fection control, and the extent of external oversight by government agencies, accrediting bodies, or other entities varies. In addition, many of these facilities do not operate in an environment in which an outbreak of tuberculosis might threaten their reputations, although they may be vulnerable to civil law suits (e.g., by inmates citing deficient health and safety measures).

An assessment of the occupational risk of tuberculosis needs to take historical context into account. As described in Chapter 1, during the late 1980s and early 1990s, outbreaks of tuberculosis in several large, urban hospitals helped focus attention on the risk of tuberculosis in health care settings. They also raised concern about lapses in infection control measures. These outbreaks occurred against a backdrop of resurgent tuberculosis that has been linked to underfunded public health programs, incomplete treatment of the disease, and increasing numbers of people at risk because of human immunodeficiency virus (HIV) infection, homelessness, imprisonment, and immigration from countries where tuberculosis is common. Although these problems have not disappeared, they have been mitigated by increased funding for community tuberculosis control, intensive programs of directly observed therapy, more effective treatments for HIV infection and AIDS, and increased attention to tuberculosis control measures in the workplace. Since 1993, national tuberculosis case rates have dropped for seven successive years.

The discussion in this chapter draws extensively on the background paper by Thomas M.Daniel in Appendix C. That paper provides a more detailed review of the relevant literature and its limitations.

CONCEPTS AND DEFINITIONS

In its simplest sense, occupationally acquired disease means disease acquired during the course of a person’s work. The focus of those concerned about workplace transmission of tuberculosis is, however, on identifying workers whose duties could be reasonably anticipated to bring them into contact with (1) people who have infectious tuberculosis or (2) air that contains Mycobacterium tuberculosis. In OSHA’s terminology, this anticipated contact—not actual exposure—constitutes occupational exposure. Thus, a respiratory therapist in a facility that treats patients with tuberculosis would normally be categorized as having occupational exposure, whereas a financial analyst in the facility’s administrative offices normally would not.

Risk has a variety of technical and popular meanings, and the committee recognizes the technical, political, and ethical controversies and debates that surround the concept of risk, the characterization of risk, and public perceptions of risk (NRC, 1983, 1996). Used in a general sense, risk refers to the probability of adverse health effects of, for example, expo-



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