The Assumptions
Behind the Assumptions
By Joseph L. Bast, February
19, 2000
Thornton’s Zero
Discharge and Clean Production principles, the last of the four assumptions
that make up his “new” paradigm, are fundamentally at odds with the
conventional scientific notion that there are exposure thresholds below which
the body’s ability to repair itself is likely to prevent permanent physical
harm. Thornton therefore devotes much space to arguing that such thresholds are
arbitrary, apt to be “artifacts of science’s limits,” and so on. (75-80) But he
does not explicitly describe the assumptions on which his alternative
perspective rests. They are legion.
There is first
the Dose-Response Relationship is Linear assumption, which lies at the base of
nearly all of his projections of damage to human health. (75, 84, 86) Yet if
the relationship between dose and response is not linear -- if it is shaped
like a hockey-stick, for example -- then the notion that exposure to very low
levels of organochlorides is dangerous is severely attenuated. A healthy
scientific debate is taking place over how many dose-response curves are in
fact curved rather than linear.
Next is the Single
Molecule is Enough assumption, which says the dose-response line is continuous
to just one molecule above zero/zero, so exposure to even a single molecule of
a toxic agent will cause lasting injury to some small number of people (74). In
400 years, science has yet to come across convincing evidence of a compound
whose dose-response curve does not reach the Y axis before (usually well
before) coming within a molecule of zero/zero; it is for this reason “the dose
makes the poison” is part of conventional science. Thornton asserts that
current tests of some organochlorides show us approaching zero/zero, and he assumes
that future researchers (especially if freed from cultural and economic
influences that blind them to the truth) will eventually establish this to be
true of organochlorides as a class. If this is not true, then Zero Discharge
and Clean Production become nonoperative.
A third
assumption is that A Mouse is a Little Man, which holds that tests on
laboratory animals give meaningful data about real world exposure by humans. He
cites the International Agency for Research on Cancer, a division of the World
Health Organization, to the effect that there is “limited or sufficient
evidence of carcinogencity for over 100 organochlorines or groups of
organochlorines, comprising over a thousand individual compounds.” (58-9) But
he overlooks the point made by Bruce Ames and others that half of all compounds
tested are found to be carcinogenic, almost without doubt an artifact of animal
testing methods.
Thornton is
critical of some aspects of animal testing, particularly of the assumptions
that lie behind establishing the no observable affect exposure level (NOAEL),
(76-80) but he falls far short of the kinds of criticism of animal testing
offered by Elizabeth Whelen, Michael Fumento, and Edith Efron. It is easy to
see why. If animals are not reliable stand-ins for humans, then nine-tenths of
the research results he reports do not show what he claims they show. Yet faith
among scientists in animal testing seems to be dropping faster than Thornton
can assemble tests showing a potential threat to human health.
A fourth
assumption is that Natural Sequestration Fails. He reports that persistent organochlorides
gradually become less bioavailable over time due to sedimentation, but says
this isn’t “good enough.” (48) If we grant his Linear Dose-Response and Single
Molecule assumptions, then perhaps he is correct. But in the much more likely
case that extremely low levels of exposure to organochlorides, like virtually
all other compounds studied to date, are not hazardous to humans, then allowing
nature to sequester PCBs and other persistent toxins in river sediments, for
example, is plainly superior to dredging them up and transferring them to
landfills. We might also be heartened by Thornton’s reports that nature
transports many errant organochlorides to the polar ice caps where they are
sequestered in ice, snow, and the fat of polar bears, pretty much removing them
from human contact.
Thornton’s fifth
unstated assumption is the Public Interest principle, which (as he formulates
it) holds that government officials almost never compromise scientific truth to
advance their own self interest, and when by chance they do, their actions tend
toward less regulation rather than more. (353) Scientists, in Thornton’s world,
may sell themselves out to corporations for status or money, but policymakers
still require “overwhelming evidence that a specific chemical has caused harm
to public health before action is taken to restrict its production or use.”
(114)
But this is a
naive theory of how bureaucrats are rewarded and penalized in the real world.
In reality they are far more likely to be risk averse than their private sector
counterparts, willing to stop any innovation no matter how promising on the
most specious of grounds since they stand to profit little by a new chemical’s
success, but to lose much if the new chemical is harmful or even controversial.
Thornton has some sense of this; he observes, for example, the progressive
lowering of legal thresholds for exposure over time, (79) but attributes this
trend to the advancing sophistication of scientific tools rather than to
bureaucratic incentives.
