The case of animal growth hormones

Regulating food safety: the case of animal growth hormones

Fred Kuchler

Regulating Food Safety: The Case of Animal Growth Hormones

The potential introduction of growth hormones manufactured using recombinant DNA (rDNA) techniques for use in milk and meat production raises an important question about food safety: Will these hormones adulterate otherwise safe and nutritious products? Government regulators, the scientific community, and consumers will have to decide.

Developments in the application of rDNA techniques promise change in agricultural production practices. The first likely commercial applications of rDNA technology will be in the manufacture of somatotropins, growth hormones that promote greater milk production in dairy cows and allow livestock to grow faster on less feed. Production of these hormones can now be carried out on a large scale. Bovine Somatotropin (bST), the growth hormone for dairy cattle, is under review by the Food and Drug Administration (FDA). At least five corporations have expressed interest in manufacturing bST. Porcine Somatotropin (pST), also under regulatory review, has the potential to greatly increase pork production.

For these new products to be commercial successes, they must be considered safe. However, the definition of food safety has varied as the perceptions held by producers, consumers, regulatory agencies, and other interested parties have changed over time. Thus, the standards used to regulate food safety have often depended on opinion as much as scientific fact.

For example, in the early 1900’s, controversy erupted over pasteurizing milk. The scientific community argued in favor of the technique, but the group of dairy owners economically disadvantaged by the new technology delayed its use by trying to convince consumers that pasteurization would cause a health risk. During the 1970’s, livestock producers continued to use diethylstilbestrol (DES) to boost beef production, although the compound had been linked to cancer in humans–illustrating the difficulties in changing established production practices. In 1982, the pesticide heptachlor was found in Hawaiian milk. Milk consumption was down for months after public health officials claimed milk was free of contaminants.

These cases demonstrate the enduring and political nature of food safety and technological development controversies. The DES and heptachlor cases have shaped the current legal and regulatory environment. They show the extent to which perceptions and the changing definition of product safety can influence product acceptance and ultimately the form and pace of technological change.

The current debate on the safety of livestock growth hormones is interesting for at least two reasons. First, bST and pST are the first bioengineered compounds submitted for regulatory review that could substantially affect dairy and livestock production. The applications will set precedents for the amount of product information Federal agencies require, and how much time they use in determining the safety of new products. Will the manufacturing process itself–the rDNA technology–be a factor in the decision? Or will the hormones be treated like other animal drugs and judged on conventional criteria–are they carcinogenic, acutely toxic, or disease-causing?

If the rDNA technology becomes important to regulatory decisions, the firms making the applications would have to supply more information and the review would likely take longer, increasing the time between development and commercial sale. These additional demands could reduce the incentive for businesses to research and develop new products for agricultural production.

Second, the unique regulatory treatment that animal drugs have received will affect Government review of somatotropins. The special treatment results from a 1968 amendment to the Delaney Clause of the Federal Food, Drug, and Cosmetic Act, known as the DES exception. This single amendment allowed DES to be used in animal production during the 1970’s, even though the substance had been shown to cause cancer in laboratory animals.

The DES exception established a “no residue” criteria for use of animal drugs. These drugs are not added directly to consumable food products, as food additives are, but are used to promote animal growth. Therefore, the question regulators have to ask about animal drugs is whether residues remain in the meat products that consumers purchase. That a substance was known to be hazardous under certain circumstances–like DES–was not, by itself, sufficient reason to preclude use.

Further, animal drug regulations employ “de minimus” risk standards. This means that drug residues cannot detectably increase the risk of cancer in humans, which is interpreted to mean no more than one added case of cancer per million people over a lifetime of exposures. The de minimus risk standards do not permit risk-benefit comparisons, as the Environmental Protection Agency may do with pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act. But the standards do permit more flexibility than the Delaney Clause, which states that any evidence, no matter how minor, that a substance is carcinogenic is sufficient to preclude its use. (See The Economics of Food Safety for more information on these different risk standards.)

Somatotropin is different from the hormones currently used in livestock production because rDNA technology produces a nearly exact copy of the animal’s own growth hormone. Hence, the biological action of somatotropin is thought to be identical to that of the natural hormone. The inability to distinguish between natural and injected hormones in an animal carcass or meat product could make deciding which substances are residues a daunting regulatory problem. Of course, abnormally high levels of any hormone resulting from a specific treatment could be considered a biological residue, requiring control measures–condemning the carcasses and edible tissues prepared from them–under current meat inspection laws. Unlike DES, somatotropin is a water-soluble protein, and therefore should not last long in animals. Because it is a protein, it should be easily broken down in the human digestive system if it is present in meat or dairy products. Even if elevated levels are defined to be residues to which consumers might be exposed, regulators must still decide whether such exposure is hazardous.

