Here are excerpts from a Frontline transcript, June 2nd 1998, that I thought was worth putting in the spotlight.
The complete transcript can be found at
Fooling With NatureFredrick Vom Saal is a Professor of Biological Sciences, University of Missouri. A leading researcher in the field of developmental biology, Vom Saal has studied the effects of both natural and synthetic hormones at extremely low doses. His studies have shown that extremely low doses of hormones can permanently alter development of the reproductive system in mice. He has also studied how manmade chemicals, including plastics, can mimic hormones at extremely low doses.
Interview conducted in February 1998 by Doug Hamilton, producer of FRONTLINE's "Fooling With Nature."
DH: You've said that the doses at which hormones affect the body are extremely low. Give me an example to make me understand that.
FvS: The issue of the amount of hormone that actually causes effects is very difficult for scientists to talk to people about because we're dealing with numbers that are outside of the frame of reference that anybody is going to be thinking about. We see changes, profound changes, in the course of development of essentially the whole body of experimental animals, and we're working with mice and rats, and we see these changes at fifty femtograms of the hormone per milliliter of blood. That's 0.05 trillionths of a gram of this hormone in a milliliter of blood.
DH: And what sort of effect does it have?
FvS: We see changes in the functioning of the prostate. We see dramatic change in the sprouting of glands within the fetal prostate. We see changes in testicular sperm production. We see changes in the structure of the endocrine control region in the brain, which is accompanied by changes in sex behavior, aggression, the way these animals behave towards infants, their whole social interaction, the way they age, the time that they enter puberty, the age at which they cease reproduction. It changes their entire life history, and these changes are capable of occurring at very low levels of hormones.
I remember when we first did this and I was a post doctoral fellow, and my advisor and I looked at the hormone levels and said, "My God, these levels are so staggeringly small and the consequences are so immense it's amazing." Even to biologists, it's amazing.
But what you have is the entire field of toxicology thinking of a millionth of a gram of a hormone or a chemical as being this staggeringly tiny amount, and to most people if I said there's only a millionth of a gram of it here you'd say, "How can it do anything?" A millionth of a gram of estradiol in blood is toxic. The natural hormone is actually operating at something like a hundred million times lower than that. So when you have a physiologist thinking of a millionth of a gram, you have that physiologist thinking this is a toxic high dose. When you are raised in the field of toxicology you are looking at that from the other perspective of "My gosh, that's such a tiny dose, it couldn't do anything."...
DH: Can you again describe the results, the developmental effects in your laboratory mice, that you are seeing with these unbelievably small changes in hormone levels?
FvS: We published a paper just a few months ago in the "Proceedings of the National Academy of Sciences" in which we experimentally elevated estradiol levels in mouse fetuses during the period when their reproductive organs were forming. And what we did was we experimentally elevated estradiol by one tenth of one trillionth of a gram of estradiol in a milliliter of blood. We estimate that we're increasing estradiol by about one molecule of estradiol per cell in the body. Okay? The consequence of this is that at the end of the first day of development of the prostate in the male fetuses we could see dramatic change in the sprouting of prostate glands. We rendered the prostate abnormally enlarged, and this was detectable within twenty-four hours of the beginning of its embryonic development. And when we looked at these treated animals as adults, that difference had persisted. They had abnormally enlarged prostates that were hyper-responsive to hormones.
Now, prostate disease is for every male in this country and for every male in the world a very, very serious concern. It's the largest bill to the medical community. It's the most prevalent disease of aging in humans. Seventy percent of men, by the time you're seventy years old, will have an abnormally enlarged prostate. We caused this to happen at the first day of embryonic life with that change in estradiol. That's how sensitive embryonic organs are to these staggeringly tiny changes in hormones....
DH: These hormone levels you're talking about are inconceivably low, staggeringly low. How do we even begin to measure them?
FvS: For some chemicals, and for some hormones, the technical capacity to measure them is actually less sensitive than the body's ability to detect them. We've been working with a chemical, bisphenol-A. It's what polycarbonate plastic, hard plastics, are made out of: CD's, the plastic in your glasses' lens, milk containers, baby bottles. It's the chemical that they use to line cans with, it's the chemical they put on your teeth as a sealant and it is a very potent estrogen. It mimics the hormone that women produce in their ovaries, and it mimics this hormone estradiol that is actually being produced in fetuses and during pregnancy that is a major coordinator or an alligator or any other animal.