A sixth unstated
assumption is that Complexity is Brittle. Thornton assumes the very complexity
of nature makes it vulnerable to the introduction of new compounds that are
created by human ingenuity. “Multiple tiny changes can cause runaway or
synergistic effects, resulting in a major reorganization or breakdown of the
system,” he writes. (340) “Chemicals that are incompatible with ecological and
physiological process have not become part of the fabric of life because that
fabric was woven by the process of natural selection. . . . An organism that
produces chemicals that it cannot degrade or excrete . . . will ultimately
perish in the course of natural selection.” (230)
But Nature is
Brittle is an assumption, not a fact. The opposite assumption, that complexity is
resilient, is just as persuasive and can be backed by as many anecdotes. The
tendency for persistent organochlorides to migrate to the poles and into the
fat of animals in those frigid parts of the world can be viewed as a marvelous
example of resilience: natural sinks emerging to accommodate the new chemical,
segregating them from areas (such as the tropics) where they might do the most
harm. This is not evidence of impending doom, but of a system able to respond
dynamically to a new challenge.
And finally, a
seventh assumption, is that Natural is Good, Artificial is Bad. Nowhere in his
book does Thornton address the argument put forward by Bruce Ames, the National
Academy of Sciences, and other authoritative sources that naturally occurring
carcinogens and hormone mimicking compounds exist in our diets at
concentrations that are thousands of times greater than the traces of
organochlorides he is able to document. If these natural substances are not
causing cancer epidemics or widespread sexual dysfunction -- and the evidence
is that they are not -- then why should we worry about the possible effects of
man-made substances that threaten to have similar effects?
Thornton gives
only a desultory defense of the Natural is Good, Artificial is Bad assumption as
part of his Nature is Brittle discussions, but his comments show a lack of
familiarity with the debate or a deliberate avoidance of the issue. Many of the
staples of modern diets date back only a century, so to claim that they are
harmless because they are the result of “evolutionary processes” is
disingenuous, at best. (230) No, Thornton is blind to the questionable nature
of this assumption because he accepts it unquestioningly, and he probably hopes
by not mentioning it, the reader will too.
Is Thornton Right
About Anything?
Thornton is most
believable when he reports that scientists have found traces of PCBs,
dioxins, pesticides, and other
chlorine-based chemicals in human and animal fat, mothers’ milk, tree bark,
fog, bogs, dolphins, whales, cows, snow, ice, and the upper atmosphere. I was
amazed -- to the point of reading it out loud to my wife -- by his report that
perc, a chemical used by dry cleaners, is so strongly attracted to fat that it
has been found in high concentrations in packages of butter sold in nearby
grocery stores. (305)
Thornton is also
persuasive when he makes the case that human activity is responsible for
virtually all dioxin production in the world (209-229), describes the
chlor-alkali business and its growing reliance on PVC products to maintain
demand for chlorine gas, the production of chlorinated byproducts during the
production of commercial products, and the release of dioxin and other
compounds during their incineration. His argument that phasing out chlorine
would cost less than industry projections is persuasive. Thornton comes across
as a more careful student of these issues than any of his predecessors.
If Thornton had
limited himself to these areas of discussion and not tried to pass off as valid
research that which is junky, or attacked the integrity of scientists in
general, or proposed a kind of workers’ paradise where first chlorine and then
virtually all other industries eventually get “sunset,” he would undoubtedly
have won more converts to his cause. Perhaps it is to his credit that he shares
this other agenda with us, rather than attempt to hide it. (As, for example,
Theo Colburn tried to do by claiming to have been surprised by her
anti-chlorine “discoveries.”) But it will surely alienate scientists, industry
leaders, and readers whose political leanings lie anywhere short of the far
left end of the spectrum.
Thornton tells us
repeatedly that the truth is as simple as 1 + 2 = 3: organochlorides as a class
are highly toxic and persistent; conventional science and regulations are not
equipped to handle this new threat; the solution is to gradually phase out
virtually all uses of chlorine. It sounds simple, but actually he’s presenting
us with a + b = c, where the values of each variable depend on the many
assumptions discussed earlier, many of them left out of Thornton’s description
of his paradigm. Once the entire paradigm is in view, it becomes an
unattractive and unpersuasive choice. (Part IV to follow)
Joseph Bast is president of The Heartland Institute and coauthor of Eco-Sanity: A Common-Sense Guide to Environmentalism.
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