Microplastics, Public Health, and the Problem of Proof
Microplastics are no longer just an environmental story. They are becoming a public health story.
Tiny plastic particles have been found in water, food, air, human tissue, and even parts of the body where we once assumed they would not appear. At the same time, many chemicals associated with plastics — including PFAS, phthalates, bisphenols, and flame retardants — have been linked to concerns about fertility, child development, metabolism, cardiovascular disease, and chronic illness.
That is enough to take seriously. But taking something seriously is not the same as treating every alarming claim as settled science.
A recent conversation between Secretary Kennedy and Dr. Leo Trasande, a pediatrician and environmental health researcher at NYU, shows both the urgency and the complexity of the microplastics debate. The interview raises important questions about chemical exposure, industry accountability, federal research, and the hidden health costs of plastic production.
The risks are real. The uncertainty is real, too. Some evidence is strong. Some is emerging. Some claims are plausible but not yet proven. That is why the right public health response is neither panic nor dismissal. It is proportional precaution: reduce avoidable exposures, strengthen chemical safety rules, invest in better research, and make sure the burden does not fall only on individual consumers.
Like in previous versions, our commentary is italicized and blocked in this color.
Dr. Leo Trasande: There is a lot of hope. There are companies that are showing leadership and using sustainable and alternative materials that are free of these chemicals. They’re thinking about a new way and part of the reason we’re stuck is there’s some entrenched interests that are keeping or holding on, gripping on tight to the $500 billion a year industry and they’re costing human health in the process.
Secretary Kennedy: Everybody, welcome to the Secretary Kennedy Podcast. Today, my guest is Leo Trasande, who is a pediatrician, one of the country’s leading experts on environmental health and toxic exposures. He’s a full professor at NYU and he’s the director of the Grossman Center for the Study of Environmental Hazards. His work focuses on how substances in our food and our air and water, especially microplastics, to affect our children’s health and contribute to chronic disease. Dr. Trisande has helped bring national attention to the hidden costs of these exposures, both in human health and in economic terms. His perspective is especially important as we launch a new effort at HHS to better understand and reduce these risks. Welcome to the show.
Dr. Leo Trasande: Delighted to be here with you.
Secretary Kennedy: I first met you when we made our announcement about we’re going to spend a lot of money now over a hundred million dollars to study microplastics for the first time and particularly the fate in your body because we know that microplastics are now ubiquitous in the environment. Talk about that for a minute. How dramatic has the increase been in our environment and also in our bodies?
Microplastics are real, widespread, and increasingly found in human tissues. But it is important to separate three related issues: visible plastic pollution, tiny micro- and nanoplastic particles, and chemical additives such as phthalates, bisphenols, and PFAS. The evidence base is strongest for many plastic-associated chemicals. The evidence on micro- and nanoplastic particles themselves is growing quickly, but still has major measurement and causality challenges. That distinction matters because good public health policy depends on matching the evidence to the specific hazard.
Dr. Leo Trasande: Well, plastics truly represent a multidimensional and urgent threat to human health. When you boil down plastics, there are multiple layers. We’re talking about macroplastics that you see on the beaches and in sea turtles. You’re talking about micro nanoplastics, visible and invisible materials. But where we’ve really recognized the urgent threat to each of us of plastics in our lives were the chemicals in plastic. We know that there are 16,000 chemicals, synthetic chemicals that are in plastic. We don’t know anything about 10,000 of them. What little we know about the 6,000 is that they harm a wildlife and they harmed human health. In particular, the evidence is extremely strong for the effects of plastic chemicals on our hormones. These are our natural signaling molecules that underlie basic biological functions, temperature, metabolism, salt, sugar, and even sex. And the impacts run from cradle to grave and womb to tomb.
We don’t know enough” is not the same as “we know they are all dangerous.” But it is a public health problem when thousands of chemicals are widely used in consumer products before their long-term health effects are well understood. A fair reading is that the absence of data should not automatically reassure us, especially when exposures are widespread, involuntary, and affect children and pregnant people.
We’re talking about … I’m going to just focus here on the chemicals with the greatest evidence. Bisphenol is used in polycarbonate plastics, phthalates used in personal care products, cosmetics, and food packaging. We’re also talking about per and polyfluoroalkial substances, the non-stick forever chemicals profiled in Mark Ruffolo’s movie Dark Waters from a large contaminated population in West Virginia.
Secretary Kennedy: Yeah. I was actually an attorney on that case.
Dr. Leo Trasande: Thank you for all your support and leadership in that regard. It really helped move the needle. And it was those studies in West Virginia that set the foundation. Those were very high level exposures, as you know. Now we know that extremely low levels of exposure that we commonly see in blood testing that the Centers for Disease Control and Prevention run through the National Health and Nutrition Examination Survey. These are exposures that literally affect us all. We assumed at first that only the dose made the thing a poison. This is a notion that was first discussed in 1500s by a Swiss philosopher named Paracelsus. And the idea was that, okay, a little bit of everything will be fine, if you will. Our bodies can adjust. Homeostasis was the common cry in that regard. But we realize that at extremely low levels of exposure to a host of chemicals, metals, lead, methyl mercury, pesticides and flame retardants can have significant consequences.
