Adverse Reactions

The United States of Toxicity

April 29, 2021 Linda S. Birnbaum, PhD, DABT, ATS, former Director of the National Institute of Environmental Health Sciences (NIEHS) Season 1 Episode 1
Adverse Reactions
The United States of Toxicity
Show Notes Transcript Chapter Markers

Retired National Institute of Environmental Health Sciences (NIEHS) Director and lifelong federal scientist Linda S. Birnbaum discusses the intersection of policy and science, as well as the effect of environmental exposures on public health, with co-hosts Anne Chappelle and David Faulkner. Dr. Birnbaum also shares her insights on how to be an effective leader and the importance of mentorship. 


About the Guest

Linda S. Birnbaum, PhD, DABT, ATS, is the former Director of the National Institute of Environmental Health Sciences (NIEHS) of the National Institutes of Health (NIH), and the National Toxicology Program (NTP). After retirement, she was granted scientist emeritus status and still maintains a laboratory. As a board-certified toxicologist, Dr. Birnbaum served as a federal scientist for 40 years. Before her appointment as NIEHS and NTP Director in 2009, she spent 19 years at the US Environmental Protection Agency (US EPA), where she directed the largest division focusing on environmental health research. 

Dr. Birnbaum has received many awards and recognitions. In 2016, she was awarded the North Carolina Award in Science. She was elected to the Institute of Medicine of the National Academies, one of the highest honors in the fields of medicine and health. She was also elected to the Collegium Ramazzini, an independent, international academy composed of internationally renowned experts in the fields of occupational and environmental health, and received an honorary Doctor of Science from the University of Rochester and a Distinguished Alumna Award from the University of Illinois. Dr. Birnbaum also has received honorary doctorates from Ben-Gurion University in Israel, Amity University in India, and the University of Rhode Island; the Surgeon General’s Medallion 2014; and 14 Scientific and Technological Achievement Awards, which reflect the recommendations of the US EPA external Science Advisory Board, for specific publications. 

Dr. Birnbaum is an active member of the scientific community. She was Vice President of the International Union of Toxicology (IUTOX), the umbrella organization for toxicology societies in more than 50 countries, and she is a Past President of the Society of Toxicology (SOT), the largest professional organization of toxicologists in the world. She is the author of more than 800 peer-reviewed publications, book chapters, and reports. 

Dr. Birnbaum’s research focuses on the pharmacokinetic behavior of environmental chemicals, mechanisms of action of toxicants including endocrine disruption, and linking real-world exposures to health effects. She is an Adjunct Professor in the Gillings School of Global Public Health, the Curriculum in Toxicology, and the Department of Environmental Sciences and Engineering at the University of North Carolina at Chapel Hill, as well as in the Integrated Toxicology and Environmental Health Program at Duke University, where she also is a Scholar in Residence.

A native of New Jersey, Dr. Birnbaum received her MS and PhD in microbiology from the University of Illinois at Urbana-Champaign.



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.

David Faulkner: Welcome to Adverse Reactions. I'm David Faulkner.

Anne Chappelle: And I'm Anne Chapelle. 

David Faulkner: And I'm a toxicologist and risk assessor. 

Anne Chappelle: What a coincidence. I, too, am a toxicologist. 

David Faulkner: And on this show, we explore the stories behind the science. 

Anne Chappelle: This is where we talk to toxicology experts from around the country and around the globe that use the field of toxicology to advance public health and also to protect the environment.

David Faulkner: In this episode, "The United States of Toxicity."

Linda Birnbaum: Why should the government—why should the American people—fund me if I can't tell them what I'm doing and tell them why it's important, what I do?  

Anne Chappelle: Featuring Linda Birnbaum. 

Linda Birnbaum: As toxicologists, we've got to take our blinders off and look more holistically at what we do and at the world.       

