It’s the dose that makes the poison. The idea behind this phrase is that a substance only becomes toxic when you ingest enough of it. Therefore, anything less than this toxic dose threshold is considered safe to consume.
Swiss born physician and alchemist Paracelsus made this observation in the 1500s, and the idea has more or less persisted up through today. Chinese medicine used low doses of poisonous substances as medicine for millennia, knowing that what might kill in excess could be therapeutic in lower doses. Regulators use the dose threshold concept to identify the relative toxicity of industrial chemicals, naturally occurring poisons, and pharmaceutical drugs
But the toxicity line is not always so clear. Consider endocrine disrupting chemicals, otherwise known as xenohormones. Small amounts of these chemicals don’t cause cell death, as we normally associate with toxic exposure. However, they may cause problems for our endocrine system.
The endocrine system is a network of glands that send signals throughout the body with specialized chemicals called hormones. These hormones guide reproduction, growth and repair, hunger, sleep cycles, and much, much more.
The system is elegant, subtle, and incredibly complex. Modern research has uncovered numerous details about how this sophisticated system operates, and has also revealed an unexpected vulnerability in the mechanism hormones use to communicate.
Doctors have known for at least a century that hormones travel through the bloodstream to deliver their messages to different parts of the body. But if blood flows everywhere throughout the body, why do some cells respond to hormonal signals and others do not?
In the 1980s, researchers unveiled the secret: that hormones work in a kind of lock and key fashion, where only the organs and tissues equipped with specially shaped receptors can be unlocked by the complimentary shape of a specific hormonal key. For the organs and tissues that lack these receptors, hormonal keys have no direct influence.
Scientists have identified over 50 different hormones in the human body, and they serve a wide variety of biological functions. Just imagine all these molecular keys fitting into precise locks in the delicate dance of the endocrine system. This network must tirelessly monitor and secrete just the right amount of hormones at just the right time 24/7 just to keep your body running smoothly.
Xenohormones upset this delicate dance. The prefix “xeno” describes something that is alien or foreign. In regard to the endocrine system, you can think of xenohormones as unwelcome intruders, subverting glandular functions in ways your body never intended.
These alien hormones can mimic the same signature key shape as our body’s naturally occurring hormones, and can either fool the body into thinking it has more of a particular hormone than it really does, or block hormones from entering the cells and impede the biological processes that your endocrine system is meant to do.
How Much is Safe?
Unfortunately, xenohormones don’t come from some far flung planet. They are found right here on earth, and they make their way inside us all the time. They’re found in the air we breathe, the food we eat, the water we drink, and the things we touch. They come from pesticides, body care products, antibacterial soaps, flame retardants, plastic bottles, and even store receipts.In significant doses, these substances are indisputably harmful. For example, a drug called diethylstillbestrol (DES)—which was used for decades to prevent miscarriages—was taken off the market in the early 1970s because it was found to cause a rare form of vaginal cancer in daughters born to mothers who took the drug.
But what about the many other endocrine altering chemicals that lurk in our day-to-day life? Take the industrial chemical known as Bisphenol A (BPA). It acts as an alien estrogen, but it has been used in our food containers and water bottles since the 1950s. Thermal receipt paper is also coated with the stuff. BPA allows for printing without ink, however, we also absorb that chemical into our skin when we handle a receipt, particularly when our hands are covered with sanitizer.
It’s clear that these everyday substances do cause problems, as shown in a 2019 review examining several common endocrine disrupting chemicals and their impact on women’s reproductive potential. The research team looked at phthalates, parabens, triclosan, organochlorine (PCBs) and perfluorinated (PFCs) compounds, as well as BPA. All exposures led to markers for infertility. BPA for example, led to decreased levels of estradiol, reduced antral follicle count, diminished oocyte quality, and reduced embryo quality. PFCs and PCBs lowered fertilization rates. Parabens and phthalates lowered the rate of clinical pregnancy and live births.
“Considering the suggested health effects, more epidemiological data is urgently needed to confirm the presented findings,” researchers wrote.
Other research has discovered links between xenohormones and other human health outcomes including alterations in sperm quality, abnormalities in sex organs, endometriosis, early puberty, altered nervous system function, immune function, cancer, respiratory problems, diabetes, obesity, cardiovascular problems, and learning disabilities, just to name a few.
The big question is: do we ingest enough of this stuff on a daily basis to actually harm our endocrine health? Regulators from the U.S. Food and Drug Administration (FDA) have been evaluating the health effects of BPA for years, and have declared it safe at the minute levels we ingest from packaged food. The agency points to hundreds of studies as proof of their position. But critics say all those studies fail to acknowledge the chemical’s endocrine disrupting potential in minute doses.
A 2021 report from the National Institute of Environmental Health Sciences (NIEHS) notes this discrepancy. The project began in 2012 as a collaboration among NIEHS, the National Toxicology Program, and the FDA, as well as contributions from institute-funded university researchers. However, authors were never able to reach a consensus. In a press release, John Bucher, PhD, a senior scientist who played a key role in initiating the report, said that, despite the aim for clarity, the health influence of everyday BPA exposure remains unclear.
“Although relatively low exposures to BPA led to essentially negative findings in the core study, many of the published university papers reported adverse health effects,” said Bucher. “This suggests that current guideline-compliant studies used in regulatory decision-making may not detect all potential hazards from real-world exposures to chemicals, especially hormone-disrupting substances such as BPA.”
Making Choices
For those who are concerned about their exposure to xenohormones, the most empowering precaution to take is to steer clear of the products that contain them. Several food manufacturers have become sensitive to this concern, owing to the widespread availability of BPA-free products. Be warned, however, some BPA alternatives, like bisphenol S (BPS) and bisphenol F (BPF) have been found to present similar risks.But the modern world is full of xenohormone sources, and much of it is impossible to escape. However, our choices can significantly reduce our exposure.
One group of endocrine disrupting compounds to watch out for are dioxins. These chemicals are produced as a byproduct of herbicide production, and have been shown to disrupt hormone signalling, reduce fertility, interfere with embryo development, and cause spontaneous miscarriage. Eating organic, particularly in terms of animal products, can reduce your dioxin intake. According to the Environmental Protection Agency, more than 90 percent of our endocrine disrupting exposure is mainly through meat, dairy, and seafood.
In addition to food, water is another common source for xenohormones. Perchlorate, for example, is a byproduct of the aerospace, weapons, and pharmaceutical industries, but traces of the chemical often wind up in drinking water. This is where a high quality water purifier or distiller can come in handy. Perchlorate has been found to inhibit thyroid hormone synthesis
Being mindful of air quality can also reduce xenohoromes in your environment. Dust can often contain endocrine disruptors, so can the air we breathe, due to car exhaust, industrial chemicals, off-gassing from home electronics, and synthetic fragrances.
Finally, cut out the triclosan. This endocrine disrupting chemical interferes with both estrogen and androgen, and is found in toothpaste, anti-microbial soaps, and body wash, and can be absorbed through the skin.
