C &EN’s latest podcast, Inflection Point, leans on our 100-year archive to trace headline topics in science today back to their disparate and surprising roots. In each episode, we explore three lesser-known moments in science history that ultimately led us to current-day breakthroughs. With help from expert C&EN reporters, this new show examines how discoveries from our past have shaped our present and will change our future.
In our fourth episode, hosts David Anderson and Gina Vitale travel back in time to relive three historical moments that were pivotal in the evolution of microplastics. They also bring in C&EN reporter Bri Barbu to discuss how biodegradable plastics, if employed responsibly, may offer a glimmer of hope.
Subscribe to Inflection Point now on Apple Podcasts, Spotify, or wherever you get your podcasts.
The following is a transcript of episode 4 of Inflection Point. Interviews have been edited for length and clarity.
David Anderson: In 1863, elephants were on the verge of extinction, thanks in large part to a new type of game the wealthy elite were really starting to enjoy: billiards. Then, in 1965, off the coast of Ireland, a boat towing a device that measures plankton populations ensnared a small but historical piece of trash. And in 1989, a husband and wife cooked up some corn in their kitchen and revolutionized an entire industry.
Gina Vitale: David, sorry, did I hear you correctly with that last part? A husband and wife cooking corn?
David: I think so, yeah.
Gina: We talked about this, right? So this is the last episode of the season, right?
David: Yes.
Gina: The first season of Inflection Point, this great new science history podcast.
David: Here we are.
Gina: And we were like, Let’s go out on a bang. Let’s do a really strong last one.
David: I’m right there with you.
Gina: [Laughs.] And you’re talking about a married couple cooking corn in their kitchen—
David: Mmm-hmm.
Gina: —an elephant extinction event—
David: Yep.
Gina: —and a piece of trash.
David: Yeah. Any questions?
Gina: [Laughs.] Come on, David. How are these related?
David: Well, all will be revealed. I know you do want to go out on a high. This is our last episode of the season. And trust me, the subject of today’s podcast is huge.
Gina: OK, I am cautiously optimistic. This is a big topic?
David: OK, technically, it’s actually very, very small, but it’s very important.
Gina: Hmm. Can I have a hint?
David: I’m sure it’s in your house right now.
Gina: House?
David: It might be in your blood, your water, your food.
Gina: Blood?
David: You might have even created some yourself today.
Gina: Oh, man, let me guess. It’s like plastic, but really small?
David: There you go. You guessed correct. Yeah, today we are talking about microplastics.
Gina: This is Inflection Point.
David: Spanning a century of reporting from C&EN, this new podcast traces discoveries from our past—
Gina: —to how they shape our present—
David: —and will change our future.
Gina: I’m Gina Vitale.
David: And I’m David Anderson.
David: Gina, first off, I do feel like maybe we should address the feeling of déjà vu in the room.
Gina: What do you mean?
David: Well, didn’t we just do a podcast on PFAS [per- and polyfluoroalkyl substances], the microscopic pollution that takes forever to break down and is accumulating in our bodies, food, and water? I think some listeners could be forgiven for saying, Hey, aren’t microplastics and PFAS broadly the same?
Gina: Yeah, that’s a really good point. PFAS and microplastics, at least in terms of their negative traits, do have a lot in common. One of them that you didn’t mention is that they are both big umbrella classes of chemicals. There are many compounds that can be considered PFAS, and many different kinds of microplastics. But the two classes are actually quite different.
David: OK, how so?
Gina: Well, microplastics, as we know, are just really small pieces of plastic. Less than 5 mm long, to be more precise. Some research also specifically looks at nanoplastics, which are anywhere from 1 to 1,000 nm long. For context, a human hair is about 80,000–100,000 nm wide.
David: Wow. So we’re talking tiny, tiny, tiny.
Gina: Right. So it kind of comes down to what exactly is plastic.
David: Right, I mean, well, you know, it’s like your grocery bag, your keyboard, your gym shorts—
Gina: Sure.
David: —Legos—
Gina: Right.
David: —you know—
Gina: It’s kind of hard to define yourself. And, important caveat here, I really struggled to find one standard definition of plastic. There still seems to be some debate about what counts and what doesn’t count. But for the sake of this podcast, we’re going to assume a simple definition of plastic that comes down to two things. The first and the more obvious one is that it has plasticity. When it’s soft, you can stretch it and shape it and mold it. Sound right?
