Adverse Reactions

Space, the Final Risk Assessment Frontier

March 10, 2022 Valerie Ryder, PhD, DABT, NASA Johnson Space Center Season 2 Episode 1
Adverse Reactions
Space, the Final Risk Assessment Frontier
Show Notes Transcript Chapter Markers

How do you set exposure limits to protect human health in a closed container floating in space? Valerie Ryder, a toxicologist at the NASA Johnson Space Center, takes co-hosts Anne Chappelle and David Faulkner into the small world of space toxicologists, where they also discuss research involving lunar dust, bone loss, and CO2.

About the Guest
Valerie Ryder, PhD, DABT, is a board-certified toxicologist with the NASA Johnson Space Center. She received a BA in chemistry with a minor in microbiology from Texas A&M University in 2000 and a PhD in pathology from the University of Alabama at Birmingham in 2004.  

As an undergraduate, Dr. Ryder worked in the oceanography department in the laboratory of Dr. Luis Cifuentes. As a graduate student, she supported the dynamically controlled protein crystal growth shuttle flight experiment on STS-105 and studied altered differentiation of adult stem cells in modeled microgravity under the NASA Graduate Student Researcher Program. 

After completing her graduate work, Dr. Ryder worked briefly as a scientific writer before joining the toxicology group at the Texas Commission on Environmental Quality in 2005. In 2008, she accepted a position as a toxicologist with Wyle’s Integrated Science and Engineering Group. In 2010, Dr. Ryder became a NASA Civil Servant and took over as the lead for the toxicology group in 2014. She leads a team of toxicologists who work to ensure that the air and water onboard spacecraft are safe for crew health.


The viewpoints and information presented in Adverse Reactions represent those of the participating individuals. Although the Society of Toxicology holds the copyright to the production, it does not vet or review the information presented, nor does presenting and distributing the Adverse Reactions podcast represent any proposal or endorsement of any position by the Society.

[00:00:00] Adverse Reactions “Decompose” Theme Music

[00:00:05] David Faulkner: Hello, and welcome to Adverse Reactions Season 2. My name is David Faulkner, and this is my co-host,

[00:00:11] Anne Chappelle: Anne Chappelle. 

[00:00:12] David Faulkner: As much fun as the first season of Adverse Reactions was, I think Season 2 is better.

[00:00:16] Anne Chappelle: Hidden.

[00:00:17] David Faulkner: Secretive.

[00:00:18] Anne Chappelle: Exactly.

[00:00:19] David Faulkner: The toxicology that happens when you’re not looking,

[00:00:22] Anne Chappelle: or toxicology that you forgot about. 

[00:00:24] David Faulkner: It’s still important, and we’re here to talk about it. Welcome to Season 2 of Adverse Reactions:

[00:00:28] Anne Chappelle: “Hidden Toxicology.”

[00:00:31] Adverse Reactions “Decompose” Theme Music

[00:00:38] David Faulkner: Valerie Ryder on risk assessment in spaaaaaace.

[00:00:43] Valerie Ryder: So, really, the important aspect is working with our engineering colleagues and making sure that we’re designing the systems and the experiments and everything appropriately so that we don’t have the exposures to begin with. 

[00:00:56] David Faulkner: Or space, the final risk assessment frontier. 

[00:00:59] Valerie Ryder: In terms of space flight toxicologists, yes, there are about 10 of us in the world, and our counterparts are in Russia. It is challenging from time to time. 

[00:01:09] Adverse Reactions “Decompose” Theme Music

[00:01:12] David Faulkner: Hello, everyone, and welcome to the Adverse Reactions podcast. I’m David Faulkner. With me is Anne Chappelle and our special guest today, Valerie Ryder from the NASA Johnson Space Center.

Thank you so much for joining us today. We’re so happy to have you on. 

[00:01:27] Valerie Ryder: Thanks. Happy to be here.

