ORRHES Meeting Minutes
June 11-12, 2001
The Agency for Toxic Substances and Disease Registry (ATSDR) and the Centers for Disease Control and Prevention (CDC) convened the fourth meeting of the Oak Ridge Reservation Health Effects Subcommittee (ORRHES) on June 11-12, 2001. The meeting, which was held at the Oak Ridge Mall in Oak Ridge, Tennessee, was begun by Chair Dr. Kowetha Davidson at 12:32 p.m.
Members present were:
Alfred A. Brooks
Kowetha A. Davidson, Chair
Edward L. Frome
Karen H. Galloway
Jeffrey P. Hill
David H. Johnson
Susan A. Kaplan
James F. Lewis
Donna Mims Mosby
Members Mr. Don Creasia, as was Mr. Charles Washington on June 11. The resignation of Dr. Ron Lands was regretfully announced, due to a change in his practice and schedule.
Ms. La Freta Dalton, Designated Federal Official (DFO) and Executive Secretary of the Subcommittee, was present.
All the liaisons to the Subcommittee attended:
Elmer Warren Akin, U.S. Environmental Protection Agency (EPA)
Brenda Vowell, R.N.C., Tennessee Department of Health
Chudi Nwangwa, Tennessee Department of Environmental Conservation (TDEC)
Agency staff present were:
ATSDR: Bert Cooper; William Carter, Greg Christenson, La Freta Dalton; Michael Grayson, Jack Hanley; Karl Markiewicz; Bill Murray; Therese NeSmith; Marilyn Palmer, Jerry Pereira.
DOE/Oak Ridge Reservation: Timothy Joseph
Tennessee Department of Health, Office of Minority Health: Robbie Jackman
Others present over the course of the meeting included:
Owen Hoffman, SENES
Bill Moore, Tennessee State Epidemiologist
Norman Mulvenon, LOC/CAP
Dwight Napp, Save Our Cumberland Mountains
Grace Paranzino, MCP MCP Hahnemann University
Debbie West, court reporter
Dr. Davidson welcome the attenders and thanked the Department of Energy for the tour of the ORNL facility provided that morning. The Subcommittee members briefly stopped by the graphite reactor, site of lithium separations process and the smoke stack associated with the those releases; the area of the underground Gunite tanks now being cleaned, the intersection of White Oak Creek and the Clinch River; the Solid Waste Storage Area #4; the molten salt reactor, and the cesium plots. Dr. Davidson also reported a meeting of the Work Group Chairs, and their discussion of the COSMOS recommendations presented at the last meeting. Designated Federal Official Ms. Lafreta Dalton also welcome everyone to the ORRHES meeting.
Dr. Davidson reviewed the agenda and drew the members' attention to inclusions in the meeting materials: a glossary of terms from ATSDR and the final draft of ORRHES Bylaws. No comments were voiced about the minutes of the March 2001 meeting, which were approved. Most of the action items listed therein had been accomplished. The minutes from April 24th conference call were also approved.
Dr. Greg Christenson, Acting Director of the Division of Health Education and Promotion, discussed some of the issues addressed by the Division and its work at the Oak Ridge site. The Search Committee for a permanent Director developed a list of candidates for ATSDR Assistant Administrator Dr. Henry Falk. They will be interviewed between July 5-20, after which a new Director may be named. Dr. Christenson is not a candidate. He noted the importance of continuity to this community, and reassured the Subcommittee members that ATSDR's activities at Oak Ridge are part of the Division's core program, and will be done. The establishment of the ATSDR office in Oak Ridge is just one indication of that commitment.
Dr. Christenson provided an overview of the Division. Its has three Branches:
The Risk Communication and Research Branch conducts case studies in environmental medicine that update physicians on the latest science and its clinical applications. About 33 case studies are complete now, and 4-5 are in development. For example, a current study in development is on iodine-131 (I-131), which should be available to be part of the George Washington University (GWU)/MCP Hahnemann University-developed Provider Education Program at Oak Ridge. Most are topical, focusing on a specific toxin or chemical, but others are more general, such as one for physicians on how to take an environmental history and another on the application of environmental health to the pediatric field.
The Health Education Branch, in which Ms. NeSmith works, develops strategies, models, and materials for educating populations in general as well as physician and provider education materials. These two Branches work together in a process to allow outreach to community members and providers to provide the information that they need.
The Health Promotion Branch conducts environmental health intervention programs, including the needs assessment being done at Oak Ridge by GWU. That is expected to result in a work plan to direct future activities to help this community, and help ATSDR's other Divisions to support those activities. Oak Ridge has the potential of using many ATSDR resources. Those processes are beginning, but as often happens, things seems to take a little longer than expected.
Mr. Lewis: What are the various components of the work plan, and how does it interact with the needs assessment? This is a health education work plan that will be developed from the analysis of the needs assessment's information, derived from the telephone survey, focus groups, and key informant information. Using that information, educational strategies will be designed to intervene to provide the necessary information for the special needs of subgroups or the population in general. The basic work plan will evolve from the health education requirements and the needs assessment, and the basic science done by the Division of Health Care Assessment and Consultation in developing of the health assessment.
Dr. Brooks: Can you provide information useful to develop a program of work to address contaminants of concern, and a loose timetable for the ORRHES meetings at which these will be discussed, for the Health Needs Assessment? We can developed a time line for the needs assessment's conduct and analysis, in general, but some things cannot be controlled (e.g., other people's schedules, and Institutional Review Board [IRB] approvals). Dr. Brooks expressed the Subcommittee's understanding that this would be a living document with likely slippage, and agreed to provide the style developed in order to have such a guidance document ready for the next committee meeting. This is not ATSDR's longer program of work document, just a brief 1-2 pager to identify the tasks on a time line.
