Some Questions and Answers about BGH/BST
Prepared by the Biotechnology Education Program of the University of
Wisconsin-Extension and the UW Biotechnology Center.
What do the letters BGH and BST stand for?
BGH stands for bovine growth hormone; BST stands for bovine somatotropin.
These are two names for the same thing: a protein hormone produced in
pituitary gland of cattle.
What is BGH/BST?
BGH/BST is a protein made in the pituitary gland. Cattle make at least four
versions of BGH/BST, two that are 190 amino acids long and two that are 191
amino acids long. Of the two with 191 amino acids, one version has amino acid
leucine at position 127, and the other has valine at position at 127. (An
analogy: as written English words are composed of strings of 26 different
letters in various orders and lengths, proteins are composed of strings of 20
different amino acids in various orders and lengths. The two different
versions of BGH/BST that are 191 amino acids long are analogous to "theatre"
and theater"--two variations of spelling that function as the same word. And
as with "color" and "colour", two versions of a protein that differ in length
can be functionally equivalent.)
Why is BGH/BST used to treat dairy cows?
BGH/BST is given to dairy cows to increase their milk production.
BGH/BST is administered beginning after the ninth week of lactation
Researchers showed in the 1930's that cows injected with BGH/BST produce more
milk on average than untreated cows. BGH/BST can be purified from pituitary
glands of slaughtered cattle. Because the amount of BGH/BST that can be
purified from the pituitary gland is so small, this has never been a practical
What is synthetic BGH/BST?
About 10 years ago, several companies developed a way to produce BGH/BST in
large amounts. Using genetic engineering and recombinant DNA techniques,
researchers gave a copy of the bovine gene for BGH/BST to a laboratory
bacterium, which could then make BGH/BST. Bacteria reproduced from this
original bacterium are grown in large numbers in a fermentation tank. The
bacteria make the BGH/BST protein, which can be purified from the bacteria.
The BGH/BST purified from the bacteria can then be injected into cows to
increase their milk production. Monsanto's version of BGH/BST has one extra
amino acid at one end of the protein.
What does 'rBGH' mean?
To distinguish it from BGH/BST made by cattle, some people call BGH/BST made
by bacteria "rBGH" or "rBST" or "supplemental BST." The "r" stands for
"recombinant," a quick way of saying "made using recombinant DNA techniques."
What is sometribove? What is Posilac?
Sometribove is the generic name used by the FDA to refer to the commercial
variety of BGH/BST. Posilac is Monsanto's tradename under which it will sell
Who makes it?
Currently only Monsanto's version of BGH/BST is approved for sale.
Who approves the use of BGH/BST and other veterinary drugs?
The federal Food and Drug Administration approves new veterinary drugs before
they can be used and sold in the US.
What criteria are used in the approval process for new veterinary drugs?
The FDA uses 3 criteria:
- Is the drug safe to humans and animals and the environment?
- Is it effective?
- Is it made with consistent quality?
Why doesn't the FDA assess new veterinary drugs based on social or economic
The FDA is not empowered by Congress to set criteria other than safety,
effectiveness and quality.
How are safety, effectiveness and quality assessed? By whom?
Safety, effectiveness and quality are tested and verified by experiments
designed by the company submitting the drug for approval, in conjunction with
the FDA. The experiments are performed by the company, which must submit all
results, both favorable and unfavorable, to the FDA. The FDA reviews the
results. The FDA can then call for further rounds of experiments until all
concerns about safety, efficacy and quality are satisfactorily answered.
Why has BGH/BST been controversial?
A whole range of concerns about BGH/BST have been raised by a range of people:
dairy farmers, consumer advocates, and activists opposed to biotechnology.
