Adverse Reactions

Speak Softly and Carry a Big Dataset: The Exposome

May 13, 2021 Darryl B. Hood, PhD, Ohio State University College of Public Health Season 1 Episode 3
Adverse Reactions
Speak Softly and Carry a Big Dataset: The Exposome
Show Notes Transcript Chapter Markers

Ohio State University’s Darryl B. Hood reveals how a database with about 25,000 environmental factors and variables associated with the public health exposome may soon lead to major breakthroughs in addressing disparate public health outcomes in various communities. He also shares with co-hosts Anne Chappelle and David Faulkner his experiences from a lifetime of firsts—from being a plaintiff in Brown v. Board of Education to transitioning from an HBCU (historically black college and university) to a program where he was the only Black man.


About the Guest

Darryl B. Hood, PhD, is an Associate Professor and environmental neuroscientist in the Division of Environmental Health Sciences in the Ohio State University College of Public Health. 

Dr. Hood received a BS in biology and chemistry from Johnson C. Smith University in Charlotte, North Carolina, and a PhD in biochemistry from the Quillen-Dishner College of Medicine at East Tennessee State University. After completing a postdoctoral fellowship at the Center in Molecular Toxicology at Vanderbilt University School of Medicine in 1993, Dr. Hood accepted a position at Meharry Medical College and served meritoriously until 2013 on the faculty of both Meharry Medical College and Vanderbilt University School of Medicine in the Department of Pharmacology and Neuroscience. During this time, he received over $11.2 million dollars of research funding. 

From 2006 to 2011, Dr. Hood led what has come to be known as the most successful Minority S11 NIEHS-sponsored initiative, referred to as the Advanced Research Cooperation in Environmental Health (ARCH) Program. The research conducted under this consortium ultimately contributed to the scientific database that the US Environmental Protection Agency (US EPA) used to reassess the levels of polycyclic aromatic hydrocarbon emissions from smokestacks. Such reassessments have resulted in public policy changes that will serve to decrease the adverse health effects associated with environmental exposures. The Meharry Medical College-Vanderbilt University ARCH Consortium was recognized as being at the interface of successful P01-like research programs in general, and for systems toxicology research in particular. This construct served as the template that then–NIH Director Dr. Elias A. Zerhouni used as the viable, futuristic model for the development of effective scientist-to-scientist interactions between research-intensive universities and historically black colleges and universities.

At the Ohio State University, Dr. Hood has continued his innovation in discovery as the co-architect of the novel Public Health Exposome framework. This paradigm-altering framework interrogates hypotheses focused on determining if there are associations between the built, natural, and social environments and disparate health outcomes observed in vulnerable populations. 

Collectively, Dr. Hood has 105 peer-reviewed publications, including book chapters, and has mentored over 15 MSPH/MPH candidates, 15 PhD candidates, and nine postdoctoral fellows. He continues to serve on numerous editorial and review boards for scientific journals, government agencies, and academia. Most recently, from 2010 to 2016, he served on the US EPA Exposure and Human Health Subcommittee of the Science Advisory Board.


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 Chappelle.

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

Anne Chappelle: And I am a toxicologist who thinks that Mr. Yuk was a great idea.

David Faulkner: What does that mean?

Anne Chappelle: You don't know who Mr. Yuk was? I have just shown my age. Seriously, you don't know who Mr Yuk is? 

David Faulkner: I'm looking it up.

Anne Chappelle: They were the little green stickers that you would put on your—

David Faulkner: Right, right. This is entirely novel to me.I'm terrified.

Anne Chappelle: Don’t be terrified.

David Faulkner: Alright. Don't be afraid. 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: Today:

Anne Chappelle: "Speak Softly and Carry a Big Dataset." 

David Faulkner: "The Exposome."

Darryl Hood: All the toxicology was a quest to learn about, why is it that people who work in these occupations live in these specific situations? Why are they more predisposed to disease than those that don't? That's just been my life's work. My life's mantra.  

David Faulkner: With Dr. Darryl Hood of the Ohio State University.

Darryl Hood: That was me 40 years ago: a little, naive kid, didn't know what they wanted to do. But if you can somehow turn that light bulb on. We got to invest a little bit more in that area with respect to underrepresented minorities and bringing them into the construct because they're, we call them diamonds in the rough. They're out there.   