David: Got it.
Gina: The second one is that it is a polymer. Now, our chemists in the audience will surely know this already—
David: Ah ha.
Gina: —but basically, a polymer is a compound made up of repeating units, which are called monomers. You can think of it kind of like links on a chain. Take polystyrene, for instance. That’s just a bunch of styrene molecules bonded together.
David: Right. Poly, styrene.
Gina: Exactly. Now, while some PFAS chemicals could have those properties, they don’t necessarily. It doesn’t define them.
David: And if you want to know more about how PFAS are defined, definitely go back and check out our PFAS episode, two episodes ago.
Gina: Right. So, to explain where microplastics came from, we first need to understand where plastics came from.
David: You know, I think I can actually help out with that.
Gina: Oh, I thought the first inflection point was something to do with billiards and—
David: Yeah.
Gina: —elephant extinction?
David: Exactly. OK, great. So we are on the same page.
[Inflection point sound effect: digital blips and tape-rewinding whir]
Gina: Well, I don’t know if we’re on the same page—
[Dramatic music]
David: Imagine this. Before the invention of plastic, if you wanted a material that was strong, weather resistant, and easy to carve into different shapes—
Gina: Yeah?
David: —you would need to kill an elephant or a tortoise.
Gina: [Sarcastically.] Oh, OK. Cool.
David: Ivory and tortoise shell have been used since ancient times to make combs, buttons, and even as a substitute for glass in lamps.
Gina: And in billiard balls.
David: And billiard balls, yes. The most common billiard game is pool, which uses 15 balls plus a cue ball. And these balls are pretty big as far as stuff made from ivory goes. So they used a lot of ivory.
Gina: Sure.
David: Billiards was growing in popularity with the wealthy, and there was increasing concern about how aggressively elephants were being hunted for their tusks.
Gina: So people were worried they would go extinct?
David: Exactly. This was a real concern at the time. However, early plastics did exist. A man named Alexander Parkes is sometimes credited as the original inventor of plastic. His creation, which he called Parkesine, was made by mixing cellulose nitrate with some solvents and oils. He displayed the material at the London International Exhibition of Industry and Art in 1862, and a guide to that event states that Parkesine was, quote, “a substance, hard as horn, but as flexible as leather, capable of being cast or stamped, painted, dyed or carved.” However, he was unable to scale up his production without sacrificing quality, so his Parkesine company folded.
Gina: Oh, that’s a bummer. So, what, the billiards guy copied his idea?
David: That would be kind of an uncharitable take.
Gina: OK.
David: Evidently, the plastic that Parkes had created wasn’t suitable, since in 1863, a year after he displayed his plastic in London, a New York billiard ball manufacturer offered $10,000 to the person who could create a useful substitute for ivory. And it wasn’t until 1869 that someone came along with something that worked.
Gina: So this New York big shot issues forth—
David: Yeah.
Gina: —a challenge like—
David: Mmm-hmm.
Gina: Somebody come up with a really good pool ball?
David: He just shouts it, shouts it out to the world. Says, 10 grand for anyone who can figure out how to make a pool ball.
Gina: OK. And it took 6 years for someone to come up with something good enough?
David: [Laughs.] Six years. Finally someone shows up, and his name was John Wesley Hyatt, a young printer from Albany, New York. And he wasn’t alone. His brother Isaiah also helped him out. They invented a new type of plastic and founded the Celluloid Manufacturing Company. Gina, any idea what kind of plastic they came up with?
Gina: Well, and, you know, this is just a wild guess, but celluloid?
David: Nailed it. Yeah, you’re good. Yeah, it was celluloid. It not only worked as a great ivory substitute in billiard balls, but it could also be made consistently and on a large scale.
Gina: Interesting. So what was their process?
David: They applied heat and pressure to a mix of cellulose nitrate and camphor. So it was plastic made with natural materials. Nevertheless, it shares a similar durability to the first fully synthetic plastic that came out about 40 years later, Bakelite. The fact that these billiard balls could be mass-produced signals the first rumblings of a plastic revolution to come, and some of those original balls are still around.
Gina: Celluloid sounds really familiar. It’s used in film, right?