Dr. Malmquist: Can you assure us that this health needs assessment will focus on the environmental impact from the reservation upon the general population? The ATSDR is not looking for general chronic health problems such as cardiovascular disease, but for health issues related to potential environmental hazards in the community
Dr. Brooks: This community distinguishes between environment hazards related to the Oak Ridge Reservation (ORR) and environmental hazards in general. Dr. Paranzino will most likely address issues of general concern environmentally and specifically target those that this community would focus on.
Mr. Lewis: In releasing messages, the major components of developing the work plan of the assessment process should be explained in a little more detail in layman's terms; and what will be the components of that educational piece, to community, physicians; using television? All the necessary information will be released on a fact sheet which should be ready relatively soon. But the information transfer process is complicated, requiring not only physician but also community training, so the latter can ask and respond to appropriate questions with their health care provider. Education for both groups will be pursued. The environmental health care intervention program will involve on-the-job training for local practitioners in which clinically experienced, environmental health experts share in seeing their patients who may have diseases related to environmental issues. This paradigm has been demonstrably successful in chronic disease (e.g., breast or cervical cancer screenings) and are hoped to be similarly helpful for environmental health applications.
Mr. Lewis: What is our status as a Subcommittee relative to some of ATSDR's other sites? Several sites are experiencing this strategy of community and health care provider education, so determination of the program's effectiveness is still pending. At least anecdotally, linking educators and communities in implementing this strategy is an effective method, even in the environment health area.
Dr. Brooks: How will ATSDR address the problem left in the community, if the study cannot prove that the health concerns they believe are ORR-associated? That is a complicated issue. Historically, it may well be that the health assessment will find association between ORR contaminants and the city of Oak Ridge's health problems. Education can not do everything, but it might be able to reduce the stress level and help provide more realism about what the potential conclusions may be. A federal agency can only do so much, and is limited in its ability in a short period of time to address the community's long-developing perception of effects may have resulted from the reservation's work. Some members of the community will not be satisfied with how ATSDR addresses that. But the best it can do is to provide the most accurate, most reflective response to the information gathered, to help the community at least understand what science knows and does not know at this point in time.
- Dr. Brooks: Will you stick around for a little while and help us allay these fears, not forever, but long enough for a reasonable effort to convey the findings through the community? ATSDR is committed to stay at the site to do the health assessment and what is necessary to explain its results, and to be certain the processes are all completed. This as a priority site. ATSDR will remain as long as a reasonable contribution is being made.
Dr. Grace Paranzino, of MCP Hahnemann University, updated the Subcommittee on the status of the Health Needs Assessment being conducted by George Washington University (GWU) and Hahnemann. They revised some of the survey tools after the last IRB meeting, which will remain in draft format pending feedback from the Subcommittee, after which they will be resubmitted for the IRBs' approval. The latter are necessary to ensure that the study is ethically conducted, scientifically founded, and properly budget. The Tennessee Department of Health also has asked to see them. Work remaining includes the key resource interviews, telephone survey, focus groups, and final report. The questionnaire format has been completed, and is in review by the various IRBs.
The key resource interviews will begin in mid-June and be completed some time in July. The geographic areas to be sampled by the telephone survey was narrowed with the Subcommittee's help; the exchanges to be called were identified, and random numbers in each will be called in August. The survey question draft is completed. About 400 people will be surveyed, which may well require ~1200 calls. The initial screening questions will help identify those willing to participate. GWU/MCP Hahnemann will submit any final suggestions from the key resource interviews back to the working group for approval and then modify the survey as needed. The focus groups, defined with the input of the key resource interviews and the telephone surveys, will be held in September. They will involve the different subsets of the population that have issues of concern and focus on the health effects and health education needs related to the ORR, along with a few general questions.
The target date to complete the Health Needs Assessment is the end of December. The final report will forwarded through the Work Group to the Subcommittee and ATSDR for comments, revisions and modifications as needed.
Dr. Brooks: Please translate your time to line to the Subcommittee meeting dates at which these things will be reported. And, will you screen the effects of the environment pollutants from the Kingston and Bull Run power plants, whose interaction with the ORR pollution concerns many people? If they are conceived as being a part of the overall ORR picture, GWU/Hahnemanns would need to separate that out.
Dr. Brooks: Is your "work plan" part of the ATSDR plan? Yes, the health education action plan is to define what people want to know more about regarding health education, to identify the forces involved (i.e., resources that will facilitate the process or that need to be developed); and how to get that information out the community and health care providers, including alternative strategies if limited resources require them.
Dr. Brooks: Does the action plan derive solely from the health needs assessment, or is there input from the health assessment? Dr. Christenson answered, both; it will be a joint effort by the Division of Health Assessment and Consultation and the Division of Health Education and Promotion.
Dr. Davidson: Is the health education action plan part of the December report? Yes.
Mr. Lewis: Will there be one or two sets of questions in the screening process, one to screen people out and another of detailed questions? Sharing the screening questions would help alleviate concerns about what is being targeted. GWU/MCP Hahnemann have no problems sharing the general theme of the questions and how they will be asked, but they cannot be a public document for fear of biasing the process.
Mr. Lewis: What were your opinions/conclusions from the documents reviewed, and how will they be used? For example, from where did such reports as the one on community diagnoses originate? How will they be used? Many surveys have been done of the ORR area, all of value in some way. GWU/Hahnemann's role is not to critique them, but just to see what they offered that might benefit this work. Some of that work's methodology was similar (e.g., focus groups and telephone surveys), but most of those focused on general parameters or general indicators of health in Oak Ridge and surrounding communities, as opposed to this project's tailoring it to be more specific to the ORR.