David Faulkner: We are joined today by Dr. Darryl Hood, from Ohio State University College of Public Health. He is a tenured Associate Professor in the College of Public Health Departments of Neuroscience and Environmental Health Sciences, former Professor at Meharry Medical College, and all-around fascinating person. Thank you so much for joining us.

Darryl Hood: Well, thank you very much, David and Anne, for having me.

Anne Chappelle: I noticed that when David was describing your background and your affiliations, I didn't hear, really, the word toxicology in there directly, so could you explain a little bit about your research and its focus and how it relates back to toxicology?

Darryl Hood: I often get that. And so Meharry Medical College is in Nashville, Tennessee, and what David didn't bring out is the fact that Meharry and Vanderbilt have an alliance.

Subsequent to my PhD, I was trained at Vanderbilt University for my postdoc, and it was in the Center for Molecular Toxicology. And at Meharry Medical College, I was able to start and build an inhalation research facility. Over the course of the next 30 years, all of my work was considered as the translational correlate for the work that's being done at the Mailman School of Public Health. And that, of course, would be the impact of polycyclic aromatic hydrocarbons on systems, uh, reproductive system, as well as the central nervous system. And so therein lies, sort of, the seed from which we blossomed. 

And, and so all of the work with benzopyrene and polycyclic aromatic hydrocarbons that the West Harlem Environmental Action Group, that would be in Washington Heights and Harlem, connected to the Columbia University and Mailman, all of that epidemiology. My job was to look at the molecular-level events that were observed in those populations to find out what was going on in terms of defining key mechanistic adverse outcome pathways from the inhalational route and so then the reproductive system primarily in the central nervous system.

David Faulkner: Very cool. Very cool. I was looking through your publications list and you've got such an incredible range of things that you've published on: areas of public health; benzo[a]pyrene, as you mentioned; health disparities in black and minority communities; about the exposome. What is the unifying theme or a constant throughout your research?

Darryl Hood: If I had to choose one, the unifying theme would be that these adverse or disparate health outcomes that we see out in America in low Census-tracked areas, and even in some cases, in high Census-tracked areas, tend to be for the most part place based. And by that I'm referring to the fact that there's a social-ecological life paradigm at work. And that's what you referred to a few minutes ago as the public health exposome. Although physiologically, we have mechanisms that govern adverse outcome pathways, they are exacerbated by place. The reason why we haven't, sort of, made any significant progress on dampening disparate health outcomes in America is because we've been looking at this from a skewed perspective.

And my epidemiological friends will appreciate the fact, now, that we've taken the time to, sort of, introduce a new framework that isn't trying to supplant conventional study design in epidemiology; it runs in parallel with that. Our design takes a social-ecological life course approach.

And with it comes big data to analytics, which means that we use combinatorial algorithms and, in some cases, parametric and non-parametric statistical methodologies coupled with paraclique. It's a new horizon, and we are very, very comfortable with where we are right now in terms of this new paradigm and framework.

David Faulkner: The concept of the exposome has come up a few times. There's all these 'omes: metabolome, the genome, proteome. Can you just expand on the exposome idea a bit more?

Darryl Hood: And so when we talk about the public health exposome, we're referring to not the endo-exposome. Heretofore, if you look at the literature and the historical literature, it tends to look inward. That's what you were referring to. We're talking about the ecto-exposome: where people live, work, play, and pray, and how the built, natural, physical, and social environment influences those particular pathways. That is the public health exposome. 

We have amassed a database with about 25,000 environmental factors and variables there. It took us eight years to curate all of the publicly available datasets, and they're now in one place, in our data bank there in Nashville at Meharry Medical College. 

Anne Chappelle: So how, thinking globally, do we do it different in the US? Are we the model for how to think about environmental justice, or are you modeling the way that you're collecting the data and assembling it off of another country? Because we can't be the only ones that are dealing with these kinds of issues in terms of the disparity in different health outcomes.

Darryl Hood: That's true. And that's a very good point. Various countries in Europe have done a very good job. One example in the UK: early-life exposures lead to later-life outcomes, adverse outcomes, right? The Barker hypothesis. But ours is a bit different. The land use in America is a little bit different. America is different. And so, what we had to do was actually curate and get all of this information into one place. We had a few grants from the National Institutes on Minority Health, and then the US EPA, you know, STAR grants and things of that nature, that have allowed us to, over that period of time, get all of this data in one place.

