Dr. Joseph Braun, a Professor of Epidemiology at Brown University, studies the potential health consequences of environmental chemical exposures in pregnant women, infants, and children. More specifically, he has a special interest in studying how early life chemical exposures—ones that we can also modify—may influence obesity and neurodevelopmental disorders like ADHD and autism.
Dr. Braun has been identified by peers as one of the top 20 pioneers under 40 in environmental public health. Dr. Braun was chosen for his exceptional work. According to a press release by the nonprofit organization, Collaborative on Health and the Environment, Dr. Braun’s work will pioneer environmental health science and catalyze policies and actions to protect the health of children, families, and communities.
In August 2017, I spoke to Dr. Braun. I wanted to learn what inspired him to research how early life exposures may affect our long term health. And I was also curious how he applies his expertise into healthy choices for his healthy living.
In addition to getting those questions answered, I got Joe’s top six detox recommendations for the average person. They involve drinking water, canned foods, plastics, carpets, cleaning, and organic foods.
Whether you’re already a parent, considering having children, or if you are just interested in healthy living, you’ll learn about an overlooked pillar of health—toxic exposures from our everyday products—and simple tips to reduce your toxic exposures.
This is an important topic that we must keep learning more about.
Please note that the transcript below has been modified to be more reader-friendly.
Sophia: I've been looking at your body of work for your published research and I just am so excited about your research and what you're focused on. When I was working on my book, it just seemed like there wasn't that much research on prenatal exposures and the potential health effects on the unborn child. To see that you've done so much research focused on that is really exciting.
Joe: Yeah, when I looked at your book, you were sort of at the cusp of when a lot of the research has come out to date that just wasn't there yet. It has really emerged in the last couple of years.
Sophia: I'm really glad that it attracted more interest, more experts, because it deserves it. So I really wanted to just get to know you better, and even you as a human being, and learn more about what led you to this pretty new and emerging field that will attract a lot more attention, but it’s kind of unique that you ended up in this expertise.
Joe: The route was sort of a circuitous one. I grew up in Wisconsin but I was really interested in science from a very early age. I had some very good science teachers in high school. I think that was really the first factor that led to my decision to pursue a career in public health because I always liked science, and I knew I wanted to be a scientist, taking as many chemistry, biology, physics classes that I could in high school.
Surprisingly, I wanted to be a particle physicist for a while, but realized that I needed to be a lot better at math, and I just wasn't good enough at math. So that was really what led me to the science end of it.
And I think the health end of it was a combination of things. But maybe the one that was most influential is that I actually had a brother with Down syndrome; and from a very early age, I learned a lot about biology and genetics that most people probably wouldn't know about.
In fact, I remember being a kid, and my mother showed me the karyotype from my brother that confirmed he had Down syndrome. At that time, to confirm the diagnosis, they would separate all those chromosomes and count how many chromosomes he had to determine that he had an extra chromosome. And I just thought that that was very interesting and that's really what led me to at least to the science end of things.
From the public health standpoint, to get into public health, that was far more convoluted in that I started as a biochemistry major, being very interested in health and science and basic biology, but finding that I wasn't as interested in the basic aspect of it, where it was so unapplied. It was really when I was going back to nursing school after I worked in a few labs that I discovered I really liked working with people, and I liked this practical application of health to people.
And I discovered epidemiology at that time, and found that I got to ask very pragmatic questions about health and science, and then answer them with data from people.
So it was during nursing school that I actually worked with my first mentor, Dr. Laura Anderkno, who gave me quite a bit of latitude to conduct analyses with some publicly available data, and that led to one of my first publications. We were focused on studying environmental determinants of learning disabilities in children. So that experience was what really solidified my interest in studying children's environmental health and using epidemiological tools to do it.
Sophia: So from your perspective since you started, what have we learned?
Joe: When I started this, I was very naive. I remember thinking that this was the most important research ever, and we’re going to change the world, and everyone should know about it.
But, at that time, when I started doing this work, it was at the beginning of sort of this second wave of studies that was coming out, studying early life determinants of children's health. Some of the first ones were some very classic studies done by investigators at University of Cincinnati and Boston Children's Hospital, studying the neurotoxicity of lead exposure. It was the sort of next wave of studies, looking at things like PCBs, and then some later studies starting in California and Cincinnati and other places that were studying on a whole host of environmental toxins and children's health. I came in right when that wave was coming up and I’ve been riding it since. I felt that I hit that at a good time. By studying children's health first, it really led me backwards to think about other determinants of children's health, which would include the prenatal period.