Hormone Use In Livestock Production

Livestock and dairy production in the United States fully integrate pharmaceuticals into standard farm management production practices. Subtherapeutic use of antibiotics–at doses below those required to treat an actual disease–is routine in swine production. Hormone treatments for cattle, which reduce the cost of beef production and hence the cost of meat products to consumers, are also typical. Available evidence suggests most beef cattle receive at least one hormone treatment, with some receiving multiple treatments. A report by USDA’s Food Safety and Inspection Service estimates 95 percent of cattle in feedlots are treated. Treatments before the feedlot stage also are common. the hormone industry claims that gains in feed conversion and growth rates are so large relative to hormone costs that no farmer can afford to forgo such treatments for fed cattle. (See Livestock Hormones in the United States for a discussion of hormones currently used in this country.)

Hormones regulate many metabolic functions, including growth rates. How any hormone promotes growth and feed efficiency is not completely understood, but it is widely recognized that nutrients are diverted, or repartitioned, from the development of fat to milk or muscle tissue. Repartitioning agents may speed up the rate at which fat is degraded back to fatty acids or slow the rate at which nutrients flow to fatty tissues, thereby slowing fat production and allowing more muscle to be built from the same nutrient intake.

Widespread use of growth hormones in red meat production will depend on consumer attitudes. The reduction of intramuscular fat could be of value to consumers concerned about cholesterol. Meat from somatotropin-treated animals could command a premium in the marketplace. However, available evidence suggests that this benefit is not especially important to consumers. Currently, lean meat is graded lower and sells for less than more heavily marbled meat.

If consumers in general decide that any new hormone used in livestock production is undesirable, the technology would not last long. Consumers may easily be able to recognize meat products produced with somatotropin. A large reduction in fat could change the appearance and flavor of meat, especially pork. If it turns out that consumers do not react negatively to the technology, growth hormone use may become routine in parts of the livestock sector that have never used hormones, such as the dairy and swine industries. Whether somatotropin could replace or complement the steroid hormones currently used in beef production is not known.

The results from laboratory tests have been quite variable. The extent to which aggregate milk production might increase is open to debate. A report by the Office of Technology Assessment in 1986 assumed that all dairy farms would produce 25.6 percent more milk once adopting bST and that all would eventually use the growth hormone. A 1987 ERS report noted there was some agreement that the average yield increase was about 16 percent on experimental herds, although response rates differed according to animal breeding, nutrition, and health. ERS assumed no more than 70 percent of dairy farms would adopt the technology. A more recent study by Cornell University agricultural economists assumed an 8-percent yield increase.

Growth hormone experiments in pork production indicate up to 28 percent greater feed efficiency, 19 percent greater growth rates, 33 percent reductions in backfat, and a 20-percent-larger loin eye. These gains mean that pST could reverse meat consumption patterns. Increases in poultry feed efficiency have made poultry prices more attractive than red meat prices, boosting poultry consumption. During the 1970’s and 1980’s, per capita meat consumption changed less than 1 percent, but the shares held by the various meats changed radically. Red meat consumption declined 7 to 8 percent, while poultry use climbed 39 percent. Greater red meat production and the accompanying lower prices could lead to a larger share for red meat in the American diet.

Balancing Competing Interests

The current regulatory environment in which somatotropins are now being examined has characteristics that can be revealed by looking at historical cases in which health and safety questions were raised over dairy and livestock production practices. The pasteurization debate shows that health and safety questions are an enduring part of technological development controversies, and that personal economic well-being is often involved. The more recent controversies over DES and the pesticide heptachlor have shaped the regulatory environment by making consumers sensitive to the consequences of changing farm production practices.

Pasteurization, a heat treatment that kills pathogens, is now an accepted practice in milk processing and has been a legal requirement for many years. However, at the turn of the century, pasteurization was a controversial topic. By the end of the 1800’s, the scientific community had recognized the importance of reducing disease-causing bacteria in milk, particularly in lowering incidences of infant mortality and tuberculosis.

But some consumer groups argued that pasteurization would adulterate an already safe, wholesome product and would allow milk producers to abandon existing sanitary practices. Owners of smaller scale milk plants supported this position partly because the new technology endangered their financial solvency by providing a cost advantage to their larger competitors. Owners of the big dairy plants favored pasteurization because the technology gave milk greater shelf life and opened up more distant markets.