Very, very exciting, innovative, and novel about our approach is the analytics that we coupled to that framework. Our public health exposome, it's the social-ecological life course approach to disparate outcomes. And then you add big data to knowledge analytics on that, when you were talking about complex networks and Bayesian analysis and paraclique combinatorial algorithms that give you sets of related nodes, which is all a paraklete is. When you have so much data, you're going to be able to sort of reveal latent interactions and associations. Now, we aren't quite there, um, with respect to causal inference, but we were going to get there. That will happen very, very shortly. 

David Faulkner: In the past, as I understand it, some of your, your datasets have been used to inform the way that the federal government tracks things like smokestack output. And, and some of the benzo[a]pyrene work there and the polycyclic aromatic hydrocarbon work has been used to inform, sort of, federal databases and standards, looking at those kinds of measurements.

Darryl Hood: Yeah. You know, you look at Columbia University, the Mailman School of Public Health, what they've been able to do with respect to interfacing with underrepresented communities and getting the epidemiology out there. And then, of course, my laboratory in Nashville, you know, using benzopyrene, um, as a surrogate, if you will, a proxy, for overt environmental pollution and us working out the molecular-level pathways that led to central nervous system dysfunction and reproductive system dysfunction.

The EPA uses our data from both institutions. My laboratory was very, very well represented in the decisions and policy changes. So, yeah, we're very proud of that. So, yes, one can impact policy from the laboratory using rodents in various experimental model systems. But now, of course, you see, we've pivoted to people and communities, and how is that going to translate? And so, you know, your career, it comes full circle. 

David Faulkner: Absolutely. Actually, that brings me to benzo[a]pyrene. How did you settle on benzo[a]pyrene as a chemical of interest, and what was your career path to get you to where you are now?

Darryl Hood: Good question. I often am called to travel around the country and give a talk as to, how did you get to where you are? And the title of mine is "Beginning Your Career with the End in Mind." 

Life does come full circle. I went to a very, very small Presbyterian college in Charlotte, North Carolina, Johnson C. Smith University, HBCU. My dad worked there for 37 years. My grandmother got very, very ill when I was at the end of my freshman year, and we were attempting to communicate with the physicians, and no one seemed to be able to. I said, well, somebody has to be able to interface with these physicians. I had better learn a little bit more about biology. I made up my mind at the end of my freshman year, I was going to major in biology. And so, there were these programs that were specifically focused on underrepresented minorities. Programs like the Research Centers in Minority Institutions Programs; the programs such as the Minority Access to Research Careers; programs like MBRS, the Minority Biomedical Support program. 

I was accepted into those programs, and that opened up a whole, another realm to me. There are no scientists prior to me in my family. I just, you know, started taking general biology, general chemistry. I was able to then get somewhat of a vocabulary in terms of the lexicon that these physicians use in terms of, you know, trying to explain to you what's happening to your grandmother. Unfortunately, as is the case back then, I mean, this was 1981 or so, my grandmother succumbed, of course, to that cancer, but that just gave me and undergirded my quest for learning about science and the mechanisms which caused her to go downhill over a course of two and a half years.

My grandfather, her husband, worked in a foundry for 50-some years. I remember the smell of creosote on him when he came home from work. Then, he came home and then he worked the farm. My mother sent us down there to work, to learn about discipline in the summer. 

The discipline it instilled enabled me to, sort of, after Johnson C. Smith go to East Tennessee State University Quillen-Dishner College of Medicine. You went to school with medical students, so were you in their classes, so biochemistry. That was eye-opening for me. That's where I got my PhD—the first African American, of course. There have been a lot of firsts in my life. Yeah, I was a plaintiff in Brown v. Board of Education

David Faulkner: Wow.

Anne Chappelle: Really? 

Darryl Hood: Yeah. Through Swann v. Charlotte-Mecklenburg School of Education. So one of those tests cases. My mom and father were civil rights leaders in Charlotte, North Carolina. Daddy, being a Presbyterian minister, marched with Martin Luther King several times. Um, all of my family, you know, civil rights leaders. And so, it's sort of in your DNA, and that's why I've ended up in this diversity and inclusive excellence. All the toxicology was a quest to learn about, why is it that people who work in these occupations, live in these specific situations, why are they more predisposed to disease than those that don't? That's just been my life's work. My life's mantra, in terms of looking at some of these issues and trying to illuminate some of these causes behind these disparities: coal-fired electrical power plants, benzopyrene.

And how that happened, David, was a result of the Agency for Toxic Substances and Disease Registry. The goal, the mission, of ATSDR is the fill priority data gaps, and they felt at the time that BaP, benzopyrene, would be a good surrogate for all of the polycyclic aromatic hydrocarbons.

