Bovine somatotropin

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Bovine somatotropin (abbreviated bST and BST) is a protein hormone produced in the pituitary glands of cattle. It is also called bovine growth hormone, or BGH.

BST can be produced synthetically, using recombinant DNA technology. The resulting product is called recombinant bovine somatotropin (rBST), recombinant bovine growth hormone (rBGH), or artificial growth hormone. It is administered to the cow by injection and used to increase milk production. Currently Monsanto is the only company that markets recombinant bovine somatotropin, under the trade name Posilac.

Contents 1 Physiology 2 Posilac 2.1 Use of Posilac 3 Controversy 3.1 Animal health 3.2 Human health 3.3 IGF-1 3.4 Lawsuit against Fox television 4 Regulation 4.1 Regulation inside the United States 4.2 Enforcement 4.3 Labeling in Pennsylvania 4.4 Response from commercial groups 4.5 Regulation outside the United States 5 See also 6 Footnotes 7 External links

[edit] Physiology

A cow's pituitary gland naturally secretes BST into the bloodstream. Some of it latches on to receptors in the liver, which then produce Insulin-like Growth Factor 1 (IGF-1) which enters the blood as well. These two hormones have many different effects in the body, including increasing the breakdown of fat for energy and helping to prevent mammary cell death.^[1] The combination of increased energy from increased fat breakdown and decrease in mammary cell death is thought to be the cause of higher milk production.

Studies have shown that there is no increase in the amount of BST secreted in the milk when a cow is injected with supplemental rBST. However, the studies have been conflicting about whether or not IGF-1 and IGF-2 output increases. The amount of IGF-1 and IGF-2 secreted varies greatly by stage of lactation and whether or not an animal is pregnant; most studies have shown that while these hormones are slightly elevated overall it falls within the normal range of variation.^[2]

[edit] Posilac

In 1937, the administration of BST was shown to increase the milk yield in lactating cows by preventing mammary cell death in dairy cattle. Until the 1980s, there was very limited use of the compound in agriculture as the sole source of the hormone was from bovine cadavers. During this time, the knowledge of the structure and function of the hormone increased.^[3] Monsanto developed a recombinant version of BST, brand named Posilac, in 1994,^[4] which is produced through a genetically engineered E. coli. A gene that codes for the sequence of amino acids that makes up BST is inserted into the DNA of the E. coli bacterium. The bacteria are then broken up and separated from the rBST and is purified to produce the injectable hormone. Growth hormones associated with injections given to dairy cows to increase milk production are known under an assortment of terms, but these terms generally refer to the Monsanto product. The Monsanto fact sheet on its proprietary product states that when injected into dairy cattle, the product can increase milk production by an average of more than 10% over the span of 300 days.^[5]

[edit] Use of Posilac

Posilac prevents mammary cell death in dairy cattle. As such, it does not increase milk production on a day-to-day basis, but rather prevents milk production from decreasing over the long term, thus resulting in higher overall production during a lactation. Because a cow's milk production increases and decreases during her lactation based upon a known curve, application of Posilac can be carefully planned to maximize results.

An average dairy cow begins her lactation with a moderate daily level of milk production. This daily output increases until, at about 70 days into the lactation, production peaks. From that time until the cow is dry, production slowly decreases. This increase and decrease in production is partially caused by the count of milk-producing cells in the udder. Cell counts begin at a moderate number, increase during the first part of the lactation, then decrease and the lactation proceeds. Once lost, these cells generally do not regrow until the next lactation.

To apply Posilac for maximum effect, farmers are recommended to make the first Posilac application about 50 days into the cow's lactation, just before she peaks. The Posilac then sustains already-present mammary cells, limiting the rate of production decrease after production peaks. After the peak, production declines with or without application of Posilac, but declines more slowly with Posilac than without. This decrease in the rate of production decline permits dairy cows to produce more milk over the span of a lactation - at its best, this will be seen by seven to eight more pounds of milk being produced per day than would be produced without the benefit of Posilac.

[edit] Controversy

Use of rBST is regarded as controversial due to its effects on animal and human health and the perceived encroachment on small farmers by large corporations.

[edit] Animal health

Two meta-analyses have been published on rBGH's effects on bovine health.^[6][7] Findings indicated an average increase in milk output ranging from 11%-16%, a nearly 25% increase in the risk of clinical mastitis, a 40% reduction in fertility and 55% increased risk of developing clinical signs of lameness. The same study reported a decrease in body condition score but speculated that it may have been attributable to, differences in feeding of treated (underfed) versus untreated (overfed) cows.