[00:01:29] David Faulkner: So, you’re the leader of the toxicology group. Can you tell us a little bit about what that entails? What does that mean? 

[00:01:35] Valerie Ryder: I have a team of six risk assessors. I like to tell folks that basically we are kind of a combined EPA and OSHA for spacecraft. So, our job is to set limits for air and water contaminants onboard spacecraft, and we receive monitoring data from various monitors that we have that are used in flight and return to the ground, and we evaluate that and provide input and feedback to the crew regarding their exposures. And then, we also set limits for those exposures. So, we, basically, my team of six people reviews every single liquid, gas, particle, and gel that is launched to or is going to a manned spacecraft.

So, we have a pretty big job. We look at thousands of chemicals every month, and we stay pretty busy and you never know what we’re going to end up facing day to day. 

So, in some ways it’s very similar to what a lot of toxicologists out there are doing day to day, and then there’s some unique aspects as well.

[00:02:44] David Faulkner: Yeah. I mean, you’re really working in some pretty extreme exposure conditions up there.

[00:02:50] Valerie Ryder: So, yes and no. I benefit from having a very healthy, adult population, right? So, I don’t have to worry about protecting children or asthmatics and those types of things that a lot of folks generally do in the general population.

At the same time, yes, microgravity is really unique. It, in and of itself, is impacting various physiological systems and changing them and modifying them, and so we have to take those things into consideration when we’re setting our limits and when we’re thinking about exposures in space. In some ways, it’s actually much easier, and in some ways, it’s more challenging.

[00:03:28] Anne Chappelle: So, what is microgravity?

[00:03:30] Valerie Ryder: Once you leave the Earth’s atmosphere, the space station, which is where we typically have people now, routinely for long periods of time—generally about six months—it’s about 200 miles off the surface of the Earth. At that location, you’re orbiting the Earth and you have some pull from the Earth, but certainly not anywhere near the level that we have here on the ground. So, we call it microgravity. It’s that weightlessness where they’re floating around and nothing’s really up or down. There is still some small amount of gravity that’s interacting with them, and certainly, they have still some interaction with the atmosphere, the outer levels of the atmosphere. And over time, if we don’t boost the space station to keep them at that altitude, it would actually come down. 

[00:04:18] David Faulkner: How does one become a space toxicologist—or if you would use that term—and does it involve culture flasks and bottle rockets? ’Cause if not, I have some purchases to return. 

[00:04:29] Valerie Ryder: So, it was a little bit of a meandering path for me. 

I knew really early on that space flight interested me. I had an uncle who worked here at Johnson as an engineer developing the simulators for the shuttle program. And so, I was exposed to it. 

In the fifth grade, I had the weekly readers at school—if any of y’all remember those—they gave them out, and it had an article that was discussing the new space station that NASA was going to build at that time, Freedom. It said that they were going to need people with PhDs in chemistry, physics, mathematics, and astronomy. And so, I decided in fifth grade that I was going to be a chemist for NASA, and I pretty much stuck with that.

I went to Texas A&M for my undergraduate and majored in chemistry. I had worked at space camp in Alabama during summers and Christmases and ended up going to the University of Alabama at Birmingham for graduate school. There, I started out in a graduate program in molecular and cellular pathology and initially worked for someone who had flown as a mission specialist who developed protein crystal growth experiments in space, and I had an opportunity to go down with that team to load experiments and put them on the space shuttle. And we got to do a tour of the actual shuttle on the launchpad, which was one of the best days of my life. I was bouncing around like a kid in a candy shop.

[00:06:11] Anne Chappelle: I believe it.

[00:06:11] Valerie Ryder: And so, I had just lots of amazing opportunities, but unfortunately, the Columbia disaster happened right about the time I was finishing graduate school and NASA was not hiring because we weren’t flying and we didn’t have science opportunities. 

