Inside the Legal Battle to Ban a Deadly Neurotoxin – with Neuroscientist Robert Sapolsky


For several years, environmental advocacy groups have been fighting to ban the pesticide chlorpyrifos from agricultural use. A turnover in leadership at the EPA has led to a moment of indecision on what to do about the chemical. Robert Sapolsky is a neuroscientist who’s spent a long time assisting in the legal battle against chlorpyrifos. We discussed the devastating effects of chlorpyrifos on an exposed nervous system as well as his work to discredit the industry science claiming its safety.

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Hello and welcome to another edition of Miles To Go. I’m Miles O’Brien. We live in an era when scientific conclusions are not given the weight they deserve. This allows politically and financially motivated people to undermine the facts, to throw a little bit of mud in the water. It happens all the time.

And it also happened in the case of chlorpyrifos. It’s a pesticide that is widely used in agriculture in the United States. It’s a very potent neurotoxin…deadly in the right doses. It’s an organophosphate. And it’s the same family that gives us the nerve agent, sarin gas, so frequently used by Assad on his own people in Syria.

For many years scientists at the EPA and in academia looked at the possible links between chlorpyrifos and other organophosphates and possible cognitive, behavioral, and developmental deficiencies in children who are exposed to this chemical. The facts were strong enough that the EPA had made the decision to ban its use completely. And that’s actually unusual. The EPA doesn’t do that often. This was back in November of 2016.

That was a pivotal moment in the United States of course. Because just as the EPA was ready to ban chlorpyrifos, there was a new sheriff in town running the EPA. And like so many other things we’ve been reporting about, the EPA under Scott Pruitt and Donald Trump did everything it could to walk that decision back. And that’s where we are now. Chlorpyrifos still in use, the EPA no longer willing to move forward with the decision to ban it, and organizations like the Natural Resources Defense Council are in court fighting to get the EPA to do its job.

In the midst of all of this comes the confusion over corporate funded science. You probably won’t be surprised to learn that this body of work suggests that chlorpyrifos is nothing to worry about. Again…a little mud in the water.

A Professor of Neuroscience at Stanford University, Robert Sapolsky, was called in to analyze this “science”. What he found is sad and predictable. I wish that it was shocking but unfortunately it is a tried and untrue tactic.

I spoke with Dr. Sapolsky as part of my upcoming story for the PBS NewsHour on chlorpyrifos.

Miles O’Brien: Without getting too deep into the chemical compounds, as best we can, what is chlorpyrifos?

Robert Sapolsky: Chlorpyrifos is one of a bunch of classes of pesticides. It’s a particular class…it’s an organophosphate pesticide. For the purpose of people using it commercially, the most relevant thing it does is kill insects by mucking pretty dramatically with their nervous systems. For the relevance to the rest of the world exposed to it, it does some of the exact same things in terms of mucking with mammalian nervous systems and with some pretty adverse consequences downstream.

Miles O’Brien: Give me an idea of some of its cousins in its family. It’s in the same category as sarin, isn’t it?

Robert Sapolsky: It’s broadly related chemically in terms of its mechanism of action, what it does to the body, to some chemical weapons like sarin for example, more potent versions of much the same.

Miles O’Brien: Without getting too deep into the chemical compounds, as best we can, what is chlorpyrifos?

Robert Sapolsky: Chlorpyrifos is one of a bunch of classes of pesticides. It’s a particular class…it’s an organophosphate pesticide. For the purpose of people using it commercially, the most relevant thing it does is kill insects by mucking pretty dramatically with their nervous systems. For the relevance to the rest of the world exposed to it, it does some of the exact same things in terms of mucking with mammalian nervous systems and with some pretty adverse consequences downstream.

Miles O’Brien: Give me an idea of some of its cousins in its family. It’s in the same category as sarin, isn’t it?

Robert Sapolsky: It’s broadly related chemically in terms of its mechanism of action, what it does to the body, to some chemical weapons like sarin for example, more potent versions of much the same.

Miles O’Brien: So, this is a serious stuff?

Robert Sapolsky: Yes.

Miles O’Brien: And it’s obviously, I guess, it goes to that saying. It’s a very effective pest killer, right? I mean, is that accurate to say?

Robert Sapolsky: Actually, I’ve no idea from the perspective of you know keeping bugs off of crops. Presumably, it is or it’s way up there in terms of cost-effectiveness for the manufacturer.

Miles O’Brien: All right, a few words about how you — the phone rings ten years ago or whatever, how did you get into this subject area?

Robert Sapolsky: What I’ve traditionally studied is some ways in which the brain gets damaged. In my own area, it’s what stress does to the brain. But along the way, focusing a whole lot on rotten things you can do to a brain cell and what exactly happens, how it goes about dying at that point.

