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Public Radio's Environmental News Magazine (follow us on Google News)

Our Stolen Future: Human Reproduction and Modern Risks

Air Date: Week of

Chemical compounds which seem to be causing problems in the reproductive ability of animals and humans have been the subject of a number of Living on Earth segments in the past year and a half. Now, a team of three scientific writers have written a ground-breaking book on the subject and it is raising much controversy. Vice President Al Gore wrote the foreword to the tome, likening the new book in importance to Rachel Carson's Silent Spring. Now the chemical industry is attacking the book and the authors in the press. Steve Curwood speaks with one of the co-authors, Boston Globe reporter Diane Dumonowski.


CURWOOD: This is Living on Earth. I'm Steve Curwood. For the last couple of years we've been bringing you reports about a disturbing new environmental concern: the suspected links between common chemicals such as pesticides, dioxin, and PCBs, and the disruption of the hormone or endocrine systems of animals and humans. It was in 1992 that Dr. Theo Colborn, the leading scientist who has been developing the endocrine disruption hypothesis, edited the first scientific volume on the subject. That book touched off a major buzz among scientists in industry, and slowly the general public has been hearing pieces of the story, especially the parts linking endocrine disrupters to declining human sperm counts. Now, for the first time, all the science has been put into plain language, in a new book written by Dr. Colborn, zoologist J. Peterson Myers, and journalist Dianne Dumanoski. It may become the most controversial environmental volume since Rachel Carson's Silent Spring first appeared 30 years ago.

The book is called Our Stolen Future. Even before its official publication date, it was the subject of a flurry of stories in major national newspapers and magazines, and of a blistering editorial in the conservative Washington Times. The first printing of the book has already sold out in many bookstores. Vice President Al Gore wrote a foreword to the book, in which he makes an urgent call for more research. The Vice President adds that Our Stolen Future takes up where Rachel Carson left off. I recently spoke with the book's co-author and Boston Globe reporter Dianne Dumanoski. She was quick to agree.

DUMANOSKI: I think this book is a direct descendant of Silent Spring, and in fact it picks up a thread that is present in Silent Spring but never gets fully developed by Rachel Carson.

CURWOOD: Uh huh. And that is?

DUMANOSKI: This is the thread of reproductive problems and sterility that's very much raised in the fable that opens Silent Spring. And Carson at various points says things like these are no ordinary poisons and there's something strange going on. But I think science wasn't developed sufficiently at that time for her to really completely explore that, and there was also the specter of cancer, which was very much on people's minds in this period.

CURWOOD: So in other words, Carson kind of got stuck at cancer, as it were.

DUMANOSKI: Yes. And Silent Spring helped set us off on a regulatory track that has regulated largely according to cancer risks. And we've largely had the assumption that if we regulated for cancer we would cover everything, that that was really the toughest standard, and, you know, if you really scrutinize chemicals carefully for whether they could cause mutations or cause cancer we were really protecting ourselves. And one of the messages of this book is that that's not true. There are many chemicals that do not cause cancer, but do disrupt hormones, and they cause a whole series, or have the potential to cause a whole series of problems that are not cancer. And may actually affect us more broadly across the population than cancer does.

CURWOOD: You mean more people being --

DUMANOSKI: It may affect more people.

CURWOOD: Can you talk about some of the effects on fertility of people?

DUMANOSKI: Well, one of the most worrisome signals is our effects on male sperm count. That would be an expected effect. It's something that's been seen in the laboratory in rat pups who are exposed before birth to these endocrine disrupting chemicals. Scientists had raised this question here in the US at roughly the same time that researchers on the other side of the Atlantic were actually believing that they were seeing dropping male sperm counts and beginning studies. These studies, when they emerged in the British Medical Journal, reported a 50% drop in male sperm count based on an analysis of 40-some studies from the US, Europe, and other places in the world. Shortly after that study appeared, 2 key male reproductive researchers in Europe put forward a hypothesis linking the drop in male sperm count and some other reproductive effects seen in males including undescended testicles, genital defects, and testicular cancer, to exposure before birth in the womb to elevated estrogen levels. And since some of the chemicals in the environment can elevate estrogen levels, these chemicals have come under suspicion as playing a possible role in this.

CURWOOD: There's some controversy over this research, though. I saw a study the other day, or a study reported, perhaps, the other day, that's still in progress, saying no, no, no, sperm counts aren't falling in this place and that place. How do you respond to this controversy?

