GEOG 430
Human Use of the Environment

Environmental Health and the Effects of Pesticides


Silent Spring:

Chemicals can have harmful effects on human health, but also what we broadly understand as environmental health. Remember how we’ve examined how humans and nature are intertwined concepts. Thus, understanding the complex relationships between exposures in nature requires tracing interactions between plants, animals (including humans), soils, air, and water.

Pesticides and fertilizers used in agriculture are essential entry points to understanding this relationship. Perhaps the groundbreaking work on this topic was published in Rachel Carson’s 1962 book, Silent Spring. In her book, Carson details the extensive harm the pesticide DDT poses to humans and non-humans alike; after DDT has been sprayed, it persists in the environment, circulating through soil, water, bodies, and food. Carson’s work challenged industry and government groups for promoting DDT spraying programs despite mounting evidence of its deleterious effects. Her analysis, expanded on by many scholars in the 50 years since the publication of Silent Spring, draws strong connections between environmental harms and political and economic policies, programs, and institutional structure. Many consider Carson’s book to be a major turning point in environmental politics in the United States, laying the ground work for the environmental movement in the United States and the establishment of the Environmental Protection Agency (EPA).

Read the excerpt from her book, found in the Week 7 Module on Canvas. As you read it, pay special attention to the everyday encounters with chemicals Carson describes, and the way she analyzes governmental and industry actions. This will be helpful to you next week when we encounter the environmental justice movement.

Changing Risks:

Since the publication of Rachel Carson's book, the use of pesticides in developed countries has become much more highly regulated (check the WHO map and think about if the regulations are equally cautious in developing countries?). While few of us today are careless when applying pesticides to our lawns (if we do at all) and many of you may have never even heard of moth prevention treatments (used by your grandma to keep moths from eating holes in woolen clothing and blankets), there are new and evolving risks that we are exposed to. For example, many carpets are sprayed with fire retardants that are now emerging as a potential health risk. And the chemical used to make your stylish new jacket waterproof are being questioned and linked to health risks.

The World Health Organization has recently published new figures showing Ambient Air Pollution as one of the top 15 risk factors for mortality globally, along with Occupational Risks (which include acute pesticide poisoning).

Although the United States and many other countries have banned DDT, agricultural uses of other pesticides continue. The impacts of these new pesticides are often less acute; however, as was the case for the chemicals described by Carson, their impacts on human health are often not well understood. In this video, Tyrone Hayes, a Professor of Biology at the University fo Californa, Berkeley, and Penelope Jagessar Chaffer, a filmmaker, discuss the impacts of a common herbicide on hormonal health, as well as other chemical compounds that can be harmful to humans and fetuses.

Click for a transcript of "Toxic Baby" video.

Penelope Jagessar Chaffer: I was going to ask if there's a doctor in the house. No, I'm just joking. It's interesting, because it was six years ago when I was pregnant with my first child that I discovered that the most commonly used preservative in baby care products mimics estrogen when it gets into the human body. Now it's very easy actually to get a chemical compound from products into the human body through the skin. And these preservatives had been found in breast cancer tumors.

That was the start of my journey to make this film, "Toxic Baby." And it doesn't take much time to discover some really astonishing statistics with this issue. One is that you and I all have between 30 to 50,000 chemicals in our bodies that our grandparents didn't have. And many of these chemicals are now linked to the skyrocketing incidents of chronic childhood disease that we're seeing across industrialized nations. I'll show you some statistics. So for example, in the United Kingdom, the incidence of childhood leukemia has risen by 20 percent just in a generation. Very similar statistic for childhood cancer in the U.S. In Canada, we're now looking at one in 10 Canadian children with asthma. That's a four-fold increase.

Again, similar story around the world. In the United States, probably the most astonishing statistic is a 600 percent increase in autism and autistic spectrum disorders and other learning disabilities. Again, we're seeing that trend across Europe, across North America. And in Europe, there's certain parts of Europe, where we're seeing a four-fold increase in certain genital birth defects. Interestingly, one of those birth defects has seen a 200 percent increase in the U.S. So a real skyrocketing of chronic childhood disease that includes other things like obesity and juvenile diabetes, premature puberty.