These concerns have included:
Safety; effectiveness; impact of increased milk production on the
profitability of dairy farming and on the federal budget; consumer confidence
in the safety and wholesomeness of dairy products; and the regulation of new
Both milk and the family dairy farm have been powerful symbols of
wholesomeness ever since the dairy industry was established in Wisconsin
following the Civil War. Proponents and opponents of BGH/BST recognize the
controversy is in part symbolic of the conflict between competing visions of
agriculture. Work on BGH/BST began in the early 1980's, when the focus in
agricultural research was to increase production. With the farm crisis in the
mid 1980's, research increasingly emphasized profitability, including an
increased awareness of the value of on-farm inputs.
Is BGH/BST safe?
The federal Food and Drug Administration states that it is. Numerous medical
and scientific associations from the US and Europe have also concluded that
supplemental BGH/BST is safe.
On November 5, 1993, the federal Food and Drug Administration approved
Monsanto's version of BGH/BST as a veterinary drug. In announcing the
approval, FDA Commissioner Dr. David Kessler said "The public can be confident
that milk and meat from BST-treated cows is safe to consume."
BGH/BST "has been one of the most extensively studied animal drug products to
be reviewed by the agency," noted Kessler. "There is virtually no difference
in milk from treated and untreated cows. In fact, it's not possible using
current scientific techniques to tell them apart. We have looked carefully at
every single question raised, and we are confident this product is safe for
consumers, for cows and for the environment."
What evidence is there that BGH/BST is not a health concern?
Here are the reasons that BGH/BST is not a concern to human health, as
provided by Dr. Paul Bertics, who researches both human growth hormone and
bovine growth hormone at the University of Wisconsin-Madison Medical School.
(We follow Dr. Bertics' use of BST as the name of the hormone.)
- BST is broken down by the human digestive system when ingested. BST is a
protein hormone. Like most proteins, it's digested when ingested. BST is and
always has been present in all milk and beef, even in milk from cows not
treated with BST. So humans have been ingesting and digesting BST for as long
as they've been drinking milk and eating beef.
- BST has no known biological activity with people, because BST doesn't bind
to "receptors" in human beings. To be active, a hormone has to bind to a
receptor on a cell, and BST doesn't stick to a human cell's receptors.
Furthermore, to be active, a hormone must not only bind to a receptor, but
that binding must occur in a sufficient number of cells to trigger activity.
So the concentration of hormone is also important to get activity. BST is
present in milk in such low concentrations (even in milk from cows treated
with BST) that the hormone would not be active even if it could bind to human
cell receptors--which it doesn't.
- BST has no known activity even if injected into humans. BST purified from
pituitary glands was once tested in humans as a possible remedy for human
dwarfism. It was not effective.
What about the slightly increased incidence of mastitis the FDA observed in
cows treated with BGH/BST?
Mastitis is a common bacterial infection of the udder of cows. The incidence
of mastitis fluctuates with many factors, including the season, the stage of
lactation, and the health of the herd. Dairy farmers routinely use preventive
sanitation measures to reduce the incidence of mastitis, and may treat cases
of mastitis with antibiotics. Traces of antibiotics are not tolerated in
milk, so dairy farmers discard milk from treated cows for several days after
treatment. Furthermore, every load of milk is tested for penicillin-type
antibiotics. If a farmer's milk tests positive for antibiotics, that milk is
rejected by the dairy plant. The farmer is not paid for the milk, and may be
fined for further violations.
The FDA therefore concluded that there are adequate safeguards to prevent
unsafe levels of antibiotics from entering the milk supply.
Where can I get more information on safety and the FDA review process of
A copy of the federal government's report entitled "Use of Bovine
Somatotropin (BST) in the United States: Its Potential Effects" is available
at http://www.biotech.wisc.edu/Education/OMB/OMB.html. Chapter 2 of the report
details the review process and explains how the FDA has answered concerns
about BST and milk from cows treated with BST, including the concern about
mastitis, antibiotics and IGF-1. Other chapters cover potential impacts of
BST on the dairy industry, on consumption of dairy products, on the
environment, on US exports, and on biotechnology and related industries.
How does the public response to the introduction of BGH compare to
introduction of other dairy-related biotechnologies?
Compare the reaction of the public to BST to reactions to Chymax chymosin.
Chymosin is the active enzyme in rennet, used in making cheese. Chymax
chymosin, made by Pfizer Dairy Ingredients of Milwaukee, is the first product
of genetic engineering in the American food supply.
Both BGH/BST and Chymax chymosin are proteins. Both are made by cattle:
BGH/BST in the pituitary gland, chymosin in the stomach.
Both can also be made in the laboratory by purifying the protein from
genetically engineered bacteria that have been given a copy of the gene for
BGH/BST, or the gene for chymosin.
Both have been approved for use by the FDA--Chymax in 1990, and BGH/BST in
November 1993. Such chymosin is now used in the production of half of all
cheese made in the US.
But BGH/BST is a hormone, while chymosin is an enzyme. The word 'hormone'
causes greater concern among the public than does the word 'enzyme.' BGH/BST
is injected into cows to increase their milk production; Chymax chymosin is
added to milk to make cheese.
Some social scientists criticize BGH/BST because they predict the increased
milk production will drive down income to farmers; Chymax maintains the
supply of high-quality cheese with no predicted loss of income to farmers.
Animal rights activists have criticized BGH/BST as a threat to animal health;
Chymax chymosin has not been criticized because it is made in bacteria, and
therefore suckling calves need not be slaughtered to obtain rennet. Some
vegetarians and religious groups that will not eat cheese containing chymosin
from calf stomachs have found cheese made with Chymax chymosin acceptable to
their personal beliefs.
Finally, some opponents of BST question its safety and reject FDA assurances
that BST poses no threat to human health; no concerns about Chymax's safety
have been raised since its approval by the FDA.
So while BGH/BST and Chymax chymosin are both made using genetically
engineered bacteria, Chymax appears to have avoided controversy because it
seems to fit in the vision of agriculture embraced by many of the people who
Are there other examples of new food technologies that have been regulated
based on socio-economic criteria?
While the Federal Government does not assess new food technologies based on
their economic impacts, the policies of the state of Wisconsin on margarine
illustrate the state's historical concern for protecting its dairy farmers and
dairy industry. For example, Wisconsin had some form of regulation on
margarine--an outright ban, a ban on yellow margarine, or a special excise
tax--from 1881 to 1973. News stories from the mid 1960's during the movement
to legalize yellow margarine clearly emphasize that the issue was margarine's
impact on the health of the dairy industry, not on any impact of margarine on
the health of the consumer:
"(a legislator) also stressed the economic straits of Wisconsin farmers in
arguing against the bill, contending that it would be a serious wrong to
repeal the oleo ban and taxes when farmers are struggling to remain in
business. 'It (the anti-oleo law) is the last weapon the farmers have,' he
asserted." (Wisconsin State Journal, May 14, 1965)
How can school districts show support for local dairy farmers, and respond to
the concerns of parents for the safety of their children, without engendering
unfounded fears about the milk supply?
School board members have a special responsibility not only to their students
but to their community at large. The influence of school boards is reflected
in the significant press coverage of school districts who are considering a
policy regarding BST. School boards face much the same dilemma that one
reporter has outlined facing dairy farmers: "If they rant publicly against
BGH, they scare consumers away from their product." (Mike Flaherty, Wisconsin
State Journal, February 3, 1994)
Even the stance of districts who have no policy regarding BST can be
misinterpreted by journalists or the public. For example, although the
Madison Metropolitan School District has no BST policy, its milk supplier,
Borden, has announced a policy not to knowingly accept raw milk known to be
from cows treated with BST. But the story below appeared in papers in late
Headline: Bovine growth hormone controversy hits the classroom
Wire Service:UPn (UPI US & World)
Date:Fri, Jan 28, 1994
MADISON, Wis. (UPI) -- The controversy over bovine growth hormone is raging in
Wisconsin schools, the state Capitol and the barn.
The Madison School District, Wisconsin's second largest, said Friday it
will not to serve milk from cows injected with bovine growth hormone, a
chemical that spurs milk production, to its 23,000 students.
The district said its supplier, Borden's Dairy, has agreed not to handle
milk from cows treated with the hormone because so many people are opposed to
The Madison District is the largest in the state to oppose use of the
Note that the last sentence leaves the mistaken impression that the Madison
Municipal School District had issued a policy to not accept milk from cows
treated with BGH. In fact, the Madison School District had issued no policy
regarding BGH, according to Frank Kelly, director of food services for the
district. Kelly noted, however, that the school district's current milk
supplier, Borden Inc., had publicly stated that it will not knowingly accept
raw milk from cows treated with supplemental BGH. This was the policy of the
Borden company nationwide, and was not a result of any request of the Madison
What are the intended benefits of a policy favoring milk from cows not treated
A policy favoring milk from cows not treated with BST is one way that a school
district may choose, for socio-economic reasons, to oppose use of BGH/BST.
Such a policy would allow a district to show support for a particular vision
of agriculture. For example, a district might choose milk from untreated cows
because some studies predict that increased milk production resulting from
BGH/BST use will decrease milk prices and income to small dairy farmers.
Allowing consumers (including school districts) to choose milk from untreated
cows is one possible way to maintain the consumer's confidence in the dairy
supply, because it provides an alternative to those consumers who are
skeptical of the FDA review process. There is no evidence, however, for
claiming that milk from cows not treated with BGH/BST is safer or more
wholesome that milk from treated cows.
What are some of the possible drawbacks of a policy favoring milk from cows
not treated with BGH/BST?
People on both sides of the issue are concerned that all dairy farmers would
be hurt if consumer confidence in milk is eroded. While choosing milk from
cows not treated with BGH/BST allows a district to support a particular vision
of agriculture, such a policy could have the unintended impact of undermining
consumer confidence in the milk production system.
A school district or its milk supplier may consider a BST policy in response
to considerable public concern about safety. This raises the question: To
what extent should public policy of governments, or private purchasing
policies of grocers, be based on consumer misperceptions about safety and
wholesomeness of milk from treated cows? When should governments or their
suppliers take the more difficult position of clarifying the misconception?
Government agencies often must be concerned not just about what they imply in
their policies, but also about the inferences that the people they serve may
draw from policies. For example, unless a policy against BGH/BST explicitly
explains that socio-economic reasons, and not reasons of safety, are the basis
for the policy, a consumer might interpret the policy as an implication by the
school district that milk from untreated cows is safer or more wholesome.
A final concern is that there is no practical test to verify claims that milk
is from cows not treated with BGH/BST. Such claims would be certifiable only
by affidavit, but not verifiable by an independent, science-based test.
The distinction between certifiable and verifiable is fundamental to the
confidence consumers rightly have in the milk supply system. Despite its
well-groomed image, cow's milk is not necessarily a wholesome, safe food. The
milk production and processing system ensures that it is. That system is
built on empirically tested principles that either have withstood or have been
improved by a century of scientific scrutiny.
In this system, milk quality and safety are not just judged, they are tested.
They are tested by reliable, reproducible methods that measure factors known
to impact milk safety and quality: bacterial counts, somatic cell counts,
assays for antibiotics, tests of protein composition, milkfat tests. In
Wisconsin the name Babcock is still revered because it was his test--his
reliable, reproducible, verifiable test--that ensured an accurate measure of
milkfat--and discouraged unethical farmers from skimming the cream and adding
water to milk. The dairy industry was founded on the confidence this
verifiable test engendered. The industry continues to be borne on the
shoulders of other tests like it, that verify for the consumer that the claims
about milk are accurate.
The challenge is to find ways to accommodate those communities and consumers
who for socio-economic reasons prefer milk from cows not treated with BST,
while maintaining the confidence ensured by a system based on verifiable food