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rBGH in Milk

Ten Years After: rBGH and Cancer

By Rita Arditti. This article was previously published, without the footnotes, in the summer 2006 newsletter of the Cambridge, MA based Women's Community Cancer Project. 

In September 1995 the Women’s Community Cancer Project wrote and distributed a fact sheet on recombinant Bovine Growth Hormone (rBGH). We briefly outlined what it was, what it does to cows, what it may mean to consumers, who benefits from it, and who makes decisions about its use and labeling/not labeling issues. Ten years later, new research on rBGH shows that our original concerns were on target.  Just as we said then, we still need to insist that the “burden be put on industry and the FDA to convince us that genetically altered food is safe” and that products with rBGH be labeled.1  What have we learned in these ten years?

While Bovine Growth Hormone (BGH) is produced by the pituitary gland of the cow naturally and stimulates the production of milk, rBGH (recombinant Bovine Growth Hormone) is a genetically modified product created using the cow gene for BGH and DNA from a bacteria, Escherichia coli. rBGH was put on the market by Monsanto, the giant chemical company, in 1993, and traded under the name Posilac. Interestingly, Monsanto now uses the term “supplemental bST (somatotropin),” in their web page obscuring the fact that this is a genetically engineered hormone. Undoubtedly this is a smart marketing decision since it avoids the words “recombinant” and “hormone”-terms nowadays currently viewed with suspicion by many, particularly those of us living with cancer.

As we said in 1995, rBGH is injected into cows to increase milk production by 5-15%.  It is different from the cow’s own hormone, it has a single amino acid substitution of methionine for alanine, though Monsanto denies it.2  The warning label given to farmers lists 20 adverse side effects.  For instance, it causes a 79% increase in mastitis (a contagious bacterial infection leading to painful inflammation of the udder, which is treated by injecting antibiotics into the udder); it causes weight loss (the animals cannot eat enough to keep up with the increased milk production); it causes aberrations of the reproductive system (resulting in dead and grossly deformed calves); and it alters the quality of the milk.  Mastitis results in increased pus in milk, and residues of the antibiotics used to treat the mastitis may appear in the milk. 

What does this mean for us humans? Antibiotics residues may contribute to the development of antibiotic resistant bacteria in our bodies, increasing the difficulty of treating infection. Bacteria resistant to antibiotics is already a problem responsible for many deaths world wide. Allergies to antibiotics may also develop.

rBGH, (and also the natural form, BGH) might not pose health trouble to humans.  since they are quite different from human growth hormone (they differ from each other in amino acid sequence by approximately 33 percent) and are digested by enzymes in the digestive tract. However, rBGH increases milk production through the stimulation of another hormone, called insulin-like growth factor-1 (IGF-1). IGF-1 is a naturally occurring potent growth hormone and cell death inhibitor that has been implicated in breast, colon, and prostate cancer as well as abnormal cell growth.3  Its production in humans peaks at puberty and declines with age. It regulates cell growth, and cell division throughout life, particularly in infants and young children. IGF-1 is not destroyed by pasteurization and the IGF-1 from humans and from cows are chemically identical. This is important to remember because it means that when we drink milk from rBGH cows we are adding the IGF-1 from that milk to our own IGF-1 levels.

IGF-1 and Cancer Risk

In the last ten years, there has been a lot of research on various aspects of IGF-1.  In trying to sort some of it out I looked for studies that examined the connection between IGF-1 levels and cancer risk in humans. I found three articles, one on breast cancer, one on prostate cancer, and one on colorectal cancer and adenoma (benign growths) in women that deserve special attention because they are prospective studies. In cancer research prospective studies follow healthy participants for days, months, or years, and record what happens regarding the agent in question and the cancer under consideration. In that way it is not possible to attribute any relationship detected between the agent and cancer as due to the presence of the cancer itself. Prospective studies are considered more reliable than retrospective studies, where people’s medical records are analyzed or they are asked to recall what they did or what they ate in a specific time period. These studies were nested in the ongoing and large Nurses’ Health Study and Physicians’ Health Study started in the late seventies and early eighties and are a rich source of excellent information.

