Why our exposure to chemicals in air, food and water violates human rights

For its first Rachel Carson memorial lecture, Pesticide Action Network UK invited the renowned American campaigner Sandra Steingraber to talk about her experiences with pesticides and other toxic pollutants. This is an edited version of her speech in London.    

Rachel Carson is the guiding light for all of us who care about the health of the planet and the people who live on it. With the publication of Silent Spring, Carson provided us four decades ago with a comprehensive exhaustively researched biological argument in simple lyrical language that anyone with or without training in the sciences could read and understand. And everyone did read it. I was less than five years old when that book was published in 1962. My father who taught High School used it as a textbook, and his students all read it. But more than that, I remember hearing the bus driver talk about that book. It was a book that reached across socio-economic lines and truly did change the way people thought about their relationship to the natural world.

The book takes a four-part argument. First, Carson says we are all being contaminated without our consent to inherently toxic chemicals in the form of pesticides. Secondly, that the risks to our health and the health of other species are really needless because there are many non-toxic alternatives, if we only looked about us and sought them out. And then third, these alternatives are more effective than toxic chemicals because besides all of the unintended consequences of pesticides, the truth is that these chemical poisons don’t really work very well in controlling pests. And finally – and this is the message I would like to elaborate because it is in the book and in her last speeches before Congress, but it is not the part that people really remember – she said we have the right to know about the risks that we are being compelled to endure, and once knowing we have the obligation to act.

Carson died eighteen months after Silent Spring was published. Breast cancer silenced her voice. She was in her mid fifties; she was the mother of a young son and a writer with ideas for many more books. We had a few things in common. Both of us were formally trained as wildlife biologists and went on to make our living writing about the environment. Both of us are mothers balancing motherhood with research and writing. And both of us had cancer. The important difference is that Carson had to live in fear that her cancer diagnosis would be made public, and that her enemies in industry would use her enduring the disease of cancer to discredit her scientific objectivity. I cannot imagine the burden that that must have placed on her: having to swear the few friends she confided in to utter secrecy; enduring the rigours of a book tour and addresses before Congress wearing her wig; trying to hide the effects of the mastectomy and the radiation treatments. Thirty years of feminist thinking that span her life and mine. At this point in history, women’s experiences and the way they live their lives are considered to be a valid way of understanding the world. When I blend the voice of a cancer survivor with the objective dispassionate voice of a biologist, I have not had to be criticised that my science was ‘off’ because of my experience of undergoing cancer treatment.

At the mid point between Carson’s death in 1964 and today, 3 December 2003, came Bhopal. It was a wretched enactment of Carson’s idea. The pesticide plant in Bhopal released the raw ingredient for a pesticide, methyl isocyanate, into the air. Eight thousand people immediately died. Another twelve thousand would die in the years to follow. No one knew what had happened to them, not even the doctors treating the patients knew what had happened because there was no right to know. The chemistry of what that pesticide plant was using was a trade secret. And so people died without knowing what kind of poison gas hit them. Their doctors struggled to treat them not knowing what antidotes might be possible. That so horrified the world that two years later in 1986 in the United States passed a comprehensive Right to Know Act on the basis that toxic chemicals used within factory walls or released into the environment that we all share – either by a terrible accident or through routine emissions into air, food, soil or water – form a public gesture and the public therefore has the right to know about them. That is now enshrined in the US legislation because anyone, including my students at University, has the ability to dial up a website, type in their zip code and within thirty seconds have a read out of all the toxic releases in their home community, from what industry, in what amounts. You can click on the names of those chemicals and find out the health effects of being exposed. It’s a very powerful tool for social activism and it was the dead of Bhopal who gave us that.