Estradiol plays a critical role in development and then normal functioning of the body for the rest of an individual's life. The amount of estradiol you're exposed to throughout your life is also the best predictor of breast cancer. This chemical mimics that hormone. The body can't tell the difference between bisphenol-A and estradiol. In other words, it sees this chemical and it thinks it's getting exposed to its natural hormone....
DH: So you're saying that the hormone that has the clearest link to breast cancer, the hormone that is responsible for sexual development in any animal or human, is found in plastics?
FvS: Absolutely. The plastic materials, if they are polycarbonates, are made with this chemical bisphenol-A. And you can think of polycarbonate as a house made of bricks. Essentially you take this brick, this building block, which is bisphenol-A, and you link it together with other bisphenol-A molecules. That's a polymerization reaction. The bisphenol-A is the monomer used to construct these plastic materials. When it's attached to another one, that forms a polymer. And unfortunately in the process of making these plastics not all of the bisphenol-A gets linked together. So you put your food or other material in the plastic and it absorbs the unreacted bisphenol-A into it. And now in your food is a sex hormone...
DH: And what are you finding to be the effect?
FvS: Okay, the chemical bisphenol-A passes out of the plastic or out of the dental sealant that's put on your child's teeth or out of the lining of cans, into the food or liquid that's in contact with the plastic. Now the important point about detection by instrumentation of the bisphenol-A is that, based on our research, the ability of the current instruments used to monitor for bisphenol-A in food is a much lower level of detection than what our animals are able to detect. It's a huge difference as a matter of fact. So that you can put food that you have in contact with plastic into a chemical analysis and say there is no plastic material there. We extract from that same food, put it into animals and we get a big effect. The animals are more sensitive to the chemicals than the machinery...
DH: So the plastics we use in daily life, the baby bottles, the food containers, leach chemicals into the food at levels that cause effects in lab animals?
FvS: One of the things that we started doing a number of years ago is we started looking at the effects of the materials that plastics are made out of in cell culture. We used human cells to see how responsive these cells were to these chemicals, and at what doses the chemicals could influence human cells to start growing and doing things differently. So, in other words, we're getting biological responses out of the cells and we were astonished at the incredibly small amounts of these chemicals that were actually able to alter human cell function...
So what we did in mice was based on the studies using human cells. We know that mouse cells are essentially identical to human cells in the way that they respond to these hormones. That's been known actually for quite a long time...
Now one of the surprising things is that when we started looking into the literature concerning the amounts of these chemicals that were being released into food from plastic containers, and we compared that to the doses active in our cell culture studies, they were the same doses. But they were also doses that the toxicological community was saying were absolutely safe...
...But there were no actual experiments that had ever tested to see if that was true. So we did something that had never been done...
DH: And what did you find?
FvS: For the males, decreased sperm count and enlarged prostates. The treatment altered virtually every aspect of the reproductive system...
...In other words, in every aspect of physiology that we look for, we see effects. And they're permanent. And the important thing about what I'm talking about is we are only exposing babies to these chemicals for very, very short periods of time in development and the consequences are for the rest of the life of that individual. Once you change the development of an organ there is no way to undo that effect. It's a life sentence -- that's a lifetime consequence. Medical science can't undo the development of organs.
DH: And you're finding that organs are affected at levels as low as those that are leaching into our food from common plastics?
FvS: That's correct...
DH: Could I just get you to repeat that in simpler terms?
FvS: OK. If you look at the fish or the human or the frog or the bird at the earliest stages of embryonic development, when the reproductive organs are forming, you're hard pressed to tell them apart. And if I were to show you the developing prostate in a human at the very beginning of its development, and the developing prostate in a mouse at the beginning of its development, you wouldn't tell them apart. And at the functional level they're essentially identical...
DH: One of your colleagues actually stumbled onto this problem with plastics. How did that happen?
