In the 5th episode of PUAN podcast, co-host Saumya Pandey interviews Historian Elena Conis on how risky pesticides were culturally accepted and what kind of role did science play in its acceptance. Professor Conis explains how scientific research during war and epidemics prioritized some types of scientific questions over others, and how this approach built an economy that was geared towards selling poisonous pesticides and making them socially desirable.
In today’s episode, I will be speaking with Elena Conis. Professor Conis is a writer and historian of medicine, public health, and the environment. Her current research focuses on scientific controversies, science denial, and the public understanding of science. Her latest book, How to Sell a Poison, is about the pesticide dichlorodiphenyltrichloroethane, or what is popularly known as DDT, a wartime chemical compound, which became one of the most obsessively used pesticides in world history and fundamentally changed the natural ecology and habitat of places where it was sprayed. Today we will be discussing how risky pesticides were culturally accepted and what kind of role did science play in its acceptance.
SP: How did DDT emerge to significance and in the process if you could explain why you decided to write about it
EC: Sure. It’s a really big question, and I could probably answer it in a couple of ways. There are so many reasons why I decided to write about this topic, but one was because I grew up having heard of this chemical, which is one of the most infamous and toxic chemicals that we had created in the course of the 20th century. And I knew that it had been banned. But by the time I was a university and then graduate student, I had heard that there were people who were arguing that we needed to bring it back. And this made me so curious to learn more about DDT’s history as a pesticide and why there was this reconsideration of its toxicity. And long story short, as I dug into why people had changed their minds about it, I suddenly realized I had material for a book on my hands. For how DDT became such an important and significant chemical, we’ve got to rewind back to the early years of the Second World War, when there was interest on the part of the Allies and finding chemicals that they could use to assist in war efforts, chemicals that would kill pests, that were problems for troops, that were problems for refugees, prisoners of war and that caused complications during combat and pests. Insect pests can spread diseases like malaria and typhus and the like. There was a lot of interest in finding ways to control the pests that spread those diseases. To make another very long story short, in the course of this research, DDT emerged as a chemical that was able to control disease-spreading pests and agricultural pests and was able to do so with two key characteristics. It seemed much less toxic than other chemicals that had been used in those applications at the time, and it also seemed to last a very long time. You could spray it or dust it today and then next week or even next month. And as the research continued several months down the line, it still had the capacity to kill bugs. So it was met with enormous enthusiasm during the war and then after the war, among Allied nations, but in particular the US. Really went all in using DDT in just about every way you can imagine in the consumer market. So it moved from a military setting to a consumer setting. After the Second World War, it was used on everything from little babies’ nursery wallpaper to dry cleaning fluids to just spraying hotel lobbies to make them comfortable for guests. It was everywhere you could find it far beyond farms, far beyond military applications, and used in a kind of intimate ways in people’s lives.
SP: It seems there is a philanthropic and humanitarian interest in the use of DDT where it is used to eradicate malaria. How was DDT’s reputation as a poisonous pesticide that was carcinogenic and toxic to humans, birds and the environment underplayed?
EC: That’s a really interesting question. So first to talk a little bit about the philanthropic interests that got involved in DDT’s use after the second world war, it become apparent that DDT could seem to protect large populations of people from diseases that we already mentioned, like malaria and typhus. And so a handful of new institutions and organizations got behind a global effort to put DDT at the center of an international campaign to wipe out malaria, specifically from the face of the earth. So there had been local projects that had taken place in north Africa and in southern Europe and also in the southern US. And elsewhere that had seemed to demonstrate that DDT was applied on a really large scale, you could actually essentially eradicate malaria from that area. And so these projects were used as the basis for justifying a global eradication campaign. The world health organization spearheaded it in the late 1950s, and early 1960s, and some major American philanthropy has gotten behind the project as well. The effort to eradicate malaria in the long run, you and probably loads of your listeners are well aware, was not successful for a long list of reasons that I actually point other readers to in my book, because so much has been written about and so skillfully.