The biggest consequences at those extremely low levels of exposure. We’re talking about grains of sand in the Sahara or grains of salt in the Olympic size swimming pool. If you will, extremely low levels of exposure based on the principles of endocrinology, because our hormones, our natural molecules run around in those same levels of exposure. And whether the chemicals are competing with hormones directly or they’re changing mechanisms behind the scenes in how our genes are expressed, they’re affecting us all. We’re talking about just to start in the cradle, we’re talking about babies being born too soon. Phthalates, these chemicals that are used commonly in food packaging contribute to 50,000 premature births in the US each year. We’re talking about kids who are born with inadequate brain development as a result of that and they’re less well able to perform in school and less well able to perform in the economy and there are additional healthcare costs that are directly related to those toxic exposures.
And I’ll talk about that. I can talk about that a little bit later. But just to move along the lifespan, we’re talking about babies being born too small as well. Those non-stick chemicals, the PFAS that we just talked about, they shrink growth such that the baby is metabolically programmed to come out of the womb in an avid calorie rich environment. They gain too much weight as a result because their thermostat is just set the wrong way and they accrue more fat than people who are not exposed to these chemicals are experiencing. And so we know that there are at least 50, perhaps 100 or more chemicals that literally make us fatter, many of which are plastic chemicals. And the impacts … As a pediatrician, I’m always going to say kids are uniquely vulnerable pound for pound. They eat more food, drink more water, breathe more air, so they’re uniquely susceptible.
Their organ systems are also just being primed. And so if you disrupt that, there are lifelong and permanent consequences of those toxic exposures that can arise. But to be perfectly candid, secretary, we are all susceptible to these chemicals. For example, again, the PFAS are associated in multiple studies with diabetes, incident diabetes in adults. In adults who’ve actually lost weight through a healthy diet and physical activity intervention, they’ve gained more weight back. And then when they looked for a mechanism, they realized that the resting metabolic rate was lower in those highly exposed subpopulations. So they had drawn serum right after they had lost the weight, working hard to keep healthy and they ended up gaining more weight back as a result of that PFAS exposure. We know that bisphenols also contribute to incident diabetes. We have a large body of evidence now that reproductive development is particularly harmful.
We are dealing with increases in infertility across the US population. We know, for example, that again, phthalates are antagonists to the male sex hormone and those impacts on the male sex hormone lead to a reduction in what we call anogenital distance. And the anogenital distance you’re born with is the anogenital distance in a population that you’ll have as an adult. Mini puberty, there’s a period in infancy where you can change that a little bit because there’s a surge of sex hormones, but we know that if you’re born with that AGD, you’re more likely to have a short AGD in adulthood and men with short AGD because of an imbalance of male and female sex hormone factors are more likely to have infertility, lower sperm count, and even cardiovascular risks. So we’re talking about a broad range of consequences. We know that hormone sensitive cancers are directly related to plastic chemicals.
We know that bisphenols are synthetic estrogens that can have ovarian impacts. PFAS have been associated with incident breast cancer. So again, we’re talking about impacts that run the entire lifespan.
Cardiovascular disease, again, nothing I’m talking about mitigates the importance of healthy diet and physical activity in combating the obesity and diabetes twin pandemics, but we know that phthalates contribute to inflammation in the coronary arteries. They can contribute to cardiovascular mortality. We’ve identified that 50,000 Americans between the ages of 55 and 64 die early because of cardiovascular disease costing the economy roughly $20 billion a year. So those are just some illustrative impacts and that’s just talking about really the chemicals that are either additives to plastic materials, monomers, in plastic materials. Mind you, plastics are long polymers. They’re rather boring polymers compared to DNA. DNA is for AGCT in the system. You can vary it a little bit. Polymer chemistry is essentially the same molecule being strung over billions of times. And we assumed for many years that plastics were what you might call inert, that they didn’t break down as part of the natural process contact with food, contact with the environment, with the water supply.
And yet we know now, unfortunately, that these chemicals leach directly into our bodies.
The evidence linking some endocrine-disrupting chemicals to reproductive, developmental, metabolic, and cardiovascular outcomes is substantial, but not every claim has the same level of certainty. Some findings come from strong epidemiologic patterns supported by animal and mechanistic studies; others remain more suggestive. The public health challenge is that waiting for perfect proof can leave people exposed for decades, while acting too broadly without precision can create confusion and backlash. The right standard is not panic. It is proportional precaution.
Secretary Kennedy: You’re talking about PFAS and PFOAs and what we call forever chemicals. Yes. And these are the plastic constituents. They can also be inflamed retardants as you pointed out and in glues and those are also ubiquitous in the environment. But one of the interesting things that I learned when we did the dark waters case is how dangerous these particular molecules are because your body has such difficulty excreting them and that’s one of the reasons they call them forever chemicals. Can you explain that?
Dr. Leo Trasande: Sure. So the earliest PFAS that we’re in manufacture were what we call eight to 12 carbon chains of molecules. So carbon atoms, I don’t mean to make … My undergraduate degree is in chemistry, so I’m going to sometimes sneak in a little chemistry and nerd out a bit, but just to take a step back, these are eight carbon molecules and that carbon fluorine bond that makes these per and polyfluoroalkal substances is extremely what we call polar. It stretches out. The electron energy is distributed in a way that makes it so that materials don’t stick. That’s really what, in the end, in the polymer chemistry, makes them such useful materials.
Secretary Kennedy: That’s why they put it on your fromican.
Dr. Leo Trasande: That’s right.
Secretary Kennedy: And that’s why you should use iron to skill it.
Dr. Leo Trasande: I love cast iron and stainless steel. Last I checked, olive oil was good for your heart.
Secretary Kennedy: So
Dr. Leo Trasande: There you go.