- Mr. Akin: How will ATSDR respond to the comments on the December draft report? Could they initiate more work? It depends on the comments. The responses would not necessarily be individual; GWU/Hahnemann would respond to the comments and direct them either to the Work Group, the Subcommittee, or ATSDR. If the comment defines a limitation that cannot be corrected, that is acknowledged; more research could be a Subcommittee recommendation to ATSDR.
Mr. David Hackett is a local professional engineer in private practice. Confusing this Subcommittee with the ORHASP, he stated that ten years of this committee's work and dose reconstruction had produced far too little. He respected Dr. Hoffman's attempt better understand "the mess here in Oak Ridge," but in his opinion, rather than science, the work done here has been a smoke screen to confuse the public. Aside from I-131, the public has not been reassured that they have not been exposed to carcinogenic levels of uranium, fluorine, nickel, arsenic, mercury, chromium, neptunium, plutonium, or beryllium. He called the work done to date pseudo science done with randomly selected exposure standards and falsified reported data. He was convinced that it was a malicious ruse by the government to convince the community it has been protected all along. Oak Ridge knows better.
He condemned "the scoundrels whose ... opinions are for sale to the highest bidder" to protect actions of the past and termed the I-131 study "trash." He called for closer scrutiny of where the data originated from. In his opinion, what Oak Ridge needs and has asked for is a health study to show the exposures have been, and health care for those already sick and dying. He cited increased local cancer rates and the disruption of many area residents' immune systems. He asked rhetorically, If it is so safe, why millions are needed to clean up the environment. He charged that exposure standards treat exposed humans as canaries were in the mines. The human response is such that on the bell curve, only a few sensitive individuals will be harmed (the canaries). It took two million "canaries" getting sick to lower the standards. He called for an end to cover-ups of toxic exposures and real study of the health effects of low doses that display no overt symptoms for years but continuously undermine the immune and central nervous systems. He felt that any decent scientists with expertise will willing acknowledge how much they don't know as well as what they do, and those who speak knowingly and confidently "... are certainly full of (manure.)"
Dr. Davidson requested that the public commenters remember the codes of conduct for the meeting and asked Mr. Hackett to provide his written comments.
Ms. Janice Stokes thanked the members for their service. While she respected the members, she had more of a problem with the past actions of ATSDR, CDC, and DOE, the source of much of the anger heard, regarding their scientific methods and the truthfulness of the documents used. She urged the panel to not accept everything provided by ATSDR as acceptable science. She also requested that public comment be allowed in the presentations by Dr. Hoffman, Dr. Widner, and Mr. Hanley, as well as throughout the meeting, so that the public who cannot wait to the specified comment periods have an opportunity to speak and ask questions on the record. Such a procedure would allow the full history of events to come out.
Dr. Davidson responded that that format had been considered, but the Subcommittee wished to avoid losing the time for full presentations and preserving time for questions. The entire agenda could be disrupted by getting caught up in questions during the presentations. In addition, four presenters were scheduled over four hours to allow time for questions. If they speak for less time, discussion is possible. Ms. Stokes asked why the Subcommittee even bothers to have the public come, if such a controlled environment is desired, and noted that there is no affected citizen on the panel.
The State of Tennessee's Oak Ridge Studies, July 19, 1999, Task One Report, was presented and discussed, focusing on the technical issues of the dose calculation, risk estimates, probability of causation, excess cancer, and thyroid cancer analysis. The discussants were Dr. Tom Widner, of JA Jones Environmental Services; Dr. Bob Peelle of the ORHASP; Dr. Owen Hoffman, of SENES Oak Ridge; and Dr. Michael Grayson of ASTDR.
Mr. Jerry Pereira of ATSDR noted the unlikelihood that anyone's opinion would be changed by these presentations on this day. He commented that the purpose for this panel was for the Subcommittee to collectively listen, learn, and perhaps make some personal judgments; and then to proceed with it work. He hoped that listening from that viewpoint would everyone to have a better perspective on the information.
Dr. Robert Peelle began with the study's background. The State of Tennessee commissioned a study of potential offsite health effects from the ORR, which DOE agreed to fund and which began in 1974. One of the priority contaminants determined by a feasibility study was radioiodine from the Radioactive Lanthanum (RaLa) process. The ORHASP Committee was reorganized during this project. The ORHASP was a committee of citizens and experts, which monitored the progress of the study and interacted with the interested public who attended their meetings. Their activity ranged between active oversight and passive review.
The panel had no interest in judging the DOE or the Atomic Energy Commission (AEC), but only to determine the facts. They pushed for a serious records search to explore anything related to potentially hazardous off-site releases. Over time, the DOE policies changed and they cooperated in searching for records. The panel also strove to produce unbiased risk estimates and to be respectful of the public's concerns. They explicitly considered the variability of the individuals affected (age, weight, size of thyroid gland, etc.) by approximating the variables' distribution of density, function, and frequency in the population. They then combined all the data available in a Monte Carlo analysis to determine the 95% confidence level. That is, the actual truth could be 5% higher or a little lower, lying within the ends of a confidence interval.
The confidence limits were so defined because there is no evidence that the median value is either the real or the best answer. This is because many of the parameters in the analysis offer little data, and because it is not certain that the best value was estimated. Finally, the panel assumed that the doses had no threshold for excess cancer risk. They addressed what appeared to be the most important pathways of contamination, and set the lesser ones aside for later study.
