts with production of plastics, right? Consumption and then ends with waste. And so even though this

this paper shows that these policies aimed mostly at the consumption and the waste side can be very effective in limiting plastic waste, though not eliminating. I think it's also very important to keep in mind that really limiting or lowering plastic pollution will require efforts at all parts of this life cycle, starting with production and ending in waste. All right, Ana, thank you so much for talking with us. Thank you so much. It was great. Ana Pop, just...

Up next, we have a custom segment sponsored by the Icahn School of Medicine at Mount Sinai. Custom Publishing Director Erica Berg chats with researchers Deepak Bhat and Philip Swirsky about the future of heart health.

Hello, podcast listeners, and welcome to this sponsored interview from the Science AAAS Custom Publishing Office and brought to you by the Icahn School of Medicine at Mount Sinai. My name is Erika Berg, and I'm the director and senior editor for Custom Publishing at Science.

Heart disease remains the leading cause of death and disability in the United States, taking more than 680,000 lives each year. Yet, heart disease is so much more than just a statistic. It's a deeply personal reality for millions, including my own family. It's a condition that sends ripples across the lifespan through families, communities, and entire healthcare systems.

But thanks to groundbreaking research, the future of heart health is brighter than ever. Today, I am very pleased to welcome Deepak L. Bhatt and Philip K. Swirsky.

Dr. Bach is the director of the Mount Sinai Fuster Heart Hospital and the Dr. Valentin Fuster Professor of Cardiovascular Medicine at the Icahn School of Medicine at Mount Sinai in New York City. Dr. Swirsky is the director of the Cardiovascular Research Institute and the Arthur and Janet C. Ross Professor of Medicine also at the Icahn School of Medicine at Mount Sinai.

Both led the development of and contributed articles to an upcoming supplement to Science magazine entitled Frontiers of Medical Research, Heart. The supplement will be jointly published by Science and the Icahn School of Medicine at Mount Sinai with our June 19th issue.

Deepak and Philip, thank you so much for taking the time to talk with me today. Oh, it's very exciting to be here with you, Erica. Thank you, Erica. Very happy to be here. So I'm going to start off asking a question for both of you. Despite decades of progress, cardiovascular disease remains the number one killer not only in the U.S., but worldwide.

What are the biggest barriers to reducing this burden? And what gives you the most hope right now? Deepak, how about you start us off? There are really two layers to your question.

One is what can we do better with the information we have right now? In fact, we know a lot about the causes of cardiovascular disease and for things like heart attack, risk factors such as smoking, high cholesterol, high blood pressure. These are things that are well known. We have effective treatments, but the challenge is implementation science.

patients that could benefit from that knowledge aren't actually getting it. But then the second layer is the need for discovery, discovering new pathways to disease, new risk factors, and new treatments. So I think that this two-pronged approach could lead to really marked advances in patient care, ultimately leading to longer and healthier lives.

Philip, anything you'd like to add there? I would echo what Dr. Batts said. What I would also add, just taking that thread of discovery, is that we are increasingly recognizing how complex and multifactorial the disease is. And this, of course, opens up many new questions.

And the answer to which will require technological innovations will require multiple teams with diverse expertise. Right. Thank you so much, Deepak. You've led...

numerous clinical trials. How is clinical trial design evolving to accelerate innovation while also ensuring patient safety? That's a great question. So there's a lot of innovation in the cardiovascular clinical trial space. And broadly speaking, it's of two flavors. One has to do with the actual science.

that is testing innovative therapies, but the other has to do with actual clinical trial design and the science behind clinical trials. In the clinical trial world, we've valued randomized trials and will continue to do so, but there is a certain inefficiency where in the cardiovascular space, we often enroll thousands of patients and follow them for many years looking for benefit in a rather broad population.

But one way of making trials more efficient is the concept of adaptive clinical trials.