A couple of the key reasons were the resistance on the part of mosquitoes that began to develop. They were no longer susceptible to DDT in the same way, and DDT and other chemicals kept having to be used in new combinations. And the assumption that malaria was essentially the same disease in all these different places across the globe proved to be a faulty one too. The mosquitoes acted differently. People acted differently. In short, the ecology of the disease was so different that what controlled it in one area didn’t necessarily mean that the same approach could work someplace else. So Global Eradication was a project that we entered into or that really Western nations entered into a lot of hope and then eventually had to abandon without having met their stated goals. All the while, there was very little discussion in this global campaign about the toxic effects of DDT. Again, DDT’s appeal was that it seems so nontoxic in the short term. There had been, especially by the time of the Global Eradication campaign, so much research into DDT’s other effects, including some of its long-term effects. These are not getting a lot of attention outside of the few esoteric journals in which they were published.
There were studies on how DDT accumulated in the fat of individuals, and how it was present in milk, including the breast milk of women. There were not yet studies linking DDT to cancer. Those would start to emerge in the late 1960s. But there were some preliminary studies that pointed to a kind of hormonal mimicry that DDT was capable of. In other words, it seemed to be able to act like a hormone in the body. These studies were really kind of misunderstood, and their significance wasn’t grasped until decades later, in the 1990s. And at that point, there was more research on DDT and cancer. But we were so far from the decades in which DDT was widely used that it became harder and harder to carry out those studies. They produced a lot of mixed results in the early years, studied in epidemiological studies initially that focused on narrowly defined populations. And then over time, we increase the number of people and the type of people in these epidemiological studies of DDT. So over time, we did end up accumulating more and more evidence of its carcinogenicity. Some of that evidence is still contested, but it turns out that DDT has been linked to several different forms of cancer. At this point, it also feels important to say that linking DDT to cancer, it’s almost too simple of a story to tell because is carcinogenic. It is what we now call an endocrine disruptor.
SP: Can you talk a little bit more about the role of science in denying the harms of DDT. Why do you think it took so long for scientists to design research against DDT?
EC: I think that one of the really interesting things about how we talk about science today is that we make sort of two assumptions. One is that science is this sort of uniform thing and it’s not scientists who have their individual disciplines and their sub-disciplines and as a result very different ways of seeing and understanding the world. Two we tend to think of science as something that gives us absolute answers. But in fact, it’s a process that generates answers um that reflect the state of our own knowledge at the time. And so you know What science can tell us today is different from what science could tell us 50 years ago and it’s different from what science will be able to tell us 50 years into the future. And all of that means that at each point in which DDT was being studied um by members of the scientific community all of these individual scientists were bringing their own disciplinary perspectives to the question of DDT’s benefits and DDT’s risks. Those scientists also had I would say probably different types of status within the society that they operated in. You know one person’s science was not always valued the same as somebody else’s and in war we elevated and prioritized certain types of scientific questions over other kinds of scientific questions and then there were scientists who brought a kind of allegiance to their own discipline and to sometimes some of their like inherently human biases and prejudices to the process of carrying out science. So, to give kind of a hard concrete example of what I mean by all of this. In one instance there was a scientist at the Centers for Disease Control who it’s during. And just after the Second World War was put in charge of a new toxicology lab that the C. D. C. The U. S. C. D. C. Had created and he was trained in a particular way. He had a lot of leeways to create this division. This division ended up growing over decades and because he was there at the start, he ended up having a lot of power within this division. And yet he understood toxicity in a particular way that reflected the way that he was trained and um how he understood the ways that at the time we needed to think about the risks associated with chemical exposures. For instance, he was you know, very convinced by studies of acute animal toxicity. So you know, give chemical to a lab animal and just watch what happens over the short term. Eventually, he did long-term studies on humans. And he only asked questions about certain physiological processes. He only studied the chemical in male study participants, and he followed them up for five years. These are just short examples of the kinds of things we know. I mean not even now just like 10, 20 years later other scientists would say well why didn’t you ask these questions or why didn’t you study them for 10 years or study their children or their wives, etc. And at the time those were simply not scientific questions that he thought were important. So, in a way he’s an example of somebody who denied a lot of DDT. Harms but didn’t actually think he was denying them. That’s wholly different from corporate actors who were aware of DDT’s harms and deliberately denied them because they didn’t want the public to believe that corporations couldn’t be trusted to put out products that um you know we’re safe for the average consumer to use. So all of this is to say that there are different types of scientific denial. There’s the kind that is the deliberate and the kind that is really just born of I think inherent humankind of bias and blind spots.