Secretary Kennedy: So go ahead. Why does that leave your body?
Dr. Leo Trasande: Well, that carbon fluorine bond also makes it hard to get out of the body because your kidney doesn’t really know what to do. In fact, it’ll actually get excreted and then reabsorbed into the bloodstream. So the body actually has this uncanny ability to recirculate some of these longer chain PFAS in particular. Now as attention with your leadership has been placed on what we call these long chain PFAS. There are now 16,000 PFAS out there. The chemical industry is very
Secretary Kennedy: Adept. That’s because every time we get one band, they alter a couple of molecules on it and then sell the same thing and then it takes us 10 years to prove that it’s doing the exact same thing as the predecessor chemical.
Kennedy is describing what environmental health researchers often call “regrettable substitution”: replacing a restricted chemical with a close chemical cousin that later turns out to have similar risks. This is a real regulatory problem. A chemical-by-chemical approach can be too slow when companies can slightly modify a compound and continue business as usual. A more protective approach would evaluate classes of chemicals and require better safety evidence before widespread use.
Dr. Leo Trasande: I don’t mean to laugh. I think it’s tragic that we have this problem. We literally whack the mole. That’s a theme in the field that I study. It keeps me gainfully employed in ways that I’d rather be put out of business, if you will, not having to deal with these chemical compounds, that the industry keeps modifying and we have to keep following a tiger that’s getting loose. And in that regard, what’s really unfortunate is we’ve gone so far to get some of the longer chain PFAS out of manufacturer. This was through a voluntary agreement between EPA and the industry some years ago and now the chemical industry has developed what we call these shorter chain, these smaller slimmer molecules. Now they aren’t living in the body forever the same way. They actually are being excreted a lot more readily, but they’re so ubiquitous in their exposure that they’re having the same impact as the older PFAS.
And I can go through examples with bisphenols and phthalates where we have the same old story where the chemistry gets modified. We find out the effects of one chemical, that’s what really accelerated the change. And then we realized that the new replacement is as problematic if not more so than the old one.
Secretary Kennedy: You mentioned fertility by virtue of me being the secretary of HHS, I also sit on the Social Security Administration Board, which means I have to go to a meeting once a year and in the meeting they talk about … I mean, one of the things they do at the meeting is they talk about the life of the Social Security trust fund. So when is Social Security going to run out of money? And one of the key metrics that they have to know in order to make that prediction is the fertility rate in American children. They do a lot of data collection on fertility and the fertility levels that we came up with in this last meeting a couple of weeks ago were stunning and historical and everybody in that room who understood the implications was in shock because we went from 1.9, which is already extremely low to 1.75 and it was the greatest drop in fertility that has been seen in human history.
Dr. Leo Trasande: Two is the replacement rate.
Secretary Kennedy: Right. Two is the replacement rate and they actually believe that we’re somewhere around 1.4 because there’s data manipulation. So it has all these kind of economic implications like our ability to support Medicare and the date when the Social Security Trust Fund is going to run out of money, but it also has all other kinds of implications about families and about just the way that we live our lives. You’re seeing young people’s behavior change and we’re seeing that we can’t explain exactly why fertility is decreasing because as you know, there are thousands of exposures that are endocrine disruptors that are disrupting it, but clearly plastics and microplastics are part of that picture.
This is a claim that deserves careful handling. Fertility rates are affected by many forces: age at first birth, housing costs, childcare costs, labor markets, relationship patterns, health status, environmental exposures, and cultural change. Endocrine-disrupting chemicals may be part of the biological story, especially for sperm quality and reproductive development, but they cannot explain fertility trends on their own. The fair position is that chemical exposures are a plausible and important contributor, not the sole driver.
Dr. Leo Trasande: Absolutely.
Secretary Kennedy: And male sperm counts, I think in this country are down 50% for teenage males. I read the other day that teenage males today have less sperm than the average 65-year-old American man and testosterone rates are dropping and then you see female fertility issues too, like nothing that we’ve ever seen before. Will you talk about that?
Dr. Leo Trasande: Yeah. So the reality here is that it’s as much a problem for fertility as it is a marker of chronic disease because we know that obesity and diabetes and cardiovascular disease are also impairing fertility. And you talk about the replacement rate when you have a chronic disease epidemic bearing down on the population, that means that the ability of the population that’s alive to serve the economy in a way that keeps that engine going, that generates revenue for the Medicare Trust Fund to stay solvent, you have almost the perfect, you have a collapse from two different ends, if you will, as a result.
Secretary Kennedy: And the Medicare Trust Fund at this point, just so that people know, is scheduled to go bankrupt in 2033.
Dr. Leo Trasande: That’s not making me very comfortable.
Secretary Kennedy: We can’t afford to move that up at
Dr. Leo Trasande: All. Exactly.
Secretary Kennedy: So go ahead.
Dr. Leo Trasande: Yeah, no problem. So we have to really take a step back here and go to Adam Smith, the father of modern economics at some level. So you make a product to earn a buck. No one here I myself here is a pediatrician who studies environmental hazards. I’m not trying to impugn-
Secretary Kennedy: Yeah, but you’re supposed to pay for all the costs of getting that product, building it and getting it to market. And what the plastic industry does is it externalize that cost.
Dr. Leo Trasande: You nailed
Secretary Kennedy: It. And put the costs on the American people so that they get to avoid the cost and they get to outcompete their competitors in the packaging industry and we end up paying for their profits essentially, which gives them that huge advantage in the marketplace.