And where I first got pulled into this was a law firm leading some of these lawsuits saying, “Hey, we’ve got some people with histories of sort of catastrophic exposure to this stuff.” All sorts of problems that arose. Including chronic seizure disorders, would you be able to explain to a courtroom where the seizures come from, and this was sort of right up my alley in terms of how you go from this type of damage to a chronic neurological disorder.

So, sort of heading in that direction. And in the process, I actually knew nothing about these compounds completely out of my area, and figured I should go read the literature and the literature most importantly which extensively showed coming from armies of Dow scientists that the stuff was biologically quite safe to mammals.

And went and sort of reading those papers, and just kind of struck with “oh my god, this is horrible science.” This is totally lousy science that went into the declarations that this stuff is safe under these conditions, and out of that that grew the sense that rather than — or in addition to just looking at these individual cases to pull together a whole bunch of trained scientists to go through the whole literature from Dow Chemical that supposedly shows the safety of this stuff.

And sort of essentially going with the idea that my god, if the literature as a whole is as lousy as the subset of these papers that I looked at, this really does bring into question lots of things, most basically whether Dow has a leg to stand on saying this stuff has been scientifically shown to be safe.

Miles O’Brien: I was just doing a post this morning on the EPA firing all its academic science — in favor of industry, it’s just right on point on that but that’s another story. So, one more point about the original suit before we get into a little more on the Dow science, when you were called into this, this was still used in household settings, right? What were some of the circumstances surrounding the lawsuits?

Robert Sapolsky: In the process of my becoming familiar with the cases, it would be some family living in a trailer park where there was massive use of the stuff spraying it in and somebody or other forgot to put a notice up saying, “Hey, we sprayed all over the place today.” Baby in the family later in the day is doing some usual baby thing crawling around on a carpet that had been heavily sprayed a few hours before, mouthing whatever toy was just there and that night has a massive outburst of seizures, the start of a whole series of these which leaves the individual very neurologically impaired years later, totally crippled developmentally by this with no prior history of…cases like that.

Miles O’Brien: Long term, permanent damage in some cases even fatalities, right?

Robert Sapolsky: The ones I focused on was just simply focusing on where this very, very damaged brain comes from with respect to exposure to this stuff.

Miles O’Brien: All right, so let’s talk a little bit about the Dow science. You say it was bad science. How could you like look at a paper and say, “Wait a minute. This is bad science.” Was it just purely bad method, bad language, et cetera? What did you see in there that screamed out at you?

Robert Sapolsky: Okay. So the sort of stuff that was most problematic, it doesn’t matter if you are a neurotoxicological epidemiologist who’s been studying this thing for years or if your area of science is completely different. Freshman science majors are not supposed to make mistakes like these.

And when we systematically went through them, there were range of mistakes but sort of the most telling ones were how the experiments were designed, how they were carried out…And in some ways, most damningly — how they were interpreted afterward and thus, what conclusions they stuck starting with the title of the paper.

This stuff is safe in this biological domain where you look closely and there’s absolutely no basis for concluding that because the science was basically empty.

Miles O’Brien: It’s one thing to be just kind of incompetent. It’s another thing to put the thumb on the scale. There’s a subtle difference. In other words, if it is bad, the badness can cut in both directions, right? Did you see something there that told you that there was something more sinister?

Robert Sapolsky: Okay. So, if one is just randomly doing bad science, some of the time you say there’s more gravity on earth than there actually is because you added up your numbers wrong. And some of the time, you can conclude there’s less because you counted it on your toes wrong. There’s a random distribution of the mistakes.

Instead, over the course of hundreds of these mistakes, there was not a single one which would have inadvertently unscientifically led Dow to conclude that this stuff was more dangerous than it actually was. Instead, every single directional error in their entire body of published papers always went in the same direction. This stuff is safe. This stuff is safe whereas there was no basis for concluding that from that particular study.

In other words, every single time you toss the coin in the air, it comes up heads over hundreds of times that really causes one to question the randomness of one’s errors.

Miles O’Brien: What was your conclusion based on that?

Robert Sapolsky: Not in a million years would I want to imply anything about the internal motivations of these scientists because you know, I don’t want to go near that one with a 10 foot pool and you certainly can’t tell that from nearly lousy science.

But nonetheless, the frequency and the magnitude of the errors and that every single time, they just happened to randomly bounce them the direction that would be to the benefit of the Dow Corporation would lead one to conclude that I would not have any faith in any science done by the scientists or the Dow Supervisors who signed off on these studies.