David: Yeah, they used to make film reels out of celluloid. It’s extremely flammable. Entire movies have been lost to time after being burned up in the early days of cinema. Nowadays, most films are digital, but if they are shot on film film, they’re made from a different, less flammable plastic.
Gina: And plastic has allowed us to innovate in many ways beyond pool balls and movies. It stores food, it’s in medical equipment, it’s in electronics. It’s pretty much ubiquitous.
David: Totally. But back to microplastics.
Gina: Mmm-hmm.
David: I’m guessing most microplastics start out as macroplastics, right? Just big pieces of plastic that wear down into little pieces of plastic over time?
Gina: Often, yes. Plastics that are exposed to nature can break down in a lot of different ways, often from the churning of the ocean or from the sun’s UV [ultraviolet] light. But they can also be manufactured in tiny pieces on purpose.
David: Aw.
Gina: Like microbeads. Have you heard of those?
David: Yeah.
Gina: They’re little pieces of plastic that can be added onto personal care products so that they can be used as exfoliants. They are now banned in cosmetics in the US, though.
David: Mm, yeah. I remember these exfoliating microbeads from skin-care stuff from when I was in high school.
Gina: Mmm-hmm.
David: It did not make my skin look good at all.
Gina: Oh no.
David: Yeah.
Gina: Well, you know, like you’re a teenager, you’re desperate. You’re like, I’ll try anything. [Laughs.]
David: [Laughs.] I was trying anything. Yeah. I’d sell my right arm just so I could have some clear skin. And of course, they took advantage of me.
Gina: That’s how they get you. But hey, you live and you learn.
[Musical break]
David: I have the same question that I had about PFAS in our earlier episode. I get that plastics, and therefore microplastics, can take a long time to break down, and I don’t want that junk in my body. So how is it getting in there anyway?
Gina: Well, we know that there are multiple ways to get exposed to microplastics. We can drink them, eat them—
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David: [Sighs heavily.]
Gina: —and even breathe them in the air.
David: Breathe them in the air? Like—
Gina: Yeah.
David: —even now? Right now?
Gina: Yeah, probably right now. I mean, there’s probably some floating around and—
David: [Takes a large inhale of air.]
Gina: Oh no, David, I don’t think you can hold your breath long enough to make a difference.
David: [Strained] Oh, I think I can.
Gina: Oh no.
David: [Still strained] By the way, is it OK if I do the rest of the podcast sounding like this?
Gina: OK, I think I’m just going to continue. So the World Health Organization [WHO] says—
David: [Exhales.]
Gina: Oh, there he goes.
David: OK, I give up. I’m Team Plastic now. I don’t care.
Gina: Yeah, it comes for all of us.
David: More plastic the merrier, I say.
Gina: [Laughs.] Anyway, like I was saying, according to the WHO, quote, “the available data are insufficient to determine whether exposure to [nano- and microplastic particles] is associated with any direct or indirect characteristic pathology.”
David: Mmm.
Gina: Basically, we don’t know enough yet to draw a lot of definitive conclusions about health impacts.
David: [Disappointed] Oh.
Gina: But there are a lot of concerns. For starters, as we talked about, plastics aren’t just one chemical, they’re a bunch.
David: Mmm.
Gina: Some of these may have more serious health effects than other ones.
David: [Huffs sarcastically.] Super.
Gina: And even if the plastic isn’t that dangerous, it may be a vehicle for something that is.
David: OK. I’m afraid to ask. Like what?
Gina: Well, like pathogens, maybe.
David: Oh, boy.
Gina: Or PFAS.
David: Wow.
Gina: It’s common for plastic to be coated with PFAS.
David: [Sarcastically] Very, very cool. My two favorite things together at last.
Well, at least I can take refuge in the idea that plastics are too big, of course, to cross the blood-brain barrier. They couldn’t possibly get in my brain. [Laughs.]
Gina: Oh no.
David: Yes?
Gina: Well—
David: [Shouts from a distance] Tell me some good news, Gina!
Gina: [Laughs.] OK.
Unfortunately, we have found micro- and nanoplastics in the brains of people who have died. And in a recent study, researchers found a higher concentration of micro- and nanoplastics in the brains of people who had been diagnosed with dementia than people who hadn’t.
David: [Sighs heavily.] OK.
Gina: Yeah.
David: Do you think that maybe for once we could do a happy podcast episode with zero existential dread?