A European Union scientific commission was asked to report on the incidence of mastitis and other disorders in dairy cows and on other aspects of the welfare of dairy cows.^[8] The commission's statement, subsequently adopted by the European Union, stated that the use of rBST substantially increased health problems with cows, including foot problems, mastitis and injection site reactions, impinged on the welfare of the animals and caused reproductive disorders. The report concluded that on the basis of the health and welfare of the animals, rBST should not be used. Health Canada prohibited the sale of rBST in 1999; the recommendations of external committees were that despite not finding a significant health risk to humans, the drug presented a threat to animal health and for this reason could not be sold in Canada.^[9]

[edit] Human health

Concern has been expressed by various groups about the levels of two substances in milk consumed by humans - BST itself, and insulin-like growth factor 1 (IGF-1), which is increased by rBST injections. Monsanto has stated that both of these compounds are harmless given the levels found in milk and the effects of pasteurization.^[10] According to the FDA, no significant difference has been shown between milk derived from rbST treated and non rbST treated cows.^[11]

[edit] IGF-1

Monsanto's studies show use of rBST in cows increases bovine insulin-like growth factor 1 in milk,^[12] a structure that is identical in cows and humans.^[13] Monsanto states that there is no danger of consuming milk or meat from cows treated by BST, and that the only difference between milk from supplemented cattle and unsupplemented cattle is the amount of IGF-1, though even these elevated levels are similar to levels found in milk from untreated cows. Further, the amount of IGF-1 consumed in milk is negligible compared to the amount produced in the body.^[10]

Opponents counter that rBGH does cause differences aside from the higher rate of IGF-1, most importantly that BST and rBST have a different chain of amino acids which can alter how a protein interacts with the immune system.^[12] A Health Canada report on rBST found no "biologically plausible" safety concerns for humans about the sale of rBST in Canada barring immune hypersensitivity that may occur in some individuals.^[14] Studies have found links between serum levels of IGF-1 some medical conditions, including breast, prostate and colorectal cancer,^[15] a higher risk of diabetes and a shorter lifespan in animal studies,^[16] and has been linked to an increased number of twins born to humans.^[17]

[edit] Lawsuit against Fox television

Fox television affiliate WTVT/Fox13 in Tampa, Florida was sued by Steve Wilson and Jane Akre, two former anchors over the issue of reporting the harmful effects of BGH on humans.^[18] The journalists--originally, with station approval--wrote a story in 1996 that stated the human health risks of rBGH. However, the station rejected it and insisted they report a different story on rBGH with statistics supplied by Monsanto. They rewrote the story over 80 times but were eventually fired by Fox.

After a five-week trial which ended August 18, 2000, a Florida state court jury unanimously determined that Fox "acted intentionally and deliberately to falsify or distort the plaintiffs' news reporting on BGH." In that decision, the jury also found that Akre's threat to blow the whistle on Fox's misconduct to the Federal Communications Commission (FCC) was the sole reason for the termination and awarded $425,000 in damages.^[19]

Fox appealed and prevailed February 14, 2003, when an appeals court issued a ruling reversing the jury, accepting a defense argument that had been rejected by three other judges on at least six separate occasions. The appeals court's decision on the verdict was on the basis that FCC policies on news agencies reporting the truth did not legally require the station to report the truth in a news story, as FCC policies are not law. The story that was subsequently reported on BGH contained no statistics that may have indicated a human health risk, as these statistics (the ones found by Akre and Wilson and mentioned in their original story) were ignored.

In 2004, Fox filed a $1.7 million counter-suit against Akre and Wilson for trial fees and costs.^{[citation needed]}

This story is featured at length in the documentaries The Corporation and Outfoxed.

[edit] Regulation

Use of the recombinant supplement has been controversial. While it is used in the United States (though not without reaction), it is banned in Canada, parts of the European Union, Australia and New Zealand.

[edit] Regulation inside the United States

In 1993, the product was approved for use in the U.S. by the FDA, and its use began in 1994. The product is now sold in 49 states, the exception being Michigan. According to Monsanto, approximately one third of dairy cattle in the U.S. are injected with Posilac; approximately 8,000 dairy producers use the product. It is now the top selling dairy cattle pharmaceutical product in the U.S.^[4] Several scientists involved in the review of Posilac were dismissed or pressured to leave the FDA expressing concerns over the process used to approve the drug for use in dairy cows and others expressed their concerns anonymously for fear of retribution.^[20]

[edit] Enforcement

The FDA does not require special labels for products produced from cows given rbST but has charged several dairies with "misbranding" their milk as having no hormones, because all milk contains hormones and can not be produced in such a way that it would not contain any hormones.^[21] Monsanto sued an independent dairy over their use of a label which pledged to not use artificial growth hormones.^[22] The dairy stated that their disagreement was not over the scientific evidence for the safety of Posilac (Monsanto's complaint about the label), but rather they were more interested in marketing milk than a drug. The suit was settled when the dairy agreed to add a qualifying statement to their previous label regarding the lack of difference between milk produced by Posilac-dosed cows and cows that had not received the drug.^[22]