I got out of graduate school and needed to eat. For a short period of time, I worked as a scientific writer, and while I was doing that work, I was contacted by the Texas Commission on Environmental Quality. And they said, “You have the experience in chemistry, and you have the experience in pathology, and so even though you didn’t learn toxicology per se, you have the background that’s necessary and we can teach you risk assessment on the job. Would you be interested?”

And I said, “Heck, yeah.” And so, I got to work for them for a couple of years, but they also were fully aware of my passion for NASA and space flight. And it turns out that one of the people who had previously been a part of that team with the state environmental agency had gone to work for the toxicology group at NASA.

And so, at SOT actually, my supervisor at TCEQ introduced me to him, and I said, “Oh, my gosh, I really want to work for NASA. If you ever have a position open up, please let me know.”

He did. I applied, and the rest is history. So, it was not what I initially had planned or necessarily trained to do, but it definitely worked out.

And I was very fortunate to be brought onto a team that is highly satisfied with their working conditions. We actually don’t hire very often, and I know that that ends up being very disappointing to students out there who are interested in doing something similar. We have a pretty small group of folks, and we are fortunate that they really like their jobs and they stick around. So, I’ve been at NASA since 2008, and I am still one of the newbies. Most of my team has been there for 25 years or more. 

[00:08:16] Anne Chappelle: How awesome that you physically were so close to Houston growing up and having those opportunities? 

[00:08:23] Valerie Ryder: Well, so, I think I was actually fortunate that I had a family member here in Houston who was working for NASA because I actually grew up in a very small town, about 90 miles outside of Houston. My career path and choice was a bit unusual for the area, and so, I feel very fortunate that I had that additional exposure. But I think you’re a hundred percent correct that, especially in this very local area, that kids get exposed to STEM every day, and it really is important.

[00:08:54] David Faulkner: When I hear your story, it sounds like you had a fairly sensible path to get to where you are.

I was looking at some of the work you did on microgravity and stem cell growth, and you could think of that as an exposure trying to characterize what happens in these microgravity environments. Could you expand a little bit more about proteins in spaaaaaace and stem cells in spaaaaaace?

[00:09:17] Anne Chappelle: He’s been dying to say that.

[00:09:21] David Faulkner: Yeah, it’s been hard. It’s been hard to restrain myself this so far this interview, but . . .

[00:09:26] Valerie Ryder: What I studied during my graduate work was also NASA focused and NASA supported. I had a graduate fellowship that actually allowed me to come work at JSC as well. 

So, bone loss is a really big issue that we still struggle with. Bisphosphonates and some other things have allowed us to combat it, but they have accelerated bone loss in microgravity that’s akin to what we see in post-menopausal women. Post-menopausal women tend to lose about one to two percent of their bone mass per year. Our astronauts in space—prior to some of the more recent implementation of those medications and exercise—are losing one to two percent every month that they’re in space. Now, they’re there for six months to a year maximally at this point in time, but that’s definitely a major concern. 

And so, what I looked at was the stem cell precursors, the mesenchymal stem cells to bone and muscle and fat and looked at those in a model of microgravity. And so, we have these rotating culture vessels that spin, and the cells are continually falling so it’s just like what’s happening with the space station in orbit right now—it’s continually falling around the Earth and that’s what creates the microgravity that they’re experiencing. So, we do the same thing at a culture level for these cells, and they’re just continually falling through the media.

What we saw is that despite giving them all of the things that they needed to become bone cells in a normal flat culture, they would turn into fat cells. And what was interesting is that in space, we were actually seeing an increase in the bone marrow fat content in addition to the bone loss that the astronauts were experiencing.

Our hypothesis was that the cell structure itself, the physical structure of the cell, was what was giving it an indication of what type of cell it should mature into, and because microgravity was causing them to round up, they were becoming fat cells. What we did was actually provide a constitutively active protein that allowed the actin, the skeleton within the cell, to form and to create the more flattened cell type that you would expect from a bone cell, and we were able to recover some of that phenotype and they looked more like bone.

What I didn’t realize is that some of my bone past life would come back because there are things related to bone loss and toxicology that we deal with—things like lead, where previous exposures are then stored in bone. There were some models that suggested that we might have very high levels of lead being released, especially from those crew members who are in countries that didn’t reduce lead exposures as long ago as the US has. As they were losing that bone mineral in space flight, that they could be releasing that lead into their bloodstream and causing some toxicity issues. So, we have to consider those types of things when we set limits for drinking water and et cetera. It’s been kind of interesting to see how things that I never would have thought were even closely related end up coming back around.

[00:12:38] Anne Chappelle: So, in your role at NASA, you talk a lot of SMAC, and for those listening, that is the spacecraft maximal allowable concentrations. 

[00:12:50] David Faulkner: Oh, my God.

[00:12:51] Anne Chappelle: I know; I’ve been waiting for that joke to throw that in there, too. So, that’s like an occupational exposure limit for the astronauts?

[00:12:58] Valerie Ryder: Yes.

[00:12:58] Anne Chappelle: But is a lot of what your role is then around the health of them? Or you mentioned some of this other research that obviously NASA is interested in. Do you get to coordinate some of that or is that more with a medical team? You said you have team of six people that you work with. 

[00:13:14] Valerie Ryder: That team of six is a core team of just risk assessors. Our job is to set those limits. We love to go talk SMAC at meetings. So, we have SMACs and SWEGs for air and water, and we are responsible for setting those limits. That’s why I said we’re kind of a combination of EPA and OSHA, because you’re right: I have occupational workers during the time that they’re in these spacecraft, but the difference is rather than being exposed eight hours a day, five days a week, for a working lifetime, they were exposed continuously for six months. It’s unique in that way, and so we set our limits based on those types of duration scenarios.

And so, typically, what we’re using are more acute and subchronic studies because at this point in space exploration, we’re really not having exposures beyond about a year. We primarily utilize information in the literature currently available to us, and we try to use factors and information that we have about changes related to space flight and implement that into safety factors for setting those limits.

But we don’t have a lot of specific research in the team, with some exceptions. There have been two very specific exceptions to that. One had just finished up fairly recently. Because we’re looking at going back to the moon, it was very important to establish limits for exposure to lunar dust. So, we had a really, really unique opportunity to work with samples that were returned from the Apollo program and actual lunar dust and do some animal studies looking at inhalation of lunar dust. And we used titanium dioxide as our negative control to show you will get some short-term inflammation, but not the long-term fibrotic-type scenario, and silica as our positive control.

Lunar dust is basically glass, and it’s impacted routinely because of the lack of an atmosphere by micro meteorites. And so, it’s really sharp shards of glass, and we expected that it would be quite toxic to the animals and we were surprised to find that it actually was between the two controls on this spectrum—and, if anything, leaned a little bit more toward the titanium dioxide. So, we were able to set appropriate limits for crew health for those exposures and help with designs for suits and habitats. 

When we went to the moon originally, when they’re on the surface, you have one-sixth gravity, so you have particles settling and things like you expect, but they would bring their suits that were covered in dust. And you can go find videos on YouTube, where the astronauts are collecting samples and they fall down and they’re rolling around and they’re just covered in dust, which they then brought back into the command module with them. Fine on the surface, but when they launched and they returned to microgravity, all of that became suspended and it was bothersome to them just from a nuisance perspective. And so, we understood that those types of exposures can and will happen and we have a better handle on how to work to reduce those exposures looking forward to more permanent habitation of the moon. 

We also had a situation with the space shuttle where some folks—and this is where we do work with the occupational hygienists—they had people at Kennedy who actually physically would adhere the tiles to the bottom of the shuttle. So, the shuttle was covered on the bottom side that faced re-entry and faced those extreme temperatures of coming through the atmosphere with these really unique tiles that protected the crew from that re-entry heat, and that adhesive was causing some of the workers to complain about issues. And so, we actually, prior to my time with the group, had performed a tox analysis to support ground ops. 