Dr. Leo Trasande: Yeah. I’ve taught undergraduates and graduate students at NYU for over a decade about the fact that Adam Smith is rolling over in his grave about externalities because if you’re a nerdy economist, you realize that that means you overproduce the materials above the market equilibrium and the cost is lower than the true social cost. So it’s really not the way the market should work, period.
Secretary Kennedy: It’s a market failure.
Dr. Leo Trasande: It’s a
Secretary Kennedy: Market
Dr. Leo Trasande: Failure,
Secretary Kennedy: Quite simply. Right. The ability for companies for the plastic industry to externalize their costs means they’re not functioning in a free market to come. In a true free market, you can’t make yourself rich without making your neighbors rich and without enriching your community. But what all polluters do is they escape the discipline of the free market and force the public to pay their production costs. And in a true free market economy, there should be incentive that the incentives, you want to punish bad behavior, reward good behavior, but if bad behavior is not punished, if it just goes for free, then you’re going to get a compounding effect. And that’s what we’re seeing with every time we catch them, they just produce a new molecule that does the exact same thing and they’re getting away with it.
This is one of the clearest public health frames in the interview. Pollution is not only a medical issue; it is an economic design problem. If companies profit from products while health systems, families, schools, and taxpayers absorb the downstream costs, the market is not pricing the product honestly. The hard question is how to estimate those costs fairly and how to design policy that reduces harm without creating new inequities or simply shifting costs to consumers.
Dr. Leo Trasande: Yeah. I’ve spent nearly my entire career studying and quantifying these externalities. I’m an epidemiologist. I’m still a pediatrician, so I still wear those hats. But what we first did back in 2015 was document for a limited number of conditions, a limited number of chemicals, the social costs of endocrine disrupting chemicals. And what’s frightening when you take a comparison of Europe to the United States is that policies predict exposures, exposures contribute to disease and disease ultimately costs us all. So in the European Union, the cost of endocrine disrupting chemicals, about 163 billion Euro, 1.2% of gross domestic product, nothing laugh at. In the US using similar methodology, $340 billion.
Cost-of-illness estimates can be useful, but they are not simple measurements. They depend on assumptions about exposure, disease causation, productivity losses, health care costs, and uncertainty ranges. These numbers should not be dismissed, but they should be read as modeled estimates rather than direct accounting. Their value is that they make visible a cost that is usually hidden.
Secretary Kennedy: And what’s the difference in Europe, they actually have taxes on producers that if you are going to have a producer introduces a product like packaging into the stream of commerce, they have to pay for its recovery. And so they’re incentivized to not only to recycle and to reuse, but also to reduce the amount of plastics. In Europe, you can’t get … I remember they used to be able to buy a CD in this country that’s this big, but it would come in a package this big. And we’ve all gotten Amazon boxes with a little tiny item in there that are filled this high with peanuts start from peanuts. And in Europe, they would never do that because it would eat up their profits because they got to dispose of every one of those peanuts. And that’s why in Europe they don’t have landfills. We have the Fresh Kills landfill is the highest point on the East Coast or North America because we’re subsidizing the disposal of garbage and packaging and in Europe they don’t do that.
They force the guy who introduces that into the stream of commerce to pay for its recovery or its disposal. And that means you get products there that are not innately wrapped because that wrapper is costing them. Here the taxpayer is paying for that wrapper. Yeah.
Dr. Leo Trasande: So flamer tardans, for example, just to build on that, were roughly two thirds of that $340 billion, 200 some odd billion dollars. The costs in Europe because they didn’t require it be added to … Again, this is a plastic related cost because they were adding it to polyurethane foam in the United States under the guise that you were going to-
Secretary Kennedy: Oh, fire safety.
Dr. Leo Trasande: Correct. They were going to slow the spread of fires and you were going to save kids’ lives. They were-
Secretary Kennedy: Meanwhile, it killed a lot of firemen.
Dr. Leo Trasande: Sadly, it didn’t do any good. It didn’t save any
Secretary Kennedy: Lives. And cancer, you have all these firemen now were suffering from testicular cancer because of the chafing from the fire gear.
Dr. Leo Trasande: Well, the biggest cost of all was the developing brains of young children because baby relies on mom’s thyroid hormone through the second trimester of pregnancy. And this is the sad part is that obstetricians, they don’t see the effects because the impacts of even in the clinically normal range of thyroid hormone, even subtle changes in thyroid hormone function contribute to cognitive deficits, autism and attention deficit hyperactivity disorder. So what you see is a silent epidemic of kids with lower IQs in the United States compared to Europe as a result of that legacy of exposure. So just to put this in context for the audience, a kid loses an IQ point, mom doesn’t notice, pediatrician doesn’t have mupiosis. Teacher doesn’t notice. No offense.
Secretary Kennedy: Back in the 1980s, we got leaded gasoline out of the gasoline and as a direct result from that, the national average IQ went up two points. I remember talking to an epidemiologist at that time and he said, “You could lose five IQ points across an entire population nobody would notice.” But that-
Dr. Leo Trasande: Getting let
Secretary Kennedy: Out again. You’re crippling that society.
