incurred if current use of subtherapeutic drugs were prohibited. Ideally, the costs associated with a ban should be compared with the benefits to consumers (valued as the benefits from reduced health problems). Because of the difficulty in measuring economic benefits, only the costs are addressed here. The estimated cost measures can be compared among themselves to elucidate the sensitivity of the results to various assumptions and to provide an understanding of the magnitude of the costs.

The best way to determine the economic benefits of subtherapeutic antibiotics is to examine what would occur if the U.S. Food and Drug Administration were to prohibit all forms of subtherapeutic drug use. To make this estimate, several areas must be considered.

If regulators were to decide to limit subtherapeutic drug use, it would become essential to define the difference between therapeutic and subtherapeutic uses more accurately. For a detailed discussion of the different uses, see Chapter 2 and Hays and Black (1989). The current practice of incorporating antibiotics in beef cattle diets in the feedlot is done to prevent liver abscesses and the diseases associated with the stress of moving and commingling animals. Under current regulations, there is little incentive to determine whether such feeding is therapeutic or subtherapeutic, and an argument can be made for either definition. Such feeding is therapeutic in that the incidence of liver abscesses and stress-related diseases would be higher if the drugs were withdrawn. If the symptoms appear after drug withdrawal, the drugs can be used therapeutically. However, a strict interpretation of therapeutic use is to treat a symptom, and if antibiotics are used to prevent a symptom, they are used prophylactically. The argument over definitions is more than one of semantics. The entire beef-feeding industry would be exempt from any ban if the first definition were applied. In the analysis, the strict definition is used, because many of the benefits of subtherapeutic use in poultry and pork industries could also be described as treating symptoms before they develop (that is, before subclinical problems become clinical). This issue is important because it implies that once a subtherapeutic-use ban were in place, there would be strong incentives to restrict therapeutic use.

The first effect of any ban on subtherapeutic use of antibiotics would be felt in the animal health industry. In 1995, this industry generated $3.3 billion in sales. In the same year, the human health pharmaceutical industry produced