So in 1994 while at Harvard University I began work on the book Living Downstream. I tried to do two things at once: summarise all the evidence I understand as a biologist, focusing on environmental contaminants on the one hand and risk of cancer on the other. Interwoven with the scientific analysis is the story of my return to my hometown to investigate my own cancer diagnosis as well as the cancer cluster that was alleged to have occurred there. I made use of Right to Know data by investigating the toxic emissions into the river, into the ground water wells in which the drinking water is gathered. I was able to find out what went on at the pesticide factory right near my high school, and what kind of toxic waste is imported to the hazardous waste land fill near the house where I grew up. The knowledge that I gained in doing so and my ability to write about it in my book Living Downstream was only made possible by the twenty thousand dead in Bhopal. And my analysis and my language and my words were made possible because Rachel Carson wrote Silent Spring before I did. So I would like you to join me in a moment of silence for the death of Rachel Carson, who lost surely about twenty years of her life to breast cancer, and the death of the many thousands of victims in Bhopal. Who knows what stories they might be able to tell us, what they might be able to write and explain to us had they not died. And in that silence perhaps we can each think of a way that in our own life we might use our own voices to speak out against those kinds of human rights abuses.

When I became pregnant at the brink of forty, I had already spent twenty years as a childless adult ecologist and my work was devoted mainly to studying the ways in which organisms interact with their environment. I first stared at the pregnancy home test kit that one is required to pee on so that the monoclonal antibodies that are embedded in that plastic wand can react with the hormone in the pregnant woman’s urine, known as human chorionic gonadotropin, causing a colour change to occur on that plastic stick. The double lines of purple that appeared in the stick were the divining rod that told me I was going to have a baby: my first reaction was “Oh, I am now a habitat!” After twenty years of studying other habitats I was now an environment for another organism to live out the first nine months of its life. I felt that I was a kind of inland ocean with this marine mammal swimming around inside of me and I became very interested to know what was going on in that environment.

And so my first personal experience of pregnancy took me back to the embryology that I had studied at university years ago and I became very interested in understanding the threats to this internal environment. What kind of toxic chemicals, what kind of damage might be happening to this environment and what risks to this life form that lived inside me did those exposures create, a life whose body was just being assembled for the first time. It seemed to me that the risks might be unique and so my interest in this topic and my pregnancy led me to Cornell University where I spent four years studying a field called foetal toxicology. So the book Having Faith, like Living Downstream, is really two books in one. It represents my best attempt to summarise the findings of foetal toxicology and what it means for us but it also tells the story of my own, very joyful pregnancy with my now five-year-old daughter, Faith. It is premised on an idea first coined by a native American midwife named Katsi Cook who lives in my home state of New York. She said a woman’s body is a first environment for all of us.

That is my starting point. Let me tell you a bit about the kind of paradigm in science that is challenging the way governments regulate toxic chemicals. These are findings that come out of the field of foetal toxicology that are mounting a very important challenge to the historical ways that we in the US and you in England and also in the EU have looked at toxic chemicals and thought about the ways in which to manage them. So I will give away my thesis statement right up front and then would like to guide you through some of the windows of vulnerability of human development. I will be talking mostly out of my book Having Faith but will include as I go some of my new research on adolescence, puberty and old age so we will be going through a whole life span and looking at certain risks to human health.

Here is the idea: the old belief was called the ‘dose makes the poison’, a phrase originally used by a mediaeval physician named Paracelsus who noticed when treating syphilis with mercury, the treatment of choice, that too much would kill the patient. ‘The dose makes the poison’ is still the principle upon which chemotherapy drugs are given to cancer patients. The hope is to give a dose the patient can tolerate, but large enough to poison the cancer cells. This is a very powerful notion in medicine and in toxicology. When a chemical is discovered to be inherently toxic – perhaps because it causes miscarriage or infertility, perhaps because it is a neurological poison that effects the brain, perhaps because it is related to cancer – instead of moving immediately to divorce our economy from dependence on such a chemical the regulatory system requires instead laboratory studies (mostly on animals, but also on possible human exposure) to decide on the maximum dose allowable in the environment. Exposure routes could be as a residue in food if it is a pesticide, levels allowable in drinking water or ground water, or how much air pollution can we allow. Regulators set these so-called safe threshold levels. The idea is that above these levels there might be human harm, but below that the harm is mostly negligible.

The new science is showing that the timing of exposure makes the poison as much or more than the dose. This draws on the realisation that we are not all middle-aged adults; we all begin our lives as embryos and go through a life span; and we are not the same individual biologically or physiologically during that entire life span. We go through important changes during our life and enter windows of vulnerability when we are exquisitely sensitive to the effects of toxic exposures – far out of the proportion that the dose might predict. Embryonic and foetal life is one of those times, and so is infancy.