Dr. Leo Trasande: That’s right. Getting let out of gasoline and paint provided a $200 billion to this day economic stimulus package because each IQ point is roughly worth 2% of a child’s lifetime economic productivity. And if on average they make a million dollars, excuse me, I’m mixing my millions and my billions, haven’t had enough coffee. That’s $20,000. You multiply that up around four million kids born in the US each year, you get a lot of zeros on the right side. And we should have learned from the success story, the public health victory getting let out of gasoline and paint. But here we are, just to use flame retardants as an example and you see this disparity where Europe only has $9 billion or so in costs and the US suffers $200 billion in lost economic productivity and other costs associated just with flame retardants because they’re being added to these plastic foams.
Secretary Kennedy: I remember seeing also studies from the lead and the gasoline because lead caused behavioral issues too and it caused violence and that generation was the most violent generation in American history. We had the riots and crime rates going through the roof. And when the lead came out, it was coterminous with a reduction in a lot of that violence, but I’m wondering if the same thing isn’t going on with plastics as plastics are not just causing physical problems. There are behavioral issues as well and that they may be connected to ADHD and depression and like you said, autism.
Lead is one of the clearest environmental health success stories: exposure fell, children benefited, and society gained. Plastics are more complicated because “plastics” includes many materials, particles, and chemical additives with different exposure routes and mechanisms. The lesson from lead is not that every plastic-related claim is settled. The lesson is that early warnings about widespread exposures deserve serious attention before an entire generation carries the burden.
Dr. Leo Trasande: So in many ways it’s a good analogy because plastics is like a lead moment. Back in the ’70s we didn’t have perfect science. We had a few studies that were very suggestive of cognitive impacts and behavioral impacts in kids, but the adage is you look at the stakes involved in the problem. Sir Austin Bradford Hill, who this British physician who described the criteria for causality, he was doing it during the tobacco war’s mine. You talk about another group of industrial activities that have had their attacks- Absolutely
Secretary Kennedy: Don’t know the Bradford Hill criteria, it’s a schematic for proving causation. It’s a series of questions that you need to answer in order to prove that a certain exposure results in kidney cancer or whatever the outcome that you’re looking for is. And it’s used in court to … It’s used throughout medicine- It’s used round medicine. … throughout the regulatory approval process, but it’s also used in court cases to show causation
Dr. Leo Trasande: And where it’s gotten manipulated over the years is we’ve assumed that we have to have a randomized control trial to prove an effect. You’re never going to be able to design, you can maybe reduce exposures to plastics, let’s say, in people’s lives and follow the populations and see what happens. But in the context of all the different plastic exposures, those are hard to control and you compare that to a drug trial where you’re intentionally giving for benefit a pharmaceutical to a population, you can have a proper control group if you will. That’s just not going to happen when it comes to chemical exposures. So we have to look at observational evidence and we have to, again, use what you talked about, the Bradford Hill criteria. You see what happens in laboratory animals in two … Tissues. You look at consistency across different observational populations, people you look at and yes, you’re not going to have that proper control group, the unexposed control group.
But when you look at the evidence for plastics in human health, you have that independent corroboration. Just to give you an example for phthalates and brain development, phthalates are also thyroid hormone disruptors by the way, and they’re linked to cognitive
Secretary Kennedy: Medicines. And that’s in plastic packaging.
Dr. Leo Trasande: That’s right. They make plastic softer, those PVC
Secretary Kennedy: Pipes. So even if you buy hamburger meat that comes with that plastic wrapper on it, that is going to be loaded with phthalates.
Dr. Leo Trasande: That usually is the case, or at least I haven’t seen industry proof that they’ve taken it out altogether. Let’s just put it that way. And so in this large Dutch cohort where we looked at phthalate exposure supported by the National Institutes of Health, mind you, so I want to give due credit where credit is due. It’s that science that really brought us to a place where we understood the impacts on human health. We not only found decreases in IQs through neuropsychological testing, these are psychologists who are testing how kids are performing on various tests and things. They looked at the brains using magnetic resonance imaging and they found smaller brains. And when you connect the dots and they did statistical tests to try to explain the pathway, the loss of gray matter, if you will, the smaller gray matter, smaller total brain volume, excuse me, explained a lot of the effects on IQ.
So there’s two things going on here. You have an explanatory path and thyroid is part of that explanatory path. It’s part of the mechanistic insight that really gives us the evidence, the strong evidence, the rigor and reproducibility. And you have different ways of measuring the same outcome, giving you the same readout. So when Sir Austin Bradford Hill talked about the criteria for causality, he always talked about it as shades of gray. There are things we still don’t know, Mr. Secretary, about lead and their impact on the general population, but now we’ve accumulated all this evidence that tells us that that was the right thing to do at the time. So you have to weigh the stakes of the action together with the available evidence because it’s never going to be perfect unless you have another generation of people who are exposed to the same toxic exposures. Yeah.
This is an important methodological point. In environmental health, we usually cannot run randomized trials that intentionally expose people to potentially harmful chemicals. That means evidence often comes from observational studies, natural experiments, animal studies, lab mechanisms, and consistency across populations. Skepticism is appropriate, but demanding a drug-trial standard for every environmental exposure can become a recipe for inaction.
Secretary Kennedy: I do want to just say a word for Herbert Nadelman. He was this very tenacious, courageous scientist who was the first one to led to the loss in IQ and all these behavioral wishes. And he was as predictably vilified and his career was almost destroyed and he was marginalized and censored and ridiculed and by the press for a lot. And mainstream press by television and radio and newspapers and the industry was funding all under the subrows of funding to destroy them the same way they did with Rachel Carson and anybody who challenges these paradigms.
