Jess visits the Natural History Museum of Los Angeles County to unearth efforts by Dr. Aaron Celestian and his team to use a groundbreaking new mineral-based method to clean up lead contamination in L.A. backyards.
Transcript
That ABC News clip is a little more than 30 years old. While leaded gasoline at the average gas pump is long gone, and lead-based paints are no longer standard in homes, lead itself is an enduring hazard to millions of people around the world.
In 2014, Flint Michigan shot into public consciousness after the city switched water sources for cost-savings. Water pipes corroded, and lead (along with bacteria) leached into the water supply for tens of thousands of people.
Lead poisoning can cause intellectual functioning to decrease, can harm physical and mental health, and can increase the chance of Alzheimer’s disease. Lead isn’t just a problem for communities with old pipes, however. Lead from a variety of sources is present right now in backyards just a few miles from where I host this show, in Los Angeles. It’s actively harming people every single day.
The good news, however, is that a team of scientists, artists, and community residents have found a scientific solution to dangerous backyard lead contamination.
I’m your host Jess Phoenix, and this is science.
Jess: I'm coming to you from the incredibly cool vault room deep inside the Gem and Mineral Hall at the Natural History Museum of Los Angeles County. Yes, there's an actual vault over there. Welcoming me to his domain is Dr. Aaron Celestian, who is the curator of mineral sciences for the museum. So if you want to see a massive chunk of gold or peer really cautiously at radioactive rocks, Aaron's your guy. And while I'm always up for staring at rocks, Aaron and the NHMLA team have been working on unlocking the superpowers hidden inside certain minerals to help clean up decades-old contamination right here in Los Angeles. And, Aaron, thank you so much for having me. And then I'd like to dive right in. So what is the Prospering Backyards project, and how did it come about?
Dr. Celestian: The Prospering Backyards project came about with a PST 2024, the Pacific Standard Time art project, and that is hosted by the Getty about every four years. And they have a theme every single year, and this theme is art and science collide. And so that's where this really kind of kicked off. And so the artist who came into the museum on a tour was looking at the minerals, was looking at some of the work that I did. And she was like...this is Maru García. She was like, "Oh, my gosh, Aaron, we need to work together on this project." I was like, "All right, what project are you talking about?" She's like, "We want to do a project where we can clean up or find ways of cleaning up lead and contaminated soils." So I was like, "Great. How can we do that?" And that's when it really kind of started off. So that's where Prospering Backyards came from. Prospering Backyards' PB is the elemental symbol for lead. And so we're trying to put it like a new spin on what lead contamination, what lead sequestration is like.
Jess: I love that the genesis for this came out of art. There's still a divide in a lot of people's minds between art and science, and there really shouldn't be. So this kind of underscores the fact that you actually need art to interpret the meaning of science a lot of times.
Dr. Celestian: And that was a big part of it. And you're exactly right, Jess. That was a big part of why this project has been so successful so far, is because it's art forward. It's communicating the science through art, is communicating with the community through art. And that's much more approachable to the vast majority of people than, like, scientific papers.
Jess: Or the periodic table, which how many casual folks who aren't scientists know that PB is a symbol for lead.
Dr. Celestian: Exactly.
Jess: But very clever naming of the project, I have to say. So give me the details, right? Like, we've heard that lead paint is bad, and lead pipes are slowly going the way of the dinosaur and being replaced slowly but surely around a lot of the country. So how did all of this lead end up in backyards in Los Angeles?
Dr. Celestian: There's a couple ways that it happened. There's lead all over Los Angeles. It's not just in the zone that we were really focusing on. The lead comes from relic leaded gasoline. That was a big problem, and it still is a problem. It's still in the soil, doesn't really go away. There is leaded jet fuel that small jets can still use and burn. There is paint, of course. Like, there's a lot of automotive paint facilities here in Los Angeles, and those went out of business. And there's also lead acid battery recycling facilities.
Jess: Okay, okay. So tell me a little bit about Exide Industries and their role in this contamination.
Dr. Celestian: Yeah, that was the catalyst for the project, was looking at this really large contamination problem that had been happening since the '80s. And the issue is during the lead recycling process, some of the lead escapes the facility, and it ends up in the soil, ends up in the air. And that is the part that started this whole conversation of, like, "How do we get lead out of the soil? How do we stop it from being biologically active?"
Jess: And that's a big one.
Dr. Celestian: Exactly. So this definitely goes well beyond Exide. This is an issue that a lot of Americans deal with within this country, is there's lead all over the place. And there's no safe levels of lead either. So how do we try to mitigate some of the side effects?