So, most of our work is for the space flight crews themselves and looking at their exposures and setting limits and making sure that we design all of our system hardware and all of our experimental hardware in a way that prevents them from being exposed to anything that could be harmful.

So, we want to have science going on on station. That’s the whole point: it’s a national laboratory, and we want and we encourage commercial folks to do experiments and to use it as a science lab, but we want to do it safely. That’s our primary focus, is protecting those crews while they’re living and working in space, but we do research projects to help out on the ground as well. 

[00:18:01] David Faulkner: I was looking at some of the stuff that you published about CO2 levels exposure, which I think is really fascinating, and it makes sense. You’ve got this closed system up there. 

[00:18:09] Valerie Ryder: And they won’t stop breathing. 

[00:18:11] David Faulkner: They just won’t stop. They just won’t stop. 

[00:18:13] Valerie Ryder: They’re just so full of hot air. 

[00:18:16] David Faulkner: Well, that’s why they float. Well, that got me thinking: you’re looking at these exposures and space of these higher levels of CO2 and affecting cognitive ability. And then I thought, aren’t we seeing higher levels of CO2 in our atmosphere? Is there a translation there? Should I be worried about the amount of CO2 that I’m breathing? 

[00:18:36] Valerie Ryder: Nominal levels on the space station are significantly higher than what we see in terms of the outdoor ambient levels here on the ground. So, even as we are increasing our ground levels, we’re still talking notably more on station. It was significantly more initially based on what we knew and data from the ground and occupational limits at the time; it was originally 7.6 millimeters of mercury, which were OSHA limits at the time. Those have been further reduced, and we know things like most people are exposed to higher levels of pollutants indoors than out, right? This is another one where that’s exactly the case, and the focus on sick building syndrome and those types of things are what really led to the research on CO2 indoors. That has caused the levels to be reduced even occupationally, so they’re closer to 5.4 millimeters of mercury right now. 

So, we were looking at maintaining those levels on station, but we were having crew complaints—and very nonspecific symptoms: headaches and fogginess and hard to specifically attribute to one particular thing. It could be stress. It could be sleep shifting—all of those things that happen to a space flight crew. But what one of the surgeons noticed was that when crew were performing a pre-brief for EVA—

[00:19:58] Anne Chappelle: EVA?

[00:19:59] Valerie Ryder: Extravehicular activities. So, when they go outside of the space station and they do a spacewalk, they breathe pure oxygen to get the nitrogen out of their system to avoid the bends, just like divers. And so, when they were breathing that pure oxygen, those symptoms would go away. That’s what led one of our flight surgeons to say, “Hey, maybe these things are related. Even though we wouldn’t necessarily expect adverse symptoms from CO2 on the ground, maybe there’s something different and there’s something going on here.”

And so, we actually looked at historical data, and crew talk to their surgeons once a week at a minimum, and then, they can of course call them anytime they need them if there’s an issue. And so, we took notes from those discussions across the history of station, and we looked at reports of headaches—and headaches in particular that weren’t resolved by standard medications on station. They were bad enough that they would report them, which is something that typically the astronauts are not going . . . they’re not complainers typically, right? So, these are pretty notable headaches, and there weren’t really all that many overall. We’re talking less than a hundred reported scenarios. And then we looked at the CO2 levels for the 24 hours and the seven days prior to those reported symptoms. We actually saw an association between higher CO2 levels and these complaints of headaches. So, we don’t know that it’s causal; there are other factors that could be contributing to this, but as we have accumulated evidence, we have been lowering the levels of CO2 on board ISS.

And there are some factors, we have fluid shift in space, right? So, you don’t have gravity pulling your blood down to your legs and extremities. You’ve got this shift of fluid to the head just by going into microgravity, and now you have CO2, which its job is to dilate your blood vessels, right? So, if you’re exposed to a potent vasodilator and you already have fluid, you can imagine that that might lead to an increase in headaches.