Sophia: I just learned about prenatal exposures, after I had my second child. My third is four years old. So it was maybe four or five years ago that I just became aware of the idea that health issues that may manifest either in childhood, or even later on as an adult, may have fetal origins. Is this a relatively new area?
Joe: This has been something that we've known about for quite some time with respect to a couple of other pharmaceutical agents. The two stories that I think are the most classic examples are the stories of diethylstilbestrol (DES) and Thalidomide.
For diethylstilbestrol, this was a synthetic estrogen that was prescribed to women in the mid-20th century to prevent stillbirth or spontaneous abortion. It was given to millions of women, and it was discovered by some researchers and a physician at Massachusetts General Hospital that this drug was causing vaginal clear cell carcinoma in the daughters born to women that took this drug pregnancy. Dr. Herbst was his name, and he discovered this cluster of vaginal clear cell carcinoma cases among these very young girls or young adults. This is the disease that normally crops up after menopause, but he observed this rash of girls in the Boston area who have this disease.
Through interviewing their mothers, he found that most, if not all of them, had taken diethylstilbestrol during their pregnancy. So this started a whole series of studies that continue to this date, looking at the long term health effects of the exposure, and finding that women born to mothers who took this drug had increased risk of a variety of reproductive problems as well as other cancers besides vaginal clear cell carcinoma.
I think this has really established the developmental origins idea, that these exposures may not produce overt birth defects, like Thalidomide, which is a teratogen, and produce infants with limb defects. Some of these agents aren't just going to produce overt birth defects or very serious clinical diseases that you can observe right away, but effects may manifest later on in childhood or even into adulthood.
Sophia: I'm so glad you brought up that example because I didn't even know about this part of our history until I was researching for my book. And if it weren't for me doing that research, which I mean most women are not researching toxic exposures that their family may encounter, it was only in that research did I start reading about - I refer to the drug as ‘DES’, I could never pronounce the full name – but I read about this history and I thought, Wow I wish I knew about this sooner. Most of the public is not aware of this important part of our history. My physicians, who are really wonderful, they don't extend this idea to everyday life, like being conservative about taking Tylenol if you're pregnant or other sorts of exposure. So I think in the scientific community it’s an important part of the history of epidemiology, but, for the public, a lot of people really aren’t aware of that.
Joe: No, and you're right. I don't think it's something that is on a lot of the public's radar and even from the physician’s standpoint, I think outside the small group of us who do this work, it’s not something that’s in the mainstream consciousness.
It gets attention from time to time. There have been TIME Magazine covers talking about the first nine months of your life and how important they are, referring to the fetal period, but something that I don't think a lot of physicians think about. Again not outside of this realm, and part of that is probably due to their training, that they're not necessarily being exposed to that during training, during medical school and residency. There's not a lot of chemicals and exposures that we know with certainty that might actually cause problems in children or later on in life, with the exception of the handful that we really extensively study, like lead, mercury, PCBs, and tobacco smoke, for instance.
So a lot of physicians don't have that knowledge base to advise women in a meaningful way without creating anxiety and alarm. So that's often why they don't. That doesn’t intervene with their consciousness and some other practice.
Sophia: Yeah, that's why having this conversation is so important just so patients can be aware that this important dialogue doesn't even happen.
Joe: Yes. There have been some studies that have been now been conducted on the granddaughters. So it’s the granddaughters of these women who were taking the drug, and there is some evidence that there may be effects of that drug on the granddaughters and that becomes very interesting to look at because when we think about it, if you're a woman, when you're in your mother as a fetus, a baby before you’re born, all of your eggs that you’re ever going to have are there, right during the beginning of gestation.
Whatever your mother is exposed to, you're exposed to, and your eggs are exposed to. So your mother is exposing her grandchildren, potential grandchildren, to whatever she is being exposed to. This has led to this idea that there could be these trans-intergenerational effects of these exposures that extend beyond just one generation.
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Sophia: Would you speak more about the second drug you mentioned Thalidomide?
Joe: Yes. Thalidomide was a drug used to treat morning sickness. It was used in Europe and wasn't approved for use in the United States. In Europe they observed a series of cases of children being born with limb defects, and they attributed it to the use of Thalidomide. That was part of the reason why it was never approved for use here in the United States. That’s another very famous example of a pharmaceutical agent that can have a very profound effect on the developing fetus.