Health and safety decisions, like that for pasteurization, do not come without a price. Empowering a Government agency to make decisions for the entire population reduces the costs of decisionmaking by freeing individuals from having to become experts in animal physiology or biochemistry, for example. However, Government-mandated decisions imply some costs. In practice, such decisions usually either prohibit everyone from using a product or allow anyone to use it, perhaps subject to a small number of restrictions. Treating everyone alike may leave some individual needs unmet.

Further, regulations that prohibit the sale of products that might be hazardous to some people could delay commercialization of items that may be beneficial to others. Thus, consumers may be missing out on some of the benefits of new technologies, including enhanced safety or reduced production expenses. Smaller costs could mean lower retail prices and greater product availability.

Balancing these opposing forces is not easy in a politically active environment. When the distribution of benefits from a new technology is not uniform and relatively large groups believe their interests are not being served, they will attempt to change the decisionmaking process. For instance, the conflicts over pasteurization and bST come down to arguments over who is likely to receive the greatest advantage from the new technology. Small-scale dairy operations have argued against bST use, demanding information on how the hormone would affect the number and location of family farms. Likewise, many dairies recognized that pasteurization would provide a cost advantage to their competitors. So a long debate over product safety ensued, even while raw milk continued to cause human health problems.

Both pasteurization and bST make milk production more efficient. bST produces more milk per cow, while pasteurization creates less spoilage. Like pasteurization, bST has the potential for uneven allocation of benefits. In both cases, groups believing themselves disadvantaged used their resources attempting to delay or prevent use of the new technology. Yet, FDA is legally bound to register–approve–animal drugs based on their efficacy and safety, not on balancing benefits and costs.

The Problem With DES

The major contribution health and safety regulations can offer is to protect a portion of the population from exposure to substances that might cause harm. Because of advances in scientific knowledge and the discovery of new information, decisions made at one time may be changed later. In the case of DES, human health concerns and development of more sensitive testing methods led the Government to reverse its initial approval of the drug as an animal hormone.

DES is a synthetic estrogen that was used as a hormone treatment for beef cattle beginning in the 1950’s. The substance was known to cause cancer in laboratory animals almost since its first production run in 1938. DES was also used by women to prevent miscarriage. From 1947 to 1971, an estimated 500,000 to 3,000,000 women took DES.

Evidence that first appeared in the 1970’s indicated a causal link between DES use and a rare form of vaginal cancer in the daughters of women who used the drug, demonstrating that DES is a human carcinogen. This discovery aroused the fear of contracting cancer from residues in meat from DES-treated animals. The Delaney Clause would have eliminated its use in livestock production, but the “DES exception” allowed continued use. FDA banned DES in feeds and animal implants on evidence of residues in beef livers, but the withrawal was vacated in 1974 because of disputes over testing methods. (FDA had used a detection method that was more sensitive than those used previously.) The implant ban was finally imposed and sales ordered to cease in July 1979. DES manufacturers were unable to prove cancer risks were less than one in 1 million. Use became illegal on November 1, 1979.

The DES ban was unpopular with many cattlemen. They believed there had been no problems with DES in 25 years of using the hormone. In March 1980, officials of Allied Mills, a division of Continental Grain, informed FDA that perhaps 50,000 of their cattle at a Texas feedlot had been illegally implanted with DES. More than 400,000 cattle in more than 300 feedlots may have been illegally implanted with DES after November 1, 1979. To date, there have been no prosecutions against any feedlots, although charges resulting in guilty pleas were secured against some DES distributors.

Truth in Regulation

When enforcement of public health regulations is not thorough, it is not surprising that consumers may be skeptical of information received from public health officials. In the case of DES, regulation failed to prevent its unauthorized use. Likewise, with the insecticide heptachlor, EPA had canceled registration for most agricultural uses in the 1970’s because the chemical was found to be a carcinogen and it persisted in the environment. Yet, in March 1982, 80 percent of the milk produced on Oahu, Hawaii, was found to be contaminated with the insecticide. Heptachlor-treated pineapple plants had been sold for feed after harvest, and the heptachlor was passed through to the milk. The Federal Dairy Indemnification Program bought the approximately 36 million pounds of contaminated milk for $8.5 million.

Despite assurances from public health officials, milk sales were depressed for 16 months following the discovery. Media coverage was found to have a negative impact on sales. Lost sales were estimated to cost $30,000 per producer.

The historical cases show that consumers have expressed their demands for safe and healthy food in three ways. Regulations, litigation, and unwillingness to purchase items have all influenced the ways that livestock and dairy products are produced and marketed. Whether consumers have made rational decisions in the past, or whether they will in the future, is a question separate from influence.

