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February 1994

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 source.

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 sometribove (BGH/BST).

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:

  1. Is the drug safe to humans and animals and the environment?
  2. Is it effective?
  3. Is it made with consistent quality?

Why doesn't the FDA assess new veterinary drugs based on social or economic impacts?

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 technologies.

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.)

  1. 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.

  2. 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.

  3. 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 BGH/BST?

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 oppose BGH/BST.

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 January:


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 its use.

The Madison District is the largest in the state to oppose use of the hormone.



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 school district.

What are the intended benefits of a policy favoring milk from cows not treated with BGH/BST?

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 label claims.


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