It's been very well studied, such that they really narrowed down the window of development that the exposure had to occur during gestation, and it’s in a very narrow window within the first trimester. What’s interesting about it is that, the exposure needs to occur during the first trimester in order to elicit these limb defects, and it has to do with the fact that’s when your limbs are actually developing. Exposure later on in pregnancy does not seem to matter or affect the risk of these limb defects.
This has led us to thinking more about these finer windows of vulnerability, or periods of heightened vulnerability, where it might not just be about pregnancy, but it could be about these narrower windows during pregnancy when there's specific biological processes going on that would be sensitive to that environmental agent.
Sophia: Again when I read about that story I was blown away. It reminded me of a time when I was pregnant and I had Coxsackie virus, which is really common among children and really rare among adults. Similar to the chickenpox, I was told, most people are exposed as children and symptoms don't even necessarily manifest. And then you have an immunity towards them.
I must have not gotten it. It's hard to imagine I was not exposed to it as a child. But when I was seven months pregnant with my third child, I got a really serious case of it. And it was pretty unbearable. And I was talking to my father, who was an OBGYN, and my OBGYN recommended I take some medication. I forget what it was. And my father’s reaction was, “Well, if you can bear it [avoid the medication], I would just avoid it.”
After I asked why, he replied, “Well, you just don't know what it might do to the baby.” And when I later read about Thalidomide, I was so glad I was extra conservative.
Joe: For a lot of pharmaceuticals, there's a growing movement towards understanding more of what pharmaceuticals would do to the developing fetus. Shanna Swan at Mt. Sinai School of Medicine, has been doing a lot of work around acetaminophen and its potential effects on the developing fetus. Others have been doing this as well. But I think there's a broad interest in studying some of these things that we assume are safe as pharmaceuticals to determine whether or not they could have potential long term health consequences.
Sophia: The developing science seems to be underscoring that we should be as conservative as possible during the prenatal period because what we do know is that there are critical windows of vulnerability. When people talk about proof of harm, you can only know what's been studied in depth. But there are tens of thousands of chemicals, and so it's just impossible to know what's safe and what's not.
Joe: The other thing I would add is for chemicals, it's easier to say we should avoid them. For pharmaceuticals, there's a balancing act for some medications. For women who have might have epilepsy or be subject to seizures, the risks associated with having a seizure to the fetus could be as worse, or worse than, the medication you take to treat and to prevent seizures.
So it's this balance for some of these drugs determining what's the consequences of leaving this disease or condition untreated versus the medication that could treat it or prevent it. And that's the balancing act that physicians are making, obstetricians are making often with their patients. And there are uncertainties there. That's what makes it difficult.
Sophia: Yeah, absolutely. That's an excellent point. So in your career, which chemicals were you first attracted towards studying?
Joe: When I started with this, I started studying lead exposure in tobacco, which had been studied a lot at the time. One of my mentors, Bruce Lanphear, said to me that lead and tobacco are not a growth industry for environmental chemicals, in that we know they’re bad. Additional studies telling us that they're bad aren’t going to really push the science forward that much more.
That must've been around 2005 or 2006 while I was in graduate school. He said that to me, and I thought, Okay, I'm going to learn new chemicals, and learn about new exposures.
I was at a conference when I decided to learn everything I can about BPA and phthalates at this conference. I watched every talk I could on BPA and phthalates, and read every paper I could get my hands on. Those were the first other set of chemicals that I started studying. As you know, those are potential endocrine disrupting chemicals. This is what led me into this first foray into the endocrine disruptors, where I still sit today in terms of study.
Sophia: From your portfolio of research, it seems that you were looking at obesity and ADHD?
Joe: Yes, I started by studying these as potential neurotoxicants, and focusing on BPA, specifically in the beginning. We were the first study looking at the potential neurotoxicity of BPA, prenatal BPA exposure in humans, and finding that girls with higher exposure during pregnancy seem to have more aggressive and hyperactive behaviors when they were two and three years of age. And where we saw no associations between mom’s BPA exposure during pregnancy and aggressive or hyperactive behaviors in the boys.
We’ve extended that to look at other endpoints like adiposity, and then also look at other chemicals. And in terms of the BPA work, by and large we have not found that it seems to be a chemical obesogen, which are a class of chemicals that may cause the developing fetus or child to gain weight more rapidly, or to have alterations in the metabolism, such that they are predisposed to cardiometabolic disorders or to more rapid—or to more—fat mass gains.