For example, all of us have something called the ‘blood brain barrier’ that works pretty well to keep out any pesticide. Insecticides operate on the principal of chemical electrocution. They are all neurological poisons. The blood brain barrier will work pretty well to ensure that insecticide residues consumed with your dinner will not leave your blood stream and enter the brain matter where they can do some more damage. However we do not get a blood brain barrier until we are six months old. Anyone younger than six months is missing the suit of armour that surrounds the brain and offers pretty good protection against the neurological damage of insecticides. So tiny, vanishingly small exposures of insecticides to someone younger than six months can create disproportionate risks to the brain, and can be a terrible saboteur of that brain compared to similar or even much larger exposures for older humans.

The human rights implications of this new science need to be fleshed out, and let me offer an overarching observation. We are not providing under the law equal protection against toxic chemicals to all citizens. The new science shows that we are discriminating by age against particular groups of people, not only the very young but also I hope to demonstrate to you that adolescence, affected by the hormonal effects of puberty, represents another window when tiny exposures can create disproportionate risks to health. And old age represents another period when we are exquisitely sensitive to toxic chemicals because we start losing defence mechanisms. The blood brain barrier becomes permeable again. It starts to fall apart. Liver enzymes are no longer as efficient. The kidneys are not detoxifying as effectively. The immune system becomes compromised. So the very old and the very young physiologically resemble each other to a large degree and then in the middle you have the experience of puberty and adolescence which for very different reasons also represents a vulnerable window of time. I argue that our current model of regulation does not sufficiently protecting these three groups: the very young, teenagers and the elderly.

Now comes the time where I explain where babies come from. Let us start when an egg and a sperm find each other at the upper reaches of the fallopian tube. You might know it takes about five days to a week for that little gondola boat to float down the canal of the fallopian tube where it opens out into the delta of the uterus and implants itself. So about a week between the fertilisation and the period of implantation occurs when that embryo actually buries itself into the wall of the uterus. We start off as a one-celled organism; by the time the fertilised egg floats out into the uterus it is 58 cells big. Those 58 cells are arranged in a little ball called the morula which buries itself in the uterine lining. Morula is the Latin for mulberry because it’s exactly what it looks like. The lining grows right up over the top of it and then long siphoning tubes are sent out from the morula into the blood filled lining of the uterus and those long siphoning tubes break open the tips of the spiral arteries as they snake through the uterus. Those arteries begin to gush blood, so even before the placenta and the umbilical cord and the life support system of the embryo is established, life begins in a pool of blood. This bloody lagoon created by the breaking open of these arteries nurtures the new life form until the life support system develops in the weeks to follow.

Before we continue the story let us look at threats to human life right at the very start: the stage of egg and the sperm. Women who smoke go into menopause on average two to three years earlier than women who do not. Something about smoking shortens the fertile life span of a woman: we now know the agent behind this is a chemical in tobacco smoke called benzoapyrene that cycles around the blood, gets into the chromosomes of the eggs, flips certain genetic switches, and programmes cell death. So we know that cells can commit programmed suicide. The threat is called apoptosis. Benzoapyrene in cigarette smoke has this effect on human eggs in the ovary and shortens the fertile life span of women smokers. Researchers began to wonder whether the benzoapyrene in diesel exhaust and in coal burning power plant emissions might be having the same effect. I do not have an answer for you yet: but we know it is true for laboratory animals. Laboratory rats exposed to benzoapyrene in the ambient air of their cages at levels in some of our larger industrial cities, experience a shortening of fertile life.

Sperm also are not immune to these effects. Studies of men exposed to pesticides through drinking water in some agricultural areas in the United States have lower sperm quantity and lower sperm quality. These men are not farmers, but are simply living in farming areas and drinking the water in rural communities. We also know that males who have exposure to certain kinds of industrial chemicals, such as diesel and kerosene, father children who are at much higher risk for certain kind of paediatric cancers. In some cases, their children have ten-fold the risk, for example of neuroblastoma, a childhood cancer that tends to kill the very young. Children of men with these occupational exposures are ten times more likely to be diagnosed with neuroblastoma in the first two years of life than children of men of a similar socio-economic backgrounds and classes but who do not have such exposures.