Gina: Maybe next season?
David: Mmm. OK, great. All right, let’s start brainstorming now. I was thinking next season we do an episode on Hawaii.
Gina: I like Hawaii.
David: Or ice cream?
Gina: Ooh, ice cream would be good.
David: Could we do an episode on a warm breeze brushing my face as I gaze with appreciation towards the kaleidoscopic majesty of the sunset?
Gina: Uh, tell you what, if you can find three inflection points for the kaleidoscopic majesty of the sunset—
David: Sun, shade, and sand.
Gina: [Laughs.] Let’s circle back.
David: There’s a lot to dig in there.
Gina: Those are really some really good ideas for sure.
David: Yeah, that’s a start. I’m just spitballing. So—
Gina: Back to the present here.
David: Yeah.
Gina: I hate to depress you more. I can tell that you’re feeling a little bit low.
David: OK, I don’t know if it’s possible to be more depressed.
Gina: Oh, I know.
David: But continue.
Gina: It’s not actually just humans that we’re worried about with microplastics.
David: I am aware.
Gina: You know this?
David: Yeah. Gina, do you remember that non sequitur at the beginning of the episode, about plankton?
Gina: Yeah, you mean your inflection points, like what the whole show is about?
David: Right, right, right, right. Inflection points. Sorry, yeah, I think I have too much, too much plastic in my brain, plastic on the brain. Anyway. [Clears throat.]
Gina: Dark.
David: Let’s journey back to 1965.
[Inflection point sound effect: digital blips and rewinding whir]
David: So back me up here. The history of microplastic pollution and regular old plastic pollution, they’re tied together, right?
Gina: Sure, broadly speaking.
David: So I kind of wanted to find out what’s the first plastic pollution on record. I think that, you know, if we try to track down the first microplastic—
Gina: That sounds like it might take a while.
David: Like trying to find a needle in a haystack, but the haystack is the size of all the world’s oceans combined, and the needle is 100 times smaller than the average needle.
Gina: You know, nobody said this podcast would be easy, David.
David: Tell me about it. Now, no doubt plastics have been littering our world since the day they were invented all those years ago, even back to that first plastic pool ball. But it would surprise you to find out how recently we became aware of this problem.
Gina: Well, I’m guessing 1965, the year you mentioned, like, 30 seconds ago.
David: You are on a roll today. Wow.
Gina: [Laughs.] Well.
David: In 1965, the first documented piece of plastic in the ocean was found by a device called a continuous plankton recorder. Since 1931, the UK’s Marine Biological Association has towed these devices behind ships to, well, you know, continuously record plankton.
Gina: The continuous plankton recorders continuously record plankton. Brilliant.
David: Yeah. Well, you know, it turns out that plankton are really good indicators of ocean health. They’re sensitive to temperature and pH balance, and they don’t live very long, so population turnover is high.
Gina: Hmm.
David: So by monitoring them, you get a really up-to-date picture of what’s going on in our oceans.
Gina: Sure.
David: The devices collect plankton along the journey, and when they arrive, someone opens up the device, looks inside to see what’s going on. And since the day they started doing this in 1931, they’ve written down everything they find in those recorders. Even trash.
Gina: So kind of incidentally, they have a great record of ocean pollution through the decades?
David: Precisely. So in 1957, there’s a note of finding a fishing line, but the record didn’t specify what the line was made out of. It could have been plastic; it could have been some natural fiber. However, in 1965, they recorded irrefutable proof that plastic was out there swimming around in the oceans. A plastic shopping bag had snagged itself on the device somewhere near Ireland. That bag was the first harbinger of a never-ending and colossal tsunami of plastic trash to come.
Gina: Wow, that’s very sobering. So when do microplastics start entering this conversation?
David: So about 40 years after this plastic bag was found, in 2004, a professor named Richard Thompson was taking samples from a beach near Plymouth, England. He found little, tiny bits of plastic in those samples, and he was the person who came up with the name microplastics.
Gina: And now about 20 years after that, just like those little pieces of plastic, this word is inescapable. The term microplastics is just part of our vocabulary now.
[Musical break]
Gina: So that’s quite dark, but there are reasons to be hopeful.
David: [Groans.]
Gina: You OK, David?
David: [More groaning.]
Gina: What’s going on?