And so, they gave us a grant. We won a grant to create a facility, an inhalation facility, where you would then be able to test and do multi-generational studies, which had not been done at that time. We fashioned an inhalation facility at an HBCU, still the only one of its kind in the country, at Meharry Medical College. 

Anne Chappelle: I was given a book a few years ago called Apprentice to Genius. And it talked a lot about the role of mentorship and that ripple effect of people being open to and excited about your research and finding ways to integrate their topics with what you're doing. And I think that that mentorship and being a good example for how to find ways to push your science forward when you've hit a wall. And that's what it seems like you've been able to do and convince people that this investment will really bring the big returns. How do you translate that passion to others effectively? 

Darryl Hood: It comes as a result of you, yourself, that individual, having those individuals that you spoke about: a very, very close-knit team. And by that, I mean someone that is very, very tough on you at certain times in your career where you can go to, someone who you can go to and cry, they let you cry on their shoulders after you receive that pink sheet back from study section. And then one that, at the same time, while you're crying, thrusts you up onto the platform at SOT into a platform presentation to sort of reinvigorate that confidence in you. And then of course, you have the quintessential individual that's just your colleague who you can talk to about things and that gives you that deferential advice. That only comes after time. 

And I had those types of mentors, and I tried to be that to whatever role I need to play to the individuals that are coming up through the CDI program at Society of Toxicology. That was me 40 years ago: a little, naive kid didn't know what they wanted to do. But if you can somehow turn that light bulb on during the weekend, when they come up. That is why we know we have to make some enhanced investments at that level. We got to invest a little bit more in that area with respect to underrepresented minorities and bringing them into the construct because they're, we call them diamonds in the rough. They're out there. And if someone lit your fire and you had good mentors, and it's incumbent upon us to be good mentors to that generation because that pipeline is really drying up. I mean, I am somewhat disenchanted, I would say, by how graduate students these days are opting not for academia.

Anne Chappelle: I didn't go into academia, not because I don't like to teach, because I love to teach and inspire. I didn't go into academia because I didn't want to fight for grant money.

David Faulkner: Yeah. 

Darryl Hood: Yes. It's your disposition that we all have, the individual disposition. So what stress did I want? I got recruited by companies A, B, and C. Now what do you want to be responsible for? You want to be responsible for potentially a $5 billion drug coming down the line as a senior scientist and then something happened? You know, so it's all a matter of, what is your allostatic load potential? You know, how much stress can, what type of stress, can you handle best? And for me, writing a grant and I'm like, oh, hey, I'll take that any day of the week. Plus, my wife: very, very inflexible career. She did not have any flexibility, you know, she had to go to work. One of us had to have some flexibility. In academia, my kids, I have twins, one on the front and one on the back, and they followed me everywhere around the campus.

David Faulkner: That's great. This might be a tougher question, but it's something that I'm very curious about. Census data shows that 13.4% of the US population is black, but only about 6% of tenured or tenure-track faculty post-secondary institutions in the US. Do you feel additional pressure to provide mentorship or to publish? I've read some articles of people feeling additional pressure; it's like, we have this diversity initiative at the university, you know. Where's our black faculty member—singular? Like, you know, put them on it. 

Darryl Hood: That is so true. And yeah, the answer is yes, but it's how you handle that. So as a junior faculty member, remember, I was at Meharry Medical College. It was very, very supportive. It is the greatest African American health science center in America. And so that was undergirded by a support system. I had that there. Everything was very structured and got it done. 

Now, I would not put that burden on a junior faculty member at a high-resource institution like the Ohio State University. See, that would be a thankless task here. Now, I do it here because there's no pressure, but for a junior faculty person to be tapped to have that extra burden, it's already a series of microaggressions, macroaggressions, I mean, implicit bias. These things are real at majority institutions for underrepresented minority scientists. 

For an example, I am the only African American male in the College of Public Health here. Now, um, excuse me, this is 2021, but with the advent of the Black Lives Matter movement and all of these attacks on my Asian and Pacific Islander brothers and sisters, I think there's a recognition now that the academy cannot continue as it has been. And there are all types of initiatives coming down the pike that will address structural inequality. Ohio State has announced an initiative, it's called INSPIRE, and seeks to hire hundreds of underrepresented minorities over the next seven, eight years or so. You know, Ohio State's huge, so we have every department, unit, college you ever want to see here. And so, we'll see.