So it's interesting for me, when I'm looking for someone who can really talk to me and talk to an audience about these things, that probably one of the most important people in the world who can discuss toxicity in babies is expert in frogs.


Tyrone Hayes: It was a surprise to me as well that I would be talking about pesticides, that I'd be talking about public health, because, in fact, I never thought I would do anything useful. (Laughter)Frogs. In fact, my involvement in the whole pesticide issue was sort of a surprise as well when I was approached by the largest chemical company in the world and they asked me if I would evaluate how atrazine affected amphibians, or my frogs. It turns out, atrazine is the largest selling product for the largest chemical company in the world. It's the number one contaminant of groundwater, drinking water, rain water. In 2003, after my studies, it was banned in the European Union, but in that same year, the United States EPA re-registered the compound.

We were a bit surprised when we found out that when we exposed frogs to very low levels of atrazine -- 0.1 parts per billion -- that it produced animals that look like this. These are the dissected gonads of an animal that has two testes, two ovaries, another large testis, more ovaries, which is not normal ... (Laughter) even for amphibians. In some cases, another species like the North American Leopard Frog showed that males exposed to atrazine grew eggs in their testes. And you can see these large, yolked-up eggs bursting through the surface of this male's testes. Now my wife tells me, and I'm sure Penelope can as well, that there's nothing more painful than childbirth -- which that I'll never experience, I can't really argue that -- but I would guess that a dozen chicken eggs in my testicle would probably be somewhere in the top five.

In recent studies that we've published, we've shown that some of these animals when they're exposed to atrazine, some of the males grow up and completely become females. So these are actually two brothers consummating a relationship. And not only do these genetic males mate with other males, they actually have the capacity to lay eggs even though they're genetic males. What we proposed, and what we've now generated support for, is that what atrazine is doing is wreaking havoc causing a hormone imbalance. Normally the testes should make testosterone, the male hormone. But what atrazine does is it turns on an enzyme, the machinery if you will, aromatase that converts testosterone into estrogen. And as a result, these exposed males lose their testosterone, they're chemically castrated, and they're subsequently feminized because now they're making the female hormone.

Now this is what brought me to the human-related issues. Because it turns out that the number one cancer in women, breast cancer, is regulated by estrogen and by this enzyme aromatase. So when you develop a cancerous cell in your breast, aromatase converts androgens into estrogens, and that estrogen turns on or promotes the growth of that cancer so that it turns into a tumor and spreads. In fact, this aromatase is so important in breast cancer that the latest treatment for breast cancer is a chemical called letrozole, which blocks aromatase, blocks estrogen, so that if you developed a mutated cell, it doesn't grow into a tumor.

Now what's interesting is, of course, that we're still using 80 million pounds of atrazine, the number one contaminant in drinking water, that does the opposite -- turns on aromatase, increases estrogen and promotes tumors in rats and is associated with tumors, breast cancer, in humans. What's interesting is, in fact, the same company that sold us 80 million pounds of atrazine, the breast cancer promoter, now sells us the blocker -- the exact same company. And so I find it interesting that instead of treating this disease by preventing exposure to the chemicals that promote it, we simply respond by putting more chemicals into the environment.

PJC: So speaking of estrogen, one of the other compounds that Tyrone talks about in the film is something called bisphenol A, BPA, which has been in the news recently. It's a plasticizer. It's a compound that's found in polycarbonate plastic, which is what baby bottles are made out of. And what's interesting about BPA is that it's such a potent estrogen that it was actually once considered for use as a synthetic estrogen in hormone placement therapy. And there have been many, many, many studies that have shown that BPA leaches from babies' bottles into the formula, into the milk, and therefore into the babies. So we're dosing our babies, our newborns, our infants, with a synthetic estrogen.

