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#693 - The Major Cause of Cancer--Part 3, 19-Apr-2000

John Gofman is a medical doctor with a Ph.D. degree in nuclear
and physical chemistry. He is professor emeritus of molecular and
cell biology at University of California, Berkeley, and a member
of the faculty at University of California Medical School at San
Francisco. During his long career, he has pursued two separate
fields of research -- heart disease, and the health effects of
low-level radiation. He has won several awards for original
research into the causes of atherosclerosis, which is the growth
of fatty "plaque" inside the blood vessels, often causing fatal
heart attacks. In 1974, the American College of Cardiology
selected him as one of the 25 leading researchers in cardiology
of the past quarter-century.

In the early 1960s, the U.S. Atomic Energy Commission (AEC) asked
Gofman to develop a Biomedical Research Division at the AEC's
Livermore National Laboratory (LNL) to evaluate the health
effects of all types of nuclear activities. In 1970, he became
convinced that radiation was more dangerous than previously
believed, and he spoke out against Project Plowshare, the AEC's
plan to explode hundreds of nuclear weapons to release gas
trapped in rock beneath the Rocky Mountains and to excavate new
harbors and canals by exploding nuclear bombs above-ground. (See
REHW #691.) He also called for a 5-year moratorium on the AEC's
plan to develop 1000 commercial nuclear power plants. By 1974,
his government funding was cut. He then began a series of books
on the dangers of radiation: RADIATION AND HUMAN HEALTH (1981);

Gofman is a superb teacher. In his books, he explains the raw
data, where it came from, its shortcomings, how it might be
improved (or why we're stuck with what we've got). Then he moves
the reader step by step toward his conclusions, explaining each
step for the novice as well as the expert. When he is forced to
make assumptions, he explains why he thinks he is making the
right ones. He often describes alternative assumptions and the
effect they would have on his conclusions. Nothing of importance
is omitted. As a result, Gofman's books are lengthy -- typically
500 to 900 pages filled with tables of data accompanied by
detailed explanations. The reader gets a thorough education in
the topic, satisfactory for both novice and professional. I
consider Gofman one of the greatest teachers of the 20th century.
His work has already changed the way the world views the dangers
of radiation, and his latest book will -- eventually, after a
long fight -- revolutionize the way the world looks at medical
radiation. Cumulatively his work will save tens of millions of

In his latest (1999) book, Gofman presents strong evidence that
medical radiation is a major cause of cancer AND of
atherosclerosis (coronary heart disease).[5] By "medical
radiation" Dr. Gofman is referring mainly to x-rays, including
fluoroscopy and CT ("cat") scans. The mechanism is simple to
state: radiation causes genetic mutations, which eventually give
rise to disease.

What is Gofman saying? Does he mean that medical radiation is
necessarily the ONLY cause of cancer and coronary heart disease?
Certainly not. Does he mean that cancer is NOT caused by smoking,
poor diet, genetic inheritance, pesticides, diesel exhaust,
dioxin, and toxic chemicals encountered on the job? Certainly
not. Cancer and heart disease both have multiple causes. For a
cancer (or an atherosclerotic plaque) to develop, a cell must
undergo several (probably 5 to 10) separate gene mutations. Some
of these mutations might be inherited but most occur from
exposure to gene-damaging substances in the environment.

Here is a way to understand multiple causation. Gofman gives the
following hypothetical example of 100 cases of cancer:

** 40 cancers caused by co-action of x-rays + smoking + poor

** 25 cancers caused by co-action of x-rays + poor diet +
inherited genetic mutations;

** 25 cancers caused by co-action of x-rays + smoking + inherited
genetic mutations;

** 10 cancers caused by co-action of smoking + poor diet +
inherited genetic mutations.

In the first case, the 40 cancers are caused by genetic mutations
that are, in turn, caused by x-rays, smoking, and poor diet. Each
of these three factors is necessary for the cancer to occur; if
any one of the three factors is missing, the cancer will not

We can see that, in this example, x-rays contribute to 40 + 25 +
25 = 90 cases out of 100. In this example, if x-rays were not
present, 90% of the cancers would not occur. Now, in the same
example, look at "poor diet." Poor diet contributes to 40 + 25 +
10 = 75 of the 100 cases. If poor diet were not present, 75% of
the cancers in this example would not occur.

You can see that, in this example, we have x-rays "causing" 90%
of the cancers -- "causing" in the sense that the cancers
wouldn't occur in the absence of x-rays. But we also have poor
diet "causing" 75% of the same cancers, meaning that 75% of the
cancers wouldn't occur in the absence of poor diet.

Thus we can see that, when Gofman says x-rays are responsible for
a large proportion of all cancers in the U.S., he is NOT saying
that x-rays are the ONLY cause of those cancers. However, he IS
saying that most of those cancers would not occur in the absence
of x-rays.

It is important to point out that Gofman is not opposed to
medical x-rays. Rather he is opposed to UNNECESSARY EXPOSURES
from x-rays. He has shown over the years -- and he is definitely
not alone in this -- that medical x-ray exposures in the U.S.
could be cut by at least 50% with no loss of medical information.
The careful use of modern x-ray equipment and techniques can
reduce x-ray exposures by half (or more) without sacrificing any
medical benefits. Thus at least half the cancers caused by
medical x-rays are completely unnecessary.