Dr. Leo Trasande: Well, science is inherently political and I appreciate this in the field having learned from Dr. Needleman’s legacy that you have to develop a bit of a tough skin and appreciate that these industries are profiting, if you will. And again, I don’t disabuse myself of the fact that people have to profit in life, but to give you a statistic that puts it in context, the plastics industry, global revenue, this is all across the world, is 500 billion or so dollars. We did a series of studies built on that endocrine disrupting chemical evidence that I talked about earlier, that $340 billion US cost. We had some other data for PFAS, some other data for phthalate impacts that we had later identified. So mind you, this is like 20 or so chemicals that we were able to isolate a subset of diseases due to the few chemicals we studied and a subset of costs due to the few diseases, due to the few chemicals we studied.
So this is an underestimate of an underestimate of an underestimate and we found the cost for $250 billion a year in the US population.
Secretary Kennedy: Well, that’s the subsidy that the industry is getting from us. Half of their revenues are subsidies.
Dr. Leo Trasande: Off of our skin. So at some level this industry, I hate to say it, is a bit of a loser. I’m not going to call anybody a loser, that’s rude, but I am going to acknowledge that we need to change our ways. And we can talk about this later on, but there is a lot of hope. There are companies that are showing leadership and using sustainable and alternative materials that are free of these chemicals. They’re thinking about a new way. And part of the reason we’re stuck is there’s some entrenched interests that are keeping or they’re holding on, gripping on tight to the $500 billion a year industry and they’re costing human health in the process.
Secretary Kennedy: Talk about the principle vectors by which microplastics get into the human body. And first of all, quantify how much plastic are we all carrying around right now and particularly in our brain?
Dr. Leo Trasande: So there are people who’ve attacked Matt Kampen at the University of New Mexico for this estimate that it’s a proverbial tablespoon of plastic in the human
Secretary Kennedy: Brain
Dr. Leo Trasande: Of micro
Secretary Kennedy: Nanoplastics. So every American on average has about a teaspoon.
Dr. Leo Trasande: If it’s a teaspoon or a tablespoon, it almost doesn’t matter. I think the point that it is that it’s there and if they’re in some substantial quantities. Now-
Secretary Kennedy: It’s about, it’s like 1% of the volume of the human brain, right?
Dr. Leo Trasande: But even if it were 0.1, Mr. Secretary-
Secretary Kennedy: Or a point?
Dr. Leo Trasande: Let’s say we could even move the decimal one way or the other. And mind you, the controversy the ataxia’s gotten are that fat can be when you put it on the instrument that you use to measure micronanoplastics, gives you what we call a polyethylene is a form of plastic, a polyethylene signature in the machine readout that is clouded by the same signature you’d be looking for the polyethylene plastics, the micro nanoplastics. Suffice it to say that even if we … I don’t even want to have that debate because it’s not worth having. It’s there and it’s there in substantial levels. And mind you, the higher levels were associated with dementia in those populations, desiccant brains with higher micronanoplastics.
The “plastic in the brain” claim is alarming, but this is exactly where scientific humility matters. Measuring micro- and nanoplastics in human tissue is technically difficult, and contamination or measurement artifacts are real concerns. The finding should not be ignored, especially if levels are rising over time or associated with disease. But association in cadaver tissue does not prove that microplastics caused dementia. This is a strong case for more research, not a settled causal conclusion.
Secretary Kennedy: The people, the cadavers who had dementia had consistently much higher levels of microplastics in their brain.
Dr. Leo Trasande: And then they looked temporally based upon the year of death. They had an annotated archive and they showed a trajectory that was upward. So it could be 0.1, it could be 0.21, it could be one. At some point I don’t really care. I think I care about what’s happening to the human body at some level.
Secretary Kennedy: And there’s no way that we know of this time of chelating it out of your body.
Dr. Leo Trasande: At the present time, no. But we’ll talk a little bit about the STOMP Initiative, I assume,
Secretary Kennedy: And the
Dr. Leo Trasande: Opportunities to look at things like that, but this
Secretary Kennedy: Is prevention is the
Dr. Leo Trasande: Cure.
Secretary Kennedy: Right. Prevention is the cure. Let me get back to my original question, so the audience can know what to avoid. What are the primary vectors? Is it bottled water? Is it eating fish with microplastics in it? What are the primary vector? Is it cooking with nonstick surfaces? What are the worst ones?
Dr. Leo Trasande: It’s a great question. And I actually don’t have the percentages to give you because we haven’t done a national human exposure assessment study for about a couple decades, unfortunately. I’m hoping perhaps administrators Elden might be interested in pushing that forward because we could really do a study of dust, of water, of food packaging of air and really integrate the totality of exposure so we could tease that out. But I can give you top line.
Secretary Kennedy: And do you do that with animal model studies or?
Dr. Leo Trasande: You would do in people’s homes, survey them the way you knock on doors and take a hundred people from one part of the country, a hundred people from
Secretary Kennedy: Another part. And then would you do a blood tester?
Dr. Leo Trasande: Well, you would do dust levels, water levels, urine levels, serum levels. You would look at a lot of different tissues and integrate the data and see what you would find out in which signals are really ticking up people’s exposures. So
Secretary Kennedy: What is your gas then?