Now two weeks ago or so, the European Union passed a law banning the use of BPA in babies' bottles and sippy cups. And for those of you who are not parents, sippy cups are those little plastic things that your child graduates to after using bottles. But just two weeks before that, the U.S. Senate refused to even debate the banning of BPA in babies' bottles and sippy cups. So it really makes you realize the onus on parents to have to look at this and regulate this and police this in their own lives and how astonishing that is.

(Video) PJC: With many plastic baby bottles now proven to leak the chemical bisphenol A, it really shows how sometimes it is only a parent's awareness that stands between chemicals and our children. The baby bottle scenario proves that we can prevent unnecessary exposure. However, if we parents are unaware, we are leaving our children to fend for themselves.

TH: And what Penelope says here is even more true. For those of you who don't know, we're in the middle of the sixth mass extinction. Scientists agree now. We are losing species from the Earth faster than the dinosaurs disappeared, and leading that loss are amphibians. 80 percent of all amphibians are threatened and in come decline. And I believe, many scientists believe that pesticides are an important part of that decline. In part, amphibians are good indicators and more sensitive because they don't have protection from contaminants in the water -- no eggshells, no membranes, and no placenta. In fact, our invention -- by "our" I mean we mammals -- one of our big inventions was the placenta. But we also start out as aquatic organisms.

But it turns out that this ancient structure that separates us from other animals, the placenta, cannot evolve or adapt fast enough because of the rate that we're generating new chemicals that it's never seen before. The evidence of that is that studies in rats, again with atrazine, show that the hormone imbalance atrazine generates causes abortion. Because maintaining a pregnancy is dependent on hormones.

Of those rats that don't abort, atrazine causes prostate disease in the pups so the sons are born with an old man's disease. Of those that don't abort, atrazine causes impaired mammary, or breast, development in the exposed daughters in utero, so that their breast don't develop properly. And as a result, when those rats grow up, their pups experience retarded growth and development because they can't make enough milk to nourish their pups.

So the pup you see on the bottom is affected by atrazine that its grandmother was exposed to. And given the life of many of these chemicals, generations, years, dozens of years, that means that we right now are affecting the health of our grandchildren's grandchildren by things that we're putting into the environment today.

And this is not just philosophical, it's already known, that chemicals like diethylstilbestrol and estrogen, PCBs, DDT cross the placenta and effectively determine the likelihood of developing breast cancer and obesity and diabetes already when the baby's in the womb. In addition to that, after the baby's born, our other unique invention as mammals is that we nourish our offspring after they're born. We already know that chemicals like DDT and DES and atrazine can also pass over into milk, again, affecting our babies even after they're born.

PJC: So when Tyrone tells me that the placenta is an ancient organ, I'm thinking, how do I demonstrate that? How do you show that? And it's interesting when you make a film like this because you're stuck trying to visualize science that there's no visualization for. And I have to take a little bit of artistic license.

(Video) (Ringing) Old man: Placenta control. What is it? Oh what? (Snoring) (Honk) Puffuffuff, what? Perfluorooctanoic acid. Blimey. Never heard of it. PJC: And neither had I actually before I started making this film. And so when you realize that chemicals can pass the placenta and go into your unborn child, it made me start to think, what would my fetus say to me? What would our unborn children say to us when they have an exposure that's happening every day, day after day?

(Video) Child: Today, I had some octyphenols, some artificial musks, and some bisphenol A. Help me.

PJC: It's a very profound notion to know that we as women are at the vanguard of this. This is our issue, because we collect these compounds our entire life and then we end up dumping it and dumping them into our unborn children. We are in effect polluting our children. And this was something that was really brought home to me a year ago when I found out I was pregnant and the first scan revealed that my baby had a birth defect associated with exposure to estrogenic chemicals in the womb and the second scan revealed no heartbeat.

