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#398 - Bruce Ames, 13-Jul-1994

The NEW YORK TIMES ran a long article July 5th explaining the theories
of Bruce N. Ames, the controversial biochemist from Berkeley.[1] Ames's
basic idea is that most of the poisons we ingest are natural toxins
appearing in our food; from this, he concludes that money spent
controlling industrial chemicals is largely wasted. The TIMES'S story
occupied 87 column-inches and contained only one sentence that
challenged Ames, thus suggesting that Ames's ideas are almost beyond
question.[2] That is not the case. Here is an incomplete list of
problems with the Ames hypothesis:

1) Production and use of synthetic pesticides (and other synthetic
organic chemicals) emits large quantities of hazardous materials into
the environment. Workers and neighbors at manufacturing and waste
disposal facilities are exposed to toxins. THE NATIONAL CANCER
CHANCE. In the TIMES, Ames acknowledged this problem when he said,
"Environmental pollutants are not an important cause of cancer. They
account for a tiny percent of cancers in Americans but might be a
problem in people like farm workers who apply pesticides if they are
heavily exposed." Or in anyone else heavily exposed, he might have

2) Natural toxins and pesticides that occur in vegetation do not build
up in the environment; nature has ways of reassimilating (decomposing)
them. On the other hand, the concentration of synthetic (human-created)
pesticides and other synthetic organic chemicals is increasing in the
environment. Synthetic pesticides are now measurable in groundwater in
many states, and the concentrations are growing as time passes. Many
pesticides, and industrial poisons such as PCBs, are measurable in all
the world's oceans, and even in the polar ice caps. There is compelling
evidence that wildlife is being harmed (in some instances, driven to
extinction) by this buildup of exotic chemicals throughout the global

3) Ames presents himself as an expert on cancer, yet he makes sweeping
generalizations that go far beyond his studies of cancer. In this, he
has abandoned science and taken up politics. (Ames opposes government
regulation on principle.) He says, for example, "We're shooting
ourselves in the foot with environmental regulations that cost over 2
percent of the G.N.P., much of it to regulate trivia." Even if it were
true that industrial chemicals cause only a small fraction of all
cancers, cancer is not the only problem that we should consider when we
examine the wisdom of dumping billions of pounds of pesticides and
other industrial poisons into the environment each year. During the
past decade, much new information has come to light indicating that
many chemicals damage the nervous, immune and endocrine systems of
wildlife (fish, birds, and mammals) and humans. According to these
studies, one clear result is reproductive and developmental damage in
the affected species, and an increased likelihood of succumbing to
bacterial and viral infections as well as cancers. Ames ignores the
non-cancer effects.

To cite but one example, the National Academy of Sciences acknowledged
in a 1992 study, "In the general population, increasing numbers of
people suffer from disorders of the immune system, such as allergies,
asthma, and AIDS. The incidence of asthma has increased 58% since 1970,
and it is well known that nitrogen dioxide and ozone, common air
pollutants, interact with allergens to increase the frequency and
severity of asthma attacks."[4] Ames ignores the evidence that
pollution weakens the human immune system; he insists that we are
wasting money curbing industrial discharges because industrial poisons
do not cause many cancers, he says --as if cancer were the only problem
created by industrial poisons. This is neither good science nor good
public policy.

4) Chemical toxicity and exposures are poorly understood because
current knowledge is based on:

(a) chemical tests that do not take into consideration children and the
elderly, people who are already sick from something else, and
populations that eat unusual quantities of one or more food items
(e.g., native people who eat a lot of fish);

(b) chemical tests that omit the combined effects of multiple exposures
because science has no affordable way of assessing combined and
cumulative effects.

This is a point worth emphasizing because Ames makes sweeping
generalizations based on data derived from testing one chemical at a
time, as if combinations of chemicals don't occur in the real world.

A recent study focused on this problem. In June, three scientists from
the National Institute for Occupational Safety and Health (NIOSH) in
Cincinnati, Ohio announced an "inherent problem with the way workplace
risks are characterized."[5] The "inherent problem" is that workers are
usually exposed to many contaminants simultaneously, while "health
standards are almost always designed to protect workers from a single
exposure." In 25 percent of cases studied, the NIOSH researchers
reported what they called an "alarming finding." They reported that,
"when animals were exposed to several [chemical] agents at once, the
animals (or their offspring) experienced a dramatically increased
number of adverse health effects." "In fact," the NIOSH researchers
said, "the reported health effects were many times greater than
expected by simply adding the effects of each substance." (They also
found, in 25% of cases, that combinations of chemicals produced FEWER
effects than they would have expected.)

The NIOSH researchers reported that exposure of rats to the common
plasticizer, di(2-ethylhexyl) phthalate (DEHP), produced prenatal death
in 16 percent of the fetuses and congenital defects (birth defects) in
21 percent of the surviving fetuses. Exposure of rats to caffeine
produced prenatal death in about 9 percent of fetuses and defects in 3
percent of the surviving fetuses. However, exposure to DEHP and
caffeine simultaneously produced prenatal death in 80 percent of the
fetuses and defects in 73 percent of the surviving fetuses.

