rBST Growth Hormone and Cows

What is rBST?
Recombinant bovine somatotropin (rBST) is a is a genetically engineered drug, a synthetic version of the Bovine somatotropin (BST) hormone found in cattle. The hormone is used by many commercial dairies to increase milk production, typically by 5-15%. It's estimated that 15-20% of the cows in the United States are injected with Monsanto Co.'s  rBST hormone. 

BST is a natural hormone that can be found in the pituitary glands of all cows. Researchers who studied BST in cows found that cows with elevated levels of the hormone produced more milk. They also discovered that BST extracted from one cow and injected into another would result in higher levels of milk production for the BST treated cow.

Increased milk production per cow was attractive to some dairy farmers and as a result, synthesized BST was developed by recombining the DNA of bacteria (E coli) to force them to produce the hormone. This synthetic BST, or rBST, was then tested in dairy cattle. In the US, the United States Department of Agriculture (USDA) determined that because rBST is a species-specific growth hormone, milk from rBST treated cows is identical to that of cows not injected with the hormone. As a result, rBST treated milk was approved for commercial sale.

It's been marketed under a number of names, but most consumers know it as rBST or BST. The use of rBST has met with some controversy from a variety of fronts, including the animal rights movement and some commercial dairy farmers. As a result, dairies that produce milk products without the use of rBST have begun indicating this on their labels. Though rBST has been banned in several countries, the Environmental Protection Agency in the United States has determined it to be safe to consume.

rBST and the FDA
Before the 1993 approval of rbST, FDA determined that the recombinant, or genetically engineered form of bST, is virtually identical to a cow’s natural somatotropin, a hormone produced in the pituitary gland that stimulates the production of milk. During that rbST approval process, FDA concluded that "there is no significant difference between milk from treated and untreated cows."

For that reason, FDA also concluded it does not have the authority to require special labeling for milk and dairy products from rbST-treated cows, and that producers have no basis for claiming that milk from cows not treated with rbST is safer than milk from rbST-treated cows. 

Opponents dispute the approval of rBST
Whether rBST is healthy for human consumption is disputed and because of this rBST-free labeling was initiated.  According to opponents of the drug, effects of rBGH were never properly studied. They say the FDA relied solely on one study administered by Monsanto in which rBGH was tested for 90 days on 30 rats. The study was never published, and the FDA stated the results showed no significant problems. Monsanto claimed no rats absorbed rBST in their blood stream--hence there was no need for long term toxicity studies--but Canadian scientists who obtained the study discovered that 20% to 30% of the rats did absorb rBST with biggest concentrations in the prostate. There were also thyroid cysts.  Further studies conducted by Monsanto showed increased elevels of IGF-1 which has been linked to health concerns in humans.

Labeling
In the US, this labeling was permitted only after some battling with the United States Department of Agriculture. In the end, dairies in the United States are allowed to use the rBST-free label as long as a disclaimer is included suggesting that no harmful human health effects have been linked with the hormone. This claim is contested by some scientists, who argue that further research on the hormone is needed before such a claim can be made.

There is, however, some agreement within the commercial dairy industry on the use of rBST being harmful to the cows, forcing them to produce more milk than is normal and safe. They argue that the synthetic hormone can cause calcium deficiency and result in bone weakness in some cows.

The use of the rBST-free label has been bitterly fought by both pharmaceutical companies and mostly large-scale dairies, who would prefer that the label not be used at all. Some of them feel that the rBST-free label unnecessarily instills fear in consumers.  In fact, as recently as 2007 the FDA  rejected attempts from Monsanto to outlaw the "hormone-free" labeling of milk.

Many nations, including those in the European Union, Canada, Japan, New Zealand and Australia have banned the use of rBST in their cattle. In fact, it by 2003 it had been banned in every industrialized country in the world except for the U.S., Mexico, and Brazil.  Many advocates against the use of rBST point to this ban, suggesting that the United States should follow suit and disallow the use of the controversial hormone.

