Scientific Program Assessment: Dose Reconstruction Projects Supported by the National Center for Environmental Health
The focus of the research and public health activities under the Memorandum of Understanding (MOU) is on health effects that may have resulted from Department of Energy (DOE) operations, including development and production of nuclear weapons and materials and other nuclear energy-related research and development activities. Under the MOU, the National Center for Environmental Health (NCEH) is responsible for conducting research related to ionizing radiation in the environment. In this context, the Radiation Studies Branch of NCEH has undertaken a series of studies to evaluate the historical exposures of members of the public to contaminants released into the environment from nuclear weapons facilities in the United States. These federally funded studies are referred to as “dose reconstructions” and arose primarily from public concern about the health risks associated with the facilities that had operated in a climate of secrecy during World War II and the ensuing Cold War era. These studies have played an important role in unveiling the details of those operations, quantifying the magnitude of exposures and doses to the surrounding populations, and assessing the potential health impacts.
There had been earlier dose reconstruction efforts in the United States, in particular to reconstruct the doses to members of the public in regions near the Nevada Test Site (NTS) who were exposed to fallout from the atmospheric testing of nuclear weapons (Anspaugh and Church 1986; Anspaugh et al. 1990). The exposure dosimetry was developed under the DOE-funded Offsite Radiation Exposure Review Project (ORERP) (Church et al. 1990). The NTS dose reconstruction effort was important for establishing a methodology to quantify individual exposures. The NTS work was expanded into a more robust and flexible method-
ology to estimate doses for a large number of individuals in a thyroid cohort study and a leukemia case-control epidemiological study conducted at the University of Utah for the National Cancer Institute (Lloyd et al. 1990a, 1990b). More recently, the dosimetry system for the thyroid cohort study was restored and updated to calculate doses in the 1980s (Simon et al. 2006).
When the Radiation Studies Branch of NCEH first became involved in dose reconstruction studies after the signing of the MOU, it used the National Academy of Sciences (NAS)-National Research Council (NRC) to provide scientific advice on dose reconstructions and to help NCEH establish research priorities (NRC 1995). The NAS-NRC organized a committee whose charge was the following:
Review and comment on the design, methods, analysis, statistical reliability, and scientific interpretation of dose reconstruction and related epidemiological follow-up studies.
Recommend ways to strengthen study protocols and analyses to enhance the quality of these studies.
To accomplish its task, the 1995 NRC committee not only reviewed NCEH’s dose reconstruction efforts at Fernald and Hanford, but also drew on the collective knowledge of 47 scientists from around the world with experience and expertise relevant to reconstructing radiation exposures of human populations. The scientists participated in a 3-day workshop in October 1993 and were asked to assist the committee in identifying criteria to be considered when undertaking radiation dose reconstruction studies, to examine the pitfalls encountered in previous studies, and to recommend areas of needed research. The committee’s findings were reported to NCEH and published in a report (NRC 1995). NCEH took account of this information as it initiated new dose reconstruction studies.
To a large extent, however, selection of the dose reconstruction studies arose out of public concern and pressure. NCEH assumed responsibility for the Hanford Environmental Dose Reconstruction (HEDR) Project following the signing of the MOU. A dose reconstruction project at Fernald was mandated by Congress, a study at Los Alamos was requested by the governor of New Mexico, and similarly, a dose reconstruction at Idaho National Laboratory was requested by the governor of Idaho. For selection of the remaining studies, NCEH stated that they also relied on the early Advisory Committee for Energy-related Epidemiological Research (ACERER)1 recommendations (see Chapter 1).