Demand for milk without using synthetic hormones has increased 500% in the US since Monsanto introduced their rbST product; organic milk is the fastest growing sector of the organic food market.^[23]

[edit] Labeling in Pennsylvania

In 2007, the U.S. state of Pennsylvania, under heavy pressure from Monsanto, adopted a regulation that would have banned the practice of labeling milk as derived from cows not treated with rBST. This prohibition was to go into effect January 1, 2008, but was delayed to February 1, 2008 in order to give interested parties more time to submit comments to the state's Department of Agriculture. This policy, had it been implemented, would have made it impossible for consumers to distinguish between milk from cows treated with rBST and milk from cows not treated with rBST. For this reason, the ban was opposed by several consumer groups, and the state reversed its position before the ban could take effect and adopted the Federal Trade Commission's recommended labeling guidelines instead. ^[24]

[edit] Response from commercial groups

Several milk purchasers and resellers have elected not to purchase milk produced with rBGH. The nation's largest dairy processor, Dean Foods, no longer sells milk from rBGH-treated cows, and the top 3 grocery retailers in the nation, Wal-Mart, Kroger, and Costco have pledged not to sell such milk in their stores. Specific examples include:

• Winder Farms, a home delivery dairy and grocer in Utah and Nevada, sells rBGH free milk.
• Safeway in the northwestern United States stopped buying from dairy farmers that use rBGH in January 2007.^[25] The two Safeway plants produce milk for all of Oregon, Southwest Washington, and parts of northern California. Safeway's plant in San Leandro, CA had already been rBGH-free for two years.^[26]
• Chipotle Mexican Grill has also announced it will serve rBGH-free sour cream at its restaurants.^[26]
• Kroger has banned rBGH-derived milk from all its stores (including its subsidiaries such as Ralphs) as of February 2008,^[27]
• Publix announced it has been rBST-free since May, 2007.^[28]
• Braum's has also issued a press release stating its milk is rBST-free.^[29]
• Starbucks Company has as of January 2008 made all dairy in beverages rBGH free.^[30]
• Wal-Mart and Sam's Club stores featured hormone-free "Great Value" brand milk, but did not label it as such in 2008.^[31]

Monsanto has responded to this trend by lobbying state governments to ban the practice of distinguishing between milk from farms pledged not to use rBST and those that do. According to the New York Times [1], a pro-rBST advocacy group called Afact has been most active in these lobbying efforts. Afact is made up of both producer members and allied industries and is closely affiliated with Monsanto itself; the group's acronym stands for American Farmers for the Advancement and Conservation of Technology. Though rbST is one of Afact's main concerns, their mission is to prevent "marketers from convincing some consumers to doubt the credibility and safety assurances from of even the most respected food safety agencies and scientific oversight organizations."^[32]

Thus far, a large-scale negative consumer response to Afact's legislative and regulatory efforts has kept state regulators from pushing through strictures that would ban hormone-free milk labels, though several politicians have tried, including Pennsylvania's (see the Pennsylvania section above) agriculture secretary Dick Wolff, who tried to ban rBST-free milk on the grounds that it would alleviate consumer confusion. Proposed labeling changes have been floated by Afact lobbyists in New Jersey, Ohio, Indiana, Kansas, Utah, Missouri and Vermont. So far, however, this effort has been unsuccessful.

[edit] Regulation outside the United States

In Japan, Australia, New Zealand, and Canada, rbST is not approved for use.^[33]

The European Union declared the use of rbST as safe in 1990, but in 1993, a moratorium was placed on its sale by all 27 member nations.

Canada's health board, Health Canada, refused to approve rBGH for use on Canadian dairies, citing concerns over animal health. ^[34] The study they had commissioned, however, found "no biologically plausible reason for concern about human safety if rbST were to be approved for sale in Canada. The only exception to this statement is the occurrence of an antibody reaction (possible hypersensitivity) in a subchronic (90-day) study of rbST oral toxicity in rats that resulted in one test animal developing an antibody response at low dose (0.1 mg/kg/day) after 14 weeks."^[35]

[edit] See also

• Genetic engineering
• Growth hormone treatment
• Recombinant DNA
• List of recombinant proteins

[edit] Footnotes

[edit] External links

• Public Health on "Public Health Aspects of the Use of Bovine Somatotrophin"
• Labeling Issues, Revolving Doors, rBGH, Bribery and Monsanto