SP: It seems that scientists somewhere knew about the harms of DDT but that regulated use of chemicals was alright. Do you think this scientific denial is different from strategic, deliberate, and calculated ignorance that serves economic imperatives?
EC: Yeah I think that’s a really good question. So one of the characters that I became really intrigued by in the course of looking at the history of DDT was one of many people that I came across who were so convinced that even though DDT had toxic qualities it didn’t matter that they outweighed by the chemicals benefits. This one particular person that I have in mind was a Berkeley professor thomas jukes who um had worked as a biochemist in a private lab setting during the war. And then after the war um came to Berkeley where he was employed as a professor. And in the sixties, he kind of watched the public turn against DDT and he heard and understood the claims that in particular ornithologists and beekeepers were making about DDT’s Harms to wildlife. And in his mind he would say things like you know suburbs and highways do more harm to wildlife than chemicals like DDT and DDT has saved millions of lives across the globe from malaria and other vector-borne diseases. So yes it’s harmful. But these harms are actually a small price to pay for the benefit of humanity. And this was an argument that he really believed and he was one of a bunch of people that I came across who would very willingly eat DDT Just swallow it in front of an audience. Um And tell people that he knew that there was DDT in his body and that he didn’t think it mattered because he felt like we were all better off for the good that DDT did for the better part of the globe, in his view.
What was interesting about him is that I have yet to find any evidence that he was paid for these views. But eventually of course, um Industry became interested in him as a spokesperson and he offered himself initially to the chemical companies when they were facing um lawsuits and other legal actions about DDT, which were primarily filed by environmentalists starting in the late 1960s. And Duke’s offered himself as a witness. And at first they thought, oh we don’t need his help. And eventually, however, they turned to him because they appreciated the kind of bigger picture ideas that he was spreading, which was that like, sure it’s harmful, but we don’t have to worry about these harms that they’re far outweighed by the benefits. And that, you can trust um scientists who work for industry and industry itself to put out products that are on the whole beneficial for the public. So it’s this almost, you know, we I think there’s an easy narrative that so many of us have heard many times before where um corporations were really leading the charge and denying science that was inconvenient to their essentially bottom line and this is entirely true. And it’s also true that they were helped along the way by quote, unquote independent academics and experts who actually share the same views sometimes for different reasons. Um and ended up becoming well and to put it diplomatically helpful spokespeople for industry um and didn’t necessarily need to be paid recorded to be.
SP: There’s this very interesting bit where you also mentioned the role of the tobacco company and I was wondering if you could help our listeners understand the kind of links and parallels you draw how did DDT become such an important part of tobacco industry?
EC: Yes. This is such a fascinating part of DDT story and as part of why I was interested in writing a book about this chemical that you know, I think most people think is a story that we finished a long time ago and filed away and doesn’t need to be revisited. But at the university where I had done my dissertation, my doctoral degree, there was a collection of corporate documents. This is the U. C. S. F. Industry documents library and well more than a decade ago I was sort of kind of playing around with the search interface for this collection and came across a couple of documents in which the tobacco industry was talking about DDT and I found it curious because I just couldn’t imagine why the tobacco industry was interested in DDT other than you know it was a pesticide and they grew crops and so like any other pesticide they would find a bit of interest. What I found over time was that in the very beginning the tobacco industry was interested in DDT as a pesticide like any other just to see if it could control you know the everyday pests that affected tobacco as it was grown and cured and stored um and transported. And they were interested you know of course the ways in which to protect the crop from pests but also in terms of how it affected the final product like how it affected the burn rate of cigarettes, how it affected the flavor of cigarettes and the like. So they were studying this chemical closely over time in the 1960s as the public began to turn against DDT In the US and now I’m focusing on the U. S. Tobacco industry specifically. Um Tobacco executives were kind of paying attention to the public debate because they knew that DDT was still being used on their crops and they knew that the public was paying attention to DDT’s effects. The tobacco industry in the early sixties had also come under scrutiny for the carcinogenic city of its own products cigarettes and um had received actually a bunch of letters from smokers saying things like have you thought about whether cigarettes are causing cancer not because they themselves are personal genic but because the pesticides used on them are the cause of cancer. So, the tobacco industry was aware that some members of the public were thinking about this.