Table 4-1 provides an overview of the DOE sites at which NCEH has been responsible for dose reconstruction activities. It is apparent from the table that the
TABLE 4-1 Overview of NCEH Dose Reconstruction Activities
Dominant Environmental Releases
Approach to Dose Reconstruction (time frame)
Releases of I-131 to air
Releases of mixed radionuclides (fission products and activation products) to the Columbia River
Hanford Environmental Dose Reconstruction Project:
Hanford Individual Dose Assessment (IDA) Project:
Uranium feed materials production
Releases of uranium and radon to air
Fernald Dosimetry Reconstruction Project:a
Fernald Risk Assessment:b:
Savannah River Site (SRS)
Plutonium and tritium production
Releases ofI-131, tritium, and Ar-41 to air
Savannah River Site Dose Reconstruction Project:
Idaho National Laboratory (INL)
Development and testing of nuclear reactors and related facilities
Releases of Cs-137, P-32, Sr-90, and I-131 to surface water
Releases of I-131, Cs-137, and Sr-90 to air INL Dose Reconstruction Studyf:
Nuclear weapons design and development
Preliminary results indicate: releases of plutonium and uranium, explosives, and volatile organic chemicals to air and releases of plutonium in liquid effluents
Los Alamos Historical Document Retrieval and Assessment (LAHDRA) Project
aInitially, the Fernald Project was a congressional mandate. It was later made part of the DOE MOU.
bRisk assessments available at http://www.cdc.gov/nceh/radiation/phase2/results.pdf. Last accessed November 2006.
cAlthough the site remains operational, the main production activities at SRS ceased at the end of 1992.
dOriginal purpose of Phase III was to do screening calculations; after the study was under way, NCEH and the Health Effects. Subcommittee jointly decided to go ahead and estimate doses for hypothetical individuals.
eAnticipated end date for SRS dose reconstruction is September 2006.
fAs a result of source term and screening analyses, the dose reconstruction focused on releases of radionuclides from RaLa process operations at the Idaho Chemical Processing Plant (ICPP) and on episodic atmospheric releases from initial engine tests (IET) in the Aircraft Nuclear Propulsion (ANP) Program. A detailed dose reconstruction of I-131 releases from the ICPP was performed (Apostoaei et al. 2005). Bounding estimates of doses to offsite members of the public from other radionuclides released from ICPP yielded low values (Apostoaei et al. 2005). (Fr this reason, a detailed reconstruction of these doses was not performed. Three IETs were identified as responsible for most of the releases during the ANP program, and could have resulted in significant offsite exposures to I-131(Behling and Mauro 2005). However, there were large uncertainties in the magnitude and temporal distribution of the releases. For these reasons it appears that a more detailed reconstruction of doses was not considered warranted by NCEH and the study was considered complete.
gAnticipated end date for LAHDRA document retrieval and assessment is 2009.
NCEH effort did not address all of the major DOE facilities within the United States. This is because some states entered into separate agreements with DOE. For example, the State of Tennessee and DOE entered into the “Tennessee Oversight Agreement,” which established a DOE funding source that allowed the Tennessee Department of Health to undertake a two-phase research project aimed at determining whether environmental pollutant releases from the Oak Ridge Reservation created public health problems (ORHASP 1999). Similarly, in June 1989, Colorado Governor Roy Romer and Secretary of Energy James Watkins signed an agreement in principle that included DOE funding for the Rocky Flats Toxicological Review and Dose Reconstruction Project. NCEH provided technical support for both of these major dose reconstruction efforts.2
Dose reconstruction studies focus on estimating the doses or risks to individuals exposed to releases from a site. These doses may be calculated for representative individuals or for specific individuals depending on the objectives of the study. In either case, the goal is to develop a good estimate of the magnitude of the releases that occurred and the doses received. In general, the studies focus on individuals who lived in the vicinity of the site and downwind or downstream of it. However, care is required during the early stages of the study not to rule out exposure pathways that may have resulted in doses to individuals more distant from the site.
Because direct measurements of individual exposures are rarely available, computer models must be relied upon to calculate the environmental exposure concentrations. This can range from taking historical measurements and applying them to times and locations for which no data are available, to reconstructing the quantities released (the source term) and the subsequent fate and transport of the material in the environment. The environmental datasets compiled from historical measurement data are typically used either to calibrate or to test the computer models employed in the dose reconstruction, recognizing that a dataset cannot be used for both purposes.