Anne Chappelle: We are really excited today to welcome Dr. Linda Birnbaum to the Adverse Reactions podcast. For those of you who haven't heard of Linda, you're what I call a rock star, celebrity toxicologist. You've spent 40 years as a federal scientist, and all the while, somehow, you managed to find enough time to still publish a number of papers and be passionate about your research linking real-world exposures to health effects, mostly adverse health effects. You also managed this double of being able to move up the leadership ladder at EPA, and finding scientists who can bridge both is somewhat of a unicorn.

And the last 10 years of your career, you spent them directing the US NIEHS. You were the first female, first board-certified toxicologist to do so. That's awesome for our field and my gender. David and I have talked a lot about what we think is interesting about you and about what we're trying to accomplish. 

David Faulkner: So, I am really interested in your career as a scientist and someone who has to balance these sort of political government spheres. You've got your integrity as a scientist, but then you also have obligations as a steward of these large programs.

Linda Birnbaum: I'm really proud of the fact that I was a federal scientist for 40 years and was responsible only to the American people. That may sound very idealistic, but that is the way I feel. Was it always easy? No. Did I get myself in trouble? Yes. But as we heard with John Lewis, there's such a thing as good trouble.

Anne Chappelle: You wrote an article about perfluorinated compounds, and it was a commentary when you guest edited?

Linda Birnbaum: I was co-editing a PLOS ONE volume, basically, looking at risk assessment and different issues that should be looked at there, including endocrine disruption. 

Anne Chappelle: And some people got very upset. What surprised you the very most about this ensuing firestorm over your opinion?

Linda Birnbaum: You know, it's interesting because the only firestorm I heard was from Congress, who were incensed.

Anne Chappelle: Do you think that those Congressmen didn't realize that science has been shaping policy for some time, or was it on this particular subject?

Linda Birnbaum: I think it was on the issue of environmental exposures and environmental chemicals, and we are, have been, in a time when environmental decisions are often not supported by the best science or the science has been used selectively to make decisions if it's used at all. Now, I understand that there are times policy is made not taking science into account. That's certainly, there are times where that may be appropriate. 

But in most cases, in my opinion, if you're talking about the issue of environmental exposures that may impact human health, we know a lot about some of those exposures. We know nothing about some others. But, you know, we know now that air pollution is associated with increased morbidity, and mortality. We know that there are early-life effects associated, you know, with air pollution and stuff like that. We know that there are certain chemicals that, you know, if they're used entirely in a closed system may be very useful industrial chemicals. But if they're escaping into the environment, we know that these can have adverse effects, and that should be something that in my mind, in my opinion, should be considered in policy decisions that would be made about them. 

David Faulkner: Did you find people's reactions was a bit different than sort of the public posturing that happens a lot? Were folks in Congress more amenable when you interact with them more one on one? 

Linda Birnbaum: I think there's a difference, sometimes, what people understand, and what they'll agree with you on, and then what comes out in a public setting, where they're trying to maintain the support of their constituencies. You know, and I'm not talking about, you know, a 180-degree difference. People emphasize different things, and, you know, we all do that and it's not inappropriate. If you're talking to other scientists, you're talking one language; if you're participating in a town hall meeting, you're using different language because you want people to understand what you're saying and where you're going. 

Anne Chappelle: Even though you officially retired in October 2019, David and I have been doing some research and understand that you've not really disappeared from really anything that you love. You're very active in those things still. So, what has been motivating you each day?

Linda Birnbaum: I mean, I get motivated by many things. I would say probably for me, number one is the love of science and the love of learning. That kind of extends into the love of talking about what I've been doing and working with others to help get other people interested and excited and doing the science. And I think one thing that's also been motivating me is the ability to continue to make a difference. I feel that my career has made a difference in the way that certain kinds of chemicals and certain kinds of toxicities are looked at. There's lots more I want to do in that realm.

Anne Chappelle: So, when you're at a cocktail party, how would you explain what you do and what you're passionate about in terms of the scientific content to someone who isn't necessarily a highly technical person?