Sophia: So BPA does not seem to be an obesogen?
Joe: Not in the work that we've done in our study and in several other cohorts that have been done on this as well. It doesn't seem to be. If anything, there's maybe some suggestion that it is associated with slightly decreased weight early in life, at least prenatal exposure. And we’ve seen some evidence that maybe it's associated with changes in the growth trajectories of girls, such that they grow a little differently. But it doesn't seem like it's causing children to become heavier. At least from the data we have so far.
Sophia: Around the time I published my book, I don't remember the exact number, but, I remember quoting something about the studies on BPA being, like, 800—that there had been like 800 studies worldwide, peer-reviewed studies (that number might be wrong, on BPA), and there was still no consensus on whether current public exposures to BPA were harmful. That seemed to be the general position within the United States, but outside the United States there were authorities urging more caution.
Joe: BPA has been one of the more polarizing exposures in the field, in terms of the opinions of others, the toxicity. Some people very adamantly believe that it's toxic for either one or more health endpoints; other people being very adamantly believing that there is no evidence of toxicity at the levels that we're exposed to. And then there's people like me who try to sit in the middle and just do good science. And that's not to say anything negative about anyone or any other people’s science, but just try to do good science and let that speak for itself.
I don't think it's clear the levels that we're exposed to are toxic. I think there's some evidence for neurotoxicity associated with prenatal exposure. There’s a variety of studies showing some signals where there may be an association between prenatal or early childhood exposure in neurodevelopment. But they're not all consistent. It's not like the studies of lead where we really observe very consistent findings between lead exposure and child cognitive abilities. It's just not as clear cut as that.
And the other piece of it too is that, these animals studies are difficult to interpret with respect to humans because we are exposed to much, much lower levels of BPA than are ever used in these animal studies. Several orders of magnitude less. And that makes it difficult to extrapolate the doses being used in these animal studies down to the levels that we perceive in humans.
Sophia: Would you speak more about the challenges of studying something like BPA? Is there no debate on whether BPA’s an endocrine disruptor?
Joe: BPA is estrogenic, and in that definition of the endocrine disruptor, then BPA would be one. But the nuance to it is whether it’s a potent endocrine disruptor, in that, is it strong in the effects? That's where some of the debate lies.
But it certainly is an estrogen. In fact, it was investigated as an estrogenic compound in the early 1900s by Dodds and Lawson to determine whether it could be used as a synthetic estrogen for women either during pregnancy or for other purposes.
Dodds and Lawson worked with the group that tested BPA and about 200 other compounds including DES. They found that the BPA was just a much weaker estrogen, or had much weaker estrogenic effects in their paths than did other compounds suggested. Including DES.
Sophia: Given your expertise, and let's just take BPA—I'm wondering, we know BPA is found in some canned foods, and it's in some plastics. So, in your home, do you buy canned foods and do you use plastic containers?
Joe: We haven’t been using plastics for a long time. We phased it out when I was doing this research as a graduate student. I phased the use of much of our plastic containers out slowly, and switched to all glass. By and large, we use glass for storing things.
Cans are hard. You know, it's tough. My example is always, it's tough to make chili without canned foods. I mean you can do it but it’s a lot more work to rehydrate beans and then get the tomatoes. I mean, it's a lot of work. So if I want to make chili very quickly, I'm going to buy some canned tomatoes and some canned beans.
In the last several years, we've really cut back on the amount of cans we use. But, there are times when you have to use it. And the advice I give to people who are concerned about this is that the food that's in those hands often is very healthy: Canned beans, tomatoes, and other vegetables, they're very good for you. We want people to eat them. So if you're not going to use canned foods, then don't replace that with something that's unhealthy. So I think that's the balance that people will have to make is making that choice.
When they do decide to make that choice that they’re going to avoid BPA exposure from cans, then they're going to have to get that nutritious food from another source. And the question is just what's that trade off. Is that trade off worth it for them?
I think you can reduce your exposure a little bit or enough, or reduce exposure some, and, by and large, still consume all the nutritious foods you want. It requires you making more choices, and expending some effort to it.
Sophia: I love asking someone like you, who is so immersed in the research on like BPA and phthalates, and gaining insight on how you balance your knowledge with everyday life.
Joe: What I've taken away from it over the years because, as I started doing a lot of this research, it's very easy to drive yourself crazy thinking about all the things you’re exposed to in all the ways it could potentially be doing some harm to you and your family. You can make some choices to reduce your exposures and there are very nice studies that show that the people can reduce their exposure to some chemicals through various interventions.