FvS: Well, it's a fascinating detective story. At Tufts University, they were doing the same types of studies that we have been doing with human cells: culturing them and then looking at the ability of the cells to respond to chemicals in the environment. They had purchased some new test tubes and the test tubes were made of polystyrene plastic, and the cells that we're using to detect estrogens require estrogens to grow and to proliferate, to go through development. And they put the cells in these test tubes and they started growing. And so the natural assumption was, "Somebody spilled some chemical in the lab that is infiltrating all of our cultures, and oh my gosh this is a disaster." Contaminated labs are a real serious problem.
Instead, after months and months of work, they realized that the lab was absolutely clean and that it was the test tube that was causing the cells to grow. So they called up Dow Corning, from whom they had purchased these test tubes, and said, "Your test tubes are causing our estrogen-responsive cells to grow. They must be releasing an estrogen. What could that be?" And Dow Corning said, "We won't tell you. We won't tell anybody what's in our products." And I'll come back to this because this is an extremely critical issue with regard to knowing what chemicals we're exposed to. Because the chemical industry will not inform scientists or the public what the chemicals in the products we're using are, and so it took months of work, of chemical analysis of these plastics, to realize that it's an additive material.
It's an antioxidant that stops discoloration of the plastic and it's added to the plastic to stop it from discoloring, and it's present in soaps, detergents, hand creams, vaginal creams. It's used in loads of different types of products. This same chemical is also used as an antioxidant in plastics. And it's a potent enough estrogen that when you put human cells into a plastic material made of polystyrene, but it's got this additive material in it, it can cause human breast cells to start proliferating. That's not a good thing...
DH: Could it be cancer causing?
FvS: Well, you can't have breast cancer if you don't have enough estrogen to cause the breast cells to undergo differentiation in development...
DH: And this is coming from soaps, creams, plastics that are in our daily lives?
FvS: That's correct...
DH This issue can't be talked about without getting into politics, it seems. Why is that?
FvS: The political aspects of dealing with the endocrine disrupter issue have really altered the course of what is happening dramatically...In the case of the endocrine disrupter issue, where the chemical that we're publishing about happens to be one of the fifty top chemicals made in the United States, it is worth billions of dollars to a few major corporations such as General Electric, Shell Oil, Dow Chemical. Each of them makes billions of dollars from this chemical...
MC: Steve Safe said to us that the levels of chemicals in the environment have all gone down.
FvS: DDT is at much lower levels in the United States today than it was in the 1970s. Of course it's also being used all over the world, and it's in the atmosphere. And the very current evidence is that while levels decreased after it was banned, we're now somewhat stabilizing. The same with PCBs. Those two chemicals do not encompass endocrine disrupters...
...Every four years, one trillion pounds of plastics are made in the world. They are being thrown away in the landfill. They are leaching these products back into our water. No one is looking for them. So as a general statement, to say that all endocrine disrupting chemicals are at lower levels today than they would have been twenty years ago is just ludicrous. Because nobody's looked. Nobody knew they were endocrine disrupting chemicals...
...what you have is the entire field of toxicology thinking of a millionth of a gram of a hormone or a chemical as being this staggeringly tiny amount, and to most people if I said there's only a millionth of a gram of it here you'd say, "How can it do anything?" A millionth of a gram of estradiol in blood is toxic. The natural hormone is actually operating at something like a hundred million times lower than that...
...We published a paper just a few months ago in the "Proceedings of the National Academy of Sciences" in which we experimentally elevated estradiol levels in mouse fetuses during the period when their reproductive organs were forming. And what we did was we experimentally elevated estradiol by one tenth of one trillionth of a gram of estradiol in a milliliter of blood. We estimate that we're increasing estradiol by about one molecule of estradiol per cell in the body. Okay? The consequence of this is that at te components of plastics. Every four years, one trillion pounds of plastics are made in the world. They are being thrown away in the landfill. They are leaching these products back into our water. No one is looking for them. So as a general statement, to say that all endocrine disrupting chemicals are at lower levels today than they would have been twenty years ago is just ludicrous. Because nobody's looked. Nobody knew they were endocrine disrupting chemicals.
The complete transcript can be found at
Fooling With Nature*