Anne Chappelle: I am famously impatient. I think a lot of America is impatient. And that's, to me, one of the inherent problems is that they're willing to make an investment now, and it's time, but are we all willing to wait the right amount of time to really see that blossom? It is this long process that I hope that America begins to develop the patience to fully realize this investment and be able to really reap those incredible people that are growing as a result of these initiatives.

But I get afraid that it's just a trend, and you know, oh yeah, we put some money at it, we'll fix it. It's bigger than that.

Darryl Hood: It is bigger than that. And you are 100% right. I mean, you know, this isn't an activity; it's a cultural change, right? And unfortunately, not enough individuals understand that. Here at the Ohio State University, we believe that the people are already out there. So, what about partnerships? Why can't we force partnerships between low-resource institutions and high-resource institutions? See, there's your pipeline right there. That is what we are pushing here. NIH, the first initiative, was emblematic of that sentiment. Many of the institutions chose not partner. So, I mean, that's not good, right? That's getting off on the wrong foot. I mean, it's not going to work if you think it's just fashionable to throw this money at this. It requires a culture change. And, and we are working on that here. 

David Faulkner: So, of the questions that we try to ask everybody: What was the most significant adverse reaction that you've experienced in your life? 

Darryl Hood: Oh, let's see. In my life? Wow. That's tough. I guess, the worst adverse reaction was the fact that coming from Johnson C. Smith University and going to graduate school, I would be the only one that looked like me in my program. And that was a moment in time where I knew that I would need some assistance, help, and support in making it through that program. 

And believe it or not, subsequent to coming here, in the biggest underrepresented minority program in America, uh, here at the Ohio State University, I met a young lady from Philadelphia, Pennsylvania. We kept in touch after spending a week here. That was in 1982. And when we finished, and she worked a year—and we were, of course, dating—and I actually said, honey, don't you want to get a graduate degree? You can come here. And she actually applied and came, and the rest is history. So that adverse reaction turned into something extremely, very positive for me and my wife and the kids, of course.

Anne Chappelle: So if you weren't where you are now, what would you be doing? 

Darryl Hood: Everyone that knows me says that I would be a preacher on a corner in an African American neighborhood. I'm a very, very spiritual person. My daddy was a minister, his daddy was a minister, his daddy was a preacher. You know, some of these things are, they're in the genes, right?

 Anne Chappelle: But like, for me, even though I don't get to live my dream as a college professor, I still find a way to teach. In a way you've been able to blend it, just a little, a little differently.

Darryl Hood: Yes.

David Faulkner: Great. Thank you so much.

Darryl Hood: Thank you all.

Anne Chappelle: This is so much fun. I love talking. 

David Faulkner: You do love talking. That’s true.

Darryl Hood: David, you weren't supposed to say that.

Anne Chappelle: My kids don't want to talk about this kind of stuff, and it is so neat and awesome and every other trivial word to just really pick somebody's brain. And thank you for spending your morning with us. We really appreciate it.

Darryl Hood: Thank you all. 

David Faulkner: I'm so glad we got to talk with Darryl today. That was an incredible interview. You know, we called the episode, "Speak Softly and Carry a Big Dataset," but I think he speaks from the heart. He speaks with wisdom and, and experience.

Anne Chappelle: Yeah. It's not just wisdom and experience; he speaks with conviction.

David Faulkner: The datasets that he has put together over the years are really astounding. And I'm so exciting to see how they’regoing to be used to make real, meaningful changes in public health.

Anne Chappelle: So, yes. It was great to talk to Darryl. Now, I can't wait to tell you about who we're going to speak to next.

David Faulkner:  And now, the teaser. 

Anne Chappelle: Next time:"More Than a Color Scheme: The Future of Toxicology in Green Chemistry." 

David Faulkner: With Meg Whittaker, of ToxServices LLC.

Meg Whittaker: A big interest of mine right now is how to connect safer chemistry, safer or green toxicology, and sustainability, and how we can try and make things more circular. 

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
Identifying and Understanding Molecular-Level Events Affecting Public Health
Exploring How Place Intersects with Public Health
What Is the Exposome?
Beginning Your Career with the End in Mind
Finding Your Mentors and Being a Good Mentor in Return
The Lack of Representation in Academia
What Was a Significant Adverse Reaction in Your Life?
If You Weren't a Scientist...
Next Time on Adverse Reactions