But let us continue our story. Let us assume that there is a viable egg and sperm. Fertilisation occurs, grows into a morula and begins to implant itself in the lining of the uterus. The risk of exposure at this point in our story is not infertility but spontaneous abortion. Here we have an important human rights issue and a possible conversation with the right to life community. I am not a member of this community. I am very much in the other camp. I believe very strongly that motherhood is the hardest job in the world. It is a lot harder to be a mother than it was to write my doctoral dissertation and I entered into it joyfully and through my own choice. I do not think any woman should be forced into it against her will. But whatever your thoughts or opinions on that topic, we might agree that if you become pregnant wilfully and with great joy, and then experience a spontaneous miscarriage because of a chemical that you were exposed to earlier on in your pregnancy, this is a violation of human rights, a violation of foetal protection and a violation of a woman’s ability to choose to have a child. It is a form of chemical abortion. Evidence suggests that solvents and pesticides that enter into the story of pregnancy in the first few weeks raise the risk of interfering with the chemical cascade that has to occur: these are chemical messages that flow from one cell to another in the morula and as the morula turns into embryo with the extra embryonic membranes such as a chorion, amnion, allantoic sac, placenta, umbilical cord. All these require a choreography of messages being sent back and forth between the cells in the embryo and interference will cause this new life form to be flushed from the system because implantation does not take place properly.

Let us go on with our story. Let us assume that a miscarriage does not occur, that implantation successfully happens. Now we are at about week five of a human pregnancy as midwives and obstetricians would date it. What happens next is a period called organogenesis. This takes place between weeks five and ten of a human pregnancy and during this time the entire human body is assembled, developing from the top down and from the centre out. The heart develops before the arms and the fingers. All of the internal organs in the centre of the body and the head of the body develop faster than those below. The heart develops faster than the gonads, for example. All this takes place in the period between weeks five and ten. At the end of week ten of pregnancy you have a human being the size of a paper clip with all the body parts present. We have thirty more weeks to come. The danger at this point is a birth defect. Any toxic chemical that enters our story at this point and interferes with essentially the process of Japanese origami that causes these flat pieces of tissue to roll themselves up and fold themselves up into three dimensional human body structures will affect the human body form in some way. And depending on the location of the birth defect we know the timing of what must have gone on. A cleft palate happens very early on in human development, and so does a cardiac defect. Undescended testicles reflect a problem with the gonads and happen later. Webbed or missing fingers and toes and missing limbs happen later in development than any midline defect.

We have pretty good evidence that exposure to pesticides during that week five to ten of a human pregnancy is linked to birth defects. There are good birth defect registries in the UK, better than those in the United States. I relied a lot on the UK registry when I looked at birth defects discussed in chapters three and four of Having Faith. Many European countries have good registries: the Swedes are excellent; Finland, Spain and Italy have nice registries as well. What these data show is that women exposed to pesticides, either because they work in farming, nurseries or greenhouses during the window of time in early pregnancy have excess rates of particular kinds of birth defects. This is shown over again, no matter what the country: certain kinds of clefts, cardiac defects, limb reduction deficits, undescended testicles and hypospadias (when the opening of the penis does not happen at the tip but by the scrotum or under the shaft). Good registry data shows time trends of hypospadias, with good evidence from interviews about the kind of exposure and the jobs of the mothers. Women who work in certain kinds of agricultural occupations have sons who are at higher risk for this kind of birth defect. The good registry data I could use in the US (mostly from California and some from Texas and Minnesota) shows similar trends. In California, the closer a woman lives to an agricultural field where pesticides are sprayed, the higher her risk for stillbirth caused by birth defects. The highest risk of all is living within a mile of an agricultural field that is sprayed with pesticides. In Minnesota, interesting evidence shows the that further west you live in the State the higher the risk of birth defects. The further west you go, the more intense the agriculture. Furthermore, there is an interesting seasonality to the data. Children born to farmers have high risks of birth defects, but even higher if their birthdays are in the winter: the period of organogenesis corresponds to the spring months of planting when pesticide use is the highest. So there is a spike of birth defects among babies born in the winter months of December and January. Now there is corroborating evidence from Iowa.