Linda Birnbaum: I would talk about, or I would say to people, well, I'm interested in how the environment impacts our health. You know, our health is more than just our genes. It's an interaction between our environment and our genes. And our environment is very complicated. It includes things like air pollution and water pollution and soil pollution. It includes things that might be in our food. It includes infectious agents that we might encounter. It includes this lovely cocktail I'm having tonight, virtually, with you on the other end. 

I think it's all that kinds of things and how that may impact us. And as a toxicologist, it's been important to me that we try to look at how exposures occur in the real world and also at levels of exposures that are relevant to the real world.

I don't think we necessarily learn a lot from extremely high dose exposures. I think we have to use something relevant. And I guess one thing that gets me aggravated at times when I hear the term, well, those toxicology studies are all high-dose toxicology studies. And what I want people to understand is no, they're not all high dose. It's important for us to understand what is actually the dose inside or the concentration in the body and relate that to the kinds of exposures that we see in people. 

Anne Chappelle: When you talk about real-world exposure scenarios, you're talking about mixtures, and those add a level of complexity that is extraordinarily difficult. 

Linda Birnbaum: You know, for well over 30 years, probably 35 years, there's been lots of talk, if we want to do mixture studies, do we do top down, where you take a real-world mixture, or do you do bottom up, where you make something? And the answer is, it depends on the question, what are you actually trying to understand? I've done a lot of work in the past, looking at dioxins and PCBs and the mixtures. And much of the work that I did was looking at binary mixtures. I take one dioxin and one PCB, or one dioxin and one furan, and mix them together. And I'd show that there was a common initiating mechanism of action and so on. And with the dioxin-like compounds, that led to work which has kind of been blessed by WHO with the toxic equivalency approach, which is really just a relative potency approach. 

Now, that kind of approach is also used for certain other complex mixtures. So, pH there's an approach. PCBs, although we know that not all PCBs do the same thing, different conjurers have different mechanisms, but the point is we tend to treat them and regulate them all as a group. So, again, you have to get to, what's your question? I'm a pragmatist. I'll do something which is sensible and maybe improves our understanding, or if it was regulatory, is more health protective, even if it's not perfect. You know, I am a believer that you don't want the perfect interfere with the good. I'll take the good, at least as a step going forward. 

So, I think mixtures are very difficult. You know, we've begun to deal with mixtures of chemicals that either have a common mechanism of action or that target a specific apical effect. And we tend to do that with some kind of dose addition or concentration addition or relative potency approach. And I think that actually is a prudent measure to use. But then when you start saying, but wait a minute, we just don't have dioxins. We just don't have PCBs. We've got them with PAHs, and we've got chromium around, too. I mean, maybe we've got chlorpyrifos, and how do you deal with that? And the answer is we haven't really worked out how to approach that. 

We can think about a top-down approach for testing. And I think people are doing some of this with some of the rapid high-throughput screening approaches, where you can at least get some indications pretty quickly. But we're going to have to talk about, for example, if you want to use drinking water, what's in your drinking water may not be the same thing as in my drinking water. So, whose drinking water do you use as your mixture? And you're going to have to just make certain decisions that this is the model that we're going to use, and this will get us further in understanding the complexity, rather than, than trying to make everything perfectly.

David Faulkner: So, I have a few different roles that I balance as a health and safety officer, as a researcher, and so on. But you have many more hats that you're wearing on any given day. Combine that with personal life, how do you find hours in the day to do all of these things? Do you just not sleep or?

Linda Birnbaum: I definitely sleep. I'm not one of those people who can survive, say, on four hours a night. You know, I can remember when I first started at NIEHS as a tenure-track scientist in 1979, I would marvel at all these people who would go home with their briefcase full of papers. And I thought I go home, and I’ve got to play with the kids, cook dinner, give them their bath, read them a story.

By the time it got to be, say 10 o'clock, I was four legs in the air. I'd be totally exhausted. It taught me to be very efficient. So, I didn't do a lot of just visiting at work, or kaffeeklatsching, or stuff like that. And I think that is something that I continued throughout my career, but I would say, I also try to surround myself with really competent people and people who could help me get what we needed to get done. Nobody can do it all alone.