Are Growth Hormones Safe?

At least two health and safety issues are raised by the proposed use of somatotropins in livestock and dairy cows. The obvious question is whether meat and dairy products produced from animals treated with growth hormones will be safe for human consumption. This question can only be answered in part by scientific studies. No technological innovation has been adopted with all the possible ramifications for human health and well-being understood in advance.

A second, more general issue is whether hormone use is safe. A definition of safety is necessary before a judgment can be made. However, the history of technological change in the dairy and livestock industries shows that safety has been a variable concept. For instance, the Delaney Clause specifies that no residues of animal drugs or feed additives can be allowed in food products if the substances are carcinogens. Litigation over the use of DES codified into law the requirement that the most sensitive testing methods available be used to detect residues. Consequently, as testing methods become more sensitive, some products once considered safe may no longer receive such approval. The ability to detect residues has increased by many orders of magnitude in recent years. Products could also be deemed unsafe even if residues were below the threshold at which a substance might cause cancer.

However, the more recent “de minimus” interpretation of risk calls for regulatory agencies to use the most sophisticated residue measurement techniques available but with some flexibility in setting standards. This flexibility in decisions for animal drugs, which does not exist for food additives (they have no exception to Delaney Clause requirements), means that health and safety standards can vary over time. Therefore, predicting whether growth hormones will be judged safe is equivalent to correctly predicting all the steps involved–the way scientific information will be used and interpreted, possible misperceptions that might arise, how health and safety standards will change in the future, and how scientific knowledge might advance.

Human health and safety issues are important to growth hormone commercialization. Consumers, Government regulators, and the scientific community must agree that milk and meat from treated animals are safe before somatotropins are fully adopted. If USDA and FDA consider growth hormones unsafe, adoption will not be allowed. If consumers judge them unsafe, treated products will not survive in the marketplace. The heptachlor case shows that consumers can react quickly to news concerning questions about food safety. Their actions directly affect the financial solvency of farms. The scientific community can influence both consumers and regulators. For a consensus, all groups need to agree that the scientific evidence is reliable and unambiguous.

FDA statements indicate that the agency believes milk produced in current bST trials is safe for human consumption. However, health concerns will be raised whenever new pharmaceutical products to promote animal growth are introduced. Problems beyond the link between DES and cancer have been recognized. Poultry production involving hormone use in other countries has been linked to abnormal sexual development in children. The long-term human health consequences of consuming beef from animals treated with existing hormones are not yet fully understood. And conventional technology is relatively well documented compared to the new. So the safety issues of replacing currently approved hormones with somatotropins in dairy and livestock production are far from resolved.

The Cost of Change

The willingness of firms to undertake product testing and commercialization in the presence of legal risks that are capable of bankrupting any corporation must be interpreted as a belief in the safety of growth hormones. Whether consumers will ultimately share that belief is unknown. If Government regulators believe bST and pST are safe, the most positive statement they will make is that the hormones have no impact on human health. A much more positive statement was made about pasteurization. Nevertheless, consumer fears delayed its use.

The regulatory process used to evaluate bST and pST and the resulting decisions will be important for research and development incentives throughout the biotechnology industry. These cases could therefore have implications for all farmers and consumers. If the industry examines the bST and pST review process and concludes that the demand for information is excessive, research on other products could drop. Declining research and development can impose widespread costs on society. The pasteurization example shows how large these costs can be. Because approval of pasteurization was delayed, otherwise preventable deaths and disease occurred, and greater product availability and reduced consumer prices were sacrificed.

Alternatively, if regulators demand too little information from industry, the likelihood of error could rise. For instance, if growth hormones are deemed unsafe when in fact they are harmless, the products will probably never be marketed. Recanting and allowing commercial use of a previously banned product would be an unusual act for any regulatory agency. If growth hormones are deemed safe but are later shown to be harmful (like DES), public skepticism (as in the heptachlor case) is likely to continue, making further developments in rDNA technology unlikely. Consumer demand might also decline and the agricultural sector could suffer as a result.

PHOTO : Pigs treated with growth hormones have up to 33-percent less backfat and a 20-percent

PHOTO : -larger loin eye (pork chop, right side) compared with conventional production practices

PHOTO : (pork chop, left side).

PHOTO : The extent to which aggregate milk production might increase because of bovine

PHOTO : Somatotropin is open to debate.

PHOTO : At the turn of the century, pasteurization was a controversial topic.

COPYRIGHT 1989 U.S. Government Printing Office

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