So let us continue with our story. Let us presume the body develops in a perfectly healthy way. There is no birth defect; the next thirty weeks of pregnancy are devoted to the growth and development of all those parts that were formed during organogenesis. One of the hallmarks of that development occurs in the fifth and sixth months of pregnancy when there is a huge spurt in brain growth development. During this month all those brain neurons that were formed during organogenesis start moving. They migrate. They spin out an axon and travel down it just like a spider that can propel down from a silken thread from the ceiling. And as these spider cells meet each other they spin the connections which are a hallmark of being human. We do not have so many more brain cells than most other mammals but we have far more connections between those brain cells, and many of those are spun in the fifth and sixth months of pregnancy. The danger here is brain damage so if pesticides, or a heavy metal like lead or mercury, enter our story at this point those brain cells stop moving. They are paralysed; they cannot find each other and the connections are not made. When the baby is born, its head looks perfectly normal. There is no malformation, there is no birth defect, but we cannot see the subtle change in the architecture in the brain underneath and we may not notice until maybe that child goes to school that there is a learning disability or behavioural problem like Attention Deficit Disorder or hyperactivity or autism. We are getting better at measuring exposure to heavy metals, pesticides and industrial contaminants in the umbilical cord blood at birth and then looking at development of the child through school and seeing, for example, whether exposure to high levels of mercury prior to birth increases the need for special educational services. Lead exposure before birth increases the risk of trouble with mathematics.  Exposed to PCBs before birth shortens attention span, or focus to stay on task. Now this is fascinating because it means we are changing the nature of the self through exposure to toxic chemicals. A child is born with a different mind than it otherwise would have.

Let us go on. Let us go to the very end of pregnancy. We have emerging evidence to suggest that certain pesticides as well as certain industrial chemicals can alter the day of birth. We might think that our birthday has something to do with our astrological chart. I can tell you as a biologist, that the kind of chemicals that your mother was exposed to when she was pregnant, probably had as much to do with the day that you were born than the stars did. That is because certain chemicals such as PCBs and now we suspect DDT not only cross the placenta, but also can get into the fibres of the uterine muscle tissue itself and alter the way calcium flows through that muscle. The flow of calcium through any muscle determines whether it will contract or not. By opening the calcium channels of the muscle in late pregnancy, the uterine muscle will start contracting sooner than it otherwise would, and essentially shortens gestation. Babies are being born early. If this is more than three weeks before their due date they are officially classified as a pre-term birth and we are beginning to realise that the stubbornly high incidence of pre-term birth in spite of good pre-natal care in the United States may be related to environmental exposures. PCBs, that old industrial chemical used in electrical fluids, is one of the few oily fluids that does not catch on fire and so is used to lubricate electrical parts at high temperature. We now know PCBs not only cause birth defects and cancer but also are officially classified as chemicals with the power to shorten human gestation. Being born before you should is the leading cause of disability in the United States and probably in England. It sometimes requires millions of health care dollars to save the lives of those babies and just bring them up to their birth dates. Very often, many of them require a lifetime of special medical needs and special educational needs.

