In 2011, more than 34 million cattle and 850,000 calves were slaughtered to provide beef for US consumers. 1 An estimated 80 percent of all US feedlot cattle are injected with hormones to make them grow faster, 2 and one government study from 2007 estimated that approximately 17 percent of all cows in the US were given the genetically engineered growth hormone rBGH to increase milk production. 4 This means higher profits for the beef and dairy industries - but at what cost? Although the USDA and FDA claim these hormones are safe, there is growing concern that hormone residues in meat and milk are harmful to human health, animal health, and the environment.
According to the European Union’s Scientific Committee on Veterinary Measures Relating to Public Health (SCVPH), the use of six natural and artificial growth hormones in beef production pose a potential risk to human health. 5 These six hormones include three that are naturally occurring – Oestradiol, Progesterone and Testosterone – and three that are synthetic – Zeranol, Trenbolone, and Melengestrol. When hormones are injected into cattle, some naturally occurring hormone levels increase 7 to 20 times. 6 The committee found that “no acceptable daily intake could be established for any of these hormones.” 7
The Committee also questioned whether hormone residues in the meat of growth enhanced animals can disrupt human hormone balance, causing developmental problems, interfering with the reproductive system, and even leading to the development of breast, prostate and colon cancers. 5
Children, pregnant women, and developing embryos are thought to be most susceptible to negative health effects from added hormones. For example, hormone residues in beef have been examined as a cause of lower sperm counts in boys. 8 The use of rBGH in dairy cows was linked in one study to increases in human twin and triplet births. 9
Growth-promoting hormones not only remain in the meat we consume, but also pass through the cattle to be excreted in manure. Scientists are increasingly concerned about the environmental impacts of this hormone residue as it leaks from manure into the environment, contaminating soil, and surface and groundwater. 9 Aquatic ecosystems are particularly vulnerable to hormone residues. Recent studies have demonstrated that exposure to hormones has a substantial effect on the gender and reproductive capacity of fish. 2
Despite international scientific concern, the United States, backed by the World Trade Organization, 10 continue to allow growth-promoting hormones in cattle. 11 The European Union does not allow the use of hormones in cattle production, has prohibited the import of hormone-treated beef since 1988, and has banned all imports of US beef treated with hormones. 12 The ban has been challenged by the US at the World Trade Organization and debate still rages between the US and the EU over its validity. 13
Industrial farms use a number of methods to increase milk production in dairy cows, including selective breeding, feeding grain-based diets (instead of grass), and exposing cows to longer periods of artificial light. One of the most common and controversial ways to force greater milk production is with injection of rBGH (recombinant bovine growth hormone), a genetically engineered artificial growth hormone.
Developed and manufactured under the brand name Posilac® by the Monsanto Corporation, rBGH was approved by the FDA in 1993, despite strong opposition from scientists, farmers, and consumers. In August 2008, Monsanto sold their Posilac division to Eli Lilly and Company for $300 million.
According to critics, rBGH has never been properly tested. The FDA relied solely on one study performed by Monsanto in which rBGH was tested for 90 days on 30 rats. The study was never published, and the FDA stated that the results showed no significant problems. A review of rBGH by Health Canada found the 90-day study showed a significant number of issues that should have triggered a full review by the FDA. 15
Visit our rBGH page to read more about the approval the hormone and its effects on human and animal health.
• According to Science News, 80 percent of all US feedlot cattle are injected with hormones. 2
• A study of cows treated with melengestrol acetate (one of the artificial growth hormones approved for use in the US) revealed that residues of this hormone were traceable in soil up to 195 days after being administered to the animals. 16
• While the average dairy cow produced almost 5,300 pounds of milk a year in 1950, 17 today, the average is more than 20,000 pounds. 18
• Many independent ranchers and farmers don’t use artificial hormones on their animals. By purchasing your milk and meat from local, sustainable farms, you are supporting a system that ensures the health and welfare of the farm animals, and protects you and your family from hormone-related health risks.
• Choose hormone-free beef and rBGH-free dairy products at the supermarket. Foods that carry the “USDA-certified organic” label cannot come from animals given any artificial hormones. When purchasing sustainably raised foods without the "organic" label, be sure to check with the farmer to ensure no hormones were administered.