Frequently, the largest releases and exposures have occurred decades earlier than the time when the dose reconstruction is performed, with the end result that the studies invariably require the source term to be reconstructed. The historical records that must be relied upon inevitably contain gaps because the records are incomplete, missing, or not sufficiently detailed. Furthermore, measurement detection limits and biases have changed over time as sampling methods and procedures, analytic instruments, and techniques have developed. This is most apparent during the early years of operation of many of the sites when much of the science was in its infancy. Consequently, there are always uncertainties associ-
ated not only with the dose estimates but also with any environmental datasets to which model predictions are compared, and these need to be quantified and used in the epidemiological assessment of risk.
For any dose reconstruction, access to documents and data is central to the success of the study. All documents containing relevant information must be examined and the useful information extracted. If difficulties arise in the document search and review for a dose reconstruction, it is in relation to classified documents. This was a central issue that had to be addressed for the dose reconstruction at Hanford, which was the first study of a DOE facility that was open to the public. At that time, “most of the documents which described Hanford activities—tens of thousands of documents in all—were kept secret by virtue of a classification process. Many documents were automatically classified as soon as they were created” (Niles 1996).
It took time and persistence to establish the need to declassify relevant documents and to achieve a working process. The Technical Steering Panel (TSP) chaired by Dr. John Till pioneered this effort, which was well under way by the time the MOU was established in 1990 and NCEH assumed responsibility for the dose reconstruction at Hanford. The experience at Hanford highlighted the importance of historical documents to the dose reconstruction process, and in March 1990 Secretary of Energy James Watkins placed a moratorium on the destruction of DOE and DOE contractor records useful for epidemiological or health studies (DOE 2000).
To facilitate access to DOE facilities by researchers and investigators involved in the dose reconstruction studies and other activities covered under the MOU, DOE and HHS jointly prepared a handbook to be used as a reference guide (DOE 2003). However, the decentralized, semiautonomous nature of administration of each DOE site has resulted in different levels of cooperation between the sites with regard to document access—none more so than at Los Alamos National Laboratory (LANL), which NCEH has found to be the most difficult to work with of all DOE sites. The Los Alamos Historic Document Retrieval and Assessment (LAHDRA 2006) report on the dose reconstruction efforts states: “Access to classified documents at Los Alamos has been more difficult than LAHDRA team members have experienced at any of the other DOE sites that have been subjects of dose reconstruction investigations.”
NCEH and its contractors were denied or restricted access to classified records or document repositories at Los Alamos. These issues continued for more than 5 years before any solution was reached. Some of the difficulties resulted from events unrelated to the dose reconstruction activities and certainly resulted in unavoidable delays. For example, early in the project in May 2000 the towns of Los Alamos and White Rock were evacuated because of the Cerro Grande Fire, and the site was shut down for a number of weeks. Much later, in July 2004 there was an extended shutdown of the site in response to a security incident that involved hard drives missing from an X-Division vault. However, there remains
the underlying impression that LANL has been unwilling to implement the degree of openness necessary for a meaningful dose reconstruction even though the procedures had been established at other DOE sites long before LAHDRA was initiated. Furthermore, the Radiation Studies Branch appears to have allowed this situation to persist for an extended period of time.
It is the committee’s understanding that when NCEH completes the LAHDRA project it will no longer be involved in dose reconstructions at the DOE sites. At this time the committee has not identified the need for further dose reconstructions at the DOE sites, but in the event that any further dose reconstructions at DOE sites are required, NCEH, or some other agency independent of DOE, should manage and direct the studies to maintain the independence of the dose reconstruction effort.