David: [Mumbles] Forget it.
Gina: Sorry, David, are you still with us here?
David: [Grumbles inaudibly.]
Gina: This is bad. I’ve seen this once before. Listener—
David: [Sighs.]
Gina: —I believe David is experiencing what we in the scientific community call being really bummed out by forces outside your control.
David: [exaggerated sigh]
Gina: Hold on, David. I know just the person to call for help.
Bri Barbu: [Facetime sound] Hello, this is Bri Barbu, a reporter covering all kinds of organic chemistry, polymer chemistry, and green chemistry for C&EN.
Gina: Hey, Bri, yeah. David’s a little down in the dumps about microplastics. We were just doing the podcast talking about it, and I think it just kind of started to get to him. Bad case of existential dread.
Bri: Ooh, yeah, I’ve been there, many times. What’s he doing?
Gina: He’s currently staring at the middle distance, just at nothing in particular.
Bri: That sounds pretty serious.
Gina: I thought it might make him feel better to know more about the solutions people are working on. Think you can help us out?
Bri: Sure. Maybe it’ll help David to learn about a topic I covered last year: biodegradable plastics.
Gina: Awesome. Yeah, no, I think that’ll be great. OK, when you say biodegradable, what does that really mean?
Bri: Ah, well, in the simplest possible terms, it just means that the plastic can be completely disassembled and metabolized by microbes into carbon dioxide, biomass, and depending on the conditions, water or methane. And for a plastic to be biodegradable, its monomers have to be linked together by chemical bonds that are easy to break by things found in nature, like water or enzymes. A lot of biodegradable plastics are made from biobased monomers, but there are some that are made from petrochemical feedstocks. Sort of important to note that just because a plastic is biobased does not mean it will biodegrade.
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Gina: But, OK, so biodegradable plastics still make microplastics, right?
Bri: That is true. To break all of those bonds, to go from, you know, your long polymer chain to something that microbes can get their little chomping enzymes into, they kind of have to become microplastics. They have to go through that stage. That’s not necessarily all bad, because they will still eventually degrade after that point.
Gina: Sure, and conditions probably matter too, right? Depending on the plastic?
Bri: Conditions matter a lot. I don’t think it’ll be a surprise to a lot of our chemist listeners that reaction rates depend on a lot of factors: temperature, what kind of microbes are around, pH. It’s important that you match the material that you’re degrading with the ideal conditions for biodegradation so that you actually get it broken down in a reasonable amount of time. PLA—polylactic acid—should go to a commercial composting facility, but polyhydroxyalkanoates—PHAs—don’t necessarily need those specialized conditions.
Gina: How does the use matter? You know, what should be a candidate for biodegradable plastics?
Bri: These are things that will, like, inevitably shed plastic into the environment as a course of their normal use. Take shoes, for example. The shoe soles are bound to lose plastics from wear and tear, so those might as well be biodegradable, according to one of the companies that I wrote about. Or fishing lines, which are pretty easy to lose in the ocean, probably a good choice to be biodegradable.
Gina: Right, so if it’s going to go into the environment anyway, and it’s not something that you can really replace with a nonplastic, that’s a good candidate for making it biodegradable. And could help in some way with plastic pollution.
Bri: We want to be removing plastic from the world faster than we create it. If we create plastic faster than we can recycle or degrade it, then we’re still adding to the net amount of plastics in the world, and that includes the net amount of microplastics in the world. It’s really important to mitigate the problem and move away from single-use plastics. But if we use them thoughtfully, biodegradable plastics can offer us a little glimmer of hope.
[Musical break]
David: [Exclaims.]
Gina: David, oh, are you back?
David: Did someone say biodegradable plastics?
Gina: Yeah, like 100 times we said that.
David: Oh, wow. Um, and is that Bri on the line? What is she doing here?
Bri: Hi, David!
Gina: [Laughs.] Bri, thank you so much for your help. I think David is back to, you know, his version of normal for now.
Bri: Yeah, you bet. See you!
Gina: Bye, Bri.
David: Later! Hey, you know, she’s really nice. We should have her come on the show sometime, like as a guest.
Gina: OK. You mentioned something about biodegradable plastics. I’m guessing this is the third inflection point, although I fail to see how this is connected to a married couple cooking corn.
David: OK, well, I will explain. First, let’s go back to 1989.
[Inflection pointsound effect: digital blips and tape-rewinding whir]
David: So, like Bri mentioned, biodegradable plastics aren’t a silver bullet, but they may be a small step of many in the right direction. One of those plastics she mentioned is called polylactic acid, or PLA.
Gina: And sure, PLA is compostable, but it requires special conditions to break down in a reasonable amount of time. Rather than just putting it in your compost bin, you have to take it to an industrial composting facility.
David: Right.
Gina: But wait a minute, you said 1989 right? I thought PLA was discovered way before 1989.
David: Right. Polylactic acid wasn’t discovered in 1989; it was actually first synthesized by a chemist named Wallace Carothers in 1932. But, at the time, it was incredibly expensive to make, at least compared to other plastics. So for more than 50 years, PLA only serves niche purposes.
Gina: Then a couple started cooking corn in their kitchen, and that—
David: Bingo.
Gina: —changed everything?
David: Are you reading ahead or something? How do you know what’s about to happen in the show?
Gina: Well, you said it. You said those exact words.
David: Right, the inflection point. The cooking the corn. Exactly. OK, so in 1989, a pair of chemists, a husband and wife, Patrick and Sally Gruber, thought they could find a way of making PLA on the cheap. They used corn to synthesize it together. They found a way to use their kitchen stove to transform corn kernels into PLA. The basic process we use nowadays is to start with starch, convert it into sugar, and then ferment it to produce lactic acid. We convert that into lactide and then polymerize it into PLA.
Gina: So by using corn to create the plastic, they could reduce the price, right? Since corn is so abundant?
David: Yeah. Before the Grubers came along, it cost $200 to make a single pound of PLA. Nowadays, it’s less than a buck.
Gina: OK. I’m relieved and a little bit surprised to find that the cooking corn inflection point made sense.
David: Well.
Gina: And it’s a—it’s nice to have you, you know, back to being sentient again.
David: Yeah. I mean, I do feel a little bit better. Reading off an inflection point always cheers me up.
Gina: Yeah.
David: But I also feel a little powerless still as well.
Gina: OK.
David: It seems like microplastics are unavoidable and we’re just waiting for these giant policy changes or remediation methods to pan out.
Gina: Look, it is overwhelming. And hopefully science and research will give us some more answers soon. But in the meantime, there are certain things you can do to lower your own exposure on an individual level. For instance, you can drink tap water instead of bottled water. You could also ditch your plastic cutting boards.
David: You know, I actually do most of those things.
Gina: OK!
David: But what about the breathing in of plastics?
Gina: Yeah, well, it can help to vacuum more.
David: OK.
Gina: And, you know, maybe surprisingly even to wash your clothes a little less often, so they have fewer opportunities to shed microplastics.
David: Guess that makes sense. I could probably do those things or, you know.
Gina: Or—or what?
David: I could find some remote hillside where microplastics have somehow, improbably, never reached, and I could just go herd goats.
Gina: You know, honestly, David, I’m not sure there’s anywhere you could even go that hasn’t been touched by plastics. I mean—
David: I could probably go to the moon—
Gina: —even the moon has plastic on it, you know that, right?
David: The moon?
Gina: Well, yeah, like you weren’t really going to move to the moon. We need Wi-Fi to upload the podcast episodes.
David: You know, that’s true. And Gina, I hope I’m not spoiling anything here, but—
Gina: OK.
David: —you and I are already hard at work on season 2 of Inflection Point.
Gina: That’s right, and we better pick up the pace. The next season is coming out later this year.
David: Jeez, you’re right. I still need to figure out the inflection points for ice cream and Hawaii.
Gina: And the kaleidoscopic majesty of the sunset?
David: Oh, of course, yeah. How could I forget?
Gina: And listeners, if you are excited to find out the real topics that we’ll be covering next season, make sure you’re subscribed to Inflection Point on the podcast platform of your choice.
David: We’ll be updating that feed soon with information about season 2, so stay tuned.
Gina: Thanks for listening.
Gina: Inflection Point is a podcast project from Chemical & Engineering News.
David: Chemical & Engineering News is the official news outlet of the American Chemical Society.
Gina: Music by Kirk Ohnstad and Shutterstock.
David: Written, produced, and hosted by Gina Vitale and David Anderson.