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9 Summary of Responses to CDC's Questions
Pages 137-155

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From page 137...
... . With regard to release of future study reports, how can CDC improve the public communication process?
From page 138...
... The subcommittee believes that the methodology used by the HEDR project to estimate thyroid doses and their uncertainties is structurally sound. The HEDR models have been subjected to numerous reviews, and the various codes have been tested by the HEDR project staff independently of the developers to ensure correct implementation.
From page 139...
... Although an attempt was made to interview a parent or surrogate to obtain recollections of the milk consumption of each subject in childhood, it was possible to do so for only 62% of the subjects; in the other cases, default assumptions were used in calculating thyroid dose. The defaults that the CIDER mode} used proved to be considerable overestimates of the average doses derived from the reported milk consumption and source in the interviews.
From page 140...
... That was appropriately addressed by modeling the relationship between dose and the probability of occurrence of a thyroid disease. The HTDS also considered a reasonable set of potential confounding variables for thyroid disease.
From page 141...
... The HTDS investigators performed an adjusted comparison of the number of thyroid cancers found in the study versus the number that would be expected in the general US population (without radiation exposure) and found no difference.
From page 142...
... Dosimetry-error issues apparently were not fully treated in the analysis of the study power. The same issue is raised by the results, in particular, ignoring dosimetry error could lead to unrealistically narrow estimates of the confidence limits that should be applied to the estimated parameter values.
From page 143...
... The HTDS investigators conducted analyses of the various thyroid-disease end points to evaluate a number of possible risk factors for confounding effects or effect modification, but they presented no tables to show a summary of the results of these analyses for any of the disease end points. Of particular value would be a presentation of results stratified by sex, age at initial exposure, magnitude of NTS and global fallout, and history of substantial medical radiation exposure.
From page 144...
... However, if a substantial, fraction of the variability of the HEDR individual dose estimates actually is due to non-Berkson error or to multiplicative errors, or if there is a substantial additional component of error due to uncertainties in milk consumption, lifestyle, and residential history, the power or tne study might nave been reduced below a point that would normally be considered acceptable. Furthermore, the apparent heterogeneity among geostrata might also have reduced statistical power.
From page 145...
... Hence, in this study in which, as it turned out, the primary issue became whether there is any association between IT exposure and thyroid diseases-the impact of possible close underestimation might not change the study conclusions appreciably, except for two caveats. First, if there was an across-the-board underestimation of doses, the true statistical power of the study would have been greater than one would estimate it to be, given the reported dose distribution; the negative results would be more persuasive than they are.
From page 146...
... The evidence of heterogeneity of many of the thyroid diseases or abnormalities among geoskata also suggests that the power of the study was weakened by geographic variations in unmeasured or unknown confounders that affected the outcomes. Such reductions of statistical power lower our appraisal of the study in relation to other studies and of the use of this study's results for making predictions about disease risk in other populations exposed to id at low doses and at low dose rates.
From page 147...
... In evaluating the HTDS, it is useful to distinguish what the subcommittee regards as two aims of the study. The first was the determination of whether patterns of thyroid morbidity among those in the study region during the fallout period correspond to likely patterns of exposure in the HTDS study sample irrespective of specific estimated doses, the likely patterns of exposure being based principally on location of residence during early childhood (distance down wind)
From page 148...
... At the time of the initial release of the Draft Final Report, the HTDS investigators indicated that residents of downwind areas should fee} relief that their proximity to the Hanford nuclear site did not result in increased risk of any thyroid morbidity. Such statements are, according to the arguments above, reasonable in specific instances.
From page 149...
... a weak association that could affect, for example, those already susceptible to thyroid disease because of predisposing genetic factors. Thyroid cancer is not a common disease, and it would be reasonable in future epidemiology surveys to identify, document, and investigate clusters by using molecular-biology probes to characterize genetic polymorphisms that could make people more sensitive to ionizing radiation or to look for oncogene prevalence in affected groups.
From page 150...
... Such information channels as newsletters, background fact sheets, and a Web site were good ways of trying to reach members of the public directly with information about the study, and they augmented the information in the mass media. The subcommittee recommends that similar public communication efforts be continued regarding this report and others by CDC.
From page 151...
... To the greatest extent possible, those working on the plan should brainstorm about unexpected situations like those which affected the release of the draft report and devise plans to handle them more effectively. it is imperative that messages from the final report take into account the venous audiences being addressed and show concern and sensitivity for the thyroid-health issues that people perceive as affecting them.
From page 152...
... Many government agencies and scientific organizations do that routinely and get much better, informed coverage because of it. As for details, the executive summary of the final report should be edited carefully to eliminate unnecessary technical jargon and complexity, which made it difficult for even educated readers to understand portions of the Draft Final Report.
From page 153...
... WITH REGARD TO RELEASE OF FUTURE STUDY REPORTS, HOW CAN CDC IMPROVE THE PUBLIC-COMMUNICATION PROCESS? Attempts to establish and maintain an information blackout before release of the Draft Final Report ran counter to the previous spirit of information-sharing with citizen groups in the region.
From page 154...
... One point for such a group to consider is the advisability of publicly releasing draft reports before external peer review and, if such a release is required by law or contract, how to do so effectively. Although circumstances in this particular situation might have forced the HTDS investigators and CDC to release a draft report to the public and the media, it is problematic to have preliminary information conveyed to the public if external peer review could suggest important changes in the final report.
From page 155...
... Science journalists, too, might need to re-evaluate how to apply their own guidelines that advocate writing primarily from peer-reviewed studies and reports as they are faced with more and more cases in which government agencies and others announce the results of unreviewed draft reports at news conferences.


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