DUMANOSKI: Well there have been a number of studies. The initial study by Carlson and Skakkebaek, that sparked incredulity among some researchers and several follow up studies. There were at least 3 studies that confirmed that there were dropping sperm counts, and some of them were done by researchers who'd been skeptics. But there was also a report from Toulouse in France that did not report a fall in sperm counts. So basically I think as the question is coming under closer scrutiny, you're seeing contradictory evidence coming from different geographical places, so it's not necessarily absolutely contradictory. We may be just seeing a pattern of falling sperm count that is different in different places.

CURWOOD: Meaning?

DUMANOSKI: Meaning people have had different exposures. In some rural places, exposure might be greater or less than in an industrial center.

CURWOOD: So, how are we exposed to these chemicals? It seems that there are all kinds of substances that people and animals would be exposed to having all kinds of results in the city, out in the countryside. How do they get into our bodies?

DUMANOSKI: Well some of us, if we're young enough, have inherited them from our mothers, so that's the first way that they can get into your body. Over a lifetime, a woman accumulates a store of persistent chemicals, and some of these are endocrine disrupting chemicals. They're stored in her body fat, and during pregnancy these chemicals are released from the body fat; they cross the placenta and they can affect the developing fetus. So -- and it's not just what the mother eats during pregnancy; it's basically a lifetime legacy, shall we say, that is passed down to the infant. These chemicals can also be passed onto a baby through breast milk. Human breast milk contains a large number of these chemicals, and in fact during breast feeding a baby is exposed to higher levels of some of these chemicals, such as dioxin, than he or she will ever encounter in their entire lifetime. So breastfeeding is potentially a large source. Then we are exposed to them through our food. The persistent members of this family, and not all of these chemicals are as persistent as others, are very attracted to fats. And so they will ride up through the food chain on fats. So in ice cream and in milk and in meat one can get exposed to many of these chemicals. You can be exposed to them in the air. We are discovering that some of these chemicals are leaching out of plastics, plastic containers, so one could possibly be exposed to some of these chemicals through food packaging. The lining of cans has been tested; there are sort of plastic linings in metal cans that have been shown to leach endocrine disrupting chemicals into the foods in these cans.

CURWOOD: So Mom can give this to you at birth. Or if Mom opens up a can of soup that has this substance in it, you could get it at the kitchen table from Mom.

DUMANOSKI: Yeah. So there are a lot of sources.

CURWOOD: Now, there are some critics that say that lots of these substances occur naturally. In plants, for example, you'll find estrogens and soybeans and rice and wheat and all kinds of things. And so that we really shouldn't be worried about synthetic things that imitate hormones. Or should we?

DUMANOSKI: Well, there's an important difference between the naturally occurring phyto-estrogens --

CURWOOD: Phyto-estrogen means?

DUMANOSKI: It means plant estrogen.


DUMANOSKI: And some of these synthetic substances. This has been a very important question because the body has protective mechanisms to keep estrogen levels from exposing a developing baby, for example, to too high a level during development. And these natural protective substances seemed to protect us also from some of the plant estrogens, and this may be a result of our evolutionary experience with these plants. But studies are now showing that at least some of the endocrine disrupting manmade chemicals can make an end run around this protective system. So if one is being exposed to these chemicals, all of it will be biologically active. The body will not be keeping most of it out of circulation.

CURWOOD: Are there ways that we can protect ourselves from exposure to synthetic hormone mimickers? What are you doing to protect yourself?

DUMANOSKI: Well, I am buying organic produce, which I actually have always done. One of the reasons to buy organic produce is not only because of the pesticides that are used, but because there are so called inert ingredients in pesticides, and what we've discovered in doing the book is that some of the so-called inert ingredients are actually endocrine disrupting chemicals. I'm as worried about those inert ingredients as I am about the active ingredient. I don't microwave in plastic because there's no way to know which plastic is safe and which isn't, and of course we don't believe that all plastic is necessarily going to be problematic, but there's no way for a consumer at the moment to know. And there is evidence that heating plastic will tend to accelerate the emergence of chemicals into the food or whatever's in the container. And I try to eat low on the food chain. And the thing that's surprising is that the kind of diet that is recommended to protect your heart, to protect you against cancer, is the same kind of diet that will protect you against endocrine disrupters. It's a low fat diet where you're eating low on the food chain and you're eating lots of fruits and vegetables and you're not eating a lot of red meat all the time or a lot of high fat cheeses.