The committee concludes that it is important for the findings of the dose reconstruction studies to be readily accessible to all interested parties, not just at the time of the studies but long after their completion. NCEH has made dose reconstruction project findings available on-line via the Radiation Studies Branch web site.3 For some of the studies, all of the project reports are made available (e.g., the Savannah River Site [SRS], Idaho National Laboratory [INL]); for others, only the final summary reports are provided (e.g., Hanford). In some cases, there are links to the studies from the individual DOE facility’s web site. This is sensible since a person seeking information about historical releases from a DOE facility and their potential health effects on the surrounding communities would not necessarily know which organizations would be responsible for studying those releases and effects. The publication of dose reconstruction study findings in the open literature appears to depend on the initiative of the contractors who performed the research. NCEH does not appear to have a consistent policy in this regard, which is probably appropriate given the different ways in which contractors are utilized by NCEH to address a dose reconstruction study and the fact that the findings may not always warrant publication.
Time did not permit the committee to evaluate all of the dose reconstruction studies conducted by the Radiation Studies Branch of NCEH in detail. Instead, the committee focused on three committee-selected DOE sites. NCEH conducted dose reconstruction activities at two of these: Hanford, Washington, and Los Alamos, New Mexico. As explained previously, NCEH did not undertake a dose reconstruction at Oak Ridge. Hanford and LANL represent the two ends of the spectrum of dose reconstruction efforts by NCEH under the MOU. More specifically, at Hanford there was a comprehensive evaluation of historical releases of radionuclides to the environment from operations at the Hanford facility, and doses to representative individuals in the surrounding populations were calculated. The results for iodine-131 (I-131), the principal radioactive material of
See http://www.cdc.gov/nceh/radiation/. Last accessed August 2006.
interest, were subsequently used in the Hanford Thyroid Disease Study (HTDS), a major epidemiological study that did not fall under the MOU. In contrast, at Los Alamos the dose reconstruction efforts are still at the initial, information gathering phase. The committee bases its review of the NCEH work upon both its expert judgment of the quality of the work and, for Hanford, a number of reports (NRC 1994, 1995, 1999, 2001, 2002) from previous NRC expert panels that provided ongoing reviews of portions of the HEDR Project, including the dosimetry system ultimately used in the HTDS.
HANFORD ENVIRONMENTAL DOSE RECONSTRUCTION PROJECT
The facility at Hanford, Washington, was designed to create plutonium for nuclear weapons. Operation of the first two plutonium production reactors began in December 1944. A total of nine nuclear production reactors operated at Hanford and were located near the Columbia River. Fuel fabrication facilities were built to prepare uranium fuel for the reactors, and chemical separation plants separated the plutonium from uranium and from fission products created during irradiation in the reactor (TSP 1994). The Hanford facility produced plutonium from 1944 to 1990.
The dose reconstruction study of the Hanford facility was a multiyear project to determine how much radioactive material was released from the Hanford site, how that material may have reached and exposed people, and most importantly, what radiation doses people may have received (TSP 1994). The study began in 1988 prior to the signing of the MOU and was conducted by scientists at Battelle, Pacific Northwest Laboratory (PNNL), a contractor at the Hanford site. A TSP composed of independent scientists and members of the public was created to oversee and direct the HEDR Project. Following the signing of the 1990 MOU, the Centers for Disease Control and Prevention (CDC) assumed responsibility for the HEDR Project.
The HEDR Project provided the dose calculation methodology that was used in a parallel project, the HTDS, that did not fall under the MOU. The HTDS was a congressionally mandated study funded by NCEH and carried out by the Seattle-based Fred Hutchinson Cancer Research Center. The HTDS also began in 1988 and took 9 years to complete.
In Phase I of the dose reconstruction study, the methods for reconstructing the radiation doses to people who lived in the 10 Oregon and Washington counties closest to Hanford were developed and tested. This phase was completed in 1990 (TSP 1990). The major research phase of the dose reconstruction project was completed in 1994, with the conclusion of the Battelle contract and the publication of reports containing estimated radiation doses to reference individuals (typical individuals) from the air and Columbia River pathways (Niles 1996), although follow-up activities that had been identified by the TSP continued for a number of years. These follow-up activities are described later.