Jess: Perfect segue into what I was going to ask you next, what are some of the real measurable effects when lead is contaminating the soil or the water?
Dr. Celestian: Some of the measurable effects are biological. One of them is that you get a change in biodiversity within the soil itself. So that's part of the project as well. We're not just looking at how to lock up the lead, but we're looking at the biodiversity before treatments and biodiversity after treatments, looking at plant physiology. We have a whole bunch of people on the project that are doing this. So we're looking not only at what happens to the soil itself but what happens to the things that are living in the soil. And is it getting better? Is it getting worse? Those kinds of things. So that's what it looks like. And in the end, we're hoping that we can just lock up the contaminants and not make them mobile anymore.
Jess: Tell us a little bit about what kind of households have been affected by this particular soil contamination that Prospering Backyards is trying to address. So this doesn't seem to have occurred in Beverly Hills.
Dr. Celestian: It did not occur in Beverly Hills. That is correct. This occurred in an industrialized part of Los Angeles, where a lot of people of low income tend to reside. And that is an issue of a source. There's this income inequality gaps and the social justice kind of things that go along with that as well. And, unfortunately, some of the highest levels of lead are in these kinds of neighborhoods. Kind of, like, the minimum or the maximum EPA limit is about...it's in the 100 ppm range. And we were measuring lead almost 10 times that in some of these yards, so...
Jess: Wow, so you're saying like 1,000 parts per million of lead?
Dr. Celestian: Easily.
Jess: For the folks who couldn't see my facial expression who are just listening to the audio, actually, my jaw dropped.
Dr. Celestian: Yeah, some of them are very, very high. Jess: And you mentioned earlier, and I just want to underscore that there is no safe level for lead to be found.
Dr. Celestian: That is correct.
Jess: Zero. Zero is safe.
Dr. Celestian: Zero is safe.
Jess: But above that, not safe.
Dr. Celestian: Correct.
Jess: Great. So don't eat lead, which also means that we need to keep it out of our soils and our water supply. So...
Dr. Celestian: That's right.
Jess: Now, my favorite stuff to get into, I want to talk about the science, all right?
Dr. Celestian: All right, let's do it.
Jess: So how does sequestering lead with zeolite crystals actually work? Like, how does it trap it and then entomb it and keep it from causing problems?
Dr. Celestian: That is a great question. I'm glad you brought it up, because that's my favorite question.
Jess: I had to ask you something that you really liked.
Dr. Celestian: So zeolite, the word zeolite means boiling rock. And when you heat up a zeolite, water just oozes out of it. And the reverse process happens as well. As the zeolite cools down, it will reabsorb the water. So on a molecular scale, it's kind of like a sponge. But unlike a sponge, sponges can absorb anything, right? You could stick it in red dye, blue dye, it doesn't even matter. But zeolites are very selective to what it wants to absorb. So it won't just select every element to absorb it. It only will absorb the ones that can fit in the pores of the sponge-like material.
Jess: So this relates to the actual structure of the mineral itself.
Dr. Celestian: Exactly. And so we've had to find a zeolite. Then there's a bunch of different kinds of them. It's like a whole family that is like 65 different minerals belong to the zeolite family. We had to find the right one that would just pick up lead and leave everything else alone, because lead was the only thing that we wanted to treat. We didn't want to absorb calcium and ammonium, things that are helpful for plants and animals. We wanted just to get the toxic stuff out. So we spent about a year trying to find the right zeolite that would work.
Jess: So how did you know, though, that that particular variety of zeolite could actually entomb the lead?
Dr. Celestian: So I kind of...this is from a previous experience. So when I was a graduate student in New York, my task, my project was to try to find ways of absorbing uranium species out of the groundwater because of nuclear waste issues, and it turned out that failed miserably. Like, the zeolites won't pick up the uranium, but I kept finding lead being absorbed into the zeolite all the time, and I couldn't figure out why. My uranium source had no lead in it, no measurable lead. The zeolite itself didn't have any lead in it. I was trying to figure out where is this lead coming from. Every time I do the experiment, it just keeps absorbing lead. And I found out that it was the water supply that I was using was leaded.
Jess: Oh, my God.
Dr. Celestian: So it was supposed to be deionized water, which means it has no ions in it whatsoever. But because of the solder that was in the pipes that held it together, this is the solder that was leaching out and bringing lead into the system. And the zeolites were so good at just absorbing just that trace amount that it just sucked it out of the ground. So I knew it would work by accident.