So, we can’t say that it’s the only thing, but we are trying to make crews more comfortable by at least doing what we can, and CO2 is something that we can change. I can’t necessarily change your sleep pattern. You have to get up for the arriving vehicle, and you have to unpack it and you might be tired. I can’t change those things, but I can affect change on the CO2 levels.

And even though we’ve lowered the levels, we’re still about twice what people typically experience and normally endorse, but we’re much closer to ground exposures now than we were historically.

[00:22:32] Anne Chappelle: When you were thinking about the applicability of what you’re doing, usually you don’t have a lot of closed containers for people to be exposed to, but then, you mentioned submarines. Then, I started thinking of other things, airplanes and other closed systems where you do have these controlled exposure scenarios. David and I have been talking about how you take tox in space and apply it—not only from the tools that they use: the ballpoint pen that writes upside down,

[00:23:01] Valerie Ryder: Or velcro, right? 

[00:23:02] David Faulkner: Oh, yes.

[00:23:03] Anne Chappelle: They’re much more applicable than what I had thought. Could you talk a little bit about that?

[00:23:08] Valerie Ryder: So, I think the things that we have learned in the space program—not only in toxicology, but across the program—are very applicable. Scenarios where we have to protect the crew and breathing systems, but it has to be lightweight. It costs a lot of money to launch every pound of hardware to the space station, so we’ve worked really hard to develop small, lightweight breathing canisters to protect the crew in the event of an off-nominal fire scenario, and those are utilized by fire crews on the ground because they, too, don’t want to carry really heavyweight equipment into a fire scenario.

I think that there really are a lot of translations back and forth. The commercial partnerships that we’ve developed over the past decade have really provided us with some additional products and research and things that we wouldn’t have had access to on our own, and then, NASA has been able to develop things that were necessary for space flight that folks didn’t necessarily think would be applicable on the ground that really benefit us every day.

So, I do think that it goes hand in hand and back and forth, and it’s important that we continue to look for ways to make sure that we’re helping the general public and that we’re not just doing our job to only protect the eight people a year that fly to the space station.

[00:24:29] David Faulkner: It strikes me that it’s the sort of thing where you have some information because there’s now, at this point, a history of the space flight program that extends back to the ’60s, but it’s still not that long. How much data could you possibly have?

And as you saw with the experiments involving the bone marrow stem cells or progenitor cells that things get weird up there in microgravity and with cosmic rays and all kinds of other stuff that happens—just physiologically, things change. This gets me thinking, “How do you deal with that shortage of data?”

We’re always talking about, “I’m a risk assessor. I’m always dealing with shortage of data,” but this strikes me as such a different context where that shortage of data exists and where could you pull information from? I guess you suggested submarines. How do you handle that, because you can’t exactly run experiments on this? 

[00:25:21] Valerie Ryder: That’s a fantastic question. There’s many aspects to it, so, one, yes, we do utilize the experience that we have from our military partners and submarines in particular. And we’ve worked with them fairly often because there is a direct correlation, and they were very interested in some of these CO2 data as well. So, they also have a scenario that’s very similar to ours in terms of kind of continuous exposure for a fairly short duration. A 90-day submarine mission is pretty typical. There’s a lot of information that we can glean from their experiences, and some of the materials are fairly similar, too, as well as the types of systems that are used to maintain the environment in a submarine and clean the air and those types of things. So, there are lots of similarities there, and we do draw on their experience as much as we can.

We do tend to utilize the ground-based data that are available to us because our n is very small. 

[00:26:20] David Faulkner: Right.

[00:27:30] Valerie Ryder: Even with a research study, if you have six to 10 crew, that’s a major accomplishment, and that occurs over years because we only have a very small number of folks who fly in any given year.