Let us talk about breastfeeding, and then I want to mention puberty and old age and the new research I am doing. Breastfeeding is probably the trickiest topic in Having Faith. I felt like I was walking on a kind of high wire whilst writing it. There are two true things about breast milk, and they seem mutually contradictory, but they are not, and it is hard to hold two true things that seem like they contradict each other in your head at the same time. The first true thing about breast milk is that it is absolutely the best food for human infants. The data on the health benefits of breast milk are absolutely unanimous and that babies who are breastfed are healthier, they die less often in their first year of life and they enjoy health benefits for a lifetime thanks to mother’s milk. Breast milk contains antibodies from a woman’s own blood stream that help protect against things like pneumonia, diarrhoea and respiratory diseases in the first year of life for reasons we do not fully understand. Breastfed children do not die as often from cot deaths, sudden infant death syndrome, perhaps because they breathe differently than bottle fed babies. When breastfeeding, breathing patterns are not interrupted. When bottle-feeding, the milk flows out too fast, the baby learns to stop its tongue against the teat so it does not choke and in that split second will stop breathing. Perhaps as breathing patterns are set, breastfeeding allows for a healthier form of breathing that is not interfered with while the baby sleeps – because cot death usually occurs when the baby is asleep and forgets to breathe. The other leading theory is that breastfed babies wake more easily than bottle fed babies so that they are aroused more. They need to be fed more during the night until their brain stem mechanism becomes fully mature and the baby will keep breathing, to the point where it sleeps the night. That is important to early survival. We do not exactly know the mechanism but the data are very clear, that if breastfeeding will protect against sudden infant death syndrome.

But the benefits go on. Breastfed babies grow into an individual at lower risk for diabetes, asthma, allergies, eczema, obesity, juvenile arthritis, Crones disease, and ulcerative colitis. There is lower risk for childhood leukaemia and lymphoma. Babies have higher IQ and less need for special education, fewer learning disabilities, better vision and better hearing. But how can that be? There are growth factors in breast milk whose job is not to be digested as food but rather that go through the infant’s gut, go into the brain and help guide all those still migrating neurons after birth to find the right connections. Even up to age two, as the infant brain is still forming breast milk promotes good brain growth development. That is probably why infants who are breastfed have better hearing and vision. We believe that the fewer autoimmune problems such as diabetes and juvenile arthritis may be related to the immune factors in breast milk. These provide temporary immunity, and go into an infant’s cells and turn on and turn off certain genes modulating the nascent immune system so that when the child grows up, it is better able to distinguish between a true pathogen and attack and kill it and something that is harmless.

There is nothing else like breast milk. Formula is an inferior pretender. Now I will say right now, I am not trying to make bottle-feeding mothers feel guilty. I am an adoptive child and my own adoptive mother fed me formula. But on the other hand, the evidence is strong, and on that basis I chose to breastfeed my own daughter Faith for three years and am now breastfeeding my son two-year-old son Elijah. I have actually been continually lactating now for five long, joyful, symbiotic years.

Here is the other true thing about breast milk. Breast milk, human milk, is the most chemically contaminated human food on the planet. Why is that? Well, you have to think like an ecologist. Breast milk occupies one rung higher on the human food chain, than the food that adults eat. What that means is that the milk making lobules in the back of a nursing mother’s chest wall have one more chance to concentrate the poison found in things like toilet deodorisers, moth-proofing agents, flame retardants, pesticides, dioxins, PCBs. These are the most common contaminants of breast milk. They are commonly found in the food, but are ten to a hundred times higher in breast milk because they are persistent and concentrate as they move up the food chain. Nursing infants that feed on their mother’s body eat one rung higher on the food chain than we who eat a combination of animal food and plant based food. For that reason, pound for pound, human infants are receiving many higher times more pesticide residues than we are. When safe levels are set for pesticide residues in food bought in the supermarket, no one thought “what are nursing infants going to receive if we allow this much pesticide residues in wheat, that much in sweet potatoes, this much in eggs, and this much in fish.” No one thought that a nursing infant will get at least ten times that amount in breast milk. No one regulates breast milk, it is not transported across state boundaries and it is not sold in supermarket shelves. If it were, United States data indicates that many women’s breast milk would not be available for sale because the amount of deleterious substances found exceed the accepted levels; the accepted maximum contaminant levels that allow you to sell something from the supermarket shelf.

So on the one hand, breastfed children are healthier, die less often, go on to be smarter, have better eye sight, have fewer immune problems, and do suffer less from allergies. On the other hand, measures of the blood of children in school, or who have been nursed, even for a period as short as six weeks, show four to five times more contaminants than their formula fed counterparts. So our breastfed children are paying a terrible price for their right as children to drink their mother’s milk. And the right of the mother to feed the child milk from her own body is being compromised. The goodness of that milk is being compromised by the presence of contaminants. I want to be careful and say that we have not yet contaminated mother’s milk to the point where it is a worse food for babies than formula – but do we want to let it get to that point? The United States has terrible breastfeeding rates, we have the worst in the world, I think, of developed countries, because we fail to give women paid maternity leave. Formula feeding is thought to kill at least four thousand infants a year in the United States. In other words if we enabled all women to breastfeed there would be four thousand less deaths of infants under the age of one every year in the US.

