If arsenic is unhealthy, then you'd think that the less arsenic the better.
Same with radiation, mercury, dioxin and a whole host of environmental
But zero tolerance is expensive. There's no free lunch. Getting rid of the
last molecule of dioxin in the environment means we'll have less money to
get rid of something else that might give us more bang for the health buck.
It's not just a question of money. Think about air quality. We support
government regulations on pollution, because we want clean air. But most of
us don't want perfectly clean air. Most of us are willing to
accept some pollution in order to have the freedom that comes with our
cars. Attaining zero pollution is too expensive, not only because it hurts
our pocketbook, but also because there are other things we value besides
Using the same logic, we ride airplanes and cars, and live in big cities.
All of these choices are more dangerous than staying at home on a ranch in
rural Missouri. (And it would have to be a horse-free ranch, because horses
are dangerous, too.) Yet we understand that it is sometimes better to
accept a little more risk in return for something of greater value.
Now along comes Edward Calabrese, a toxicologist at the University of
Massachusetts, whose review of research done on toxins shows that a little
bit of exposure to toxins can actually be good for your health. That's
about the closest thing you can find to a free lunch. The phenomenon is
called "hormesis," from the Greek work for excite. Thousands of studies
confirm that at super-low levels, toxins like radiation, arsenic and
mercury have beneficial effects on plants, people and other living things.
(You can find out more about Calabrese's work at www.discover.com by
searching on calabrese)
How can hormesis possibly be true? Poison stimulates. It mobilizes the body
in complicated ways. At high levels, the body is overwhelmed. But at very
low levels, the body can respond in good ways. Think of so-called healthy
things like Vitamin C. Too much Vitamin C is harmful. A little television
can be educational. A lot of television turns you into a couch potato. One
man's meat is another man's poison. And, as it turns out, one man's poison
is another man's meat.
Calabrese is not a crazy man. He doesn't advocate the ingestion of just the
right amount of mercury, or hanging out near a lead smelter. His work
doesn't mean we can ignore the dangers of toxic chemicals. It doesn't mean
we should gut environmental regulations. The tipping point where a poison
becomes harmful is hard to measure, and it will differ for every
individual. Better safe than sorry remains a good working hypothesis. But
Calabrese's work does challenge our obsession with creating a risk-free
world. And measuring the correct relationship between good health and
exposure to various chemicals may lead to important health breakthroughs in
A clear example of the benefits from understanding hormesis is called
alcohol. We know that excessive drinking can rot your liver and kill you.
But the evidence appears overwhelming that a little bit of alcohol is good
for you, particularly for men over the age of 40. A drink or two at dinner
apparently reduces the risk of heart disease and stroke.
So is alcohol a good idea or a bad idea? It depends. We may long for the
black and white of "Don't drink." But a lot of life's most interesting
choices involve risk, ambiguity and the ability to embrace moderation.
Edward Calabrese's analysis shows the wisdom in the old proverb, "Danger
and delight grow on the same stalk." It's not a bad lesson to remember.
Some risks are worth taking, because the benefits outweigh the costs.
And some risks might not even be risks at all. For some of us, at least
when we look at the wine list at dinner, it's a lesson that might help us
live long, and live well.