We are very fortunate that our atmosphere is extremely clean. Our water is extremely clean, so we have never even approached the limits for most of the compounds that we set—with the exception of things like CO2. For the majority of contaminants, we actually have a very, very clean environment, and we don’t have a scenario where we have to worry about whether or not we’ve incorporated an adequate margin of safety because the actual exposures and the total duration of exposure is relatively short overall. When we do have an elevated concentration of something, it’s typically not even for a full mission duration if and when it does occur. So, really the important aspect is working with our engineering colleagues and making sure that we’re designing the systems and the experiments and everything appropriately so that we don’t have the exposures to begin with. 

[00:27:30] Anne Chappelle: So, risk assessment is a bit of a guessing game with the application of the safety factors and such. 

[00:27:37] Valerie Ryder: Hoodoo. Voodoo.

[00:27:38] David Faulkner: Yeah. 

[00:27:38] Anne Chappelle: Yes. You have a very small n, but you actually probably follow these astronauts for a looong time. One question would be: Are you right? Are they still healthy because they get back to contaminated Earth, and that’s an issue? The other question around that is how do you feel about carcinogens, then, in space? Risk assessment for those kinds of substances?

[00:28:02] Valerie Ryder: Well, it’s actually very similar to what’s done on the ground. So, an example: we actually had some elevated benzene readings on one of our monitors, which turned out to be an issue with the monitor—but of course, at the time, we didn’t recognize that—and so we had to expect and anticipate that the crew were being exposed to elevated levels over what we normally see, which is undetectable. Initially, the response was hyperreactive in some ways because everybody recognizes benzene as a carcinogen, right? However, in order to get those effects, you really do have to have a long-term exposure, and I don’t think that people recognize the dose that they get when they’re filling up their car tank, et cetera. So . . .

[00:28:47] Anne Chappelle: It’s true.

[00:28:48] Valerie Ryder: Generically, we don’t set our limits based on those carcinogenic endpoints for those compounds that truly require extended duration exposure that we’re just not going to see and we’re not going to have.

There are situations where we have much higher limits than occupational or environmental limits for that very reason—because we don’t consider the carc endpoint, where other folks do. However, certainly if there’s a scenario where we have a mutagenic compound and even a short exposure is going to potentially cause the crew problems, then obviously that would be our adverse endpoint of concern, and we would set our limits based on that. 

One of the other challenges that we face, moving into exploration especially, is our bigger concern and potential cancer-causing agent is the radiation exposure that crews have in these extended missions that far outweigh the chemical exposures and potential increased cancer risk from that.

But you’re right. We do follow crews basically for their lifetime, and they have not experienced problems that we have ever been able to link directly to an occupational space flight–type exposure. There have been situations where former astronauts have said, “Hey, I developed this, and I had that exposure. Is there a relationship there?” And we have had to evaluate the data that we have and provide an opinion on whether or not they might be related. But those are few and far between, fortunately. 

[00:30:21] Anne Chappelle: So, we have a couple of other things. What is the most significant adverse reaction that you’ve ever experienced? 

[00:30:28] Valerie Ryder: So, when I first took over as the lead of the toxicology group, it was almost 10 years ago—and again, I was one of the newest people in the group—and here comes this young female whippersnapper from outta nowhere. I think some of the most adverse reactions that I had were overcoming that stigma of “she doesn’t know what she’s talking about because she’s young and female” and helping people to recognize that I am an expert. I have had experience. I do know what I’m talking about. 

I don’t feel like that’s an obstacle at all anymore. I feel quite respected by everyone at NASA. But it took some time to get there, and so I think that’s the biggest challenge for people, in general, is to not make judgments based on what you see and perceptions and things. We all have biases. We’ll all walk into the room and make assumptions. I think it’s important that we really try our best to not let that influence how you receive that person and to hear what they have to say and to understand where they’re coming from and not let those assumptions influence whether or not you will believe what they have to say.