But at the end of the day, I think what it really speaks to is that these shouldn't be individual-level. These shouldn’t be decisions we leave to the individual. We should be having better policies and regulations that protect people from chemicals at the population level. So if we suspect that something like BPA is harmful, we should do something about it. So rather than leaving it to individuals to try to reduce the exposure, which they can do, but it’s difficult, we should actually take action at the national level to reduce exposures.
Sophie: I agree. It just seems really hard to enact those policies in the United States.
Joe: The Europeans are ahead of us in that respect, in that their new legislation called REACH is supposed to make sure that all chemicals are tested before they enter the marketplace. Whereas here in the United States, the status quo, until recently, was that chemicals were innocent until proven guilty, so to speak. So there was little or no premarket toxicity testing. Most of that did not involve testing for potential development toxicity to the fetus or development as a child.
And so we don't really have good information on a lot of these chemicals that are used, and, as you said earlier, there are tens of thousands. The last number I actually saw was over 80,000 being used in commerce. So it's overwhelming to the individual to try to reduce their exposure, and that's why we need the regulations to protect people.
Sophia: Absolutely. But in the meantime, there's a lot we can do because I remember when I was reading about this stuff, I definitely was upset that there wasn’t more thoughtful regulation on these
chemicals in the United States. But I also knew that now is my children's window of vulnerability. And it seems like there are some choices we can make that will help. So for example, what you've done over years and I have too is to phase out plastics as much as you can and use glass containers. But, with a healthy balance, and, with, like the canned foods, cut down when it's not a big deal. But when it will really add nutrition to your dinner, then go for it. But being more mindful of it is helpful.
Joe: No, and, it's not just limited to BPA and phthalates. For things like pesticides, it’s shown that you can reduce your exposure to pesticides by consuming organic foods. And there’s been several intervention studies that show that people can do that. So I think that's another place where people can make a difference as well.
Where it gets harder is a lot of these chemicals that have very long half lives in our body. So things like some of the flame retardants. They can have biological half lives on the order of years; meaning, they stick around for a very long time.
So it's very hard for us to get rid of those exposures, and we don’t really know of any ways that we can get rid of those exposures if they’re in us right now. So, again, that speaks to the fact that we need to prevent those exposures.
Sophia: There was this study years ago… I think it was at Harvard. I don’t know if it was children, or I don't remember the demographic profiles of the participants of the study, but the body burden of certain pesticides were measured before the study, and then at the end. And I think it was a five-day study and they found that by the participants eating a purely organic diet with foods—not from canned—like fresh whole foods, not canned, not around plastics, the level of pesticides…and I might be confusing studies…but the point is that with some chemicals in the body, when you do make changes like choosing to eat more organic foods, the pesticide levels in your body can decrease.
Joe: Yeah, there was a study by Alex Lu and his colleagues looking at pesticide exposures and switching away from pesticides containing foods and showing that—and there was another study out of the Silent Spring Institute by Ruthann Rudel—where they did an intervention study, a small intervention study, that got families to switch to non-plastics, or to foods not stored or processed in plastics. I believe they did organic as well. And they showed there that they produced urine levels of BPA in some of the phthalates in those participants during that intervention period.
So it's remarkably effective. There was one study that’s been done that’s sort of interesting is that it was a German group where they had five people fast for, I think it was a full day, if not two days. And the only people I can imagine doing this were people working in that lab group. So some poor souls had to suffer through a day without eating. They were allowed to drink water and that sort of thing. But their BPA levels plummeted remarkably during that period of fasting because most of our exposure is from the diet.
So we know we can make a real difference in our exposure through the diet. And I think that's part of the key message if we want to do something regulatory-wise is that we can probably do it by intervening on diet.
Sophia: Yes, but, also, as a consumer, if you make different choices, your body can decrease its load of chemicals, like BPA and the pesticides. Right? If you cut down on the input into your body, then your body is able to flesh out some of them.
Joe: Yes, so for these chemicals, like BPA and phthalates, they have very short half lives in our bodies. I mean, they don’t stay in us long. So something like BPA has a half-life of about six hours. So that means that after about 30 hours, we got rid of over 95 percent of the BPA that was in us before. So BPA, we can reduce our body burden of that quite quickly.