That is, during the course of a trial, actually seeing might there be a subgroup that doesn't benefit and then stopping further enrollment of that subgroup. Maybe there's a subgroup that particularly benefits, then enriching the trial as the trial moves forward with those sorts of patients. The idea that we can do trials more efficiently. And by that, I mean perhaps getting answers more quickly, more cost effectively, and more

that sort of clinical trial adaptation can be further enhanced potentially with machine learning. Wow, that's kind of exciting stuff. I'm a bit of a clinical trial nerd, I have to say. Philip,

Over to you now. So your work is exploring the immune system's role in cardiovascular disease. How has our understanding of inflammation and immunity shifted the way we think about and treat heart disease? The role of the immune system in cardiovascular health and disease has been appreciated certainly in the laboratory for several decades.

fundamental work to understand the role of immune cells, the immune system in general, and its inflammatory component as an important contributor of cardiovascular disease. But your question also touches on something a little broader that in order to understand the cardiovascular system,

We begin to investigate other physiological systems because of course the body is this collection of physiological systems which commingle, communicate with each other and have specific roles. It is this consideration of how these systems contribute that will bring us closer

to understanding cardiovascular health and cardiovascular disease. Sounds like a tall order. Just understanding one of those systems in isolation has to be hard enough, and now you're trying to understand them all together. Well, maybe technology could help. AI is being used to predict risk, diagnose disease earlier, and personalize treatment. Can you

talk about how this technology is transforming the cardiologists toolkit. I don't know if your choice of words was purposeful in terms of transforming, but I'm actually leading a trial called Transform where we are taking patients that don't have any obvious cardiovascular symptoms, trying to see if

an AI-enabled algorithm that uses coronary CT angiography, non-invasively obtained pictures of people's heart arteries, and then using an AI algorithm to take the information and other information to more accurately predict their risk. Our hope is to really transform cardiovascular prevention with imaging, but also using artificial intelligence to go beyond where imaging has gone before.

Thank you. So if we revisit this conversation 10 years from now, and let's just plan to do it, what's one breakthrough or transformation in cardiac care that you think we'll be talking about? And what will it take to get us there? Of course, everyone is biased as to the particular thing that

they are paying particular attention to. So I would be tempted to say that it is going to be our discoveries in brain body, in brain heart, in brain immune. We are on the precipice of making very meaningful discoveries that are going to really tell us that indeed what

what we've known all along that the systems work together and that health is really about the balance between the various physiological systems. Wow, that was a really good answer. Well, you know, I think there's going to be a major paradigm shift in cardiovascular medicine next decade. Right now, we're pretty good at treating disease. So I think there's going to be a big shift from just trying to treat disease, but to actually preventing disease.

And I think that's going to be through personalized care. I think everybody's going to get genotyped, at least be in the medical record. I think there'll be panels of biomarkers on people and then everything else in their electronic health record. That is their chest x-rays or

ultrasounds, whatever other imaging they've gotten, really powerful AI-driven risk engines will be able to integrate the genetics, the biomarkers, the usual demographics, also the imaging data, and put that all together and much more precisely be able to define a person's risk. But not just for the sake of defining their risk, but then tailoring their therapy based on that information.

So this person, we might say, yeah, you really do need to go on a low salt diet because that actually will help your form of blood pressure. Or somebody else, yeah, you can go on a low salt diet, but your form of blood pressure, it's not going to do that much. We really need to start you on medicines now. So I think

It's going to be a much more refined, precise way, tailoring risk, tailoring therapy to the individual that hopefully will be much more effective at preventing fatal and non-fatal complications of cardiovascular disease.

Fantastic. It sounds like we'll have a lot to talk about 10 years from now. And I'm really hoping that I end up being one of the people that can have as many potato chips as they want, and it will not impact my health in any way. Fingers crossed I have those biomarkers. Thank you so much, Philip and Deepak. It was such a wonderful conversation. Thank you for joining me. Wonderful being with you. I look forward to chatting again in 10 years to see which of our predictions were right and which ones were wrong.

Thank you for having us. And I'd also like to thank the Icahn School of Medicine at Mount Sinai for sponsoring this interview. I'm Erika Berg. Thank you for listening. And that concludes this edition of the Science Podcast. If you have any comments or suggestions, write to us at sciencepodcast at aas.org. I'm also seeing some comments on Spotify, so you can go there to find us on podcasting apps like Spotify, Overcast, and Apple Podcasts.

search for Science Magazine or listen on our website, science.org slash podcast. This show was edited by me, Sarah Crespi, and Megan Cantwell. We had production help from Podigy. Our music is by Jeffrey Cook and Wenkui Wen. On behalf of Science and its publisher, AAAS, thanks for joining us.