Avoiding rBST
By most accounts around 80% of cows are not treated with rBST. However, the milk from many different cows and dairies is often mixed together before being packaged. This means that unless otherwise labeled, most milk sold in the United States probably includes some from rBST-treated cows.
Public demand has forced some retailers to rethink where their dairy products come from.  In 2008 Wal-Mart Stores Inc. announced that all the store-brand milk sold in both Wal-Mart and Sam's Club stores in the United States would be produced by cows not treated with artificial growth hormones.

The company's move was seen as a victory by consumer advocates but was not expected to produce any major impact on the dairy industry.  It did however, show that the demand for healthy food had reached the mainstream, they said.

"It's reached the tipping point," said Ronnie Cummins, director of the Organic Consumers Association. "I think things are accelerating now and people are getting more health conscious and are getting more conscious about the connection between their personal health and the health of the environment."

Cummins continued, "When you look at all the surveys of consumer attitudes about food safety, hormones consistently rank way up there, along with pesticides."

What are the risks of rBST milk?
Studies have found that cows injected with rBST produce milk with abnormally high levels of insulin growth factor 1 (IGF-1). This is concerning because humans naturally have IGF-1, and increased levels in humans have been linked to higher risks of breast, colorectal and prostate cancer.  To date, there has been no direct connection made between elevated IGF-1 levels in milk and elevated IGF-1 levels or cancer in humans.  That has not stopped scientists from voicing their concern over the possibility of this relationship.  In animal studies, high IGF-1 levels have been connected with an increased risk of diabetes and early death.

In addition, the use of rBST has been linked to an increased incidence of infections in cows.  This has lead to increased use of antibiotics and an increased risk of antimicrobial residues in milk.   Many proponents of the hormone worry about the development of antibiotic resistant bacteria in response to the elevated use of antibiotics. 

Additional studies of animals exposed to rBST raise concerns about potential changes in milk protein that could lead to increased levels of allergies.


Should we drink milk from rBST treated cows?
While research has shown that milk from rBST treated cows has some elevated risks (IGF-1, allergies, cancer, antibiotic resistant bacteria) there has been no direct connection found between drinking it and known medical problems.  However, by ingesting GMOs you are acting as a test subject.  We do not know yet what the consequences will be for consuming foods that have been modified. 

Knowing that there are studies showing that rBST has been linked to possible health concerns, it is up to you use your own judgement.  Much of the developed world has already made the decision not to allow rBST to be used and many of our retailers are following suit.  Your buying power speaks loudly about your beliefs. 

I can tell you that we avoid any GMOs in our house and any dairy products that we purchase are rBST free.  Hopefully this post will help you to choose wisely.


Sources:
Holmes, Pollak, et. al. “Dietary Correlates of Plasma Insulin-like Growth Factor I and Insulin-like Growth Factor Binding Protein 3 Concentrations” Cancer Epidemiology, Biomarkers, and Prevention, Sept. 2002, p. 852-861

 Chan, Stampfer, et. al.“Plasma Insulin-like Growth Factor-I and Prostate Cancer Risk: A Prospective Study,” Science, January, 1998, p 563-566; Yu, Jin, et. al, Insulin-like Growth Factors and Breast Cancer Risk in Chinese Women, Cancer Epidemiology, Biomarkers, and Prevention, August 2002, p. 705-712.

“Report on Public Health Aspects of the Use of Bovine Somatotropin,” issued March 15-16, 1999, and available from The European Commission—Food Safety. (Antibiotic resistant bacteria)

“Report on Public Health Aspects of the Use of Bovine Somatotropin,” issued March 15-16, 1999, p.16, and available from The European Commission—Food Safety. (Increased Canncer Risk)

“Report on Public Health Aspects of the Use of Bovine Somatotropin,” issued March 15-16, 1999, p. 17, and available from The European Commission—Food Safety. (Allergies)