Phthalates are similar. They have half-lives of 6 to 24 hours so if we stop our exposure to those, we can reduce it, our body burden, considerably in the course of a day or a couple of days.
It's these other chemicals that have these long half-lives that are really challenging to do something about because they leave our body very slowly, taking years just to decrease the amount by half. So it’s those chemicals that are really challenging for us, and we don't want have the interventions to deal with those yet. But there are people thinking about that, and working on ways to either reduce our exposure to them or try to help us get rid of them faster.
Sophia: And what do we know now about that potential health effects from phthalates in our bodies?
Joe: So the phthalates are interesting in that the rodents studies that have been done, there’s been very compelling evidence that phthalates are anti-androgenic. Meaning, they seem to be associated with a decrease in the synthesis of testosterone in rodents, particularly male rodents. And those phthalates exposures in male rodents are associated with genital abnormalities as well as other problems with the male reproductive system. And there seems to be some evidence of human studies that’s consistent with this, suggesting that phthalate exposures are kind of anti-endogenic with the developing fetus, particularly the male fetus. And this work has been extended now to look at other endpoints like neurodevelopment as well as adiposity.
There also seems to be some good evidence suggesting that the phthalates may be associated with some neurobehavioral problems, a wide range of them, as well as decreases in IQ or cognitive abilities.
Several years ago there were a series of good studies done by a group in Europe, showing that childhood phthalate exposures seemed to be associated with allergic diseases as well as asthma. So there's a wide range of potential effects that phthalates would have on human health both from prenatal exposures and early childhood exposures.
Sophia: And do you know if there have been studies on whether affected children had improved symptoms if their phthalate exposures were reduced?
Joe: That hasn’t been done. And that’s a very good idea for some of these health endpoints, like things like allergic diseases or symptoms of asthma. I’m not aware of anyone who’s done that yet but that would be a very clever study to do for some of these things that have, you know, flare-ups, so to speak, where you have symptoms that become more pronounced from certain things. Whether you can reduce exposure, whether that would improve someone’s symptoms. That would be a very powerful design to have a study because it would apply some level of cause—it would be more common that it could be causal.
Sophia: So you went from studying lead in tobacco to BPA and phthalates. And then did you move on from that group?
Joe: Well, we’re still somewhat looking at BPA but we really moved into looking at phthalates and triclosan as well as perfluoroalkyl substances. And now I've been doing more work looking at some of these new replacement flame retardants. Well, the replacement flame retardants as well as some of the established, older flame retardants that have been used that are being phased out of production now.
Sophia: For those listening, a lot of these chemical names are unfamiliar, but the chemicals you've talked about, what are common products that they’re used in?
Joe: It varies by chemical so I will say that not all of these are used in everything but the things like phthalates, they can be used in some plastics, in some medications and pharmaceuticals. They’re used in some personal care products as a scent retainer.
Things like BPA are used in plastics and resins.
Some of the triclosan and some of the other microbials can be used in hand soaps. Triclosan was actually recently banned from use in hand soaps, but is still used in some toothpastes.
Things like the flame retardants are found in things like foam furniture, also found in electronics, carpet padding. And it’s even found in some things like baby products in order to meet certain flame retardant standards. All of these chemicals are in a lot of different products we use. By and large, we’re exposed to lots of them on a daily basis.
Sophia: Would you speak more about replacement chemicals? Because you mentioned you were studying flame retardants that were used widely, and I think you said you were looking at replacement flame retardants?
Joe: Yes, so I think this is really an important topic right now because a lot of manufacturers and retailers are very aware of consumers’ concern about the potential health effects of these chemicals. Wal-Mart announced a list of chemicals that they’re going to phase out of its stores over the next several years. And Wal-Mart has enormous sway in the marketplace because they purchased so much and then sell them. So if they demand that certain companies quit using something like triclosan or parabens, the market will follow and stop using it.
So I think that's one driving force behind this as well as what I refer to as the mommy bloggers who have really gotten very involved in raising awareness about this. So chemical companies, retailers, producers, they’re all very aware of this. But they still need chemicals in their products. And so the flame retardants are a great example where for years, and decades actually, these very persistent chemicals were used as flame retardants in foam furniture as well as carpets and electronics.