Dr. Leo Trasande: Yeah, I think food’s number one. I’m not a person who wagers, but food packaging and food contact materials are likely the biggest source. And I think this is multidimensional threat as I talked about. So I’m giving you the best available data based on the chemicals more than the micronanoplastics. We don’t actually have a lot of data right now about the sources of micronanoplastics exposures. What I can tell you is when it comes to plastic chemicals, there’s enough PFAS in the water supply of 150 million Americans such that the National Academy of Sciences suggest clinical testing for these populations. And I’d argue suggest the opportunity for water filtration and steps because you can improve lipid levels, you can reduce the risk of thyroid cancer or thyroid dysfunction. Sorry, it’s actually not thyroid cancer, kidney and testicular cancer that have been increased most
This is one of the most useful moments in the interview because Trasande acknowledges what we do not know. Public health messaging often jumps directly to individual advice: avoid this, buy that, switch products. But if we do not yet have a strong national exposure assessment, we should be cautious about ranking personal behaviors with too much confidence. Food packaging is a plausible major source, but better exposure mapping is exactly what public agencies should be funding
Secretary Kennedy: Of the time is the outcome we sued in the dark water this case.
Dr. Leo Trasande: Right. And so I can tell you that dermal exposure is an unappreciated route. I’m a runner. Well, running requires often a lot of materials that are tightly adherent to the skin. The way the designers have developed them over the years is mostly polyester or nylon. I have adapted a lot more towards cotton or at least using an inner layer that’s natural to try to avoid that. But that gives you an example. Cosmetics are a major source of exposure and that’s because things just absorb into the skin quite readily. Thermal paper receipts are unfortunately a significant source of bisphenol exposure because that is a polycarbonate film that is often … I think some of the industries will debate whether it’s still polycarbonate. I’d like to see the data and then I’ll back off the claim when that’s really given to me, but you touch that material, particularly if you use hand sanitizer or alcohol or lotions, that will also facilitate the absorption into the skin and ultimately directly into the serum.
It bypasses the liver. So the first time around the body, it can have a even more significant effect. So we inhale these chemicals as well and inhale particularly a concern about micronanoplastics is that these act like particles. That’s the big debate here too is when we’re talking about micronanoplastics on the one hand and chemicals in plastic on the other, are they toxic drug delivery systems for the chemicals or are the particles like punching bags or literally fists hitting tissue and being wrecking balls directly? That’s akin to what we thought particulate matter was doing to contribute to lung cancer, asthma, chronic obstructive pulmonary disease and such. That’s where the STOMP initiative can break a lot of ground because from a scientific perspective, I can’t tell you what those micronanoplastics are doing. Mind you, we use in medicine micronanoplastics as drug delivery systems. Those sustained release capsules are plastic particles.
Now that might make people shutter a little bit, but the intent is to actually deliver beneficial drugs to tissues. But that’s just the imaginative perspective I can give you in that these micronanoplastics are not inert and they are good at delivering chemicals on the one hand beneficial when it comes to pharmaceuticals like omeprazole or what have you. And on the other hand, toxic chemicals like phthalates or bisphenols.
Secretary Kennedy: You mentioned a couple of times STOMP and just so the audience knows that’s a program that we announced from ARPA-H, which is part of my agency and it develops cutting edge solutions and it can act very, very quickly. It’s very nimble and we’re putting $145 million into that to look for the first time at the fate of various kind of plastics in the human body. And so there are, as you say, thousands of constituents and there are different families of plastics and some of them may be inert. Some of them we know are very, very dangerous and yet we don’t know what different ones do when they enter your body, where they migrate to and where they lodge and what kind of arm they do. And so for the first time we’re going to have that map and we’re going to be able to characterize it. But talk for a minute about plastic water bottles.
A major federal investment in microplastics research is welcome, especially if it improves measurement, exposure mapping, and health-risk assessment. But the credibility of this work will depend on transparent methods, independent peer review, careful communication of uncertainty, and protection from political cherry-picking. The science is too important to become either industry reassurance or activist overstatement.
Dr. Leo Trasande: Yeah. So plastic water bottles I wrote in my book, Sick or Fat or Poor, when I originally was just focused on endocrine disrupting chemicals as a broader issue, everything from pesticides to plastic to other materials. I talked then about the fact that you’re in the car, you’re going to grab a water bottle that’s been in the sun and there’s been a lot of weathering to that plastic bottle and that plastic bottle is just not inert enough to handle it. And the plastic leaches in variety of forms, micronanoplastics on this hand and then chemicals as well. And that kind of leaching has been very well described and it’s probably an important source and contributors. That’s a big reason why I drink from other materials, stainless steel water bottles. If I’m getting on a plane, I’m going to clear security with an empty water bottle or have some ice in it and then top it up with water so I can get where I’m going.
And often when you’re buying a plastic water bottle, you’re really buying not the water but the plastic bottle.
Secretary Kennedy: Right Because the water’s free. It’s coming out of the ground or it’s coming from the tap and they’re treating it slightly for nothing. You’re paying for the packaging, you’re paying for the plastic bottle and the cardboard case that it comes in.
Dr. Leo Trasande: That’s absolutely right. I mean, as I was alluding to, every water supply is a little bit different. So there are certain circumstances where you might not want to pour from the tap or you might want to filter your water or even more aggressively use like a reverse osmosis filter if you have a significant PFAS contamination issue. But buying that plastic water bottle and assuming it’s free of toxic chemicals is maybe a bit foolish to assume because-
Secretary Kennedy: How about the big plastic bottles that people put in the little water machine?
Dr. Leo Trasande: Well, those have a recycling number seven and sometimes have polycarbonate in them and polycarbonate is a polymer of bisphenols typically.
Secretary Kennedy: And is there a difference when you buy a gallon jug of water? Some of the water bottles are cloudy and some of them are clear. Is there any difference between those two?
