RACHEL'S ENVIRONMENT & HEALTH WEEKLY #598
---May 8, 1998---
BREAST CANCER, rBGH AND MILK
BREAST CANCER, RBGH AND MILK
A study of U.S. women published May 9 in the LANCET links
insulin-like growth factor-1 (IGF-1) with breast cancer.[1,2]
Earlier this year a study linked IGF-1 to prostate cancer.
(See REHW #593.) Prostate and breast cancers are major killers
of men and women in the U.S. and in other industrialized
countries. IGF-1 levels are now being artificially increased in
much of the cows' milk being sold throughout the U.S. These new
cancer studies raise serious questions about the wisdom of
allowing IGF-1 levels to be raised in milk.
The latest study found a 7-fold increased risk of breast
cancer among pre-menopausal women younger than age 51 with the
highest levels of IGF-1 in their blood. The prostate cancer study
published in SCIENCE in January, 1998, found a 4-fold increase in
risk of prostate cancer among men with the highest levels of
IGF-1 in their blood. Thus IGF-1 in blood is associated with
larger relative risks for common cancers than any other factor
It is not clear from these studies whether IGF-1 causes these
cancers, or whether elevated IGF-1 accompanies some other factor
that causes these cancers. At the very least, researchers are
hoping that measurements of IGF-1 will identify individuals at
high risk of getting these cancers, so that surveillance might be
increased. (However, it would be common practice in the U.S.
for people under such surveillance to find their health insurance
canceled, which tends to discourage participation in surveillance
IGF-1 is a powerful naturally-occurring growth hormone found in
the blood of humans. Dairy cows injected with
genetically-engineered bovine growth hormone (rBGH) give milk
containing elevated levels of IGF-1, and the IGF-1 in milk can
pass into the blood stream of milk consumers. Cows' IGF-1 is
chemically identical to that in humans. Ingested IGF-1 would
ordinarily be broken down in the stomach, but the presence of
casein in milk prevents such breakdown.[4,5,6,7,8] (See REHW
#454.) Thus these latest cancer findings raise important public
health questions about the safety of milk from cows treated with
bovine growth hormone (rBGH).
rBGH is injected into cows to extend by several weeks their
period of lactation, and thus to force them to produce more milk.
rBGH is not needed in any way because U.S. dairy cows already
produce such an excess of milk that the U.S. government spends
more than $200 million each year purchasing surplus milk, a
subsidy to the milk industry. (See REHW #381, #384.) Because rBGH
injections can cause numerous ill effects in cows, veterinarians
in Germany have refused to administer rBGH to cows on grounds
that it violates their professional code of ethics, which forbids
intentional harm to animals. (See REHW #483.) U.S. veterinarians
have not taken a similar stand.
The latest study of IGF-1 and cancer, reported this week in the
LANCET --approximately the British equivalent of the JOURNAL OF
THE AMERICAN MEDICAL ASSOCIATION --examined 397 women with breast
cancer, and 620 carefully-matched controls. Their blood had been
drawn before any of the women were diagnosed with breast cancer,
so this was a prospective study --the most convincing kind there
is. (The prostate cancer study reported in January was also a
The study found no relationship between IGF-1 in blood and breast
cancers among the entire group, or among the post-menopausal
group. However among pre-menopausal women increasing levels of
IGF-1 in blood were strongly associated with increasing risk of
breast cancer in a consistent dose-response relationship.
Adjusting for other known breast cancer factors (age at which
menstruation began; age at birth of first child; number of
children; family history of breast cancer; and weight in relation
to height) did not change the results.
Two previous studies had reported a relationship between IGF-1
levels in blood and breast cancer.[9,10] However those were
"retrospective" studies in which the IGF-1 levels in blood were
measured AFTER the diagnosis of breast cancer, so it was possible
that the cancers caused the IGF-1 increases instead of the IGF-1
increases causing the cancers. This latest study minimizes the
likelihood that IGF-1 levels are raised by breast cancers.
The authors of the latest study say there is "substantial
indirect evidence of a relation between IGF-1 and risk of breast
cancer." They point to experiments showing that IGF-1 enhances
the growth of cancerous breast cells in mice, and growth of
healthy breast cells in rhesus monkeys. In humans,
very-low-calorie diets protect against breast cancer and they
also reduce blood levels of IGF-1. Low birth weight is
protective against breast cancer and low birth weight also leads
to low levels of IGF-1. Tall women tend to have an increased
likelihood of breast cancer and they also tend to have increased
levels of IGF-1. Tamoxifen, a chemical now being used to prevent
breast cancer, is known to reduce IGF-1 levels in the blood.
