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1 Introduction Over the past several decades, public concern over exposure to ionizing ra- diation has increased. This concern has manifested itself in different ways de- pending on the perception of risk to different individuals and groups within the population of the United States and the circumstances of their exposure. One such group is made up of servicemen who participated in the atmospheric testing of nuclear weapons at the Nevada Test Site or in the Pacific Proving Grounds, who were involved in cleanup activities in Hiroshima or Nagasaki in the fall of 1945 and the spring of 1946, or were prisoners of war who may have been as- signed work duties in those cities at the times of the bombings or shortly thereaf- ter. Initially, this concern focused on the veterans themselves and may have been stimulated by early reports of an excess incidence of leukemia among par- ticipants in the 1957 Nevada test shot known as SMOKY (Caldwell et al., 19831. The Radiation-Exposed Veterans Compensation Act of 1988 (Public Law 100- 321) recognized this concern and identified 13 cancers (specifically, leukemia, multiple myeloma, lymphoma except Hodgkin's disease, and cancers of the thy- roid, breast, pharynx, esophagus, stomach, small intestine. pancreas, bile ducts, gall bladder, and liver) that were deemed presumptively service connected, and thus compensable. In 1994 this act was amended to include two additional sites of cancer, namely, the salivary gland and urinary tract (Public Law 102-578~. Now the concern of some people extends beyond the health risk to the vet- erans and involves health issues related to their children, grandchildren, and 9
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10 AD VERSE REPRODUCTIVE OUTCOMES spouses. As a result of the concerns expressed by the spokespeople for these veterans, their spouses, and children, the Committees on Veterans Affairs of the House of Representatives and the Senate in Public Law 103-446, Section 508, Study of Health Consequences for Family Members of Atomic Veterans of Ex- posure of Atomic Veterans to Ionizing Radiation, directed the Secretary of Vet- erans Affairs (VA) to enter into an agreement with the Medical Follow-up Agency (MFUA) of the Institute of Medicine (IOM) to convene a panel of ap- propriate individuals to carry out the following: 1. An evaluation of the feasibility of a study to determine the nature and extent, if any, of the relationship between the exposure of veterans to ionizing radiation and the occurrence of (1) genetic defects and illness in their children and grandchildren, (2) untoward pregnancy outcomes experienced by their wives, and (3) periparturient diseases of the mother which are the direct result of such untoward pregnancy outcomes. 2. If such a study is feasible, the committee was asked to estimate how much time and money would be required to organize and implement it. 3. Finally, the committee was asked to determine if other sources of infor- mation would yield similar results at a lower cost or in less time (while experi- mental animal studies could address some of the scientific issues discussed in this report, the committee has interpreted this charge to pertain to alternative epidemiologic studies that could yield similar results at a lower cost or in less time). The panel was directed to submit its evaluation to the Secretary not later than 180 days after the date of enactment of Public Law 103-446. The veterans covered under this law include (1) any serviceman who was ex- posed (as determined by the Secretary) to ionizing radiation as a result of (a) par- ticipation while on active duty in the Armed Forces in an atmospheric nuclear test that included detonation of a nuclear device, or (b) served in the Armed Forces with the United States occupation force in Hiroshima or Nagasaki, Japan, before July 1, 1946, or (c) was interned or detained as a prisoner of war in Japan before that date in circumstances providing the opportunity for exposure to ionizing radia- tion comparable to the exposure of individuals who served with such occupation force before that date, and (2) any other veteran who the Secretary designates for coverage under the study (Public Law 103-446~. For the committee's evaluation of the issues implicit in its charge to be thor- ough, it was necessary that its members represent a broad array of disciplines. Accordingly, members were chosen to represent expertise in radiation dosimetry, epidemiology, ethics, genetics, radiation biology, reproductive biology, teratol- ogy, and statistics. To discharge its responsibilities, the committee has met monthly since it was constituted.
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INTRODUCTION 11 AIMS OF THIS REPORT Through its deliberations, review of relevant documents, understanding of issues relative to conducting epidemiologic studies, and discussion of various study strategies, the committee answered the questions established under Public Law 103-446, Section 508. The committee evaluated the feasibility of a study to determine the nature and extent of the relationship between the exposures of defined groups of veterans to ionizing radiation and selected health effects on their children, grandchildren, and wives. To determine the feasibility of an epi- demiologic study, it is necessary to establish which health endpoints are thought to be associated with a particular exposure or exposures. Although Public Law 103-446, Section 508, describes the general categories of health effects that are to be evaluated, to meet its charge, it was important for the committee to obtain information from the Atomic Veterans regarding their specific concerns. The testimony provided by the Atomic Veterans and their representatives gave the committee a framework for the determination of the scope of the health effects to be considered. Since the Atomic Veterans have identified a variety of potential health effects among their wives, children, and grandchildren as being of concern, the committee had to conduct a thorough evaluation of the feasibility of studying diverse health effects occurring over a number of years in a geo- graphically dispersed population. The overarching aim of the committee's deliberations was therefore to search for a workable approach to addressing these concerns. This search en- tailed evaluation of feasibility considerations in two general areas The first area related to the logistic aspects of conducting a scientifically valid epidemiologic study. Here, the issue of feasibility revolved around the definition and assess- ment of exposures, confounding factors, and outcomes and hinged on the avail- ability and quality of the data. These were largely practical matters that must be considered in determining whether an epidemiologic study that would meet the requirements for good epidemiologic research could be conducted. Ancillary to that are questions regarding the ethics of conducting studies if their potential ability to address the concerns of affected individuals is limited. The second general area of feasibility is the scientific background that sup- ports the conduct of a study. Feasibility concerns here include the evidence on which one would base estimates of the anticipated magnitude of increased risk. This led the committee to the consideration of three additional areas: (l) the evidence for a biological basis and mechanisms for the effects; (2) the increase in risk that might be anticipated and the statistical power of a study to identify those levels of increased risk, if present; and (3) the potential contribution of factors other than the exposure of interest to any apparent increase in risk. The aims of the committee included consideration of all of the above issues in a search for a feasible approach to addressing the concerns raised by the Atomic Veterans and their representatives.
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12 ADVERSE REPRODUCTIVE OUTCOMES In addition to evaluating the feasibility of an epidemiologic study, the committee was asked to estimate how much time and money would be required to conduct such a study, if one was deemed to be feasible. It is important to note that such an estimate is predicated not only on determining feasibility but also on determining the scope necessary for a study to address the concerns of the veter- ans and their families. The type of study design and the data sources to be used also play a key role in determining how much time and money would be re- quired. For example, a case-control study based on accessing, reviewing, and abstracting existing records would be much less expensive than a cohort study that required tracking subjects over time and conducting interviews for primary data collection. Cost and time are also affected by the numbers and types of outcomes to be studied, and in reviewing the outcomes included in Public Law 103-446, Section 508, it is not clear that all of them would have equal weight. The third charge to the committee was to determine whether there are other sources of information that could yield similar results at a lower cost or in less time.