Thursday, Aug 30, 2012
Is epidemiology a science? Last week's WN said it's not but a lot of
people disagreed. I got far more mail than I could answer. This is my
response. Im a physicist by training, and a troublemaker by inclination;
a lexicographer I am not. So I consulted a number of dictionaries; not one
classified epidemiology as a science. However, they characterized it as
a "branch of medicine." Does that make epidemiology a science? I don't
think so, but I doubt if I will ever again say it's not. The distinction I
wanted to make is that science is concerned with the cause-and-effect
relationship between physical events. Epidemiology, by contrast, looks for
correlation. That's important too. It guides scientists in the search for
causality, but to confuse causality with correlation is a serious error in
logic. It's also a very common mistake.
For nearly two decades staff writer Paul Brodeur performed a genuine public
service by informing New Yorker readers of the health hazards of exposure
to everything from asbestos, to microwave radiation. Brodeur, however, has
no science background and no sense of what the numbers mean; radiation was
radiation, whether it was power-line fields or microwaves. In 1979, when
epidemiologist Nancy Wertheimer charged that 60 Hz power-line radiation
is responsible for childhood leukemia, Brodeur wrote a series of supportive
articles in the New Yorker about the dangers of power-line fields. They
were gathered together in books with lurid titles like Currents of Death.
Brodeur was not there in 1996 when the National Academy of Sciences
released the results of an exhaustive three-year review of the possible
health effects of exposure to residential electromagnetic fields. He had
been fired by the New Yorker four years earlier. The unanimous conclusion
of the NAS panel was that "the current body of evidence does not show that
exposure to these fields presents a human health hazard." Why had it taken
so long, and why had there been no comment from epidemiologists? Perhaps
the scientific community should use more direct language in stating
conclusions that are so obviously wrong and so dangerous.
We need to explain the basics of the electromagnetic spectrum to every
literate person. It shouldn't be that difficult. Children are transfixed by
the sight of a prism breaking sunlight into a rainbow. They need to
understand that the visible rainbow is only a tiny sliver out of a spectrum
of electromagnetic radiation that ranges from harmless radio waves to
deadly gamma rays. The same spectrum should hang on the walls of every
classroom and appear in every news article that talks about cell-phone
radiation,skin cancer, and x-rays.
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