Several other chemicals thought to protect against breast cancer
--such as vitamins A and D --may also lower blood levels of
It will be difficult for the U.S. Food and Drug Administration
(FDA) to acknowledge that milk from rBGH-treated cows might be
implicated in common cancers. Historically, FDA has maintained a
very close relationship with Monsanto, the chemical company that
spent a billion dollars developing rBGH. FDA approved rBGH for
cows in 1993 and issued regulations that made it appear to be
illegal to label milk rBGH-produced or rBGH-free. Some of the
FDA officials who approved rBGH and who established the
regulations discouraging labeling had previously worked for
Monsanto. (See REHW #381.) In 1994, Monsanto sued two grocery
stores that labeled milk rBGH-free, because the chemical giant
feared that, given a choice, consumers would reject rBGH-produced
milk. FDA's anti-labeling regulations --signed into law by a
former Monsanto official --were clearly intended to help Monsanto
succeed in this marketing ploy. Eleven separate surveys have
shown that Americans strongly prefer to have rBGH-treated milk
labeled as such. (See REHW #381.)
Monsanto officials say their rBGH product has been so successful
among dairy farmers that they are building a new factory in
Augusta, Georgia to produce a lot more of it. They say they
intend to market the product world-wide. However in Canada
and the European Union, rBGH has so far not been approved for
use, partly because of unanswered health questions. The new
studies linking IGF-1 to breast and prostate cancers are unlikely
to help rBGH gain approval in Canada or Europe.
Because of FDA's and Monsanto's aggressive steps to prevent
labeling of rBGH-produced milk, U.S. consumers of milk, chocolate
milk, buttermilk, cream, whipped cream, ice cream, iced milk,
cheese, cottage cheese, cream cheese, yogurt, frozen yogurt,
custards --and perhaps many baked goods as well --are very likely
ingesting increased quantities of IGF-1 today. (See REHW #383,
The milk industry --a powerful lobby in the U.S. --is currently
conducting a campaign to increase milk consumption and top U.S.
health officials are participating in the campaign. Recent
advertisements show Donna Shalala, the U.S. secretary of health
and human services, with a glass of milk in her hand and a "milk
mustache" on her upper lip. Ms. Shalala oversees the U.S.
FDA, among other agencies.
A few bold companies --such as Ben and Jerry's, makers of gourmet
ice cream --now label their products as rBGH-free. However,
other companies, such as Whole Foods, Inc. --an "organic" grocery
chain that owns Fresh Fields stores --claim to sell no dairy
products containing rBGH. Yet the Annapolis, Maryland Whole
Foods outlet sells cheeses from Cabot Dairies in Vermont and
Cabot readily acknowledges that it uses some milk from
rBGH-treated cows. Thus rBGH may be even more widespread than
advertisements and store policy statements would lead consumers
to believe. In the U.S., it is legal for merchants to mislead
consumers in this way.
Dr. Samuel S. Epstein at the University of Illinois in Chicago in
1996 published a paper arguing that IGF-1 from rBGH-treated cows
may well promote cancer of the breast and of the colon in humans
who drink such milk. Epstein pulled no punches: "In short," he
wrote, "with the active complicity of the FDA, the entire nation
is currently being subjected to an experiment involving
large-scale adulteration of an age-old dietary staple by a poorly
characterized and unlabeled biotechnology product [rBGH, which is
genetically engineered by Monsanto]. Disturbingly, this
experiment benefits only a very small segment of the agrichemical
industry while providing no matching benefits to consumers. Even
more disturbingly, it poses major potential public health risks
for the entire U.S. population," Dr. Epstein wrote.
Monsanto has bet the company's future on genetically-engineered
products, and rBGH is the first such product to be marketed.
Therefore, it seems unlikely that Monsanto will voluntarily
terminate the uncontrolled IGF-1 experiment being conducted now
on the American people. This is a company that plays hard ball.
As we saw in REHW #593, Monsanto lawyers frightened Fox TV
executives into killing an investigative series that raised
questions about rBGH and cancer. Just last month Monsanto wrote
a threatening letter to Vital Health Publishing in Bloomingdale,
Illinois over the proposed publication of AGAINST THE GRAIN, a
book by Marc Lappe and Britt Bailey. Monsanto said the new book
would libel its best-selling product, the herbicide Roundup
(glyphosate). Lappe is an established medical writer and an
acknowledged health policy expert. His earlier books include
TOXIC DECEPTION (1991), BREAKOUT --THE EVOLUTION OF DRUG
RESISTANT DISEASE (1995), and THE TAO OF IMMUNOLOGY (1997).
Lappe and Bailey run the Center for Ethics and Toxics in Gualala,
California (telephone 707-884-1700). After receiving Monsanto's
threats, Vital Health Publishing abandoned its plans to publish
AGAINST THE GRAIN --even though the book had already been printed
--for fear of a Monsanto lawsuit, which might put them out of
business even if Monsanto lost in court. Happily, Common Courage
Press (Monroe, Maine; telephone 800-497-3207) will publish
AGAINST THE GRAIN in September. AGAINST THE GRAIN is a detailed
account of the perils of the new genetic technologies in
agriculture. Monsanto's rBGH represents the tip of a very
(National Writers Union, UAW Local 1981/AFL-CIO)
 Susan E. Hankinson and others, "Circulating concentrations of
insulin-like growth factor I and risk of breast cancer," LANCET
Vol. 351, No. 9113 (May 9, 1998), pgs. 1393-1396.
 Jeff Holly, "Insulin-like growth factor-I and new
opportunities for cancer prevention," LANCET Vol. 351, No. 9113
(May 9, 1998), pgs. 1373-1375.
 June M. Chan and others, "Plasma Insulin-Like Growth Factor-I
and Prostate Cancer Risk: A Prospective Study," SCIENCE Vol. 279
(January 23, 1998), pgs. 563-566.
 C.J. Xian and others, "Degradation of IGF-I in the adult rat
gastrointestinal tract is limited by a specific antiserum or the
dietary protein casein," JOURNAL OF ENDOCRINOLOGY Vol. 146
(1995), pgs. 215-225.
 R.K. Rao and others, "Luminal Stability of Insulin-Like
Growth Factors I and II in Developing Rat Gastrointestinal
Tract," JOURNAL OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION Vol.
26, No. 2 (February 1998), pgs. 179-185.
 Toshikiro Kimura and others, "Gastrointestinal Absorption of
Recombinant Human Insulin-Like Growth Factor-I in Rats," THE
JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS Vol. 283,
No. 2 (November 1997), pgs. 611-618.
 Douglas G.G. Burrin and others, "Orally administered IGF-I
increases intestinal mucosal growth in formula-fed neonatal
pigs," AMERICAN JOURNAL OF PHYSIOLOGY Vol. 270, No. 5 Part 2 (May
1996), pgs. R1085-R1091.
 A.F. Philipps, "Growth of artificially fed infant rats:
effect of supplementation with insulin-like growth factor I,"
AMERICAN JOURNAL OF PHYSIOLOGY Vol. 272, No. 5 Part 2 (May 1997),
 Peter F. Bruning and others, "Insulin-Like
Growth-Factor-Binding Protein 3 is Decreased in Early-Stage
Operable Pe-Menopausal Breast Cancer," INTERNATIONAL JOURNAL OF
CANCER Vol. 62 (1995), pgs. 266-270.
 J. P. Peyrat and others, "Plasma Insulin-like Growth
Factor-1 (IGF-1) Concentrations in Human Breast Cancer," EUROPEAN
JOURNAL OF CANCER Vol. 29A, No. 4 (1993), pgs. 492-497.
 David J. Hunter and Walter C. Willett, "Diet and Body Build:
Diet, Body Size, and Breast Cancer," EPIDEMIOLOGIC REVIEWS Vol.
15, No. 1 (1993), pgs. 110-132.
 See Monsanto's rBGH information at
http://www.monsanto.com/protiva/ where rBGH is referred to by its
trade name, Posilac, or by another name Monsanto invented for the
product, bovine somatotropin or BST.
 One of Ms. Shalala's milk ads was reprinted in the BRITISH
MEDICAL JOURNAL Vol. 316 (February 14, 1998), pg. 498. The
caption reads, "Donna Shalala, the United States secretary of
health and human services, has been criticised for her promotion
of milk. The milk industry is a powerful lobby in the US and
critics say the endorsement could be the first step on a slippery
 Samuel S. Epstein, "Unlabeled Milk from Cows Treated with
Biosynthetic Growth Hormones: A Case of Regulatory Abdication,"
INTERNATIONAL JOURNAL OF HEALTH SERVICES Vol. 26, No. 1 (1996),
Descriptor terms: milk; igf-1; rbgh; bovine growth hormone;
monsanto; carcinogens; breast cancer; prostate cancer; fda; donna
shalala; canada; europe; whole foods; fresh fields; ben and
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