OLR Research Report

February 7, 2007




By: Joseph Holstead, Associate Analyst

You asked (1) for information about the recombinant bovine growth hormone, Posilac; (2) for the reasoning behind European bans of the product; (3) if 95% of U.S. dairy farmers boycotted the product after its approval; and (4) what the federal Food and Drug Administration (FDA) currently says about it.


Bovine somatotropin (BST) is a natural protein hormone that regulates milk production in cows. The hormone can be produced using recombinant DNA technology. Recombinant bovine somatotropin (rBST), also known by its Monsanto trade name Posilac, is a biosynthetic version of the naturally occurring pituitary hormone in cows. When injected in cows, rBST can increase milk production by 10% to 20%.

The FDA approved rBST on November 5, 1993, but use was delayed for 90 days pursuant to a provision in the Omnibus Budget and Reconciliation Act passed by Congress in August 1993. Sales of Posilac were allowed to begin on February 3, 1994 following completion of a report by the executive branch reviewing available evidence on the impact of rBST use.

European bans of the product were based on fear of potential health risks rBST posed to humans, including cancer, and animals, according to contemporary reports. However, Monsanto argues that the ban was based on economics and politics. We were unable to find reliable estimates on the number of U.S. farmers who may have boycotted the product. However, the FDA's March 14, l995, “BST Update: First Year Experience Report” stated of Posilac, “more than 14 million doses have been sold for use on 13,000 dairy farms, representing about 11% of dairy farmers in the United States, according to the company [Monsanto].” From this March 1995 estimate, we can presume that, at the time, 89% of dairy farmers were not using the product.

The FDA has not changed its 1993 position that rBST is not harmful to humans. For example, FDA documents from 1995, 1999, and 2003 have continued to affirm its initial position that the product is safe for human consumption.

Concerns about rBST have not ceased, however, as evidenced by food store chain Safeway and coffee chain Starbucks announcing in late January 2007 that they would no longer sell or serve milk from cows treated with rBST, according to a January 26, 2007 Capital Press article. Capital Press is an Oregon based, independent farm and ranch newspaper serving California, Idaho, Oregon, Washington and other western states, according to its website (


In 1993, controversy surrounded rBST's (Posilac's) approval with some people and organizations in the U.S. and other countries expressing concern about human and bovine health effects. For humans, concerns included risks due to potential increases in milk antibiotic residues resulting from alleged higher levels of mastitis in cows administered rBST and increases in IGF-1 (Insulin-like growth factor) levels, which some feared could lead to increased cases of breast cancer, and other problems in people. Among bovine health concerns that were raised were: lowered resistance to infectious diseases, increased stress, increased mastitis, and lowered fertility. The European Community and eventually, Canada, banned the product and products from cows treated with it based on health concerns for both humans and animals. However, FDA, citing its research and various studies since then, has stood by its position.

European Ban

According to a September 21, 1999 article entitled, “European ban on bovine growth hormones should continue: expert,” from the Canadian Medical Association Journal, Europe banned use of the hormones over fears that they pose a health risk; it subsequently banned imports of hormone-treated Canadian and US meat. In 1997, the World Trade Organization (WTO) ruled against the ban, and Europe paid sanctions and fines to keep North American meat out, according to the article. In 1998, the WTO gave Europe 15 months to develop data about its concerns and a full-scale trade war threatened to break out over the issue, with the US imposing huge retaliatory tariffs on many products from Europe, the article went on to say. The entire article is attached, or visit the website:

Shortly thereafter, the European Union, at its December 16 and 17, 1999 Council of Ministers meeting in Finland, prohibited the use of rBST in the European Union (although this further ban was based on animal health concerns, as the EUs scientific bodies found no negative effects on humans). The ban took effect on January 1, 2000, according to an article entitled, “The Regulation Of rBST: The European Case,” in AgBioForum, The Journal of Agrobiotechnology Management and Technology, Volume 3 /Number 2 & 3 (2000). We have attached a copy of the article, or visit:

On the other hand, Monsanto's website currently states:

[t]he European Community placed a ban on the use of rBST on economic and political grounds. This had nothing to do with rBST safety. In January 1993, the Committee for Veterinary Medicinal Products of the European Union reaffirmed that food products from cows treated with rBST are safe for human consumption, and they recommended the approval of two rBST products based upon their review of all aspects of safety and effectiveness.