Jess: Well, that's pretty fascinating. So, you know, uranium aside, you figured out how to get another really dangerous contaminant out of, well, in that case, water. So you were able to port that, that same ability that zeolite has, onto soils.
Dr. Celestian: Right. And that's how the zeolite works, is that it has to have water. So that's the only criteria. So you just put it on the ground, and the zeolite won't work until you water it. So during the raining season, it's great. There's tons of natural water, and it just does its job completely spontaneously.
Jess: Okay. And so let's say you have a backyard with...you know, you don't have to give me specific numbers, but like a moderate amount of lead contamination in the soil. How many treatments with zeolite would that require to remove all of the lead or can it remove all of the lead?
Dr. Celestian: Yeah, that was a great question. And we didn't know the answer to that at the beginning of the project. So that was the real kind of the crux of the question. Like, how much will this zeolite absorb? Will it work in the natural environment or the backyards versus the lab? And how much water? How long does it take? Those are all unknowns at the time. And I guess it depends, because we found out that a lot of the lead in the soil is not bioavailable, meaning that even if we interacted with it, the lead wouldn't come into our system. A lot of the lead is just locked up in complex chemicals, and even if it gets into your stomach, your stomach won't process it, and it'll just pass through your kidneys, and that'll be the end of it. So about 30%, approximately about 30% of all the lead that we found in the soil is bioavailable. So if it was 1,000 ppm, that would mean about 300 ppm of it would be bioavailable, which is very high.
Jess: It's still bad.
Dr. Celestian: It's still terrible.
Jess: You don't want that.
Dr. Celestian: So we didn't try to, like, lowball it. We wanted to highball it. We wanted to put enough zeolite in it to make sure that the soil would work. We did a treatment. All we did was just spread the zeolite on the ground, water it right away so it so it percolates into the soil. And then we would stay with the household for a year, and we would monitor it constantly. Every month we would take soil samples and analyze the soil, look for the zeolite, do bioavailability tests, do DNA, environmental DNA testing and all that. And it works. It works quite well. If there was 300 ppm in it, it would bring it down to about 5 ppm, and that happened within the first month.
Jess: That is dramatic.
Dr. Celestian: It's huge.
Jess: Okay, so this is highly effective, at least from what you guys have been able to produce out in the actual world. And so that's pretty exciting. But I want to know if you can give us a picture of what actual, like, on-site remediation looks like, because, obviously, this isn't a giant superfund site. You know, you don't have dump trucks going into people's backyards. So how do you remediate someone's backyard?
Dr. Celestian: I don't think we can classify it as a remediation process. Remediation, I think that's more of like an EPA-defined kind of thing, Environmental Protection Agency, where you're taking the soil away and you're doing something with that, bringing in clean soil. We're leaving this in place.
Jess: That's really less disruptive.
Dr. Celestian: Yes, it's much less disruptive. And you can get every single nook and cranny with this powdered mineral. So the mineral itself is a powder, and we just dust it onto the soil and water it. So after we've done our work, it looks no different.
Jess: That is so funny because it's very high-tech, you know, very clever use of this mineral. And yet the application is like, oh, just make sure it's a powder and spray some water on it and wait a month. Wow.
Dr. Celestian: In the process of doing this, we also found that not all species of the zeolite worked. So this particular species is clinoptilolite. And if we get clinoptilolite from one mine, it may have too much calcium in it, and it won't absorb the lead. We had to find one that had only sodium in it, and when it was just in that form, that's when it would work. Otherwise, it wouldn't work. So not even every version of clinoptilolite would work. We didn't know that going into the project. Yeah.
Jess: That is, you know, trial and error. I think that's part of science, right? It's an iterative process. And so tell me a little bit about how we find zeolite. How much of it is there? I mean, it sounds like right now people obviously are interested in it as a potential solution here for lead contamination. But is this a rare mineral? Is this easy to find?
Dr. Celestian: This is super easy to find. So the mine that I paired up with on this was really interested in the project, and they are the ones that supplied all the zeolite. They are ZeoSource, I believe, is the name of the company, and they're in the Mojave Desert here in Southern California. And it's plenty available. Like, they just take a backhoe, scoop it off the ground. It's really close to the surface of the soil. So there's not much overburden mining issues associated with classic types of mining. Most zeolites are found near the surface. So it makes it easy, easy pickings.
Jess: That's really encouraging, actually.
Dr. Celestian: There's a lot of it, too.
Jess: Tell us some of the other places that we may have encountered zeolite without knowing it in our day-to-day lives.
Dr. Celestian: Oh, my gosh. There's so much uses for zeolite. Zeolite is used in detergents. So if you use a powder detergent, you use a particular kind of zeolite to absorb the calcium out of the water, and that makes the soap work better, makes the detergents work better. They feed zeolites to cattle to kill pathogenic bacteria. They do the same thing for chickens to absorb ammonium out of chicken feces so it doesn't get into the groundwater. Zeolites had been used in the military to clean up wounds as well because they're highly absorbing of water. So that was used for it. And one of probably the biggest money-making uses of zeolites is in catalysis. So the oil refineries use zeolites to break apart really crude oil into gasoline, and zeolite is a big part of that process.
Jess: Okay, so just an all-around generally useful mineral.
Dr. Celestian: You're exposed to it even if you don't know it. Sorry, a long explanation.
Jess: Oh, no, zeolites are lurking in your household helping you out. Okay, so that's a bit of the technical side of things. I want to know how you went about communicating with the residents in these affected areas to actually get them to allow you access to their homes and their yards and their lives, especially for a year at a time.
Dr. Celestian: That was tough. So I don't think I could have done that. I think a lot of the residents may be a little wary of scientists because scientists have been in and out of their household for so long that they probably have developed a distrust that scientists don't follow through with particular older projects. So we needed to break down those barriers. And that's where the artist part was critical. Working with Self Help Graphics, which is a local art studio and art institute that helps people get off the ground and helps them do the art that they want to do. They're very well respected in the community, and so working with them was essential. I think that was probably the only reason how we were able to get into people's backyards and work on this project, was to have local support and community support.
Jess: So was Maru García pretty instrumental in that?
Dr. Celestian: Maru García, she's the lead on the project, and she was absolutely instrumental. She's the one that came up with all the design of how to communicate science in a way that is accessible, approachable…
Jess: You know, I used to live in East Los Angeles, and I went to Cal State Los Angeles for my graduate degree, one of them. And I know those areas are heavily Spanish-speaking. And so I'm assuming that bilingual communication was really important as well.
Dr. Celestian: Yeah, it was. Especially with the older generation that were the ones that were migrating into Los Angeles, communicating with them was also a really big part because they are well respected in their community, and getting them on board took a lot of communication, a lot of trust.
Jess: I mean, it's how we need to be doing science that actually makes people's lives better. You've got to find the ways into the communities and build, rebuild in some cases, that trust. Just giving people a bunch of technical information doesn't actually speak to them on a level that is accessible.
Dr. Celestian: We had a lot of workshops where we would have them get to know soil a little bit better, get to know minerals a little bit better. We brought the community into the lab, and we had workshops here at the museum. They were also a part of the experiments as well. So they get firsthand knowledge of, like, how their soil is being treated and what we're doing with it.
Jess: Did you get any or a lot of pushback from folks in those areas? Were there some people who were just 100% resistant, like, "No, I won't let you do this"?
Dr. Celestian: I don't think there was that. I think it was the opposite. I think we had so many people that were interested in being a part of the project because of how we rolled it out. It wasn't just like, "Here we want to do this, and you want to be a part." It was a slow burn of how to get people interested in it. We have too many people to sign up for it, and we ended up just settling on 15 households. And mostly that was because of the workload. I couldn't handle more than that. Processing that many samples was tough.
Jess: So then the natural follow-on to that is what does the future of the project look like? Is there going to be additional funding to do more of this kind of work? Or what do you see coming up ahead?
Dr. Celestian: I'm still pursuing it even without funding. We don't have any more funding right now to pursue the project, but we do see it evolving into various forms. So we're trying to apply for more funding for the project and make it even bigger, make it more inclusive of L.A. community. Look at more than just lead. Look at other toxic elements that are in the soil as well. So, yeah, we definitely think it's promising. There's been people that I've been communicating with in Chicago, Chicago Safe Soils, that have taken on...that heard about us and they're using it as well. There's folks in Riverside County that are taking this on as well. And so I think it's spreading in a good way. It's spreading in a good way that this is a possible solution.
Jess: Yeah. Yeah. And, I mean, obviously, we need to use a terrible geology pun, leave no stone unturned, when it comes to pushing back against the effects of industrial contamination So, Aaron, what's been your favorite part of working on this project?
Dr. Celestian: I think my favorite part has been how I've changed my approach to doing science. I have completely changed. I used to be, like, get papers, just get those out, get grants and get that out. But, really, working with Maru, working with the community, I see there's different ways of doing science and still getting tons of stuff done but in a way that can help people, in a way that can communicate the science a little bit better, because that's what really I want to do.
