A Dangerous Oversimplification

“The dose makes the poison.”

We’ve all heard this familiar phrase before in our school science textbooks. It’s a central tenet in the field of toxicology and used often to describe a linear or montonic dose response – when a higher dose has a greater effect.

A little history on the man behind the original quote; “All things are poison and nothing (is) without poison; only the dose makes that a thing is no poison.” from Toxipedia:

Paracelsus (born Philippus Aureolus Theophrastus Bombastus von Hohenheimborn November 11 or December 17 1493 in Einsiedeln, Switzerland, died September 24, 1541 in Salzburg, Austria), sometimes called the “father” of toxicology. He was born to a chemist father in Switzerland in 1493 and contributed greatly to the fields of medicine and toxicology. He rejected Gnostic medicinal traditions such cauterizing wounds and amputating injured limbs and advocated keeping wounds clear of infection and allowing them to heal on their own.  But also considered to be renaissance physician, botanist, alchemist, astrologer, and general occultist.

Funny name aside, Paracelsus was a man before his time and contributed valuable insights into medicine and science. But we must remember that his observation, while correct in many cases, has been shown to be incorrect to apply as a rule to all substances. Enter the field of endocrine disruption. This field of science did not exist in Paracelsus’ time. Neither did the thousands of man made chemicals that are produced and used by industry today. The World Health organization says:

Endocrine disrupting chemicals (EDCs) and potential EDCs are mostly man-made, found in various materials such as pesticides, metals, additives or contaminants in food, and personal care products. EDCs have been suspected to be associated with altered reproductive function in males and females; increased incidence of breast cancer, abnormal growth patterns and neurodevelopmental delays in children, as well as changes in immune function.

Human exposure to EDCs occurs via ingestion of food, dust and water, via inhalation of gases and particles in the air and through the skin. EDCs can also be transferred from the pregnant woman to the developing fetus or child through the placenta and breast milk. Pregnant mothers and children are the most vulnerable populations to be affected by developmental exposures, and the effect of exposures to EDCs may not become evident until later in life. Research also shows that it may increase the susceptibility to non-communicable diseases.

Our regulatory system’s chemical and pesticide testing is centered upon this faulty assumption. None of the pesticides on the market are tested for endocrine disruption (or a great many other harmful effects) before being approved for use. The level of a chemical that produces no observable effects in animals is used to extrapolate a ‘safe’ exposure level. This is based on the assumption that toxicity decreases in a steady linear fashion until it is no longer toxic. Very little testing is done at these extrapolated levels to determine if they are safe.

As shown in a 2012 meta review in the journal Endocrine Reviews, there are hundreds of published studies showing non-monotonic and non-linear doses. The chemicals tested were actually more toxic at low levels, and often even at the lowest doses.

“We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from the cell culture, animal, and epidemiology literature. We illustrate that nonmonotonic responses and low-dose effects are remarkably common in studies of natural hormones and EDCs. Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities. We conclude that when nonmonotonic dose-response curves occur, the effects of low doses cannot be  predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health.”

Our current testing methodologies are both dangerous and unscientific by making assumptions that all chemicals follow a linear dose response. Safety cannot be assumed by testing at high levels. All chemicals and pesticides must be tested for endocrine disrupting effects.

For more information on endocrine disruption science, visit The Endocrine Disruption Exchange (TEDX) website.

The late Dr. Theo Colborn, author of the book Our Stolen Future reads an open letter to the President and First Lady at Tedx outlining the harms of EDC’s and what needs to happen now.



About NonToxicDoverNH

Advocating for safe and healthy public spaces for Dover, New Hampshire residents.
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