The principal radioactive material of interest released to the air was I-131
(TSP 1994). Detailed I-131 dose calculations were prepared for the years of maximum release (1944-1951). The largest doses were calculated for a hypothetical child who drank milk produced by a backyard cow that was fed fresh pasture supplemented by alfalfa and grain. The median cumulative thyroid dose for such a child at Ringold, the maximally exposed location, was about 2.35 Gy (235 rad) (with a dose range from 0.54 to 8.70 Gy [54 to 870 rad]) (TSP 1994).
River water was used to cool the reactors and resulted in releases of radionuclides to the Columbia River. Detailed dose calculations were prepared for the period of largest releases (1950-1971), and ingestion of resident fish was identified as the most significant exposure pathway. The median cumulative effective dose equivalent for the maximally exposed person at Richland, Washington, for all years (1944-1992) was estimated to be about 15 mSv (1.5 rem) with the 10-year period 1956-1965 accounting for most of this cumulative dose (TSP 1994).
Previous NRC Reviews of the HEDR Project
The Radiation Studies Branch of NCEH used the NRC to provide an independent technical review of portions of the HEDR study. The review was considered important by NCEH in light of considerable public concern regarding the historical releases. Furthermore, NCEH hoped that the evaluation of the Hanford site might serve as a model for studies planned by NCEH at other sites. However, the NRC review was not the sole source of independent technical review for the HEDR Project. The TSP provided independent guidance to the project, and TSP activities were conducted in an open public forum. All reports were available in draft form for public review and comment, and many of the technical reports received scientific peer review. Typically, PNNL also organized its own scientific peer review of technical reports prior to any subsequent reviews arranged by the TSP. A brief overview of the different reviews performed by the NRC is provided below.
NCEH first asked the NRC to review four of the early HEDR reports that provided data and procedures for determining the annual and cumulative releases of I-131 (Heeb 1992), techniques for modeling environmental movement of radionuclides (Shipler and Napier 1992), and parameters for calculating doses (Snyder et al. 1992). The NRC issued a favorable review of these four documents and found the modeling approach to be conventional and sound (NRC 1994).
The NRC was later asked by NCEH to critically review draft versions of two HEDR summary reports (Farris et al. 1994a, 1994b). One documented the methods used to estimate doses received by representative individuals who were exposed, directly or indirectly, to I-131 released to the air; the other documented the methods used to estimate doses received by representative individuals who were exposed, directly or indirectly, to radionuclides released to the Columbia River. The committee published its review of the two draft reports the following year (NRC 1995). It commended the authors for producing reports that were signifi-
cantly improved over those the committee had reviewed earlier for the feasibility study, but it also indicated some concerns. The review offered a number of recommendations for improving the reports, and specific comments were presented in an appendix. After the dose estimates had been made for the HEDR Project, NCEH initiated a number of studies to address some remaining issues that had been identified by the TSP or that emerged following publication of the project findings. Those studies are described below.
In 1997, NCEH asked the NRC to address a number of specific issues related to the validation of the HEDR atmospheric I-131 pathway models. A central issue was the discrepancy between sagebrush vegetation measurements and concentrations predicted by the HEDR model. The task required the NRC to review components of the HEDR Project that had not previously been examined in any detail. The NRC issued a letter report concluding that the HEDR model was structurally sound, but there had been errors in the HEDR estimation of I-131 concentrations in pasture grass that needed to be formally documented (NRC 1999).
The HEDR Project focused on I-131 doses to members of the public located off-site. The doses to persons who worked or lived on-site, such as military personnel stationed on the reservation and construction workers present after the first reactors and processing plants became operational, were not addressed. Of potential concern was the exposure of on-site workers to short-lived radionuclides, and the exposure to episodic releases of large radioactive particles in the late 1940s and early 1950s. Radiological Assessments Corporation (RAC)4 was contracted by NCEH to develop a computer program to estimate “worst-case” doses to people living or working near the production facilities from radioactive particles and short-lived radionuclides. NCEH subsequently asked the NRC to review the draft report prepared by RAC. The NRC issued a letter report of its findings (NRC 2001). RAC’s final report to NCEH (Voillequé et al. 2002) took into account the comments of the NRC.