And in response to mounting evidence that they were persistent and potentially harmful to our health, the manufacturers switched to a different set of compounds. And of course these other compounds have never been tested for, or have less testing on them, for potential toxicity. So almost overnight now you have a whole new set of chemicals out there in the marketplace that we know little to nothing about. We don't even know if we’re exposed to them to begin with. And that makes it very challenging as scientists who are trying to study this in terms of figuring out is this something we should be concerned about. And this is not just limited to flame retardants. This happens for other chemicals as well whether things like phthalates, instead of using phthalates, they might use a compound that looks a lot like phthalates but it’s just very subtly different from that phthalate chemical.
Sophia: It must have been ten years ago, I was just learning about the idea that there are toxic chemicals in everyday products and I was looking for a crib mattress. In trying to understand how do I identify a safe crib mattress for my daughter, I got connected to a store owner in San Francisco who said that--I'd never heard this before but it made a lot of sense and it stuck with me—he said that when a chemical starts being associated with a strong, like proof of harm or emerging evidence that indicates harm, the chemical companies will just tweak the chemical structure of that chemical a little bit, and rename and then use that. And so this new chemical has no history of harm because it's brand new, but it's chemically not that different from some chemicals that we maybe know are harmful. Do you think that's true?
Joe: Well, I can't speak to what that other person said, but you know from phthalates, that is the case for one particular phthalate, that is shown to be anti-androgenic in rodents. After a very large number of studies have shown potential harmful effects of this particular phthalate, they now switched to a chemical that’s virtually identical to its structure, with the exception that it has some additional hydrogen atoms on it. So it’s much like what you spoke of, where they just alter just a tiny bit and tweak it, and it does the same thing the other one did. But we don't know anything about its potential toxicity.
Sophia: What about like BPA-free products? Some of them contain this chemical BPS. Are you familiar with how similar BPS may be to BPA?
Joe: No, and that’s another great example where it’s a drop-in replacement, so to speak, where you just substitute one very similar chemical for another and BPS is another great example of that. And we don't have good health data on it. There are some people that have been able to respond to that change and do some experimental studies in rodents or in these in vitro systems and show that maybe these chemicals could be as harmful as BPA in certain model organism systems.
But we don't have any good human health data on it yet. And there's people trying to figure that out but it’s a long game that you play to do that, right? Because to do these sorts of studies well, it takes years. And these manufacturers can switch these chemicals in and out in a much shorter timeframe. So we're always playing catch up. I refer to this as the chemical whack-a-mole. You hit one of them down and another one pops up somewhere else. You hit that one down and then another one pops up; and you just keep playing the game. And you’re not going to win at it because the moles are always going to just keep popping back up.
Sophia: What do we know as a community about obesogens?
Joe: So there’s been a considerable number of studies on some of the, what I call legacy chemicals, like some of the pesticides with some evidence that they may be obesogenic. But they’ve been less on the more contemporary chemicals that we worry about like BPA and phthalates, although our group and others have contributed to that literature considerably in the last few years.
It depends on the chemical you’re talking about, but there does seem to be some evidence that some chemicals could be obesogenic, even some of our well-established endocrine disruptors, like DES seems to be obesogenic. So it seems plausible that DES may have some obesogenic fat, perhaps, and maybe some of these other chemicals could also be associated with obesity.
And I think the ones that I personally think there’s a strong evidence for are things like polyfluoroalkyl substances, I think are particularly concerning with regard to obesity. And we’re doing some studies on that right now to look into this as are others. That body of evidence has really grown in the last few years to suggest that maybe there are some obesogenic effects of that chemical blast in humans.
Sophia: Is the acronym for that PFOS?
Sophia: PFAS. Okay. And what kind of products are those used in?
Joe: So the polyfluoroalkyl substances are used in a lot of different commercial and even some industrial applications. In commercial products, they’re used to make stain and water repellant coatings. So thinking like Gore-Tex or Scotchguard, which is applied to fabrics. They’re used to make things to help repel water and oils from textile.
They are also used in some firefighting foams, especially for certain chemical fires. They’re very good at putting fires out.
And then they're also used in the industry in surfactants when you’re making these fluoropolymers. These chemicals get released into the environment when they’re being used to make these different products, or they can be formed when they degrade from other products that they’re used in.
We think that exposure is predominantly in the diets of most people because this class of chemicals seem to bioaccumulate through the food chain. So levels of it get higher as you go further up the food chain. Humans being the apex predator on the planet right now consume a lot of things that we know have high levels of this.
There have been some cases where contaminated water is a major source. There have been several instances where these chemicals end up in local water supplies, and resulted in populations having higher exposure to these chemicals. So that's another potential concern. But probably less of a contribution for most of us on a day-to-day basis.