In the late 1960s, a handful of European countries started to set lower tolerances for tobacco on crops. And in particular a couple of countries we’re poised to lower the amount of DDT Allowed on um tobacco. And so, US tobacco companies suddenly realized that they were facing regulations in Europe that were going to cost them a significant um part of their export market. Something like one-third of US Tobacco products at the time was being exported to Great Britain and Germany both of which were considering um DDT tolerances or limits on the amount of DDT that would have made US tobacco unsalable there. So, the tobacco industry started pressuring US government regulators and also their own growers to use less DDT. But DDT was so persistent that they quickly realized DDT had to be banned outright because if it was sprayed anywhere if it was sprayed on a neighboring farm drift or if winds could carry it over to tobacco it would stay in the soil and it would be present in their crops for years. So, in the late sixties and then into the early seventies you have the tobacco industry now pressuring regulators essentially to ban DDT and in the US One of the results of this is that one of the first limited bans and that the US government passes on DDT is actually a ban on its use on tobacco. This is before this is years before the chemical is banned outright essentially for all uses in the US that happens in 1972. The chemical is still manufactured in the US however, it’s still manufactured abroad. It’s still used abroad. Although gradually. Over the course of the 70s and 80s, more and more countries around the globe begin to ban it. Until finally, it’s manufactured in just a handful of countries by the 1990s. And at that point there’s a global movement to um ban what are called the pops, the persistent organic pollutants chemicals that persist in the environment long after they are manufactured or applied. And DDT Ends up on this list of the quote unquote dirty dozen pops that are slated for global Ban through an international convention that takes place in the late 1990s called the Stockholm Convention. So as the Stockholm Convention is taking place, focused on getting a ban on these chemicals. There are a set of other um global diplomatic meetings taking place focusing on tobacco. And in particular, the outcome of these meetings um is a plan to regulate tobacco more like a narcotic. Um And two do a number of other things including focus more on the effects of second hand smoke and the tobacco industry kind of catches wind of these two things happening and at the time ends up being approached by a conservative think tank that puts forth a proposal to create a communications campaign to publicize the fact that after DDT was banned by Western countries, malaria increased in poor countries, particularly in sub Saharan Africa. And as a result millions of not just people but especially Children were dying each year of a preventable disease that was only persisting because of DDT’s Band decades earlier in the West and its inaccessibility as a result to poorer countries, the idea behind the communication and spread of this version of DDT story was that it would hopefully illustrate that Western led global health efforts couldn’t be trusted because they only served the interests of wealthy, industrialized nations. And one of the other aims of this campaign was that it would create a divide an argument essentially between public health groups and environmental groups and divide the supporters of added regulation. And one of the final ideas behind this communications campaign was that it would publicize the idea of malaria as a major global health problem one bigger than tobacco and therefore distract attention away from tobacco as a cause of health problems. So, this communications campaign, dreamed up by conservative think tanks, was then funded by a tobacco industry which was essentially simply interested in protecting its own product and to do so publicized a story about a completely different product, in the hopes of undermining public support generally for regulation and in the hopes of undermining the coalition of groups that supported that kind of regulation. It’s a complicated and messy story, but a fascinating one as to why tobacco, which never manufactured or made DDT had such an interest in these chemicals fate over time.