Hoffman et al. (1997), under contract to ATSDR, reviewed the HEDR Project dose estimates for radionuclides released to the Columbia River and suggested that I-131, cobalt-60 (Co-60), and strontium-90 (Sr-90) should have been included in the HEDR dose calculations and in the Hanford Individual Dose Assessment (IDA) process.5 This question was evaluated by RAC under contract to NCEH. NCEH asked the 2002 NRC committee to review the draft report prepared by RAC on this topic. The 2002 NRC committee issued a letter report with its review (NRC 2002). The review found the methodology that RAC developed
to be adequate but identified a number of inconsistencies between input data used by RAC as compared to that documented in HEDR, and the review recommended that the inconsistencies be corrected. The inconsistencies were corrected and the results presented in the final report (Grogan et al. 2002),6 taking into account the 2002 NRC committee’s review. Grogan et al. (2002) did not conclude that HEDR Project dose calculations were warranted for I-131 or Sr-90. The risks calculated for Co-60 accounted for a small fraction (1 to 2 percent) of the total risk from the river pathway scenarios that were evaluated. RAC recommended development of improved release estimates for Co-60 before attempting any further dose calculations. NCEH did not believe the study results indicated the need for any further analysis of this topic.
As stated previously, NCEH did not engage the NRC to review the entire HEDR Project. Instead, NCEH identified specific components for the committee to review as the project progressed. NCEH’s approach of assigning isolated portions of a project that lasted more than a decade for NRC review concerned the TSP. Following the earliest reviews, the TSP noted that some of the review conclusions implied that important work was not being done, when in many cases, these concerns were addressed in other reports that were not included in the review (Niles 1996). Furthermore, the NRC reviews were critical of the direction of some of the work and the level of effort invested in the river pathway, for example. TSP Chair Mary Lou Blazek disagreed with the conclusion, stating: “Given Hanford’s past operating history, and the huge amounts of radioactive material that we know went into the Columbia River, we had an obligation to those people who lived along the river to thoroughly evaluate the dose they may have received from Hanford releases to the river. I believe the work we have done fulfills that obligation” (Niles 1996).
It is not unusual to find instances in which resources are allocated to an issue that is relatively insignificant from a scientific perspective in terms of dose or risk. The dose reconstruction studies were initiated in response to public concern; although some issues may have a low priority based on scientific analysis, they can be important for establishing the credibility of the project.
LOS ALAMOS DOSE RECONSTRUCTION PROJECT
Los Alamos Laboratory began in 1943 as Project Y of the Manhattan Project with the mission of developing the world’s first nuclear weapon. This was achieved in August 1945. The laboratory continues to operate, and its mission has expanded from nuclear weapons development and testing, to stockpile steward-
Helen A. Grogan is a member of the current review committee and was a subcontractor to RAC on some NCEH studies (see committee biographies). The present committee did not evaluate Dr. Grogan’s work but reports an evaluation done by a previous NRC committee (NRC 2002).
ship, nuclear reactor and accelerator research, high-explosives and ordinance development and testing, waste disposal and incineration, and other chemical, biological, and energy-related studies. Currently, LANL’s mission is described as national security.
LANL is the DOE facility at which NCEH has begun many dose reconstruction activities. A 3-year study to review historical documents about off-site releases from LANL operations and to establish a publicly available database of relevant documents began in early 1999. The LAHDRA was performed under contract to NCEH by ENSR International, ChemRisk, Inc., and Shonka Research Associates, Inc. NCEH extended the contract to 5 years because the task took longer than anticipated. The interim project report issued in July 2004 (LAHDRA 2004) stated the following:
While millions of documents have been reviewed at Los Alamos, the information gathering is not complete. For various reasons that are discussed in this report, document review at Los Alamos has taken significantly longer than expected. There are now known to be significantly more documents at LANL than was originally estimated, and the processes for access to classified documents and for public release of relevant documents have been more complicated and time consuming than was expected … CDC will evaluate whether to competitively procure another contract to continue towards completion of information gathering and assessment at Los Alamos.