Dr. Tom Widner, who was the Project Director of the work described by Dr. Peelle, provided more detail. The initial feasibility study reviewed Oak Ridge work from the beginning of the site's operations, and identified four materials of concern. The dose reconstruction explored those, fed by a systematic document search. The final deliverables of the Oak Ridge dose reconstruction were the draft and final task reports, a nine volume set; the ORHASP report; and a project summary which briefly covered the whole project and offered sample exposure scenarios to demonstrate how people could have been exposed to multiple contaminants over time. The Tennessee Department of Health Website has extensive information (he also brought hard copies to this meeting), and many of the source documents will soon be available on the Internet.
Dr. Widner focused on the RaLa process, which resulted from Dr. Robert Oppenheimer's request for it to help Los Alamos' early weapons explosion design testing. The source material for this radioactive lanthanum was radioactive barium 140, which was made in Clinton, in the Oak Ridge area. At Los Alamos, a round sphere containing the lanthanum was exploded; the lanthanum's very high gamma rays were used to measure the timing and uniformity of the implosion.
RaLa Process: The RaLa processing was the dominant iodine source due to its short cooling time and the large number of barium slugs processed. Natural uranium was placed into a reactor and divided into fission products, including barium, which decayed to the lanthanum 140 desired by Los Alamos. In the RaLa processing building, those fuel solutions were quickly dissolved in nitric acid (due to barium's short half-life). This process also released other fission projects such as I-131. The iodine-to-pasture pathway was still unknown at that time, and little environmental or process sampling for iodine was done.
Lanthanum processing emission points included: 1) the caustic scrubber, which was designed to reduce the acid vapor emissions, but may not have reduced the iodine as well, and 2) the processing equipment itself, which was used well beyond its design capacity. Designed to make 1000 curie batches of barium, they instead made up to 65,000 curie batches without upgrading the equipment.
The study screened out I-133 as a contaminant of concern when it was found to not have elevated the ingestion pathways. That was supported by a systematic document search of ~40 record repositories and interviews of current and former workers. The Clinton processing lines were prioritized because they involved large amounts of nuclear fuel with relatively short decay times, or had well-documented instances of off-site contamination before the off-gas treatment systems were perfected at Oak Ridge.
The source term is the quantity released, its timing, and the forms of the release. The records provided a chronology of ~80 RaLa batches. The study calculated how much iodine was within each of the fuel slugs. Some decay occurred between the 2-14 hours between removal from the reactor and its placement in the dissolver, but the slugs from Hanford took 5-6 days to transport. Original operations and health physics logbooks enabled classification of each dissolving batch, based on how likely its releases were to have bypassed the caustic scrubber. In some cases, the leaks were so strong that the operators had to wear respirators to complete the run.
The RaLa process was unpredictable. To compensate for the lack of monitoring, the study estimated iodine behavior in the system in several ways: expert opinion, modeling of the process, and the experience of other sites. The iodine species in the dissolver was thought to be either elemental, organic, or particulate iodine form. They estimated the mixture of iodine isotopes in the dissolver, how much was released to the gas removed from the dissolver to the scrubber and the stack, and how much was left on the scrubber. Dr. Widner outlined some the expertise of those who were consulted.
There were virtually no measurements of the iodine species in the dissolver, but they estimated it to be 94-99% elemental and fractional amounts of volatile organic, non-volatile, and particulate forms. Oak Ridge did not use any organic reagents in the process, so only trace organic iodine was thought to be present. The scrubbers were supposed to be 99% efficient in capturing the elemental iodine and 1-10% efficient for the volatile organic and particulate forms. A scrubber model that was developed estimated 99% capture efficiencies for the scrubber when the caustic solution was used. When water was used instead, the efficiency was lower by a factor of ten.
However, the study experts consulted thought those collection efficiencies to be overestimates. Based on Oak Ridge monitoring studies and scrubber experience at other sites, and a RaLa monitoring study done at one point in time over the 13 years, they concluded a 90-99% efficiency for elemental iodine and 50-99% when water was in the scrubber. Particulate releases were estimated from processing stack sampling data.
Modeling of the elemental iodine releases estimated a line loss of 20-70%. The well-documented line problems prompted the study to increase the line loss factor. The elemental, organic, and particulate releases were summarized. The modern-day annual intake limit is .0005 curies. Much higher releases were documented in 1954 during an uncontrolled release that lasted from one-half to four hours. However, these releases ended up to be a very small fraction of the routine releases (280 of 21,000 curies normally released).
Elemental iodine can break down the presence of sunlight to form other forms of iodine; organic iodine does so at a much slower rate. So, the most important chemical transformation would be from elemental to organic iodine, a transformation the dispersion model took into account. However, organic or particulate iodine remains in those forms while traveling to the receptor. Depletion or reduction could occur during wet deposition (washed out of clouds by rain and dew). Dry deposition was also modeled with what meteorological data were available. Some hourly data could be analyzed as well to develop a statistical set of probability distributions for each month and each hour of the day by wind speed, direction, and atmospheric stability.
Deposition is a parameter that describes the iodine's rate of transfer from the air to the surface of ground or vegetation. The ratio of the air concentration to the deposition flux, to the ground or to the plants, is called velocity of deposition. There was good such data for the time of the 1954 accident, which was modeled for the 38 kilometers around the X-10 central stack. That area was divided into sixteen directional segments or sectors, with about 25 distances in each direction, in a dispersion grid.
The air dispersion model was validated with monitoring data available from 1967 to 1969 at nine sampling stations near or on the reservation, which were compared using the ISC and IAC models. The study's model results were within a factor of two of the observations, and the other models were within a factor of three. That indicated the model's adequacy for estimating routine releases of iodine from X-10.
To estimate short-term releases, health physics reports of specific iodine curies released were compared to the modeling results. For two episodes, the model prediction and actual measurements were within the 95% confidence interval; the model under-predicted other episode. Appendix 11 of the study report provides the dispersion model's detailed concentration estimates for the study domain and the estimated concentrations in the other environmental media.
Vegetation deposition is important for iodine. The literature provided parameters with which to estimate the behavior of iodine released on vegetation, and there were some field measurements of deposition velocity. Those, with available rain data, produced deposition distributions over time, correlating precipitation data to the routine releases. The transfer from pasture to food/milk was then calculated. Some validation of predictions of iodine concentration in milk were done with milk measurements from 1962-64, compared to the monitoring stations' measurements. Almost universally, the average measured concentrations were in the predicted 95% confidence level.
Distribution of food products was accounted for (time lapse of milk/food processing to delivery) in the reduction of iodine concentration in the consumer, based on literature reviews and interviews. Food intake by humans was estimated for different age groups and genders, and for inhalation. Internal dosimetry is enabled by standard calculated dose coefficients to the thyroid gland for a given intake of I-137. The mass of the thyroid gland was a key parameter in calculating the dose to the thyroid. The smaller the mass, as in children, the higher was the energy deposited per unit mass and the dose. The dose factors were also recalculated in uncertainty analysis to try to determine which parameters of the dose calculations most contributed to the overall uncertainty of results. Ultimately, the data indicated that the smaller thyroid mass was offset by the faster clearance time of iodine from the thyroid glands. In the end, the study's calculated dose factors were very close to the calculated dose factors of the International Council for Radiation Protection (ICRP).
Calculation of Excess Risk. Next, the study examined thyroid risk per unit of radiation dose. The literature has established that x- and gamma radiation of the thyroid causes thyroid cancer as well as adenomas to people exposed under age 15. Relative risk is a factor by which the background risk of cancer is increased by a given iodine dose. Absolute risk is an average number of cases of thyroid cancer observed above the expected amount for ten thousand person-years of exposure.
The sources of relative risk factors were defined for young children (<14 years) came from the 1995 National Cancer Institute (NCI) study of Ron et al; the atomic bomb survivor studies provided those for older adolescents aged >14 years. The studies showed no effects exposure above age 40. Females are generally more sensitive than males.
Modifying factors include the relative effectiveness of I-131 compared to external radiation by X- or gamma rays, and age at exposure (e.g., 1.0 for children aged <5, .2 for those aged 10-14 years, etc.). Those most exposed are those aged <5 years. Above age 14 involves a different relative risk factor. Females are .2 to five times as susceptible as males. Each value between .2 and 5 had its own probability; and compared to external radiation, iodine ranged from equally effective to five times less effective.
Background risk was determined with the Tennessee Department of Health's thyroid cancer incidence rates from 1988 to 1995 for all Tennessee counties except the four counties around Oak Ridge. Most thyroid nodules are benign, and ultrasound finds more nodules than palpation of the thyroid glands. But since only ~28% of thyroid cancers are diagnosed and reported, the total possible cancers could be 3-4 times the number estimated in this study, based on clinical diagnosis. There is evidence of radiation exposure's association with non-neoplastic thyroid diseases such as autoimmune hypothyroidism. These are discussed in the report, but the incidence rates of benign tumors or autoimmune diseases were not estimated.
Other variables were reflected in the study report's contour data plots of concentrations in the environment media; locations, age, and gender of the receptors, and diets (four were modeled, including those who drank cow's and goat's milk). A plot of thyroid cancer for people born in 1952 who ate local produce and drank a backyard cow's milk showed a pattern of contamination, with dose patterns roughly following the ridge and valley terrain from the southwest towards northwest. Concentrations decreased with distance out to the 38 km. The nine birth years were similarly charted to bracket the exposure, keeping in mind that RALA releases were from 1944 to 56.
At points of exposure, females born in 1952 received the highest exposure, higher for those drinking backyard cow milk. The influence of local fallout from Nevada Test Site (NTS) atmosphere weapons testing was added to the study doses. Bradbury was one of the most affected locations, with doses dominated by the X-10 releases. Its upper bound was 200 centiGrays (or 200 rad) compared to the 48 from the NTS fallout.
Estimation of health effects included estimation of the number of thyroid cancers expected between 1950 and the year the 2020 from the contamination of milk from X-10 releases. The calculations of average time and space concentrations, volumes of milk produced in the area, and the dose and risk factors earlier described, produced an expected 6-84 excess thyroid cancers within 38 kilometers; 1-33 from backyard cow milk consumption; 14-103 excess cancers within 100 km, and 25-149 within 200 km. Most of those cancers could be expected to occur after 1970; a few could occur up to 2020.
Some changes were made to the I-131 report between November of '98 and the June 1999 final report. A written summary of all of the changes showed most of them to be typographical or made to facilitate distribution (printed, electronic), or to emphasize points. Two areas of controversy were somewhat de-emphasized: 1) non-neoplastic thyroid disease, and how strong a statement could be made about how many other thyroid effects would be expected beyond thyroid cancer; ad 2) comparisons made with the Tennessee disease registry between thyroid cancer incidence for the four local counties compared to the rest of the state. A basic comparison between the four local counties and the rest of the state implied one conclusion; but when estimates of the uncertainty of observed differences in thyroid cancer for whites and blacks, and comparison of thyroid cancer rates among whites in the four counties to whites statewide, implied another conclusion.