Jess: That is brilliant. And I want to put that in skywriting everywhere across the world. Yeah, we have to apply what we know. Otherwise, why do we know it all? I mean, it's great to know things for the sake of knowledge. But when you can actually put that knowledge into action and improve people's lives, then by all means. What other problems do you see minerals like zeolite or maybe other minerals, what other problems can they help us solve potentially?
Dr. Celestian: Lots. I was working with AstraZeneca using zeolite and zeolitic materials to cure diseases, to cure blood diseases like hyperkalemia and things like that. That one just got FDA approval, and I helped them figure out how their mineral worked or how their compound worked. And so there's lots of really sophisticated ways that these things can be used to treat diseases or treat environmental problems or even help solve the energy crisis. So what I mean by that is I'm using a zeolitic material to absorb lithium out of the seawater. And instead of having these hard rock mines that are really kind of environmentally problematic...
Jess: Kind of?
Dr. Celestian: ...it would be great to be able to just passively absorb lithium out of the seawater. And I've been in talks with some people from the county about desalination processes and using the zeolites to also mine the water during the desalination process. And we have a material that works for it. We had to design it. In fact, it's naturally occurring, but not in great abundance. So we had to learn how to make it and then learn how it worked to absorb lithium.
Jess: Wow. And it's a zeolite? It's related to zeolites?
Dr. Celestian: It's related to zeolites. It's actually a spinel.
Jess: Oh, yeah. Our mineralogy listeners, will get that.
Dr. Celestian: But it turns out a spinel can absorb lithium and hydrogen. And the tunnels are very, very tiny, so it can't absorb anything else, but it will absorb lithium and hydrogen.
Jess: This is the stuff they didn't teach me in intro mineralogy. But this is absolutely fascinating. And, I mean, the applied side of it is the part that really gets me. And the fact that you are taking this from people's backyards just down the road from here where we're talking in central L.A. to the oceans and potentially into treating people's health issues. This is pretty cutting-edge stuff.
Dr. Celestian: Thank you.
Jess: Wow, Aaron. Like, this is awesome. I mean, huge congratulations to you and the whole team with Prosperous Backyards, because this is one of the most exciting things I've heard about in terms of, like, taking pure science and turning it into action. So super cool to talk to you about this. And I do have a last question that I ask all of my guests on "This is Science." And it's a two-parter. You're a scientist. I'm a scientist. We are the Union of Concerned Scientists. So, Aaron, why are you concerned?
Dr. Celestian: I am concerned about the environment, and I'm concerned that I'm not doing enough to try to help it. And that's why I came to the museum, was so that I could have an opportunity to interact with the community in a much more meaningful way than I could when I was a professor. That's why I'm concerned. The environment needs help. And this is one way to do it.
Jess: And because I don't want to end on a downer, we like to have a little optimism. So what are you doing about that concern? I mean, you've told us some of it, but give us more.
Dr. Celestian: My whole area of research focus now is finding ways to fix the problems that humans have affected our planet. So it could be disease, increasing diseases like climate change. It could be soil diseases like lead contamination, chromium contamination. Just whatever it takes, I think that's what I'm going for. And if papers come out of it, then so be it. But, really, at the end of the day, if it can't be used to help a problem, then I'm not interested.
Jess: That was excellent.
Dr. Celestian: All right.
Jess: So thank you so much for...
Dr. Celestian: You're going to make me cry.
Jess: No, no, I've actually had people cry when I asked them those questions. So you would not be the first.
Dr. Celestian: All right.
Jess: But, no, what you're saying is it's not publish or perish, which in academia, that's what we hear. It's more like put your research to work or people will perish. So, yeah, action. So maybe I'm going to just start calling you Action Man Aaron. But thank you so much for being on the show and for making us welcome here in this awesome space.
Dr. Celestian: You're welcome.
Jess: And I can't wait to see what else comes out of your work.
Dr. Celestian: Great. It's been great having you here, Jess. SOUND: Music (Theme)
To learn more about the Prospering Backyards project, visit prosperingbackyards.com. I’d like to thank the Natural History Museum of Los Angeles County for hosting us…we had an absolute blast! Be sure to check out our Instagram, Facebook, and TikTok (@sciencewithjess) for videos we shot behind the scenes at the museum. Rare fish, slug genitals, and mystery-solving birds…we had an amazing time learning! Thanks as always to Omari Spears for production help, and to Josie Spanier for filming on location and making our awesome videos. Get out there and science, y’all!