So my child's death, my baby's death, really brought home the resonance of what I was trying to make in this film. And it's sometimes a weird place when the communicator becomes part of the story, which is not what you originally intend. And so when Tyrone talks about the fetus being trapped in a contaminated environment, this is my contaminated environment. This is my toxic baby. And that's something that's just profound and sad, but astonishing because so many of us don't actually know this.

TH: One of the things that's exciting and appropriate for me to be here at TEDWomen is that, well, I think it was summed up best last night at dinner when someone said, "Turn to the man at your table and tell them, 'When the revolution starts, we've got your back.'" The truth is, women, you've had our back on this issue for a very long time, starting with Rachel Carson's "Silent Spring" to Theo Colborn's "Our Stolen Future" to Sandra Steingraber's books "Living Downstream" and "Having Faith." And perhaps it's the connection to our next generation -- like my wife and my beautiful daughter here about 13 years ago -- perhaps it's that connection that makes women activists in this particular area.

But for the men here, I want to say it's not just women and children that are at risk. And the frogs that are exposed to atrazine, the testes are full of holes and spaces, because the hormone imbalance, instead of allowing sperm to be generated, such as in the testis here, the testicular tubules end up empty and fertility goes down by as much as 50 percent. It's not just my work in amphibians, but similar work has been shown in fish in Europe, holes in the testes and absence of sperm in reptiles in a group from South America and in rats, an absence of sperm in the testicular tubules as well. And of course, we don't do these experiments in humans, but just by coincidence, my colleague has shown that men who have low sperm count, low semen quality have significantly more atrazine in their urine.

These are just men who live in an agricultural community. Men who actually work in agriculture have much higher levels of atrazine. And the men who actually apply atrazine have even more atrazine in their urine, up to levels that are 24,000 times what we know to be active are present in the urine of these men. Of course, most of them, 90 percent are Mexican, Mexican-American. And it's not just atrazine they're exposed to. They're exposed to chemicals like chloropicrin, which was originally used as a nerve gas. And many of these workers have life expectancies of only 50.

It shouldn't come to any surprise that the things that happen in wildlife are also a warning to us, just like Rachel Carson and others have warned. As evident in this slide from Lake Nabugabo in Uganda, the agricultural runoff from this crop, which goes into these buckets, is the sole source of drinking, cooking, and bathing water for this village. Now if I told the men in this village that the frogs have pour immune function and eggs developing in their testes, the connection between environmental health and public health would be clear. You would not drink water that you knew was having this kind of impact on the wildlife that lived in it. The problem is, in my village, Oakland, in most of our villages, we don't see that connection. We turn on the faucet, the water comes out, we assume it's safe, and we assume that we are masters of our environment, rather than being part of it.

PJC: So it doesn't take much to realize that actually this is an environmental issue. And I kept thinking over and over again this question. We know so much about global warming and climate change, and yet, we have no concept of what I've been calling internal environmentalism. We know what we're putting out there, we have a sense of those repercussions, but we are so ignorant of this sense of what happens when we put things, or things are put into our bodies.

And it's my feeling and it's my urging being here to know that, as we women move forward as the communicators of this, but also as the ones who carry that burden of carrying the children, bearing the children, we hold most of the buying power in the household, is that it's going to be us moving forward to carry the work of Tyrone and other scientists around the world. And my urging is that when we think about environmental issues that we remember that it's not just about melting glaciers and ice caps, but it's also about our children as well.

Thank you.

As you watch the video, take note of how human and environmental life are entwined. What are some of the ethical and justice considerations this video raises for you? What are some of the regulatory issues it raises? How does the video discuss generational issues? Don't forget to pay attention to the ways these presenters make their argument. How do they set the stakes of what they're discussing?

Global Perspective:

Now for a global perspective, read the World Health Organization's page on Agri-chemicals and pay attention to the map showing the number of chemical poisoning in each country around the world. Consider where your own food comes from and how your own consumptive patterns might be implicated in these exposures. How could this be a part of a commodity chain analysis that we've covered in Week 6?