SP: DDT has been enthusiastically celebrated by civilians. Today, pesticides use, and consumption has only increased, which I imagine makes it far more difficult to do scientific research specifically to trace back the harm to DDT use because it’s an assemblage of so many factors that one can easily discard the importance of one particular factor. This also makes me think about the pandemic. I remember seeing this image in a newspaper where migrant workers made to sit on the road and were sprayed with disinfectant by government officials to fight coronavirus. It seems that in this risk calculus epidemic fear play a greater role than environmental and bodily harm
EC: Mhm. Yeah. Yeah. You put it so well just then I ended up illustrating it in my book with a look at DDT use against epidemic polio. In the late 1940s and early 1950s. Because I was so surprised to learn about this episode, we all know that in times of emergency our risk calculus changes and that we’re we’re willing to use technologies that address the immediate threat and postpone any investigation of their longer term potential harms in exchange for short term Salvation. We in the 19 forties had so much evidence that DDT was effective at controlling vector borne diseases. That when suddenly the US was faced with epidemic levels of a new relatively new infectious disease polio. Um we treated it in a way that we knew how to treat it. So we searched for a vaccine. We tried to control it through the age old practices of like quarantine and isolation and contact tracing. And we also thought that it might be spread by flies. And so that made us treat it like it was malaria, which meant in the late 1940s spraying entire towns houses people with DDT to prevent polio spread. We continue to do this even well after scientific studies showed that DDT was not an effective means of controlling polio. And yet we did it because we had no better tools. And so it was a kind of expression of both faith and science and hope that science had offered us a tool that was going to offer protection. You know, fast forward. Um really throughout DDT story at every moment in this chemical’s lifespan, we had different reasons for weighing its risks and benefits differently in one moment than we did in the previous moment. And this again goes under the category of why I was interested in writing about this book because it was the sort of technology where you could say it saved lives and you could say it was harmful and you could easily say from the beginning that it was harmful to insects. It was harmful to birds. It was harmful to amphibians. And that those environmental or ecological harms were undeniable from the start.
You know in the face of polio many people chose to disregard those harms. Once polio was under control, those harms literally began to get more attention scientific attention and also public attention and began this is just kind of one small example about of how that risk benefit calculation would shift from one moment to the next. The other part of your question about you know, the bigger longer term effects of really our encounter experience with DDT is that eventually the US and so many other nations got to a point where DDT’s costs were no longer justified by its benefits. And so countries phased it out, banned it. And yet and I think that the experience in the US illustrates us so vividly just because we banned DDT didn’t mean that we were abandoning uh an approach in particular an agricultural system that was entirely dependent on chemical and other technological approaches to controlling insect pests. So, the long term result was that we banned DDT and other um similar chemically similar types of chemicals with similar characteristics as DDT. We replaced them with other kinds of chemical pesticides when those proved problematic. We began to replace them with yet another category of pesticides which we’re using now.
And not only that but as you pointed out, total pesticide use has only increased since the time of DDT’s ban in the 1970s. So, the ban was almost like a scapegoat in a way it gave us the kind of false assumption that we had solved the problem of toxic chemicals. But in fact, we just replaced it with another set of problems that we really as a society haven’t been paying um close enough attention to, in my view it’s pretty well established that we don’t have the insect um diversity and volume that we once had And going all the way back to the early days of DDT there were agricultural scientists who championed the chemical and in the same breath said. But hold on we need to be careful because we need insects for our survival. Yes, they complicate things but without them we have no agriculture, we have no food um without that we don’t even have humanity. And so that warning was issued you know the better part of a century ago now. And there are others who are making similar claims today that the destruction to our insect populations is reaching an apocalyptic scale. And yet we’re really not doing anything about it to date.
SP: Hmm. This seems to be a very anthropocentric perspective. It’s like for as long as humans need the birds and the insects, and for the water to not get contaminated, it matters. Did you at any point while researching feel that perhaps most of these scientific documents and research were in fact very human-centric.
EC: Yeah, that’s such a good question and it’s almost um unfair consequence of how I’m condensing the story in the book itself. I really tried to show how important ornithologists and bird lovers were to the kind of legislative turn against DDT Um some of the environmental groups that were successful in getting a lot of attention to the harms of DDT were groups that were devoted to the preservation of bird populations. And yet even they at some point were so conscious of the fact that if they were going to convince more members of the public to get on board with their cause, they would have to make it about more than just the birds. In fact, one of the scientists I talked to said like it was always just about the birds. But then going back and reading his papers and his letters from the time from the 1960s and 70s, I saw him writing then to his colleagues like people care about their health and we need to scare them about DDT by letting them know that this could be harmful to their health too. So, health was for these environmental groups away to engage the public and get them to care about environmental concerns. Before these environmental groups, the United Farm workers had taken up the cause of DDT And as they called them, the other hard pesticides and what they did was also amplify the health effects of these pesticides. To get the public to demand that such pesticides not be used and essentially to get the public to boycott crops that had been sprayed with such pesticides. So, what we see are groups who may or may not have had anthropocentric concerns putting those at the core of their care. Their campaigns out of the assumption that that was the best way to bring the rest of the public on board.