Dr. Leo Trasande: That’s hard to say, unfortunately. All I can tell you is based on the recycling number, that’s the number with three triangles in the middle. The ones I try to avoid across the border, three, six, and seven. Three is for polyvinyl chloride, which includes phthalates as an additive typically. Six is polystyrene. Styrene, the monomer is a known carcinogen and seven is a bit of a hodgepodge class. I should take a step back and just clarify that it includes polycarbonate plastics and some bioplastics, but the specificity and the declaration on the label is a bit ambiguous. So I usually suggest avoiding three, six and seven in general. But also in general, I would suggest trying to use stainless steel or glass whenever possible.
Secretary Kennedy: Can you just talk a little bit more about angiochrine disruptors?
Dr. Leo Trasande: So I’d start by saying there are safe and simple steps that we can all take to reduce endocrine disrupting chemical exposure.
Secretary Kennedy: And endocrine disruptors are chemicals that interact with our sexual development or our hormone system.
Dr. Leo Trasande: Any variety of hormones from temperature, metabolism, salt, sugar, and even sex are affected by these endocrine disrupting chemicals. And the good news is they’re safe and simple steps that don’t require PhD and chemistry and they don’t have to break the bank. Reducing canned food consumption can reduce your bisphenol exposure besides thermal paper receipts, which we already talked about having as a potential source of bisphenol exposure. Avoiding microwaving and machine dishwashing plastics is important. We already talked about that hot water bottle leaching plastic micronanoplastics and chemicals of concern. We know that microwave and machine dishwashing plastic is just inviting at a molecular level at an invisible level these chemicals or micro nanoplastics to leach into food. Now, air is something to think about as well. During the pandemic, there were some studies done at Brown University that did greater air filtration and found PFAS flame retardant and phthalate levels to drop substantially.
Practical advice matters, but it can easily become inequitable. Not everyone can afford new cookware, water filters, fresh food, safer cosmetics, or housing upgrades. Public health should avoid turning chemical exposure into another lifestyle burden placed on individuals. The best advice combines realistic personal steps with stronger rules for food packaging, drinking water, product labeling, and chemical safety review.
This was in concert with colleagues at Sound Spring Institute, a great research group that documented this. So as much as we talk about infectious transmission being reduced by air filtration, you also have the benefits of reducing chemical exposure in the process.
In another setting, just taking healthy building materials and putting them into place can reduce dust levels of these chemicals as well. A little bit more of a higher level intervention, maybe a little bit more out of your control. But again, if you talk about reducing your canned food consumption, using more glass and stainless steel, last I checked cast iron and stainless steel pans are not that much more expensive than nonstick cooking materials and not microwaving or machine dishwashing plastic if I haven’t talked about that already. These are steps again that don’t have to break the bank. And short-term changes have shown big impacts. There are studies that have shown 30 to 50% decreases in urinary levels. The phthalates and bisphenols, for example, in contrast to the forever chemicals that we call them everywhere chemicals because they’re everywhere and they recirculate in and out of the body super fast.
The exposure picture is messy. People may encounter plastic-associated chemicals through food, water, air, dust, skin contact, consumer products, and occupational settings. That complexity is exactly why individual responsibility is an incomplete solution. Consumers can reduce some exposures, but they cannot inspect every receipt, package, textile, cosmetic, pipe, filter, and food-contact material in their daily lives. Systems-level policy has to do some of the work.
Their half-lives, that’s the time it takes to degree about half of them is 24 to 48 hours. So it shouldn’t surprise you that if you take a dietary intervention in a high income population or even in a low income population, just reading the label and selecting cosmetics without the word phthalate, that’s a mouthful to spell. PHTH is what I always tell people to look out for or fragrance. Fragrance is a big loophole, if you will, that you can drive a MAC truck through, unfortunately.
Secretary Kennedy: Oh, you should avoid phthalates. You should avoid fragrances when you get your cosmetic.
Dr. Leo Trasande: Yes. These short-term exposure reductions can, when sustained, change hormone levels in weeks and then in the long term contribute to reductions in chronic disease risk. And when I wrote the book, Sick or Fat or Poorer seven years ago, that was the hope was to get that message out there and change us from a situation where one to 2% of us know about it and bring us to three to 5%. I’m really grateful, gratified to have your support and leadership in so many ways in this space through the ARPA H initiative, through listing microplastics as water contaminants. The generally recognized as safe exemption is something that you’ve shown just some tremendous leadership in pushing out there and I hope you keep pushing. There are a lot of petitions out there in the Food and Drug Administration that with your pen, you could get rid of so many of these chemicals that are in the food supply.
You have so much power and this is a really crucial moment. I know you’ve got the support of so many people out there in the general public.
Secretary Kennedy: And we’re
Dr. Leo Trasande: Working on it. I appreciate that.
Secretary Kennedy: Dr. Leo Trisande is the director of the Grossman Center for the Study of Environmental Hazards at New York University and thank you Dr. Trisande for joining me today.
Dr. Leo Trasande: It was an honor and joy to be with you.
Thank you so much. Produced by the US Department of Health and Human Services.
It is reasonable to welcome stronger federal action on food additives, chemical safety, water contaminants, and microplastics research. But public health should judge leaders by implementation, not rhetoric. The test will be whether agencies produce transparent science, enforceable standards, meaningful exposure reduction, and protections that reach low-income communities, workers, children, and people living near contaminated water or industrial sites.