This and other information is available at Monsanto's 'questions and answers' about rBST webpage:


In 1999, Canadian health officials banned rBST, because an independent committee of scientists decided that the risks posed to cows were too great (although, a separate committee found the drug posed no direct risks to human health), according to a January 16, 1999 Washington Post article, “Canada Rejects Use of Cattle Hormone.”

Again, others argue that Canada's ban was for economic reasons: “[t]here is no scientifically validated link between rBST and any human or animal disease. Canada and the EU banned rBST for political reasons. Both rely upon government-mandated 'quota systems' for milk production intended to keep supply in balance with demand. The increased milk production that is the result of rBST use would disrupt these production systems, at high cost to taxpayers,” according to Blair Thompson, Consumer Communications Manager, Washington Dairy Products Commission (which was created by the Washington legislature in 1939 to promote dairy products in the state and educate people about the dairy industry), in the November/December issue of Washington Free Press, an independent news journal run by volunteers, according to its website,

U.S. Labeling

On September 12, 2003, FDA issued warning letters to four manufacturers of whole milk, reduced fat milk, and ice cream, informing them that their products were misbranded because the labels contained the false statements, “No Hormones” or “Hormone Free.” The letters explained that “No Hormones” and “Hormone Free” are false claims because all milk contains naturally occurring hormones, and milk can not be processed in a manner that renders it free of hormones. FDA noted that food manufacturers who do not use milk from cows treated with rBST may inform consumers of this fact on their product labels or labeling, provided that the statements are truthful and not misleading, according to a September 12, 2003 FDA press release.

The press release stated that FDA determined that the recombinant, or genetically engineered form of BST is virtually identical to a cow's natural somatotropin, and concluded that there is no significant difference between milk from treated and untreated cows. Thus, 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, according to the press release, which is available at FDA's website:

Consistent FDA Position

After the controversy surrounding Posilac's approval and market debut, and since, as discussed above, FDA consistently found its initial findings to have been accurate. For example, it did so in response to a review of the 1999 European Commission Directorate General XXIV “Report on Public Health Aspects of the Use of Bovine Somatotropin—15 -16 March 1999,” which concluded FDA's assessment methods of Posilac's safety concerning IGF-1 were flawed. FDA disagreed and stated in an April 13, 1999, FDA Center for Veterinary Medicine (CVM) update, “[n]umerous independent researchers and scientific committees have examined the data on the dietary exposure of IGF-I and related proteins present in milk. The data provide ample evidence that the amount of IGF-I and truncated forms excreted in milk following the administration of rBST to dairy cows is safe for all consumers, including infants. Additional exposure data are not necessary.”

The update went on to say, FDA's determination that food products from cows treated with rBST are safe for consumers has been supported by numerous scientific and regulatory bodies including the Joint Food and Agricultural Organization/World Health Organization Expert Committee on Food Additives (JECFA), an international panel of experts in the field of toxicology and chemistry of animal drug residues that meets to evaluate the safety of animal drugs…In 1998, JECFA reaffirmed the safety of milk and meat from rBST-treated cows. The entire update is available at:

In 1999, FDA also countered Canadian reports (which contributed to that country's ban) that were critical of FDA research. Specifically, an April 1998 Canadian governmental report stated FDA had “misreported” the absorption of oral rBST based on serum antibody levels in the rats, and toxicity to the rats. Following this scrutiny by the Canadian government in its review of rBST, which caused controversy there, several groups and individuals in the U.S. again raised questions about the safety of milk from rBST-treated cows. According to a February 5, 1999 CVM update, CVM in response prepared a “Report on the Food and Drug Administration's Review of the Safety of Recombinant Bovine Somatotropin,” which affirmed the original review of the 90-day rat oral toxicity study, which concluded that there were no biologically significant observed effects in either the thyroid or the prostate gland, according to the CVM update.

We did not find any reports indicating FDA's position is any different in 2007. More information about concerns shortly after rBST's approval in 1993 is available in the attached OLR Report, 1994-R-0111, or see: