The Environmental Safety and Benefits of Growth Enhancing Pharmaceutical Technologies in Beef Production

By Alex Avery and Dennis Avery, Hudson Institute, Centre for Global Food Issues. Growth promoting hormones are a key component of North American beef production.
calendar icon 7 December 2007
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Executive Summary

Their use over the past 50+ years (since 1956) has proven beneficial not only to beef producers, but to consumers and the environment, who benefit from lower costs and more efficient use of scarce natural resources. In short, they allow us to achieve the old Yankee maxim of producing more from less.

Every food safety authority that has examined their use and the resulting beef products have found them to be both safe and wholesome, helping to produce an overall leaner beef supply with minimal residues of no practical health consequence. This assessment is shared not only by the Food and Drug Administration of the United States and Health Canada, but also by the Codex Alimentarius Committee of the World Trade Organization, the Food and Agriculture Organization of the United Nations, the World Health Organization, and even a conference established by the European Agriculture Commission.

There are six hormones approved for use in beef production in more than 30 countries. Three of these are natural, three synthetic. The three natural hormones (testosterone, estradiol, and progesterone) have been deemed completely safe for use in beef production, are a natural part of all mammalian physiology, and are released into the environment at levels well within natural ranges. Their use is uncontroversial.

The three synthetic growth enhancing hormones are melengestrol acetate (MGA), trenbolone acetate (TBA), and zeranol. These are more stable analogs of the three natural hormones. All three of these synthetic hormones enter the environment predominantly in the same way as the natural: via cattle waste. All three have undergone extensive eco-safety assessments, including worst-case estimates of their levels in cattle waste, runoff from cattle feedlots, and runoff from land on which the waste has been applied. In addition, there is a growing body of science regarding their fate in real-world environments.

But beyond this reassuring history, there are enormous environmental benefits to be gained from use of these products. Increased feed use efficiency, reduced land requirements, and reduced greenhouse gas emissions per pound of beef produced have all been conclusively demonstrated.

Comparing conventional beef production to an alternative grass-based beef production system using an economic/production model created by scientists at Iowa State University shows that growth promoting hormones and ionophores decrease the land required to produce a pound of beef by two thirds, with fully one fifth of this gain resulting from growth enhancing pharmaceuticals. Whereas grass-based organic beef requires more than 5 acre-days to produce a pound of beef, less than 1.7 acre days are needed in a grain-fed feedlot system using growth promotants.

Grain feeding combined with growth promotants also results in a nearly 40 percent reduction in greenhouse gases (GHGs) per pound of beef compared to grass feeding (excluding nitrous oxides), with growth promotants accounting for fully 25 percent of the emissions reductions.

In short, growth promoting implants safely and responsibly allow humanity to produce more beef from less feed, using less land, and creating less waste.

Human Safety of Growth Enhancing Pharmaceuticals

The first and foremost question about growth promoting hormones, of course, is whether their use is safe for consumers. In one word, Yes.

The first safety factor is the way they are given to cattle. Except for MGA (administered via feed), FDA regulations only allow growth promoting hormones to be administered through time-release implants placed under the skin of the animals’ ear. Each implant contains a specific, legally authorized dose of hormones. The implant ensures that the hormone is released into the animals’ bloodstream very slowly so that the concentration of the hormone in the animal remains relatively constant and low. Because the ear is discarded at harvest, the implant does not enter the food chain.

Second, there is no incentive for producers to “overdose” an animal on hormones. Each implant contains the optimal dose for maximum economic return, and administering simultaneous implants would have little impact on further weight gain. It would only waste money. This economic reality, coupled with the USDA’s annual monitoring program, safeguards the system and ensures that hormones are used properly and safely.

Third, the doses are low. The science indicates that use of supplemental hormones in cattle has only a miniscule impact on hormone levels in beef – well below the natural hormone levels in beef or the amounts produced naturally in our own bodies. According to the US Department of Agriculture (USDA), a person would need to eat over 13 pounds of beef from an implanted steer to equal the amount of estradiol naturally found in a single egg!1 One glass of milk contains about nine times as much estradiol as a half-pound of beef from an implanted steer. And remember, it’s not just animal products that contain hormonally active chemicals. A half-pound potato has 245 nanograms (ng, or 1 billionth of a gram) of estrogen equivalent, compared with 1.3 ng for a quarter pound of untreated beef and 1.9 ng for beef from an implanted steer.2

The whole world’s health experts say beef hormones are safe, not just those in the United States and Canada. So do the World Health Organization (WHO) and other European scientific bodies. The Joint Expert Committee on Food Additives of the World Health Organization and United Nations’ Food and Agriculture Organization (WHO/FAO Expert Committee) calculated that even assuming the highest residue levels found in beef, a person consuming one pound (~500 g) of beef from an implanted steer would ingest only 50 ng of additional estradiol compared to non-implanted beef.3 That’s less than one-thirtieth of the Acceptable Daily Intake (ADI) of estradiol for a 75 pound child established by the WHO/FAO Expert Committee.

And don’t forget that our own bodies produce these same hormones every day in amounts a hundred times or more higher than found in beef. A pound of beef raised using estradiol contains approximately 15,000 times less of this hormone than the amount produced daily by the average man and about 9 million times less than the amount produced by a pregnant woman.

The WHO/FAO Expert Committee extensively modeled theoretical consumer exposures to growth promoting beef hormone residues based on worst-case exposure estimates. They found, as did the FDA and USDA, no indication of appreciable risk. This issue is at the heart of the EU’s justifications for not allowing the sale of U.S. and Canadian beef to European consumers since 1989, a long-running and bitter trade dispute. The only way that the EU has been able to concoct enough theoretical risk to even remotely justify to the World Trade Organization (WTO) their ban on the sale of North American beef in Europe has been to give cattle three- and 10-fold doses of the synthetic hormones and then declare that U.S. regulators cannot guarantee that such misuse isn’t happening. (There is a complete lack of any evidence of such misuse in annual USDA monitoring). Even with these unlikely overdoses, hormone residues exceed the ADIs set by the WHO/FAO Expert Committee only in cow livers, not any other edible tissues. Despite this, the European Commission has maintained its prohibition on the sale of U.S. and Canadian beef based on a group of studies collectively called the “Copenhagen Assessment.”4

The British government’s Sub-Group of the Veterinary Products Committee estimated a “worst-case” exposure to residues of TBA (the synthetic hormone that mimics testosterone) based on the maximum amount the Sub-Group could extract from tissues following proper use of TBA. The resulting exposure estimate didn’t exceed half of the conservative ADI for children set by the WHO/FAO Expert Committee. The highest TBA residue they found in muscle and fat translates into a pound of hamburger containing only 2.4% of the WHO/FAO Expert Committee’s ADI for children. An extensive review of the world scientific literature on hormone metabolism and toxicity in humans can be obtained from both the Food Research Institute and the Sub-group of the Veterinary Products Committee.5

More than 30 other countries currently allow use of these hormones in beef production, and even European scientific groups have deemed hormones safe for use. Here is just a partial list of the high-powered expert groups that have declared the use of supplemental hormones in beef production safe:

  • U.S. Food and Drug Administration, which has approved nearly a dozen different formulations since the late 1980s;
  • European Economic Community Scientific Working Group on Anabolic Agents, chaired by Dr. G. E. Lamming in 1987;
  • International Codex Alimentarius Committee on Residues of Veterinary Drugs in Foods, in 1987; The Codex sets safety standards for international trade under the WTO.
  • European Agriculture Commission Scientific Conference on Growth Promotion in Meat Production, in 1995;
  • FAO/WHO Joint Expert Committee on Food Additives (JECFA), 1981, 1983, 1988, 1999;
  • Sub-Group of the Veterinary Products Committee of the British Ministry of Agriculture, Fisheries, and Food, 1999.


1 Foreign Agricultural Service, USDA 1999. A Primer on Beef Hormones. Available at:
2 Ibid.
3 Joint FAO/WHO Expert Committee on Food Additives. 1999. Summary and Conclusions of the Fifty-second Meeting.
4Acta Pathologica Microbiologica, Microbiologica et Immunologica Scandinavia, Supplementum no. 103, vol. 109, 2001.
5 Doyle ME. 2000. Human safety of hormone implants used to promote growth in cattle: Scientific literature review. Food Research Institute, University of Wisconsin. Available at: ; and, Review of the Scientific Committee on Veterinary Measures relating to Public Health, Report 30, April 1999.

Further Reading

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December 2007
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