Anne Chappelle: No. It sounds like deciding how and when to delegate and having trust in your delegation capabilities, that that is a mark of a good leader. You know, figure out who needs that extra help, who can you push along, or just check in with? I think in a number of leaders, especially in the scientific field, you know, you have the stereotypical, bumbling scientist, and that's not really who a lot of us are. I'd like to think that we are working more towards finding people and teaching them how to communicate if it isn't something that comes naturally to them.

Linda Birnbaum: You're talking, or really asking, about two different issues. One is leadership and one is communication. And they're both extremely important. So, when we talk about leadership, there are different kinds of leadership. Different kinds of leadership may be called for in different situations. But I believe leadership is not something that you're born with. I think it's something that you learn. Understanding that being a great bench scientist is not enough for many people. It wasn't enough for me. Getting that training, and again, leadership and management, aren't the same thing, but understanding that, and understanding different kinds of leadership and how you can empower others to be leaders, for example. 

And then, communication. And I will tell you that I continue to believe that communication is one of the hardest things for many scientists to do and is exceedingly important. I mean, I worked for the government. Why should the government—why should the American people—fund me if I can't tell them what I'm doing, and tell them why it's important, what I do? And again, I think communication skills are something that are learned, and I would encourage everybody to make sure that they learn how to communicate. 

Anne Chappelle: And isn’t that the fundamental part of science, is being able to have an educated discussion and be able to change your mind when you hear a valid point? Or you can agree not to disagree, or you can say, I hear what you're saying, but I'm going to come back to that. There has been so much criticism of scientists who've changed their mind about COVID. Oh, well, they used to think this. Well, that's science. That's what we do. We investigate. We publish, we read, we consider. We don't argue face to face and then move away. But this idea of using the platform of science to really demonstrate that opposing views really can be heard calmly and representatively and make a decision based upon good facts.

Linda Birnbaum: So, science is always evolving. And I think that's something that the general population does not understand. So that what you knew at one point in time, you may, in fact, as you get more information, may not be what you know later on. I totally agree with the fact that science, we have to be able to talk about it. 

And I think that goes along with the idea where you see the polarization. I used to, when I was at SOT, said we shouldn't only be talking about industry and government and academia. I said, we need to include advocacy as well, or community, citizen groups, and stuff, because they have a valid point of view. And part of our responsibility as scientists is to be educators. You know, I think a lot of times we fall short there. 

David Faulkner: Just thinking about how we get at this problem of misinformation, and what is the role of scientists in that? What is the role of government in that? 

Linda Birnbaum: Yeah, that's a really hard question, David. The science, the level of science literacy in our country is pretty horrific. And I think that's been so obvious during the pandemic. You know, I am a believer in the value of education and the education starting earlier. I think there are so many people who get turned off, anything about science, when they're in grade school. And, once you turn off a kid, forget it. 

I think another point is people think that data is science, but that isn't real science. Data is what you use to draw conclusions based upon what else you know. I think all too often, someone will look at data and say, you know, the sky is blue, and the other person will say, what do you mean? It's gray outside. And the point is, is they're looking, they're bringing something different to it. We have to try to come together, rather than go apart, to say, why did one of you say it was blue and the other one says, says it's gray? And then, you know, those are the discussions that have to be had. And that's really important when you start developing consensus in science. 

Thirty years ago, I was testifying before a House of Representatives committee. And it was about dioxin, and I think I might've made the comment, dioxin is the most toxic man-made chemical, or something like that. Or I said, the scientific consensus is that. And someone on the committee said, oh, I've heard different viewpoints. You know, I've heard people who don't agree to that. And I said, according to Webster's, consensus is not a hundred percent. It's a, it's a large majority. And I think that those are things that people don't always understand. But I do think bringing people together to try to understand why people draw different conclusions from much of the same data is an important thing to do. And I think that's true when you get beyond science as well. 

Anne Chappelle: I love being able to call myself a toxicologist because in my head is this all-encompassing investigator, curious person, of things that are adverse. And pushing the dose and really thinking about society as a, as a whole. And you can have so many different specialties. I'd like to get your perception of kind of the state of toxicology and the role of toxicology as a science and a translational science between different disciplines. 

Linda Birnbaum: I appreciate the question because I believe that toxicology requires a certain general and broad view. In other words, I think that it's helpful for me, I think my training really as a molecular biologist was very helpful for me because I could understand the molecular toxicology people were talking about. Well, I did a biochemistry postdoc, so I can understand some of the biochemical stuff. Then, I actually did another postdoc in pharmacology, you know. And that helped me understand some of that. And I think having that broad expertise is very helpful. 

Instead of talking about toxicology as the science of poisons, we talk about toxicology as the science of safety. Understanding when things are safer, when they're healthier, when they're better. Now, you know, you can never prove negatives, right? But you know, you can demonstrate when things appear to be safer, and I think that that is a approach to understand talking about tox as a science is really helpful. 

And what I try to stress with people is the important things you need to do is always say, what's the question you're asking, and then design an experiment or model you're going to use to address that question. And every model isn't going to address every question. Not appropriately. 

Anne Chappelle: Whenever I'm asked to talk with a student, a graduate student, no matter what their field, they like chemistry? Come be a toxicologist. You can do so much with it. You know, you really like a biochemistry? Cool. Come be a toxicology. There's always something that is applicable to our discipline. Public safety, health, chemicals.

Linda Birnbaum: So, I look at toxicology as being a multidisciplinary field. And then, I think, as toxicologists, we need to be more multidisciplinary and interact with people outside of toxicology. So, it always drives me crazy when people say, well, you know those epidemiologists. Well, you need to talk together. You need to understand. People say, oh, well, our, we found that this chemical was toxic, and then they went out and looked. I can tell you that a lot of the chemicals that we've looked at are based upon what was observed in human observational studies and epidemiology studies. And that led us to look for other things in tox.

And you want to have these kinds of two-way streets. You want to be talking to the exposure assessors. You want to be talking to the biostatisticians and the data people, and you should certainly be talking to the chemists. But, you know, I think as toxicologists, we've got to take our blinders off and look  more holistically at what we do and at the world. 

David Faulkner: And you've talked about this in some of your work, about expanding the concept of what an environmental exposure could be. And I think that that's really interesting. In terms of reaching across disciplines, do you know of any efforts to try to expand interdisciplinarity and funding to try to encourage people to sort of reach across those lines?

Linda Birnbaum: So, at NIEHS I can tell you, we did that. For example, all of our centers programs—and we have many different kinds. We had environmental health core centers. We had children's centers. Um, we had Superfund centers. They had to have a community engagement core because our communities often are very knowledgeable about what is going on in their community. And they have a different perspective of how you look at things. And getting them involved, not to helicopter in and say, here comes a scientist and we're going to take samples you and bye-bye. You know, maybe we will or we won't come back and tell you, but to have community involved from the beginning is very important. And of course, many of the communities that have special needs would be communities that were disadvantaged or diverse in one way or another. And it was very important to involve them. 

I mean, look what we've seen during the pandemic, where some of our African American communities and our Hispanic communities and even some of our Asian communities are at increased risk. Now, some of that may be socioeconomic, some of it may be related to dietary preferences that can vary. But you know, now we know how important, or we're beginning to give credence to how important, our microbiomes are, and what you eat is very, very critical to your microbiome and your microbiome not only talks to your immune system but talks to your brain. So, these are the kinds of things that I think we have to be trying to incorporate, or at least remember, as we design some of our more experimental studies, and we need to be communicating our findings so that they can be involved in the kinds of questions that in epidemiology studies are being asked.

Medical people will often say well, you can't do a double-blind, randomized control trial, or you haven't done it, so you can't prove that this exposure is associated. Well, I would challenge that, because I do think we have the Bradford Hill considerations. You don't have to meet every consideration in order to support causation. But I think when you meet several of them, and then you have the animal data to support it, not surprising that some people would show effects.

David Faulkner: So, thinking about the different ways your career could have gone, if you weren't a scientist and researcher, what would you have done or what would you be doing? 

Linda Birnbaum: I always loved history, and I also loved archeology. But I know me. I don't have a lot of patience. I like instant or quick results. You know, when I ran an experiment, I loved it if there was a colorimetric reaction so I’d know whether something was working right away. But I don't know whether I would have had the patience to have, say, gone on a dig and sat there with a little paintbrush, brushing aside the dirt and the dust of the, the ages. I, you know, I probably would have loved to have been professor. I've had adjunct professorships, and now I have a scholar and residency, so I've always had interactions with students and stuff. But, you know, when I got the job at NIEHS, in many ways, that was pseudo-academics without the hassle of having to apply for my own funds. 

Anne Chappelle: Exactly. The opportunities that you've had to find creative ways to mentor people, whether it's through these adjunct professorships, whether it's walking down the hall of someone else's laboratory, or communicating science in some other way, has been really inspirational. It's a good model.

Sometimes, I think as scientists, we can be a little selfish with our time, but promoting other people, promoting women, promoting diversity, really makes all of us stronger. And you have really demonstrated that by getting to the heights that you have in your career in terms of leading such challenging organizations.

Linda Birnbaum: I will say that one thing I believe has helped me with all the mentoring is I'm very responsive to people. If somebody sends me a note or called me on the phone and wanted to talk, I would always make time, and if I couldn't do it then, I would always set up time. And, you know, I think being approachable is a very important trait for senior scientists to have. 

David Faulkner: That's very wise, and I hope that listenership will take that to heart. It's been so great talking with you. I really enjoy all this discussion about public health topics, and your career has been so important in the field of public health, and it's inspiring. 

Anne Chappelle: This has been a lot of fun today. Thank you so much for your time in helping us to see what the state of toxicology is. And clearly, I think David will agree, it's a lot better that you've decided to stay active in it.

Linda Birnbaum: I'm having too much fun to totally go away. And thank you, both Anne and David, for some really great questions and interesting discussions. 

David Faulkner: So that was our interview with Linda Birnbaum.

Anne Chappelle: I'm so glad that we had her kick off our first episode.

David Faulkner: Yeah, talk about a celebrity guest.

Anne Chappelle: And now we're ready for the tease.

David Faulkner: Next time. 

Anne Chappelle: "DNA Isn't Destiny. So What Is?" 

David Faulkner: Featuring epigenetics expert Dana Dolinoy, of the University of Michigan. 

Dana Dolinoy: If our genome is the hardware, our epigenome is all the various different software programs that run the computer.

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

David Faulkner: And thank you to Dave Leve at Ma3stro Studios. 

Anne Chappelle: That's Ma3stro with a three, not an E. 

David Faulkner: Who created and produced all the music for Adverse Reactions, including the theme song, "Decompose." 

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, 

David Faulkner: definitely,

Anne Chappelle: not vetted or reviewed the information presented herein,

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

Anne Chappelle: You can find out more information about the show at,

David Faulkner: and more information about the Society of Toxicology on Facebook, Instagram, LinkedIn, and Twitter. 

Anne Chappelle: I'm Anne Chappelle. 

David Faulkner: And I'm David Faulkner. Hopefully, at least half of you make it back for the next episode.

Anne Chappelle: This podcast was approved by Anne's mom. 

Introduction to the Episode
About Being a Federal Scientist
Government Policy and Environmental Exposures
Understanding How Our Environment Impacts Our Health
Finding Career and Life Balance
Leadership Qualifications and Communicating Science
Misinformation and Science
On Toxicology and Its Future
The Need for Interdisciplinary Science
If You Weren't a Scientist...
Next Time on Adverse Reactions