Page i4 - The Michigan aily-- Frtda May 11 1984
Scientific report studies cancer causes

NEW YORK (AP) - It was one more
in the endless-stream of scientific stud-
ies that seem to find cancer lurking
everywhere.
This time the culprit was beer. Re-
searchers linked it to an excess of
rectal cancer in Japanese men in
Hawaii.
SUCH STUDIES pointing to possible
causes of cancer are so common they

have led many people to conclude that
almost everything causes cancer.
Forty-six percent of Americans now be-
lieve "There's not much a person can
do to prevent cancer," according to a
government survey.
Such beliefs are unfounded, the ex-
perts say.
The actual number of known causes
of cancer is small. The National Cancer

Institute unofficially lists about 30
causes of cancer. The American Cancer
Society's working list includes some 40
substances or activities.
MANY OF THESE substances are.
industrial chemicals or drugs with un-
pronounceable names and restricted
uses. Others are better known-smok-
ing and radiation, for example.
"There aren't a heck of a lot of things

Cancer experts list carcinogens

NEW YORK (AP) - Both the American Cancer Society
and the National Cancer Institute have drawn up unofficial
lists of substances that cause cancer in humans. Here are the
names of the substances that appear on both lists, followed
by where the substances are commonly found. This is not a
complete list.
Aflatoxinhs - naturally occurring in grains, peanuts.
4-Aminobiphenyl - manufacture of rubber and dyes.
Arsenic, inorganic arsenic compounds pesticides, manufac-
ture of glass and ceramics, food, drinking water, smelting
of metal ores.
Asbestos - insulation, brake linings, manufacture of
asbestos-containing items.
Benzene - manufacture of chemicals and plastics; paints,
adhesives, gasoline fumes.
Benzidine - manufacture of dyes.
Bis Chloromethyl ether - manufacture of chemicals, plastics.
Chromium, chromium compounds - manufacture of metal
alloys and protective coatings on metals; paint, sometimes
a contaminant in food and drinking water.

Cyclophosphamide - an anti-cancer drug.
Diethylstilbestrol (DES) - synthetic estrogen female sex
hormone, used to treat hormonal abnormalities, symptoms
associated with menopause, sometimes breast and prostate
cancer.
Hematite and iron oxide - mining of iron ore.
Isopropyl oils - manufacture of isopropyl alcohol; rubbing
alcohol.
Melphalan - an anti-cancer drug. -
Mustard gas - chemical warfare agent.
2-Naphthylamine - manufacture of dyes.
Nickel, nickel compounds - manufacture.of metal alloys and
metal plating; paint, sometimes a contaminant in food and
drinking water.
Soots, tars, mineral oils - manufacture of coal tar and
creosote, crude mineral oils and cutting oils, shale oils.
Tobacco, tobacco smoke - cigarettes, pipes, snuff.
Vinyl chloride - manufacture of plastics.
X-rays, radioactive materials, other radiation - sunlight,
medical examinations, industrial processes.

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known to cause cancer in people-out-
side of tobacco, which causes 30 percent
to 35 percent," says Frank Rauscher,
senior vice-president for research at
the American Cancer Society.
Finding the causes has proven to be
an enormous task. "We know what
causes about 50 percent of our can-
cers," says Rauscher. "The other 50
percent is a gray area. Much of that is
thought to be related to diet and nutri-
tion,"
STUDIES TO determine exactly
which items in the diet might cause
cancer-or protect against it-are only
beginning, so nothing can be said with
certainty.
One of the difficulties is that scien-
tists still do not understand exactly how
known cancer-causing agents actually
trigger the disease.
Another problem is that 30 or 40 years
can pass between exposure to a car-
cinogen and the appearance of cancer,
as often happens with lung cancer and
smoking.
AND, TO MAKE things worse, people
seem to have differing susceptibilities
to carcinogens. Everyone knows some-
one who smoked heavily for a lifetime
and died peacefully of old age.
Earl Pollack, the National Cancer In-
stitute researcher who led the study on
beer drinking and rectal cancer, hasn't
concluded beer drinking causes cancer.
"All we can say is there was a statis-
tical association" between beer and
cancer, he says. "But we can't say it
was due to the beer."
IT MIGHT SOUND like doubletalk,
but Pollack has chosen his words care-
fully. He is not begging the question.
Maybe beer drinking causes cancer,
maybe it doesn't. The most eminent
scientists simply don't know.
There are undoubtedly many differ-
ences between beer drinkers and non-
drinkers. Beer drinkers might smoke
more or eat different foods. Pollact took
those differences into account, and still
found an excess of rectal cancer. But in
any statistical study, questions remain
about whether all such differences have
been properly considered.
THE EXCESS rectal cancer in beer
drinkers might only appear in Japanese
men in Hawaii, for unknown reasons. Or
it could be a mere coincidence, a statis-
tical fluke.
"This is sort of a flag to continue to
look in this direction," says Pollack,
whose study appeared in the New Eng-
land Journal of Medicine March 8.
Many more studies would be needed to
prove conclusively that beer causes
rectal cancer.
Explaining that to the public, how-
ever, can be difficult. If Pollace were
asked to do it, he says with a laugh, "I'd
refuse."
THE CLOSEST thing to an official list
of causes of cancer is a collection of
about 30 volumes prepared by the In-
ternational Agency for Research on
Cancer, located in Lyon, France. The
weight of the evidence varies from one
substance to the next.
"There's really a continuous range
of evidence, from very good evidence to
very poor evidence," says Robert Mc-
Gaughy, a biophysicist in the office of
health and environmental assessment
of the Environmental Protection Ag-
ency.
Scientists have three kinds of tools to
search for cancer causes. One is the
statistical study like Pollack's, based
on medical records and questionnaires.
Each of these studies has its flaws.
"You always look back and wish you
had asked different questions," says
Pollack.

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The Michigan Flyers
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