Miles O’Brien: I think intuitively, we would say that if the scientists and the research are bought and paid for by Dow, there’s an inherent conflict of interest. So give us — I mean scientists are very proud of their ability to separate themselves from their conflicts of interest, and there are many industry scientists who would tell you, “No, I leave the corporation at the doorstep when I go and assess these things.”

Give us a couple of words on what your thoughts are on industry-funded science in a context like this.

Robert Sapolsky: The question becomes what’s the motive behind this, likewise what’s the motive in our assessment of the stuff in terms of an academic scientist’s potential biases.

And way we did this analysis, we, in this case, was I recruited a team of about a dozen Stanford Neuroscience post-docs. In other words, trained accomplished neuroscientists, who went through this literature independently blinded, assessed these studies along this criteria where they did not know the nature of the lawsuit. Eventually, they were looking at studies by other Dow scientists, by other industry scientists as controls — to control for a general anti-industry bias.

In addition, about half of these post-docs had industry connections, half didn’t and it turned out they had absolutely equal rates of detecting errors. So, lots of internal controls on our side to make sure this was not an anti-industry bias. And what we saw was not only were there a staggering number of some very serious errors in these papers, but when the same Dow scientists were researching other topics, there were significantly fewer errors.

When other Dow scientists were doing their own stuff, there were significantly fewer errors. When you looked in the technical journals in which the papers were published, there were significantly fewer errors by other scientists whether industry or academic. And when you looked at the literature of people, academic scientists saying exactly the opposite, “This stuff causes lots of damage to the nervous system.” There was a drastically lower rate of such errors.

Problems with these studies by these scientists as soon as it came close to home with this particular compound, whether this was conscious, whether this was unconscious, whether this was a series of confirmation biases. I haven’t a clue. Again, I would not in a million years be brave enough to be willing to say what motivations might have been.

But at the end of the day, I mean, if I had a first year grad student who made errors like this over and over, I’d be questioning the wisdom of having let this person into the program.

Miles O’Brien: I know scientists impugning other people’s motivations or integrity, et cetera, is treacherous grounds for a scientists. But it’s difficult to come up with any other motive except that Dow wanted this answer.

Robert Sapolsky: All I could say in that context is the random ball bouncing in one direction hundreds of times every single time certainly is convenient for their interests.

Miles O’Brien: Your research was on the research itself. Did you go any further? Did you take your own look at this chemical and what it may or may not do?

Robert Sapolsky: Personally, no. Simply because all I did was read the entire literature. Again, there’s academic scientists who’ve spent 30 year-careers studying this stuff. For example, one individual, various esteemed scientist at Duke University who’s focused on the effects of this class of pesticides on the developing brain. And what do you know showing with sort of astonishing, convincingness over the course of a whole career that it does bad stuff.

At my sort of point of entry into this, all I was doing was looking at the entire literature and saying, “Wow, we and my team of objective neuroscientists going through these studies are just seeing some like catastrophically bad errors over and over and over in these Dow papers, and errors that always just happened to go in the right convenient direction.”

Miles O’Brien: So, you as much as anybody have read in on this subject, based on your survey of the literature, I assume that obviously, some things might have changed in 10 years but I suspect not too much about the basic properties of this chemical. Those things tend to just stay the same. What are the consequences of using chlorpyrifos in proximity where humans have direct contact to it? What happens? How serious is it?

Robert Sapolsky: There’s a huge literature by now by independent academic scientists showing this stuff does miserable things to the nervous system. It causes explicit, immediate brain damage. It sets you up for all sorts of long term chronic neurological disorders like massive serious seizure disorders.

It particularly does this to young developing nervous systems and at levels of exposure that are absolutely commensurate with what humans get exposed to working with this stuff inadvertently being exposed to the stuff, et cetera. And at the same time, what one has to conclude is that the far smaller literature, from Dow scientists reporting to show that in fact this stuff is safe in all of these domains is science that I think would not stand up to a freshman Biology class.

Miles O’Brien: It’s interesting how that kind of science frequently gets injected into the legal system on an equal footing with real peer reviewed of stuff. That’s the crux of a larger story but a big problem, isn’t it?

Robert Sapolsky: Yeah, absolutely! Because — unless you spend a lot of time doing this, a published scientific study by official scientists with “joe scientist” slapped on their forehead and a lab coat to boot. It carries a certain degree of credibility.

Miles O’Brien: Was this Dow science — did it appear in some kind of journal or was it just industry science that was introduced as evidence or some combination?