CURWOOD: Dianne, let's talk more about some of the possible effects that the endocrine disrupters have. In your book you talk about hormone-like chemicals possibly affecting human behavior, and our ability to cope with stress. Can you tell me more about these findings?

DUMANOSKI: Yes. This has been one of the sleepers in the story, I think. There's been so much emphasis to date on estrogen mimicking chemicals and possible effects on sperm counts. That's been the hot story. I think that there is a new story emerging, that has to do with thyroid hormones and the possible impact of thyroid disruption on the development of the brain and behavior.


DUMANOSKI: When Theo was first doing her work, she was quite taken by a study that was done in the early 80s by a couple called the Jacobsons, who studied the children of women who had eaten Lake Michigan fish. And they found a distinct difference in the children of these women as compared to women who had not eaten fish.

CURWOOD: And the difference was?

DUMANOSKI: They found measurable motor differences. They found that the children weighed less; they had smaller head circumference. And basically their neurological and motor development was retarded.

CURWOOD: Are you saying they weren't as smart as kids?

DUMANOSKI: I don't think their study, it was one where you could talk about as smart, but they were definitely slower in developing. And these were subtle effects. This was not what you'd call profound retardation. It was the kind of effect that would be visible to psychologists doing sensitive tests. But it would be within the range of normal. The suggestion was, however, that these children had in some way been slowed down. That they had not, because of this exposure to the chemicals in the fish, become what they might have become. Now this study was quite controversial. It was difficult to do, there was a lot of criticism saying well they should have done this and they should have done that. So more recently, a team at the State University of New York at Oswego decided to try to replicate this study and to do a parallel animal study. So they have been looking both at humans and at rats who have been eating Great Lakes fish. And they now have preliminary results that were reported last year, and they have found many of the same effects that were found in this earlier study. They have found there is a difference in these children. A lot of their reflexes are different; they're not as sharp; you know, they have delayed reflexes. And they have done tests that are thought to have, to predict intelligence later. And there does appear to be some diminishment of babies whose mothers have eaten the astonishingly small amount of 40 pounds of Lake Ontario salmon in their entire lifetime. Now 40 pounds of fish is not a lot of fish if you're in a sport fishing family.

CURWOOD: And the result is a little less intelligence, perhaps.

DUMANOSKI: Perhaps. Another part that seems very worrisome to me is that these infants of mothers who had eaten fish did not seem to be able to cope with stress or negative stimuli, as the psychologists would call it.

CURWOOD: Huh. How do you measure that?

DUMANOSKI: This is very interesting. They will do something to startle a sleeping baby. They will shine, the researcher would shine a light in the baby's eye or ring a bell, and the baby will startle awake. And the normal response is for a baby to, after it's been disturbed 2 or 3 times, to start saying oh yeah, it's that guy shining the light in my face again. And the baby gets less upset each time; it becomes habituated. And what the researchers at SUNY-Oswego have found is that the children of women exposed to Great Lakes, to Lake Ontario fish, don't get used to it. Some of them get more upset as they get disturbed. And this obviously has implications for how easy you're going to get through life if you get more and more upset at unpleasant experiences, rather than becoming used to it and letting it roll off your back.

CURWOOD: This has enormous implications for society. You're telling me that all those cranky cab drivers and other people in traffic that I'm having a hard time with, maybe they're victims of endocrine disruption and they're less tolerant of the stress of being --

DUMANOSKI: Well that's certainly a theory that we ought to explore. Helen Daly, a researcher working with this team, did parallel work on rats to see whether rats would be a good model for exploring these effects, and she found exactly the same result in her rats. The rats basically did fine until life got a little bit unpleasant, and then they just sort of lost it. She used to say they would go bonkers. So you know, if you had the same response in your personal life it's going to be very difficult for you.

CURWOOD: Well wait a second. You're saying that these chemicals are widely dispersed in the society, that they're in virtually all of our bodies --

DUMANOSKI: At some level.

CURWOOD: At some level. And that research shows that if you're exposed to these chemicals...

DUMANOSKI: You're less robust and tolerant of stress.

CURWOOD: And cranky. So you mean society could be breaking down in part because...

DUMANOSKI: Well I wouldn't go so far as to say that, but I'd say that you're posing a question that we'd better start researching and exploring pretty quickly. Because I think these behavioral implications are quite worrisome.

CURWOOD: I guess they are. My guest has been Dianne Dumanoski. Along with Theo Colborn and John Peterson Myers, she's author of Our Stolen Future. Thank you.

DUMANOSKI: Thanks, Steve.



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