Dr. Peelle summarized the lack of monitoring and late recognition of the milk pathways of contamination. He noted that Oak Ridge city residents and workers were not highly exposed at work because the air inhalation was not the important pathway. Only those aged 5 and drinking a lot of milk were at high risk, particularly those who drank goat's milk. There was a large range of risk. Some thyroid cancers occurred, but most were within 25 miles, even though the highest-risk individuals were right across the river. The large number of exposures at a lower risk related to most cancers, which total perhaps a couple of dozen. That is the scale of the problem. Finally, he stated that the threshold of risk from a radiation dose to the thyroid would not be a very large problem because the risk was very small for a large number of people. Nonetheless, the study assumed that there was no threshold of risk, the conservative path.
The ORHASP issued nine recommendations, most dealing with the study's body of work. But the first recommendation, thought by most of the panel to be the most important, pertained to communication to the public and their perceptions of the problem. The residents' concerns often appeared unrelated to the most significant releases identified. A series of initiatives and public health activities were was recommended: ensuring that physicians get information so that they can look for thyroid problems; strong consideration of a clinic to evaluate those who may have been affected; and advice against doing an epidemiological study of some of the contaminants. The ORHASP members remain fairly certain that this is not a feasible study, even though they are convinced that there have been thyroid cancers. They believe that meaningful results will be prevented by either a large cohort diluting the number of risk-associated cancers, or such a small number at high risk that there would not be enough study power to detect the association.
Discussion, held after a short break, included:
Dr. Eklund: How did the release estimates change during the I-131 project? Dr. Widner: The final report describes the decline from the 1996 rough screening assumption of an 80% iodine efficiency capture, through more detailed analysis of, principally, the scrubber efficiency using the uncertainty analysis of the Monte Carlo assessment.
Mr. Manley: What happened to the workers involved in the X-10 and Hanford incidents? Those in the building immediately left and stayed away at least 12 hours due to high radiation levels. Thyroid counts on those workers have been reviewed, but there was no evidence of long-term follow-up found. Dr. Peelle was present that day, and reiterated that iodine most affects children under age 14.
Ms. Sonnenburg: Where did the figure of 28% of the total thyroid cancers in population being diagnosed and reported come from? That is a nationwide average. Dr. Hoffman added that this information comes from the Institute of Medicine IOM) in Washington, D.C., which reviewed the National Cancer Institute (NCI) study on I-131 and fallout. They found that diagnosis of existing thyroid cancers in a population depends on the physician's practice (the common physical palpation of the neck or ultrasound). But the ratio between what is diagnosed and what actually exists in a population comes from autopsy data. Many people who have thyroid cancer die of something else.
Dr. Frome: What kind of assumptions about the distributions and the various risk groups in the geographic area did you make in doing your calculations of excess risk? The assumptions include what the amount released and what fraction of contaminated milk was consumed by children under age 15, regardless of where they lived, to produce a reasonable estimate of the expected excess cases, and the assumption that over age 15 the risk is markedly less. Dr. Frome: How do you know that the parameters for children would differ from those for adults? That isn't known, exactly; the the range of scientific confidence is known, which is expressed as an uncertain variable. But the main difference is in the mass of the thyroid; any other metabolic difference between children and adults is small.
Dr. Brooks: There appear to be inconsistencies in the report about the scrubber, regarding practices, and that the sparse performance data provided is experimental data that lies well outside the assumed range of distribution function for scrubber efficiency. This ignoring of book parameters, without any definitive discussion of why, raises questions. And, the Knoxville reference diet is urban, with no backyard cows, differing from that of rural areas such as Oak Ridge. What difference would the predicted rates be with a more exurban diet. Dr. Peelle responded that the diet was not Knoxville's, but commercial milk, and in 41 locations. Average numbers are given for commercial milk from the region.
- Ms. Stoke objected that commercial milk in this area came from backyard cows; in fact, some of Knoxville's milk came from her grandfather's farm. And even today, metropolitan areas still have local producers. She asked if the tumor registry data was available to the public? Dr. Bill Moore, the Tennessee State Epidemiologist, reported that the cancer registry is alive and well, but is 3-4 years out of date. It is updated every day, but this a passive surveillance system that depends on voluntary reporting by institutions and physicians. Delays in reports are normal. Requests for information should be sent to Dr. Tony Bounds, who is in charge of the state registry, in Nashville.
Dr. Owen Hoffman was the task leader for the I-131 study, which took four years to do. The final report on the I-131 task was delivered by the City of Oak Ridge to the State of Tennessee in November 1998. Since then, SENES has put the report contents in a computer code, which he demonstrated.
But first, Dr. Hoffman discussed the health implications of combined exposure to multiple sources of I-131 other than the RaLa releases. He defined the measurement term of one rad as 1/100 of a Gray, or one centiGray. A very high dose of about 2000 centiGrays, the dose used by therapeutic medicine, can destroy the thyroid gland. The patient takes hormone replacement for a lifetime to offset hypothyroidism. The only environmental examples of such thyroid destruction are the few children on Rongelap, Marshall Islants, who in 1954 were exposed to fallout from Shot Bravo, the highest iodine exposure event known. At lower doses (<100 cGy/rad), thyroid cancer or benign thyroid growths called neoplasms can occur. The greatest risk is in females, especially those exposed in childhood, and to children in general. There is a 90% survival rate 20-30 thirty years after thyroid cancer treatment; it is seldom fatal.