Robert Sapolsky: We examined both in-house reports and what wound up in the published literature out therein, technical journals, toxicology journals and basically, the errors were identical because essentially, what you do is you do your study, you generate an in-house report, and then you gussy it up in certain sort of conventionalized ways and submit it to a journal. So, it was essentially the same databases.

Miles O’Brien: What kinds of journals would these have appeared in?

Robert Sapolsky: Okay. So for example the number of journals in the area of the Life Sciences.

How biological systems work. As of 10 years ago, when I was doing this analysis, there were about 250 such journals publishing about 50,000 papers a year. Your average paper has a heartbreakingly tiny impact on the future research of the field because everything moves in 8th of an inch of a time, a glacial pace. So, there are lots of journals out there of highly varying qualities and these were not particularly earth shattering scientific journals that they were published in.

Miles O’Brien: In other words, if you want to get it published, it can probably one way or another?

Robert Sapolsky: Pretty much, yeah, if you got enough tenacity and resilience in the face of rejection.

Miles O’Brien: There were some specific phrases and if you don’t them on the tip of your tongue, it’s okay but there were some words like “spurious” and “impossible”, the words that didn’t feel like — you wouldn’t normally see them in something you’d read in science. What were some of those like red flares that you saw as you read the copy as it were?

Robert Sapolsky: They ranged from pretty trivial to massive ones. What did the massive ones look like? One example of one that would come in the realm not how you would — design or carry out the experiment but how you would interpret afterward.

So the purpose of the experiment is to see whether A causes B because nobody has ever looked at this before. So, you go and study this and it turns out that A causes B, and your results absolutely show that.

Then in the discussion part of the paper where you assess what this all means, you say, “Well, we observed that A causes B, but here’s the phrase that just popped up over and over in their papers that became this sort of mantra of like what the problem was here.”

The phrase “biologically implausible” because we thought it was biologically implausible that A caused B, we decided that was just a spurious finding and in the summary of the paper, we say, A doesn’t cause B.

So, does A cause B? Yes, A causes B and there’s no way A causes B. So, if we saw A causes B, that’s not really worth reporting. That type of error over and over. We assumed this was just a random finding whereas an entire universe of stuff called statistical analyses tests for the randomness of stuff and scientific studies have all these rules as to when you decide something is too random and these were not in random. Phrases like that but the biologically implausible, that and thus, we decided to discount the findings.

Miles O’Brien: Even for those of us who are not practicing scientists, that seems like the conclusion before the horse as it were, right?

Robert Sapolsky: Yup. Another version of the sort of mistake that they made and this is one which if college freshmen were making consistently would be a bit worrisome. What do you do with your control group?

Okay. Everybody understands controls. So, we take a bunch of rats and we expose them to this toxic stuff, the experimental group and a bunch of rats that we don’t expose to it. And then, we compare whatever afterward, and so for example, we see five units of bad stuff happens to the control rats and 50 units of bad stuff happens to the experimental ones, whoa! That sure looks like that, indicate say, a biologically adverse effect of this toxic stuff you threw with the experimental rats.

So, here’s what they would do also over and over in their discussions. They would say, “Well, only five of these bad things happening to the control animals, that just seemed really unlikely to us. There must have been something wrong with the control animals, so we went back in our records and we found a control group back from 1492 in some other study we did that had 49.5 bad events happened to them. So, we decided it was appropriate to use that as the control group instead. And look at that, 49.5 in the controls and 50 in the experimentals, this stuff is safe.”

What? They threw out their control group and decided it was biologically implausible that the control group was at that level? And then went back in the archives and pulled out of the back of their refrigerator or different control group. You don’t do that

Miles O’Brien: That is varsity level cherry picking.

Robert Sapolsky: Yes, that is. Actually, that’s Junior League cherry picking. That’s like —

Miles O’Brien: Did you reach out and have any conversations with these researchers to try to get in their brain or did you keep your survey to the data, the published stuff?

Robert Sapolsky: The suggestion from all the law firms involved in this was like don’t make any contact. During this period, I lived in dread that one day inevitably, I’d be on a plane flight and turned out to be sitting right next to one of these guys and we’d have an incident on the flight or something. No, never any contact with them. And I have no idea who they are. I made a point of not finding out where they got their degrees from, anything like that.

It was just looking at the science and the team of post-docs analyzing these studies had no information on what this was about or who these folks were.

Miles O’Brien: Does this give science a bad name or corporations a bad name or both?

Robert Sapolsky: Naturally, as a scientist, I think this is not a vote against science. This is a vote for making sure science was actually done. I’m in no position to say if this is damning of industry science corporate, all I feel comfortable saying is about these studies done by these folks and signed off by these Dow supervisors and how if that’s the literature, which it is, purporting to show this stuff is safe. There’s not a shred of scientifically admissible evidence to conclude this.