How many unnecessary cancers are we talking about? Gofman
calculates that in 1993, 50% of all cancers in women and 74% of
all cancers in men were attributable to x-rays. In other words,
about 60% of all cancers in the U.S. in 1993 were attributable to
x-rays. About 500,000 people die of cancer each year in the U.S.
If 60% of these deaths are attributable to x-rays and half are
unnecessary, we are talking about 150,000 unnecessary cancer
deaths each year in the U.S.

Gofman calculates that the proportion of coronary heart disease
(CHD) attributable to x-rays is slightly higher than the
proportion of cancers. Among men in 1993, 63% of CHD deaths were
attributable to x-rays and among women, 78%. So, in rough
numbers, 70% of CHD deaths are attributable to x-rays, Gofman
believes. Since CHD caused roughly 460,000 deaths in the U.S. in
1993, if Gofman is right then 70% (or 322,000) of these deaths
are attributable to x-rays and half of these, or 161,000 are
unnecessary. Thus we can see that x-rays are responsible for
about 150,000 + 161,000 = 311,000 unnecessary deaths each year in
the U.S., if Gofman is right.

Gofman's study takes a novel approach, avoiding certain
difficulties inherent in all data linking medical radiation to
health. Here are the difficulties: there are no reliable
estimates of the average per-capita radiation dose that the U.S.
population receives now from medical x-rays, or has received in
the past. (Gofman explains why in chapter 2.) Secondly, there are
no reliable estimates of the cancer risk per unit dose from
medical x-rays because no one is sure of the precise exposures
received by various groups that have been studied for cancer
effects. (Again, see Gofman's chapter 2.)

Avoiding these difficulties, Gofman developed a novel approach:
he found disease statistics for the entire U.S. population,
broken down into 9 census districts (1940 to 1990 for cancer, and
1950 to 1990 for coronary heart disease). Then he correlated
these disease statistics, year by year, to the number of
physicians per 100,000 population in each of the 9 census
districts. The density of physicians per 100,000 population
provides a RELATIVE measure of the medical radiation per 100,000
population in the 9 districts, year by year.

Gofman shows that cancer death rates RISE in lock-step with
increasing density of physicians in a census district, while
non-cancer deaths DECLINE in lock-step with increasing density of
physicians per 100,000 population EXCEPT in the case of coronary
heart disease (CHD), which follows the rising pattern of cancer.
Thus Gofman's hypothesis that CHD is linked to medical radiation
"fell out of the data." Because he had decades of experience
researching the causes of CHD (he has written three books on
heart disease), and because he knows the radiation literature so
well, Gofman was able to put 2 and 2 together: radiation induces
mutations in the coronary arteries, giving rise to what he calls
"dysfunctional clones" (mini-tumors) in the smooth muscle lining
the arteries.

Interestingly, using his "physician density" method Gofman
estimates that medical radiation caused 83% of female breast
cancer in the U.S. in 1993. Using a completely different method,
Gofman in 1995 had estimated that medical radiation was
responsible for 75% of U.S. breast cancer. The two estimates, by
two completely different methods, are remarkably similar.

It will not be easy to convince physicians to take special care
to minimize radiation to their patients. Familiarity breeds
contempt and many physicians and dentists treat x-rays as if they
are entirely harmless. Recently I broke a tooth. My dentist, who
is first-rate, needed to document the injury for insurance
purposes. "I'll just snap an x-ray," he said. I asked, "Is there
some other way?" He nodded and immediately scribbled a note: "I
broke my tooth and I don't want an X-ray." "Sign this," he said.
"The insurance company is required to accept it." One unnecessary
x-ray avoided.

Next time someone says they're going to give you an x-ray, don't
put them on the spot but mention that you're curious what dose of
radiation you will get. If your experience is anything like mine,
the person giving the x-ray will not know the answer and you will
be told, "Don't worry. It's completely safe."

But it's not.

--Peter Montague (National Writers Union, UAW Local 1981/AFL-CIO)


[1] John W. Gofman, RADIATION & HUMAN HEALTH (San Francisco:
Sierra Club Books, 1981); ISBN 0-87156-275-8.

[2] John W. Gofman and Egan O'92Connor, X-RAYS -- HEALTH EFFECTS
OF COMMON EXAMS (San Francisco: Sierra Club Books, 1985); ISBN

Nuclear Responsibility, 1990; ISBN 0-932682-89-8.

[4] John W. Gofman (edited by Egan O'Connor), PREVENTING BREAST
CANCER (San Francisco: Committee for Nuclear Responsibility,
second edition, 1996); ISBN 0-932682-96-0.

[5] John W. Gofman (edited by Egan O'Connor), RADIATION FROM
HEART DISEASE (San Francisco: Committee for Nuclear
Responsibility, 1999). ISBN 0-932682-98-7. Available for $27.00
from Committee for Nuclear Responsibility; telephone/fax: (415)
776-8299. E-mail: cnr123@webtv.net.

Descriptor terms: radiation; x-rays; cancer; john gofman; heart