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In summary, people living in the vicinity of the TMI nuclear power plant
should not be considered to have a significantly increased risk of cancer
or other long-term health effects as a result of the radiation they received
following the accident. Even if the risks should exceed the above estimates
by a factor of 100, the health effects of the accident would still be too
small to be detected against the normal background of naturally occurring
cancer and other diseases. Hence, there is every reason to expect that
a followup study of the exposed population will not be able to detect any
radiation effects. There is also no reason to believe that a followup of
the TMI population could contribute new knowledge of the effect of ionizing
radiation on human health.

IV. POSSIBLE FOLLOWUP AND OTHER STUDIES

The existing data indicate that any followup study is most unlikely to
detect any radiation-induced health effects in the general population
in the vicinity of TMI. However, the intensity of public concern about
possible radiation effects, plus the possibility of obtaining information
on the psychological and social impact of the incident that would help to
minimize the consequences of future incidents of this kind, have prompted
suggestions for action. The CDC has proposed support of three activities:
full enumeration/census of the population closest to the plant (within 5
miles) to be used if followup health studies should for any reason seem
desirable in the future; continuation of an ongoing study of pregnancy
outcomes in this close-in population; and a survey of the mental health
impact of the total emergency episode. The Secretary, HEW, has already
moved to support these activities, as publicly announced on May 30, 1979.

STUDY PLAN (CDC/NIOSH)

A. Population Enumeration/Census

Approximately 30,000 persons (10,000 households) live within five miles of TMI. Door-to-door household interviews will be conducted for this entire population, beginning June 20, 1979. Home interviews will be conducted followed by revisits and telephone contacts for persons not initially at home. Questions being asked are shown on the attached precoded form (Appendix 3.) They include identifying demographic data for each person (with social security number), occupational history, smoking history (essential in view of the possibility that the enumeration/census data might later be used to study cancer incidence in the population), history of the whereabouts or evacuation status of persons during the crisis period, and history of possible pregnancy among women of childbearing age. Records from the enumeration/census will be maintained by CDC and by the Pennsylvania Department of Health (PDH) for possible future use in health followup activities.*

*Studies proposed by CDC/NIOSH and the State of Pennsylvania may include biological studies outside the Subcommittee's assigned responsibilities.

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Based in part on data from the enumeration/census, each woman of childbearing age (age 15-44), whether stated to be pregnant or not, will be re-interviewed by phone in December 1979 with respect to possible pregnancy outcome in the interim.

For the past 5 years, under a Federal research grant (HSA) terminating December 1979, the State of Pennsylvania has conducted an epidemiologic study of pregnancy outcome in an area that includes much of the population living within 10 miles of TMI. The proposal now is to use the data-collection procedures of that study to obtain postTMI information on pregnancy outcome in the population resident within 10 miles of TMI. This would enable pre- and post-TMI comparisons to be made on essentially the same population. It is also hoped to use the same observational procedures concurrently in another location about 80 miles from TMI where the living conditions and the people are similar. The State investigator is, however, interested in the possible effects of radiation on pregnancy outcome and appears hopeful that the expected negative results of the new study will prove reassuring to the people involved in the TMI incident. Funds have already been obligated for the study. This represents the status as of May 10, 1979.

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It is proposed to assess the impact of the accident on the mental health of the TMI population, and to examine the social-psychological factors involved in its perception as a potential human disaster. A sample of 1,500 households, about 4,500 persons, will be randomly selected in the process of the door-to-door enumeration/census. Extensive interviews will be conducted with these households using a questionnaire schedule already developed for emergency survey assessments of this sort. Comparisons will be made with responses in a household sample of equal size chosen from a similar rural area of Pennsylvania remote from TMI. Thereafter, depending on evaluation of responses to survey questions, a series of followup interviews will be conducted with persons or households judged to show particularly abnormal response patterns. Hospital and mental health clinic records in the area around TMI will be reviewed for 2-month periods preceding and following the accident as a means for assessing incidence of acute mental health episodes potentially related to the accident.*

*A contractor of the Nuclear Regulatory Commission plans to study the social attitudes of population groups living near nuclear power plants, including TMI, and the impact of TMI on those attitudes.

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The estimated resource requirements of these three studies are outlined in Appendix 4. All work will be conducted under the direction of the Pennsylvania Department of Health in cooperation with university groups as well as local and State public agencies in Pennsylvania. Federal Government agencies, however, are expected to provide most of the necessary resources to support these studies, either in the form of direct funding or through temporary assignment of Federal personnel. The cost estimates shown reflect the level of support anticipated if the Federal Government were to undertake all the work itself directly. If State and local personnel resources can be used, particularly in the enumeration/census project, total Federal costs would be substantially reduced.

E. Evaluation

None of the three proposals seems at all likely to contribute new knowledge about the effects of ionizing radiation on human health. The census is, nevertheless, desirable as an insurance policy against the unlikely event of a future need to examine some aspect of the experience not now considered to be important. The study of pregnancy outcome has interest, not as a search for an effect of ionizing radiation, but as a possible source of new information on the effect of a near-disaster upon this health parameter. The fact that the State is concluding a fiveyear, pre-TMI study of pregnancy outcome in the same area creates an especially attractive research opportunity. However, the avowed investigative interest in the possible effects of radiation on pregnancy outcome seems to the Subcommittee to lack scientific merit. Any justification for this aspect of the study must derive from other considerations.

The NIMH proposal to study the impact of the TMI incident on mental
health, and the way in which it led to temporary disruption of
family and community life, while not directly related to the biological
effects of ionizing radiation, seems eminently worthwhile. Whether or
not the survey provides new information on the mental health impact of
such an incident, it should lead to a better understanding of the forces
that took control and escalated the incident into a problem of national
concern. It could provide information that would enable the Nation to
handle better any subsequent incidents of this nature.

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The Subcommittee reviewed the possible information that may be derived from studies of chromosome damage. It was concluded that cytogenetic studies at this time would be unlikely to add any useful information regarding health effects for individual members of the public or even for workers. Chromosome studies currently appear to be too insensitive to distinguish any effects, given the relatively low levels of exposure. If higher worker exposures occur as a result of recovery and related operations, cytogenetic studies in this group may become worthwhile.

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