Contaminated breast milk is not killing four thousand infants a year. A risk benefit analysis would argue that as long as it is killing fewer than four thousand, then we should do nothing. But a human rights analysis should say, that no child should be harmed by contaminants in mother’s milk. If we can raise the goodness of mother’s milk, then we should do it and we should get chemicals out of milk. The answer is not to use formula milk, but to say that any chemical that is (a) known to be inherently toxic, and (b) known to accumulate in mother’s milk, has no place in the twenty first century economy and we need to immediately phase out any dependency that our economy has, whether industrial or agricultural on the use of this chemical.

Some words about puberty. This amazing rite of passage between childhood and adulthood is made possible by parts per billion concentration of steroidal hormones. You might remember the profound effects that puberty had on your psyche, your body, your thoughts, and your emotional life. Just parts per billion concentration of hormones elicited this huge change. We do not know a lot about the biology of puberty yet. But we do know that the body is growing rapidly, the skeleton is being mineralised and cells are dividing fast, so a lot of DNA is replicating. Whenever DNA replicates, it is more vulnerable to injury than when in its quiet state. All kinds of parts of the body develop hormone receptors so that they can become targets of hormones such as oestrogen, testosterone or some of the hormones that your adrenal gland is producing, your pituitary gland, your thyroid gland. Not just gonads, but all these glands in the body from your brain to your thyroid to your adrenal gland that sit on the back of your kidney are all playing a role in this great hormonal response that is going on. We in the biological community are worried about the effect that endocrine disrupting chemicals in the environment might be playing on this body that is primed to respond to hormones, because we know that there are chemicals out there that have the ability to mimic hormones inside the human body.

The question is whether exposures to certain kinds of pesticides are altering the timing and experience of puberty. And the data are just beginning to come in. In Belgium some provocative work shows that immigrant children from developing nations that still use DDT and live in certain neighbourhoods are at high risk for premature or precocious puberty – girls developing breasts before the age of eight or nine. They have an eighty fold higher risk. On the other hand girls who are growing up in those countries, who still presumably have these exposures, do not develop precocious puberty. Nor is precocious puberty found in the native born Belgian children living in the same neighbourhood. So what might be happening is some kind of interaction between nutrition and pesticide exposure. Pesticide exposure early in life is priming the body in such a way that if, later in life, nutritional status goes up, you get precocious puberty. Whereas children who remain in developing countries and consume a limited number of calories, do not experience precocious puberty, nor do the children who have plenty of calories but do not have pesticide exposure. It takes both high nutritional status and pesticide exposure to elicit this problem. A lot of work remains to tease apart the effects of high nutritional status, changing experience and timing of puberty, and the interactive effects of environmental chemicals. Now in the US we have terrible rising rates of childhood obesity, we do not yet know if that is driving the apparent rise in early puberty, or whether that is acting together with something like pesticide exposures. I am now looking at the data in this area.

A word about old age. One of the things that interests me is dementia. And again, autobiography drives my science; my own dear adopted father was diagnosed quite a long time ago with Parkinson’s disease. It developed, as in the case of 30 per cent of Parkinson’s patients, into full-blown dementia. Just this year he was institutionalised in a nursing home. One of the things that people with Parkinson’s dementia often suffer from are delusions and hallucinations. My father became deluded that my mother, his own dear, beloved wife of 57 years, who he worships, was having an affair. He followed her around shouting accusations and my sister and I were worried for her safety. My father was a veteran of World War II and served in a distinguished way in Italy, and he began to relive his war life. The combination of believing that he was in the War and that my mother was cheating on him was a dangerous combination that led to our family’s decision. This leads to questions about the role the environment might play in dementia. Some preliminary evidence, mostly from the UK, from laboratory animals, shows that early life exposures to certain kinds of pesticides, is associated with Parkinson’s dementia. Laboratory animals exposed early in life, followed by an exposure in adult life, have two injuries to the brain, one very early and one later. The combination can elicit the cascade of neuro-degenerative changes leading to full blown Parkinson’s. There is something about silent toxicities early in life, matched by exposures in adult life, that elicit changes and appear to be behind Parkinson’s dementia.

