No Safe Amount: The Handshake Theory of Chemical Toxicity
The medieval physician Paracelsus said: "Poison is in everything, and no thing is without poison. The dosage makes it either a poison or a remedy." Often quoted in paraphrase as the dose makes the poison, this truism has dominated regulation and chemical management for centuries. Agencies strive to keep people and the environment healthy by establishing the "safe" level of a chemical.
At the same time that regulatory systems have proceeded on the "safe" level theory, biochemists have expanded the state of knowledge about the role of chemical messengers in the body. And the clash of cultures is about to change the way we think about chemicals in our lives. What does it mean for you?How to Understand Chemical SafetyThis change can be compared to Einstein's General Theory of Relativity. As ordinary individuals, we experience the laws of nature at a high level. Our gut reactions to the world around us stem from that experience. Just as we can understand an apple dropping from a tree, or judge the speed of traffic to cross a street, we know that a glass of wine with dinner feels fine but a bottle of vodka after work will end up as a raging headache.
But explain the theory of time dilation, the idea that traveling close to the speed of light slows down time, to we ordinary mortals and we are stunned at the thought. You might also be stunned to consider what a delicately balanced organism you inhabit at the molecular level. At this level, chemicals act more like a handshake than like that third pint of beer.
Think of it this way: under the dose makes the poison argument, if you send 100,000 letters of application out to random addresses, you might land a job. Under the handshake theory, if you network with ten people in a position to offer a job that fits your skills, you will probably be employed soon.What does it mean to us?In the first place, it means that the chemical testing we currently do to establish if a chemical is safe may not be sufficient. In particular, we may not be targeting nor understanding the effects of extremely low levels of chemical contaminants during critical phases when the organism is "listening" for chemical messengers. This occurs, for example, during fetal development and during changes that occur in puberty. The first question we need to be asking is: does this chemical mimic any of the messenger chemicals that organisms depend upon for survival?
In the second place, it means that we will see changes in the way regulators deal with chemicals. That is good if you think about reducing the number of five-legged frogs, but can lead to clashes if you think about the effect that banning or restricting chemicals might have on the economy or our way of life. Are we doomed to suffer a life without the convenience of plastic products that use bisphenol-A or the phthalates DEHP, BBP and DBP.
It will indubitably hurt. But stay tuned for continuing news on the green alternatives to chemical hazards which could usher in a booming new economy based on better chemistry.
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