[00:31:37] Anne Chappelle: Do you think the culture has changed a bit in the last 10 years?

[00:31:41] Valerie Ryder: I would say probably so. I think that just, in general, workplace diversity across all sectors has increased and continues to do so, and I think it’s important for people to see people who are different. And I think that’s a useful thing, though, about NASA and the International Space Station and the cooperation that we do have with so many different teams and so many different people and so many different perspectives.

So, in some ways, yes, I think it has changed and improved. We now have another female director here at the Johnson Space Center, and so there are certainly more females that are in visible roles of leadership than there were when I first got here, but I would say that I have always seen female leadership and a cross-representation of so many different people in so many different things. That’s what’s unique about the work that we do. It has improved and changed over the last 10 years, but I think we were somewhat ahead of the game in terms of the general workforce just because of the work that NASA does. 

[00:32:45] David Faulkner: Well, thank you so, so much for talking with us today. This was fascinating. I feel like I have so many more questions. You have the coolest job. 

[00:32:54] Anne Chappelle: This podcast makes me really jealous of all of the neat things that people get to do that you don’t hear about all the time, and you’ve been a wonderful, eloquent guest. Thank you so much for all the work you do to help the astronauts stay safe, but also to see how some of that could apply to other disciplines. So, thank you. 

[00:33:16] Valerie Ryder: This was fun. Yes. Thank you so much for having me. 

[00:33:19] Adverse Reactions “Decompose” Theme Music

[00:33:25] Anne Chappelle: On the next episode of Adverse Reactions. David, have you ever made a wise choice?

[00:33:32] David Faulkner: Uh, well, that’s ominous. Maybe once or twice.

[00:33:35] Anne Chappelle: “Toxicology Is a Wise Choice,” or “One Health, Many Ecosystems”: environmental toxicology with John Wise.

[00:33:45] John Wise: When we started measuring chromium levels in the whales, we were surprised to find whales that had levels that resembled levels found in the lungs of occupationally exposed people who had worked with chromium for 20 or more years.

[00:33:58] Adverse Reactions “Decompose” Theme Music

[00:34:01] Anne Chappelle: Thank you, all, for joining us for this episode of Adverse Reactions, presented by the Society of Toxicology. 

[00:34:08] David Faulkner: And thank you to Dave Leve at Ma3stro Studios. 

[00:34:10] Anne Chappelle: That’s Ma3stro with a three, not an E.

[00:34:13] David Faulkner: Who created and produced all the music for Adverse Reactions, including the theme song, “Decompose.”

[00:34:20] Anne Chappelle: The viewpoints and information presented in Adverse Reactions represent those of the participating individuals. Although the Society of Toxicology holds the copyright to this production, it has, 

[00:34:31] David Faulkner: definitely,

[00:34:32] Anne Chappelle: not vetted or reviewed the information presented herein,

[00:34:36] David Faulkner: nor does presenting and distributing this podcast represent any proposal or endorsement of any position by the Society.

[00:34:43] Anne Chappelle: You can find out more information about the show at,

[00:34:48] David Faulkner: and more information about the Society of Toxicology on Facebook, Instagram, LinkedIn, and Twitter. 

[00:34:54] Anne Chappelle: I’m Anne Chappelle.

[00:34:56] David Faulkner: And I’m David Faulkner. 

[00:34:57] Anne Chappelle: This podcast was approved by Anne’s mom. 

[00:35:01] Adverse Reactions “Decompose” Theme Music

Introduction to the Episode
What Is a Space Toxicologist?
How Do You Become a Space Toxicologist?
Stem Cell Growth and Bone Loss in Space
Talking SMAC and Lunar Dust Experiments
Determining Safe CO2 Levels in Space
Applying Space Research to Ground Scenarios
Dealing with a Small Data Set and Tracking Astronaut Health over a Lifetime
What Was a Significant Adverse Reaction in Your Life? Workplace Biases
Next Time on Adverse Reactions