A 1998 study looked at IGF-1 levels in the blood of 397 women with a history of breast cancer, and 620 carefully matched controls.  The blood of the participants had been drawn in 1989-90, years before any of the women had been diagnosed with breast cancer.  The researchers did not find a relationship between IGF-1 levels in the blood and breast cancer risk in the group as a whole or among the post-menopausal women.  However, the risk of breast cancer was more than twice as high in pre-menopausal women and more than seven times as high in pre-menopausal women under 50 years of age with the highest level of IGF-1 compared with those with the lowest level. The authors concluded that, “with the exception of a strong family history of breast cancer… the relation between IGF-1 and risk of breast cancer may be greater than that of other established breast-cancer risk factors.”4

In the study on prostate cancer, also published in 1998, the researchers looked at the association between blood IGF-1 levels and prostate cancer risk in 152 men with prostate cancer and 152 controls who were matched for age and other factors.  As in the previous study on breast cancer risk, there was a strong positive association between IGF-1 levels and prostate cancer risk.  Men whose blood contained high levels of IGF-1 were 4.3 times more likely to have developed prostate cancer than men with the lowest IGF-1 levels. The effect was particularly pronounced in men over 60 years of age.  In this group men with the highest level of IGF-1 were eight times more likely to develop prostate cancer than men with low levels.  Again, here the elevated IGF-1 levels were present years before the diagnosis of prostate cancer was made. The blood samples were collected in 1982 and on average 7 years passed between plasma collection and the diagnosis of prostate cancer.5  I found this study particularly interesting not only because of the strong association of IGF-1 with prostate cancer risk but also because the currently widely used PSA (prostate specific antigen) test can only detect prostate cancer already present.6 

In the study on colorectal cancer and adenomas, the participants, 79 with colorectal cancer and 197 with adenoma (both early stage and intermediate/late stage) were matched with controls and followed for 6 years. The authors looked at the relationship between IGF-1 and IGF binding protein-3 (IGFBP-3), a substance that opposes the effect of IGF-1.  The results indicated that high levels of circulating IGF-1 and particularly low levels of IGFBP-3 were associated independently with an elevated risk of late colorectal adenoma and cancer.7

If these studies are confirmed, IGF-1 could become a marker for breast cancer risk in premenopausal women, for prostate cancer risk, and for colorectal cancer risk and could be used for preventive purposes.

But what makes the levels of IGF-1 vary among individuals? Could it be genetic traits or environmental factors such as nutritional patterns? We don’t really know the reasons for the variability of the levels of IGF-1 and up to this day there has not been a direct study to assess the effect that IGF-1 in milk from cows treated with rBGH  has on children or adults. So, when official pronouncements are made regarding the safety of rBGH and cancer we must point out to the lack of data on this fundamental question. And here, we need to bring the Precautionary Principle into the picture. 

The Precautionary Principle is a public health principle drafted in 1998 by a group of scientists, activists, government officials, and lawyers dedicated to preventing harm to the environment and to our health. It has been widely used in Europe and in international treaties that the U.S. has signed. It states, “When an activity raises the threat of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. In this context, the proponent of an activity, rather than the public, should bear the burden of proof.”  This is the old common sense approach “better safe than sorry,” that many of us follow intuitively.8  The Precautionary Principle stresses the right of the community to have complete and accurate information on health and environmental impacts of products.  Plus it shifts the burden of proof. Instead of our having to prove that an agent is harmful it is up to those who introduce products or services to provide evidence that they are harmless.  From a Precautionary Principle perspective it follows that we have to insist that Monsanto withdraw rBGH from the market until independent scientists unquestionably demonstrate its safety.

In the meantime, we must continue educating ourselves and others about the issue and encourage the consumption of organic dairy products. Canada, the European Union, Japan, New Zealand, and Australia have not approved the use of rBGH. Dairy products imported from those places are rBGH free. One caveat: the label “rBGH free,”does not necessarily mean “organic.” A truly organic product means that the organism producing the product has not been treated with genetically engineered drugs, is free of antibiotics, pesticides, and herbicides, has not been irradiated, and no synthetic fertilizers have been used in the process.  It should carry the round green and white sign from the Department of Agriculture or a sign /statement of an organic consumer association accredited under the national standards.9 

Monsanto’s Heavy Handed Tactics

Given the data furnished by the prospective studies on cancer risk and IGF-1 levels, should we worry about increasing our levels of IGF-1 when we drink milk from rBGH treated cows? No, says Monsanto, denying that such increase takes place:  “…IGF-1 concentration in milk of r-BST treated cows is unchanged,” and “…there is no evidence that hormonal content of milk from rBST treated cows is in any way different from cows not so treated.” Not so, says Peter Montague in Rachel’s Environment and Health News, pointing to scores of studies by independent scientists presenting a very different picture. In fact, Monsanto seems to be the only party that denies an increase in IGF-1 in the milk of treated cows. Even the FDA, which has been quite friendly to Monsanto’s procedures and practices, acknowledges that the level of IGF-1 is elevated in milk from treated cows.10

rBGH proponents, changing strategy, respond that even if the level of IGF-1 is elevated, it does not matter, because IGF-1, which is normally present in human saliva anyway, is broken down during digestion. But, it turns out, it does matter, because research has recently shown that, in the presence of casein, (a protein in cow’s milk) IGF-1 is protected from the digestive enzymes, remains intact in the gut, and is absorbed into the blood stream.11

According to Monsanto, of the nearly 9 million dairy cows in the U.S., approximately 35% are in herds injected with rBGH.  The drug is sold in all 50 states, and is the largest selling dairy animal pharmaceutical product in the U.S. A visit to the Monsanto web page is instructive. You can see how Monsanto promotes the drug, the obfuscating language it uses, and the views of the company on the health and safety of cows and humans exposed to it.

