since World War II, which launched a new era of synthetic organic chemicals. She pointed out that we are now living with persistent industrial chemicals in a way our ancestors never did. “For the first time in the history of the world, every human being is now subjected to contact with dangerous chemicals, from the moment of conception until death,” she wrote. Oras The Who put it in 1966, “I was born with a plastic spoon in my mouth.”
Carson didn’t know that many of these compounds have the ability to alter human hormone systems, but she presciently described chemicals accumulating in the sex organs of birds and mammals and corresponding drops in sperm levels. She was struck by reports that roosters were losing their wattles and that sperm counts were found to be low in pilots who sprayed pesticides from the sky.
The term endocrine disruptor wouldn’t be coined for another thirty years, when a concerned group of wildlife biologists gathered to exchange research on everything from intersex fish to birds that refused to act like parents. To the scientists, the evidence was mounting that synthetic compounds in polluted areas, notably the Great Lakes, were altering the cells, bodies, and behavior of these animals in ways not seen before.
Until that time, most people thought synthetic estrogens showed up only where we intended them to, namely, in medication. But hormones are famously sneaky. They do their work in our bodies in infinitesimally small quantities. One molecule of a hormone fits into one receptor on a cell like a key in a lock, unleashing a chain of biochemical events. These are the keys that govern everything from cell division to metabolism to hair and breast growth to cognitive performance on spatial tasks. Hormonal changes during women’s monthly cycles affect how they smell things, how they perceive the faces and bodies of the opposite sex, and even how they think. Some studies show that when estrogen levels peak midmenstrual cycle, women reportedly get better at verbal and finemotor skills.
If a foreign imposter shows up on the receptor, however, the body’s responses become all but impossible to predict. Some foreign estrogens, called xenoestrogens, occupy the receptors so native estrogens can’t do their jobs. Others pass the security test and turn on estrogenic responses. Some seem to mess with the body’s feedback loops, causing the brain to release more or less hormone than it otherwise would.
It is now known that some imposters occur naturally, like estrogenic substances in plants. Why would plants bother to make estrogen mimics? For the same reason they make acids, poisons, and thorns. Plants are smart, or at least evolutionarily successful. One jaunty example is marijuana, which figured out how to make THC (tetrahydrocannabinol), a compound that happens to fit perfectly into pleasure receptors in the human brain, all but ensuring its spread around the world. Which begs the question, do humans cultivate marijuana, or is the plant actually cultivating its human growers? Marijuana also releases compounds that inhibit testosterone in people who consume it. Long-term male stoners are known to sometimes grow small breasts, and they also face increased risk of breast cancer. Is this a coincidence, or is the plant somehow benefiting from having less aggressive users who giggle easily and croon folk songs?
A couple of dozen plants are known to produce high levels of phytoestrogens, which essentially act as oral contraceptives, in order to knock back their predators. When sheep eat a particular strain of clover, they can’t reproduce. Humans have long taken advantage of these plant properties, using certain herbs and fruits to prevent pregnancy or induce miscarriage. Hippocrates knew that the seed of Queen Anne’s lace, when eaten, worked as a contraceptive and morning-after pill, as did an infusion of pennyroyal. Giant fennel,found by the Greeks in the seventh century BC, was so coveted for
Carson didn’t know that many of these compounds have the ability to alter human hormone systems, but she presciently described chemicals accumulating in the sex organs of birds and mammals and corresponding drops in sperm levels. She was struck by reports that roosters were losing their wattles and that sperm counts were found to be low in pilots who sprayed pesticides from the sky.
The term endocrine disruptor wouldn’t be coined for another thirty years, when a concerned group of wildlife biologists gathered to exchange research on everything from intersex fish to birds that refused to act like parents. To the scientists, the evidence was mounting that synthetic compounds in polluted areas, notably the Great Lakes, were altering the cells, bodies, and behavior of these animals in ways not seen before.
Until that time, most people thought synthetic estrogens showed up only where we intended them to, namely, in medication. But hormones are famously sneaky. They do their work in our bodies in infinitesimally small quantities. One molecule of a hormone fits into one receptor on a cell like a key in a lock, unleashing a chain of biochemical events. These are the keys that govern everything from cell division to metabolism to hair and breast growth to cognitive performance on spatial tasks. Hormonal changes during women’s monthly cycles affect how they smell things, how they perceive the faces and bodies of the opposite sex, and even how they think. Some studies show that when estrogen levels peak midmenstrual cycle, women reportedly get better at verbal and finemotor skills.
If a foreign imposter shows up on the receptor, however, the body’s responses become all but impossible to predict. Some foreign estrogens, called xenoestrogens, occupy the receptors so native estrogens can’t do their jobs. Others pass the security test and turn on estrogenic responses. Some seem to mess with the body’s feedback loops, causing the brain to release more or less hormone than it otherwise would.
It is now known that some imposters occur naturally, like estrogenic substances in plants. Why would plants bother to make estrogen mimics? For the same reason they make acids, poisons, and thorns. Plants are smart, or at least evolutionarily successful. One jaunty example is marijuana, which figured out how to make THC (tetrahydrocannabinol), a compound that happens to fit perfectly into pleasure receptors in the human brain, all but ensuring its spread around the world. Which begs the question, do humans cultivate marijuana, or is the plant actually cultivating its human growers? Marijuana also releases compounds that inhibit testosterone in people who consume it. Long-term male stoners are known to sometimes grow small breasts, and they also face increased risk of breast cancer. Is this a coincidence, or is the plant somehow benefiting from having less aggressive users who giggle easily and croon folk songs?
A couple of dozen plants are known to produce high levels of phytoestrogens, which essentially act as oral contraceptives, in order to knock back their predators. When sheep eat a particular strain of clover, they can’t reproduce. Humans have long taken advantage of these plant properties, using certain herbs and fruits to prevent pregnancy or induce miscarriage. Hippocrates knew that the seed of Queen Anne’s lace, when eaten, worked as a contraceptive and morning-after pill, as did an infusion of pennyroyal. Giant fennel,found by the Greeks in the seventh century BC, was so coveted for
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