The limits of epidemiological detection (ability to find an effect that is truly present) is between ~10 and 30 cGy. But the inability of an epidemiological study to detect below these levels does not mean that the risk is zero. The recent literature indicate that the risk for I-131 is not much different than any other type of radiation in inducing thyroid cancer (as seen in NTS and Chernobyl exposures). Epidemiological studies' statistical power is compromised due to the very high uncertainty of the dose estimate, and low statistical power most likely prevents the ability to see an effect. The NCI recently agreed that the weight of uncertainty leans toward no difference at all for I-131 than from other radiation exposures; that there is no dose below which there is no risk; and that the risk markedly decreases with increasing age at exposure, with only a small difference due to gender. The NCI's updated epidemiological tables parallel the confidence intervals of the risk factors for excess risk per Gray found by the Oak Ridge dose reconstruction, and recent epidemiological data of children exposed to the NTS fallout and Chernobyl are similar.
Other health outcomes from exposure to radiation include non-cancerous growths to the thyroid and benign nodules; thyroid function diseases such as autoimmune thyroiditis, such as Hashimoto's hypothyroidism (under-active thyroid) or Graves Disease (over-active thyroid). In some cases, these affect the quality of life more than thyroid cancer. The IOM's summary of the evidence indicated that the risk of autoimmune thyroiditis can occur at doses <100 cGy, but it is unlikely at <10 cGy. Therefore, the elevated risk is plausible at a range of 10-100 cGy.
Sources of I-131 exposure include medicines, nuclear facility releases (especially from accidents), and nuclear weapons testing. SENES believes that the release estimates from Oak Ridge should include the caustic scrubber and X-10 releases and be raised. In addition, Hanford released ~900,000 Curies (Ci) of I-131 (a curie is 37 billion disintegrations of radioactivity per second; the international unit is the Becquerel, one disintegration per second). The Savannah River site released ~65,000 Ci in the most recent estimate; Chernobyl released ~50 million Ci; the NTS released 150 million Ci and the Marshall Island testings released ~8 billion Ci. The amount from the former Soviet Union has yet to be totaled.
About 100 atomic tests were detonated in the atmosphere, from towers, tethered balloons, or test sites. Depending on the height of the mushroom cloud, the wind carried these clouds in different directions, but mostly to the east. The U.S. depositions were estimated by mathematical models from the deposits on a gummed film network, 8½x11" sheets of paper placed at breast height and changed daily. The models calculated the gross beta activity to how much I-131 would be in air, and then adjusted for local amounts of rain (which aided deposition). The measurements in the gummed film areas are more certain than those a distance from them. Fallout raised radiation background exposure substantially, and that occurred at the same time as the X-10 releases.
Dr. Hoffman showed the NCI's map of the U.S. with the average I-131 dose per person for each U.S. county. Most of the dose appears to be in the west and some in the northeast, but it focuses on the average individual and the average date. The map of those who were children at the time (born in 1946) and drank millk showed no counties with an average dose of >30 rad; 130 counties with 10-30 rad exposure; 1,600 counties between 3-10 rads, for children born in 1946. But the same counties, for children born in 1952 who also had average milk consumption, showed six counties with an average dose of ~30 rads; 914 at 10-1000 rad; and 700 at 3-10 rad. And those with the same birth date but drinking higher-than-average amounts of milk, 236 counties had an average dose of 30 rads; and 1912 had doses at 10-30 rads.
The Oak Ridge dose reconstruction was the first to add in the impact of NTS fallout. The map of Tennessee, initially seemingly unaffected, is included in the >3 rad county dose. That dose is high enough to induce auto immune thyroiditis, particularly if a child drank goat's milk and to a lesser extent backyard cow's milk, regardless of the location of residence. Fallout exposure alone places one into the risk range for auto-immune thyroiditis.
With that, Dr. Hoffman demonstrated the updated SENES dose and risk calculation program for combined exposures locally. It included I-131 released from X-10, the original estimates from the dose reconstruction, the caustic scrubbers and other ORR releases; and the NTS fallout, but not that from the Marshall Islands or the former Soviet Union. It follows the milk pathway and estimates probable doses with a Monte Carlo simulation. The latter produces subjective probability distributions for each uncertain parameter, through a mathematical model that produces alternative realizations of the true (but unknown) value of the thyroid dose, and eventually of the thyroid risk. Its result is expressed in the 95% confidence interval of one central estimate. The program, IRAD, or Interactive Risk and Dose Calculator, is a prototype, which Dr. Hoffman hopes to put on the Web for public access. IRAD does not yet address the additional contribution of leafy vegetables or cottage cheese, but those can be added.
He used the program to calculate the dose to a Bradbury resident who was female and born in 1952, present in the Oak Ridge area from to 1957, and drank milk from a backyard cow (the program can also calculate for regional or local commercial milk and dairy goats). The calculations showed the Bradbury NTS fallout to be less of a risk than the X-10 RaLa releases. Those are an order of magnitude higher than any regulatory standard. The excess lifetime risk for NTS fallout ranged from several chances in ten thousand up to ~2 in 100 from X-10, in a total range of ~2 chances in 1000 to 7 in 100.
From a medical point of view, these are minimal risks; a person currently free of disease is likely to remain so. But if a person has thyroid cancer, the probability of causation comes into question. That, in fact, is the main focus of the current update of the 1985 radioepidemiological tables, the estimates of which parallel the dose reconstruction's 1998 estimates. They concluded that NTS fallout alone provided an 11-80% chance of causing an existing disease; or a 26-94% chance that X-10 releases had, for a backyard cow scenario.
Dr. Hoffman did the Oak Ridge calculations for both regional and local commercial suppliers, for an average consumption of three 8-oz. glasses a day. Since most of the milk came from regional dairies, the ORR releases were diluted, resulting in lower risks than those from a backyard cow milk in Bradbury. For X-10 operations, they were again lower, ~3:10,000 chances, and an upper limit of 3:1000. The probability that an Oak Ridge resident's thyroid cancer was caused by ORR exposure is low, although NTS fallout could still be a substantial contributing factor. Dr. Hoffman then did the same calculations for local commercial milk, which raised the Oak Ridge milk dose from <1 rad to ~12, and raised a probability of causation (>50% for Oak Ridge releases). Subsequently, Dr. Hoffman calculated a dose for a member of the public, Ms. Janet Michell.