The controversy about rBGH has prompted consumer groups and small farmers to demand that rBGH milk be labeled so that the public would be informed of what it is buying. The saga around labeling deserves a book in itself.  Suffice it to say that when some dairy companies labeled their products “BGH-free” Monsanto asked the FDA to establish “rules” on labeling of products from cows not treated with rBGH. The FDA found the term “BGH-free” problematic because all milk contains some natural BGH and the term “rBGH-free” also misleading because the recombinant and natural cow hormones cannot be distinguished with the current technology used. As a result they came up with the recommendation that dairy companies who use voluntary labeling add an explanation of the context such as:  “No significant difference has been shown between milk derived from rBGH-treated and non-rBGH-treated cows.”12 This is what Ben and Jerry (and others) print in their labels if they announce that their products are rBGH-free.

Monsanto has sued companies that labeled their rBGH-free milk, and succeeded in preventing mandatory labeling for rBGH milk in spite of the fact that public opinion surveys consistently show support for labeling rBGH milk.  However, as several commentators have pointed out, the public is voting with its wallet: sales of rBGH-free milk went from $16 billion in 1996 to almost $31 billion in 1997, a rate higher than that of nearly any other food product.13

Monsanto has successfully pressured Fox Television to suspend a series on rBGH prepared by two award winning investigative reporters, Jane Akre and Steve Wilson. The reporters, who were fired for refusing to change their information on rBGH, took their case to court.  Akre was awarded $425,000 by a jury that agreed that Fox “acted intentionally and deliberately to falsify or distort the plaintiffs’news reporting on BGH.”14  However, the decision was reversed on appeal saying that Akre “failed to show the station violated any state laws” and the station used that ruling to ask for nearly $2-million in attorney’s fees and costs. In 2004, a judge ruled that the reporters were not liable for the lawyer’s fees but the station could appeal the ruling.  Actions like this have had a chilling effect on potential critics of Monsanto and may well have contributed to a general sense of hopelessness (“rBGH is a fait accompli,” an otherwise fiery activist told me recently sadly) about the possibility of having  the FDA change its policy on rBGH and be withdrawn from the market. 

Monsanto is also reported to have tried to bribe Canadian scientists into approving rBGH in Canada. Lending support to this accusation is the fact that in January 2005 Monsanto was fined $1.5 million by the U.S. Department of Justice for offering bribes to Indonesian officials to gain their approval for genetically modified cotton.16  And a recent agreement with the University of California obliges Monsanto to pay $100 million up front and at least $5 million a year for 17 years to settle a lawsuit accusing Monsanto of violating UC’s patent for rBGH.17 

Since people in the U.S. consume dairy products in such high volume-in 1992 an average of 564.6 pounds of cow’s milk and milk products such as ice cream, butter,  cheese, various dips, yogurt, etc., were consumed per person, the issue of IGF-1 and cancer promotion is shaping up as a truly major public health concern.18  Discarding the work of independent scientists The National Dairy Council, an industry lobbing group, continues relentlessly to promote milk consumption through ads, like the “3-a-Day of dairy” campaign and to support studies financed by the dairy industry.19

In terms of activism regarding rBGH, in 1999 the Center for Food Safety in Washington D.C., together with other groups, filed a legal petition with the FDA requesting that rBGH be removed from the market. The petition was denied the following year. Also, Jeffrey Smith, a well-known critic of genetically engineered foods and director of the Institute for Responsible Technology has started a GM-Free School Campaign, aiming to remove genetically modified foods, including rBGH milk, from school meals.20 Children are the largest consumers of milk, cheese, and dairy products and some Parent and Teacher Associations (PTAs) have passed rBGH-free resolutions. More than 100 school systems across the country buy only rBGH-free milk.21  And in Oregon, Physicians for Social Responsibility started a campaign whose goal is to “Discontinue the production of any dairy products within Oregon from cows treated with rBGH.”22  The campaign has done education presentations to groups, such as Rotary clubs, parents’ organizations, businesses and university and high school classes.  They have contacted institutional buyers of dairy products, such as restaurants, schools, grocery stores and catering companies, asking them to change to rBGH-free products and also contacted dairies directly and asked them to discontinue rBGH. And they have worked with Health Care Without Harm (HCWH), a national organization that encourages hospitals to reduce risk and enhance healthy practices, encouraging them to adopt a position statement opposing the use of rBGH.23 HCWH officially adopted a position opposing rBGH on June 2005.