NCEH chose to continue the study, awarding a second 5-year contract in September 2004. Document review did not start until February 2005 because LANL was shut down following a number of security incidents. The work was performed by a team led by ChemRisk, Inc., and including Shonka Research Associates, Inc.; ENSR International; and Advanced Technologies and Laboratories International, Inc. The most recent interim report (LAHDRA 2006) issued nearly 7 years after the project started states: “The CDC project at Los Alamos is in the initial information-gathering phase. The process of information gathering and assessment is partially complete.”
The interim report (LAHDRA 2006) provides a summary of the information that has been obtained by the LAHDRA project team regarding
Historical operations at Los Alamos,
The materials that were used,
The materials that were likely released off-site,
Development of residential areas in Los Alamos, and
The relative importance of identified releases in terms of potential health risks.
The report also states: “Based on the project’s findings, CDC will work with stakeholders to determine if more detailed assessments of past releases are war-
ranted, they might be in the form of screening level evaluations, or could progress to detailed dose reconstructions for those releases of highest priority.”
The dose reconstruction effort at Los Alamos has progressed extremely slowly compared to any of the other DOE facilities where dose reconstruction studies have been conducted. Although some of the delays have resulted from circumstances beyond the control of NCEH, the length of time required to date suggests a lack of commitment on the part of LANL/DOE toward the dose reconstruction effort and an inability on the part of NCEH to find timely solutions. This extended delay undermines the credibility of the dose reconstruction process.
CONTRIBUTIONS TO DOE
For many of the DOE facilities, NCEH conducted dose reconstruction studies of historical exposures of the public independent of DOE. NCEH has established a scientifically sound public record of the operations of these facilities and the magnitude of the doses received by members of the surrounding communities. This independent and scientifically sound analysis benefits DOE by providing credible dose estimates to the public.
At the request of NCEH, the NRC identified and documented (NRC 1995) the different components and steps that comprise a high-quality, credible dose reconstruction. NCEH used this information to help design and conduct subsequent dose reconstruction activities.
Every DOE facility is different, in terms of the materials and quantities released to the environment, the time periods of releases, exposure pathways, demographics, and degree of public concern. This necessarily impacts the appropriate design of a dose reconstruction.
The NCEH program has provided valuable data to the communities surrounding DOE facilities in particular, and to the public in general, about the historic operations of those facilities, the environmental impacts, and the doses or health risks of individuals exposed to releases from the site.
FINDINGS AND RECOMMENDATIONS
1. The LAHDRA project at Los Alamos is the sole remaining dose reconstruction activity of NCEH and the public would benefit from the information derived from this activity. The initial data-gathering phase of the LAHDRA project is taking an inordinate length of time compared to similar stages at other DOE facilities. Therefore the committee recommends that:
NCEH complete this project as expeditiously as possible and provide as
much evaluation of the compiled data as feasible to inform the public regarding historical doses and risks.
2. The NCEH program has conducted dose reconstruction studies that are independent of DOE. These studies have provided valuable data to the communities surrounding DOE facilities in particular, and to the public in general, about the historic operations of those facilities, the environmental impacts, and the doses or health risks of individuals exposed to releases from the site. Therefore, the committee recommends that:
NCEH continue to make the findings of its dose reconstruction studies available to the public on-line, ideally including a direct link to the study results from the facility’s web site.
In the event that any further dose reconstructions at DOE sites are required, the committee recommends that NCEH or some other agency independent of DOE should manage and direct the studies and the funding for the studies should be provided by DOE.
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