The researchers point out that risk assessments should consider not
only job-related chemical exposures but also prescription and non-
prescription drugs. In addition, they say physical agents such as
vibration, heat and noise must be considered as well. (And, if Ames is
correct in his estimate of the potency of natural toxins in our food,
natural toxins must be factored in too.)

The NIOSH team points out that, in nearly every work environment, there
is a pervasive physical agent: non-ionizing electromagnetic radiation.
One type of non-ionizing radiation, radio-frequency (RF) radiation, is
used in a number of industries, including communications, electronics,
medical and manufacturing. Many workers in these industries are exposed
to RF energy at the same time they are exposed to exotic chemicals.

For years, RF exposures were assumed to be benevolent because they do
not ionize (knock electrons off of) molecules or cells the way higher-
energy radiation (ionizing radiation, such as x-ray energy) does. To
test the hypothesis that RF might enhance the effects of chemicals, the
NIOSH researchers exposed rats to a combination of 2-methoxyethanol
(2ME) and RF energy. 2ME is a common glycol ether used in some
degreasing solvents, and in some paints and varnishes. Alone, 2ME
causes developmental toxicity in every species of animal tested to
date, including non-human primates (monkeys). To test the interaction
of RF energy and 2ME, rats were exposed to these substances on the 13th
day of gestation, alone and in combination. RF radiation caused
malformations in 30 percent of the rat fetuses, and 2ME produced
malformations in 14 percent. Yet, combined exposure to 2ME and RF
induced external malformations in 76 percent of the fetuses, "and these
malformations were more severe than after single-agent exposure," the
NIOSH researchers reported. Subsequent studies of different doses
during various gestation times confirmed these findings, they said.

Another study reported by the NIOSH researchers indicates that noise
and solvents combine to induce hearing loss in workers to a greater
degree than either solvents or noise alone. They studied 200 workers
(50 controls, 50 exposed to noise, 39 exposed to organic solvents
alone, and 51 exposed to noise and toluene, a common organic solvent).
The authors concluded that simultaneous occupational exposure to
excessive levels of toluene and noise increased the probability of
developing hearing loss. The NIOSH workers summarized, "The effect of
combined exposure also suggested a synergistic [multiplier] interaction
between noise and toluene on hearing loss. The level of hearing loss
was much greater in workers exposed to both hazards than would be
predicted by adding the effect of each agent."

Thus we can see that Bruce Ames --and others like him who belittle
effects of chemicals on human and environmental health based on
incomplete data and erroneous assumptions --may be underestimating the
true hazards because they test only one substance at a time. Humans
almost never encounter substances one at a time. Toxins in food, drugs
(both pharmaceutical and "recreational"), air pollution, water
pollution, noise, vibration, heat, electromagnetic radiation and
ionizing radiation usually impact us simultaneously. They not only
cause cancer but they affect the nervous, endocrine and immune systems
in ways that are poorly understood. Risk assessment has no way to take
into account such complex and cumulative interactions. The only
approach that can consider all these effects together is prevention,
the principle of precautionary action. (See RHWN #284, #319, and #378.)
Bruce Ames represents solid 19th-century toxicological thinking, but a
complex technological world requires that we adopt more modern and more
prudent views, based on real-world exposures to combinations of natural
and industrial hazards. For developing such a modern approach, many of
Bruce Ames's sweeping generalizations are not only wrong and wrong-
headed; they are also largely irrelevant.

--Peter Montague


[1] Jane E. Brody, "Strong Views on Origins of Cancer," NEW YORK TIMES
July 5, 1994, pgs. C1, C10.

[2] In Brody, cited above, David Rall, former director of the National
Institute of Environmental Health Sciences, says Ames's generalizations
are based on "incomplete data" since "most of the chemicals we're
exposed to haven't been tested for carcinogenicity."

[3] "Statement from the Work Session on Environmentally-Induced
Alternations in Development: A Focus on Wildlife; Wingspread Conference
Center, Racine, Wisconsin December 10-12, 1993." [A consensus statement
from 23 scientists published, accompanied by a news release, April 20,
1994 by the World Wildlife Fund in Washington, D.C.; for a copy, phone:
(202) 778-9510 or (202) 778-9536.]

(Washington, D.C.: National Academy Press, 1992), pg. 1.

[5] B.K. Nelson, David L. Conover, and W. Gregory Lotz, "Combined
Chemical, Physical Hazards Make Exposure Harder to Calculate,"
OCCUPATIONAL SAFETY AND HEALTH Vol. 63, No. 6 (June 1994), pgs. 50, 52-

Descriptor terms: bruce ames; cancer; carcinogens; policies;
immunotoxicity; immune system; nervous system; endocrine system; niosh;
occupational safety and health; standards; regulations; studies;
teratogens; dehp; caffeine; electromagnetic fields; radio frequency
radiation; non-ionizing radiation; 2-methoxyethanol; glycol ether; 2me;
toluene; solvents; hearing loss; noise; synergism; multiplier effect;
precautionary principle; prevention;

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