All this, of course, is in controlled animal studies. However, we also know that certain kinds of farmers are more prone to dementia than other people and that certain kinds of veterans of wars where pesticides were used, such as the Vietnam War are at higher risk for Parkinson’s. Now we are looking closely at the Gulf War veterans. The first, as far as I am concerned misguided, of the two military ventures in Iraq in 1991 has led to an entire generation of disabled veterans. Lou Gehrig’s Disease, or what is called ALS, is one neuro-degenerative disease that these veterans appear to suffer from and perhaps Parkinson’s is another one. We have new evidence to suggest that welding metals may put some welders at higher risk than the general population. So right now provocative evidence from both human and animal studies suggests environmental links to Parkinson’s disease. I am now looking closely at the data, and I would like to expand that to include Alzheimer’s disease. I have not yet cast my net there, but I would like to look at the entire human spectrum, the ways in which we enter and leave these vulnerable times, and the human rights problems connected to exposures during these periods of time.

More importantly, I would like to look at ways in which we can re-cast our entire regulatory system, our entire way of delivering goods and services, and of growing foods so that we no longer need to use toxic chemicals. We can, as Rachel Carson encouraged, seek out alternatives and to stop taking counsel from those who tell us that the only way is to use poisons.

I always close my lectures with a short reading from one of the more lyrical and joyful passages of my books. I want to remind us that when all is said and done, this is really about human life and its joy. Behind every data point, is a human life and that is the reason for our interested. This is from chapter four of Living Downstream. This is the scene of my own amniocentesis with Faith. Amniocentesis is more routinely practised in the US than here, for better or worse. It is a procedure offered to what they call elderly prima gravida, meaning old mothers, like myself and in it about 30ccs or one short glassful of amniotic fluid is removed from the belly of a pregnant woman. In that fluid is contained skin cells of the foetus, which can be cultured and grown to show the DNA, to see if there are any gross chromosomal abnormalities. The woman can make her decisions based on those results. So I underwent this procedure and here is what happened after that.

The needle is out. We’re done. The mood is still upbeat. The obstetrician hands the pair of vials to the technician, who holds them up to the light like glasses of fine wine.

 ‘Nice colour,’ she says. ‘Do you want to hold them?’ And she passes the vials, hot as blood, into my hands. The fluid inside is pale gold, it seems to glow. ‘Well, it’s like liquid amber!’ I sputter, ‘Like an amber jewel.’ It occurs to me that amniotic fluid might be the loveliest substance I have ever seen.

The obstetrician touches my arm, ‘That’s baby pee,’ she says, smiling. ‘We like it yellow. It’s a sign of good kidney functioning’. I look at the vials again, Oh right.  …

The obstetrician is finishing up, she reminds me to drink plenty of water today. Drink plenty of water. Before it is baby pee, amniotic fluid is water. I drink water and it becomes the blood plasma which suffuses through the amniotic sac and surrounds the baby – who also drinks it.

And what is it before that? Before it is drinking water, amniotic fluid is the creeks and rivers that fill reservoirs. It is the underground water that fills wells. And before it is creeks and rivers and ground water, amniotic fluid is rain. When I hold in my hands a tube of my own amniotic fluid, I am holding a tube full of rain drops. Amniotic fluid is also the juice of oranges that I had for breakfast, and the milk that I poured over my cereal, and the honey I stirred into my tea. It is inside the green cells of spinach leaves and the damp flesh of apples. It is in the yoke of an egg.  When I look at amniotic fluid and I am looking at rain falling on orange groves, I am looking at melon fields, potatoes in wet earth, frost on pasture grasses. The blood of cows and chickens is in this tube. The nectar gathered by bees and humming birds is in this tube. Whatever is inside humming bird eggs is also inside my womb. Whatever is in the world’s water is here in my hands.