In truth, the story of what has happened with rBGH during these ten years speaks of the incredible power of the Monsanto Corporation and the dairy lobby to intimidate, silence its critics, and continue its relentless pursuit of profit while putting our health and lives at risk.

Revitalizing the conversation on rBGH in the women’s cancer movement, mobilizing against its use, insisting on a Precautionary Principle perspective, and supporting those who have continued to raise the issue, is work we need to engage in for the sake of our health and that of our children.

For a list of companies nationwide that do not use rBGH, see rBGH-free dairy map.


1. Fact Sheet on recombinant Growth Bovine Hormone: Whose Risk? Whose Benefit? Who Decides? Women's Community Cancer Project, September 15, 1995.

2. Juskevich Judith C. and C. Greg Guyer.  “Bovine growth hormone: human food safety evaluation.” Science, Vol. 249, No. 4971 (August 24, 1990) pp 875-884.

3. H. Yu and Rohan T. “Role of the Insulin-Like Growth Factor Family in Cancer Development and Progression.” Journal of the National Cancer Institute. Sept 20, 2000, 92 (18): 1472-1489. S. Moschos and Mantzoros C. “The Role of the IGF System in Cancer: From Basic to Clinical Studies and Clinical Applications.”  Oncology, Nov 4, 2002, 63(4):317-332.

4. S. E. Hankinson, and others.  “Circulating concentrations of insulin-like growth factor 1 and risk of breast cancer,” The Lancet, vol 351, No. 9113, 1998, pp. 1393-1396.

5. June M.Chan and others. “Plasma insulin-like growth factor 1 and prostate cancer risk: a prospective study.” Science, Vol. 279, (January 23, 1998), No. 5350,  pp 563-566.  

6. Marcia Barinaga. “Study suggests new way to gauge prostate cancer risk”.  Science. Vol  279,  (January 23, 1998) No. 5350,  pp 475.

7. Edward Giovannucci et al.  “A Prospective Study of Plasma Insulin-like Growth Factor-1 and Binding Protein-3 and Risk of Colorectal Neoplasia in Women.” Cancer Epidemiology & Prevention.  April 2000, Vol. 9, 3345-349. 

8. For more on the Precautionary Principle see Carolyn Raffensperger and Joel Tickner (eds) Protecting Public Health and the Environment: Implementing the Precautionary Principle. 1999.  Island Press. Washington D.C. See also Rita Arditti, “Cosmetics, Parabens, and Breast Cancer” in Women’s Community Cancer Project Newsletter Summer 2004 and in the web: go to http://www.organicconsumers.org/, and write “parabens” in the Search Box. 

9. For more information on what “certified organic” means go to the web page of the US Department of Agriculture, www.usda.gov and type “organic” in the search box. Organic standards are currently being challenged by the Organic Trade Association, a food-industry group. See “What is Organic?  Powerful Players Want a Say ” by Melanie Warner.  New York Times, November 1, 2005. 

10. Quoted in Montague, Peter.  “Milk Safety, August 10, 1995.”  Bulletin #454 of Rachel’s Environment and Health News. 

11. C. Xian. “Degradation of IGF-1 in the adult rat gastrointestinal tract is limited by a specific antiserum or the dietary protein casein.”  Journal of Endocrinology, (August 1, 1995)  Vol 146, No. 2,  p 215. 

12. M. Nestle. Safe Food: Bacteria, biotechnology, and bioterrorism. 2003.  University of California Press, Berkeley, CA. p 203.

13. Ibid. 

14. J. Smith. “Whistleblowers, Threats, and Bribes.”  GeneWatch. Volume 18, Number 3, May/June 2005. 

15. Go to http://www.foxbghsuit.com for updates on the case. 

16. Ibid of note 14 and for more details go to http://news.bbc.co.uk and write Monsanto on the Search box.

17. Bob Egelko in San Francisco Chronicle, “UC-Monsanto suit over patent settled”.  February 28, 2006.

18. Quoted in Montague, Peter.  “Milk Safety, August 10, 1995.” Bulletin #454 of Rachel’s Environment and Health News. Go to www.rachel.org and write “rBGH” in the Search box.

19. “Milk’s good friends in high places.” Oligopoly Watch.  Sunday, September 12, 2004. 

20. J. M.Smith.  Seeds of deception: exposing industry and government  lies about the safety of the genetically engineered foods you’re eating.    Yes! Books.  September 2003.

21. See www.mindfully.org 

22. “rBGH-free Oregon Campaign Fact Sheet.”  Physicians For Social Responsibility (PSR), Oregon Chapter.   See their webpage: www.oregonpsr.org.

23. e-mail from Rick North, Project Director, Campaign for Safe Food, Oregon Physicians for Social Responsibility, 11/29/05.

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