Sophia: What have we learned about neurodevelopment?
Joe: What we know is that there is a wide range of chemicals that seemed to be associated with a variety of neurodevelopmental disorders. And I think where the evidence is stronger is for things like pesticide exposures, being associated with possibly increased risk of autism spectrum disorders as well as other behavioral disorders like ADHD.
And then for some of these other chemicals of emerging concern, I think the evidence is not clear yet. But in some cases, like for BPA, there’s suggestion within that literature that this chemical may be a neurotoxicant. For others, we just don’t have a lot of data yet to make firm conclusions. We know, for some very established neurotoxicants, like lead and PCVs and methylmercury. So in those cases we have very good evidence to make those conclusions. But we're just not there yet for some of these other ones.
Sophia: As an epidemiologist and a researcher, how do you feel about our resiliency?
Joe: I think that’s a really interesting question and it’s one we’re starting to think about more in our group in terms of can we adapt to these exposures? And thinking, too, about children in that they’re amazing and they can take these stressors and adapt to them.
Sophia: I’m sorry, what do you mean by that?
Joe: For instance in terms of brain development, the developing brain is really in a very plastic state in that it is changing. And there's the hypothesis that maybe because it's in this very plastic state, it can adapt to a stressor. So for instance, children might be able to, in a clinical case, they may be able to recover better from some sort of mild lesion in their brain, for instance, from a traumatic head injury or a mild head injury.
But we don’t know this for chemicals. We don't know whether or not children can get better. And I think that's really what I'm thinking about with this, is that—is there an ability to, in a way, a resiliency to these exposures where children might be able to compensate in some other way and adapt to exposures, not in an evolutionary sense.
Sophia: From reports I had read, I kept reading about children being uniquely vulnerable to certain things, like certain toxic exposures, like lead. But one time I spoke to a geneticist—I wish I remembered her name. We spoke briefly and she made a comment that children are much more resilient than adults are. And it confused me because it was in conflict with most of what I read, but I thought that I know she's from the perspective of genetics and I was just, I don't know if you have any insight on that, that children can be both more vulnerable in some ways than adults, but also more resilient.
Joe: Yeah, it is a little bit of a paradox, but I think so much of it depends on the severity of any sort of stressor in terms of its effect on the developing nervous system as well as where that child is of age. And in some ways related to their functional capacity to deal with those stressors.
One of the examples where resiliency comes in, is in some work that’s done by Tom Guilarte and some of his colleagues—I believe he’s at University of Florida now, but used to be at Columbia when he did this work. He showed that in lead-exposed rodents, he could actually alter the effects of lead by getting the rodents in an enriched environment.
So normally, rodents are stored in these very sterile-looking plastic cages with some food pellets hanging in there and some water. Instead of storing the rodents in those cages like that, he would give them these enriched environments where they had little logs to climb in, and there’s grass, and other things for the rodents to do and play with; and it is seemed to make a difference in terms of the effects of lead on these rodents’ neurodevelopment.
We know very few people who have asked that in humans, and explored whether an enriching environment seems to buffer some of the effects of neurotoxicant exposure to brain development. But that could lead to interventions that could help us deal with this, deal with the potential effects of some of those chemicals.
Sophia: I have read about diet—breast milk and breastfeeding—also providing some protective benefits. I don't remember against which chemicals, and also maybe folate and like spinach, but some studies are out there, but probably it's not a strong enough body of science.
Joe: No, and it really has not taken hold yet. I'm not sure why, but I think it's something that is worth looking at more because if we’re not going to be doing something about preventing exposure to chemicals that we’re going to maintain the status quo, then we need to have some ways to mitigate the effects that they can have on children after their exposure occurs. And those are the types of studies that we need to do whether it's breastfeeding, micronutrient support, or an enriched environment.
Sophia: I’m so curious how someone like you applies what you know into your everyday life. One question I have is, Do you drink filtered water?
Joe: We do use a water filter at home, and I do suggest to people if they are concerned about contaminants in their water, to use one. I think the key to that is just remembering that if you install the filter, you have to use it, and you have to maintain it. So those filters need to be changed periodically in order for them to be effective. It’s just, again, a little more commitment on your part. But I think it’s something that is a relatively low-cost, low burden thing that people can do if they’re concerned about exposures from water.
Sophia: What are your top three to five tips on what people can do that are practical and high impact?
Joe: In no specific order I think:
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