Miles O’Brien: As a scientist, you’re supposed to be dispassionate — you look at the data, you don’t call the guy, you hope you don’t see them on the plane, et cetera.

But were you a bit outraged?

Robert Sapolsky: Yeah, you know. We, scientists are humans. We’re not machines of objectivity and it’s mighty hard to look at this and not feel a good populist sense of outrage. Really, every damned time they do crappy science, it just happens to go to the financial advantage of Dow Chemical and the selling of the stuff and really every time this happens, this would weaken the capacity of some victim of the stuff to go to into a court of law and say, “It’s not safe. Look what it did to me.” And Dow scientists saying it is safe have absolutely no means of stating that.

You know, at the end of the day of shuffling numbers and being joe scientist with your pipet, it’s hard not to come home pretty outraged at this.

Miles O’Brien: It is worth remembering. We are talking about young children who are permanently damaged.

Robert Sapolsky: Yeah. We’re talking about young children. We’re talking about all sorts of folks. These are not middle class people who move into a home that was just coated in pesticide and oh, nobody remembered to tell them that these are people moving into trailer parks. These are all sorts of our like classically marginalized, disenfranchised people. And these are migrant farm workers getting sprayed with this stuff day after day without protective clothing.

Without warnings, working in the hot sun where all your skin is set up for then is absorbing stuff that you’re exposed to in the atmosphere. All you’re set up for then is having your lungs nice and dilated. So, when you’re breathing in the stuff, it is just getting into you as efficiently as it can be. These are exactly the people who are least able to protect themselves from this sort of institutional abuse.

Miles O’Brien: What’s happening to us, to human beings when they’re exposed to this in reasonable quantities?

Robert Sapolsky: Chlorpyrifos and other pesticides and chemical weapons of this general category – what they do is essentially cause a massive burst of release of one particular class of neurotranmitters.

And the mechanism by which they do that is not that critical but the main point is, it causes a huge excitatory burst in the nervous system. And what that could do right on the spot is cause a seizure, cause disorientation, cause massive thought disorder, cause coma, cause things of that sort.

So okay, so that’s the acute effect. Where does the chronic problem come from often this burst is so severe that essentially you burn out, you kill some neurons right on the spot. So you got a nervous system with a gaping hole there and what nervous systems tend to do is they try to pull off some recovery and remaining neurons might grow some compensatory processes to try to go and fill in the circuit that’s been damaged. And nervous systems have not really been doing a whole lot of that stuff since they were a fetus getting wired up.

They’re not great at it. They make mistakes. One of the things that sometimes happen is the wiring goes sort of haywire and a neuron will wind up coming back and stimulating itself. So, that every time it fires, it stimulates itself and if fires — and what you’ve now set up with a positive feedback loop like this is a chronic seizure disorder which when it pounds away at a nervous system long enough, if it’s severe enough especially if it’s a young fragile just getting wired up nervous system, chronic epilepsy of severe seizures causes massive developmental damage.

Miles O’Brien: Thank you for explaining that. We were talking yesterday about parallels to lead. Since Roman times, we knew lead at high level was a bad thing but it’s only relatively recently that we realized there’s no really safe amount of lead.

Would you suggest that there’s a parallel story here for this chemical?

Robert Sapolsky: You know, all I can say subjectively as a scientist is I sure as hell would not have wanted my babies exposed to any of this stuff.

Miles O’Brien: At any level.

Robert Sapolsky: At any level.

Miles O’Brien: Should it be banned from use in agricultural settings?

Robert Sapolsky: I think that given the clarity and quality of the literature ranging from lab rats to humans exposed to this stuff showing that it is absolutely damaging and the absolute absence of an acceptable literature showing this stuff is safe, we have no business letting this stuff loose on the earth.

Miles O’Brien: Strong words from a scientist who understands the human nervous system and how it can be damaged as well as any human being on the planet. It’s a shame that his credibility, his knowledge gets lost in the junk science and the political spin cycle. And the corporate payoffs and lobbying.

Those who are harmed by chlorpyrifos don’t really have any leverage in this discussion unfortunately. And that too is all too common.

I’d appreciate it if you’d take a moment to rate and review what you just heard. We’d love it if we could get a little more traction for this podcast, and we could use your help with that. Also, go to our website and you can sign up for our weekly newsletter. Just once a week. No junk. Just one little email filled with facts and information and links to future podcasts and future stories we’re doing. You can stay in touch, and we’d like that.

Thanks for listening to Miles to Go. I’m Miles O’Brien.

Banner image credit: Markus Spiske | Unsplash.

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