He noted that the present estimates of the probability of causation exceed the eligibility criteria recommended for compensation and care of DOE workers (i.e., the upper 99th percentile of the probability of causation exceeding 50%). That means that if the present-day rules for compensation of workers were extended to children, those who were children in the 1950s would qualify for the compensation and health care if they drank milk and currently have thyroid cancer or a thyroid nodule.
To Dr. Hoffman, this provided a sufficient basis for the Subcommittee and ATSDR to consider potential public health response, but not necessarily mass screening for thyroid disease, due to the danger of false diagnosis. But screening of a targeted population could be done; those with thyroid disease exposed childhood and who drank milk. He also called for quantification and adjustment of the RaLa releases with regard to the caustic scrubber, and rather than using annual conditions, he would match release periods with the prevailing meteorological conditions, terrain, and time-varying releases, as well as the cumulative effect of exposure to all fallout radioiodines including the NTS, Marshall Islands and Soviet Union.
Dr. Michael Grayson, a health physicist and environmental engineer with ATSDR, reported their review of the dose reconstruction document and the ORHASP report of the dose reconstruction's technical matter. ATSDR did so due to interest in using these two documents in its public health assessment, and to determine if the ORHASP document was an appropriate way to communicate with the local residents. Dr. Grayson related the results of ATSDR's technical review of for both documents in a general overview.
In the dose reconstruction technical review experts examined at three primary areas:
The source term analysis was generally found to be complete and reasonable. While other assumptions could be made, the range of the risk was not thought likely to change dramatically.
The sensitivity analysis produced a very wide range of comments about its quality, from appropriate, to reasonable, to questionable (i.e., it should not be used further in the work on uncertainty and sensitivity analysis). That reviewer preferred to use the central values rather than the upper and lower bounds of the dose distribution. However, all the reviewers approved of the use of Monte Carlo simulations in the sensitivity and uncertainty analyses. They all called for more detail and justification by the report authors of their choice of input parameters for the code (i.e., again, preferring to use a central estimate over upper and lower bounds).
The public health effects conclusions were shared by the reviewers and most of the presenters this day: that doses and the risks were too small to have significantly affected Oak Ridge residents, although certain groups had higher risks (females born in 1952, people between infancy and the age of five years during the times of the releases, etc.). The reviewers found the dose reconstruction report to clearly describe the potential adverse health effects from iodine exposures, and to give a good explanation of the differences between relative or hypothetical risk and actual risk. The dose reconstruction was based on specific diets, so those risk values apply only to those specific diets.
- In short, the reviewers found the methodology to meet the current standards, that the report covered all aspects of the dose reconstruction, and that generally the outcomes reported were reasonable.
ORHASP Report Review. Dr. Grayson then reported
the comments to ATSDR on the ORHASP document, "Releases
of Contaminants from Oak Ridge Facilities and Risks to Public
Health". In general, all the technical reviewers found the
technical information to be well conveyed for the general
public, and the recommendations to be reasonable. Improvements
suggested included clarification for the general public
of why an epidemiological study may not detect any increased
risk; to include zero in the lower bound of the risk estimates;
and to emphasize the central estimate and de-emphasize the
lower and upper bounds of uncertainty.
included the following:
Mr. Pardue congratulated Dr. Hoffman on his presentation and the model. He asked if he correctly understood that Dr. Hoffman considered the risk of thyroid cancer to be greatly increased in the U.S.; and that he basically agreed with ORHASP report except that it should include other sources. He asked if Dr. Hoffman's estimate that this would increase the worst-case scenarios by only a factor of two or three over the few dozen found would raise total number of those affected by the Oak Ridge area releases to only 50-60? Yes. The re-evaluation of the caustic scrubber could increase or decrease the releases, but his intuition, based on the work at Hanford and to be done in Idaho, is that the estimates will not change much. However, if the probability of causation for workers is extended to the public, small differences will make big differences in eligibility. That would be the only reason to fine-tune those results.
- Mr. Pardue: How many people might be eligible for that compensation? Thyroid cancer is rare; about 0.06% for females over a lifetime. Autoimmune thyroiditis is very common, but not a dose response compensation matter.
Mr. Mike Napp asked what other I-131 releases at the Oak Ridge site were not included in the original I-131 source term? Dr. Widner responded that one not included in the evaluation, as mentioned in his presentation, was iodine isotope production processing. It was lower in relative importance because only a relatively small number of fuel solutions were fed through that process. And, since the desired end product was the I-131, they went to great lengths to capture that, so the initial evaluation found it of less importance than the RaLa processing. For the one run where the scrubber ran dry for a portion of the run, iodine would have been released; analysis did reflect essentially no removal for a fraction of that dissolving batch. Did that occur late in the program or near the beginning the program? The details would have to be re-reviewed, but it may have occurred late, which probably be lower in concentration. Was the line loss accounted for in the source term? (Yes). So if the line from the stack to the scrubber is counted as a removal, then the median removal efficiency would ~98 ½%, right? Yes.
Ms. Janet Michell asked if Dr. Hoffman wished to respond to anything in Dr. Widner presentation. Dr. Hoffman noted that one of SENES' recommendations about the dose reconstruction was to delete the early mathematical model of the caustic scrubber, which was clearly overstating the efficiency by orders of magnitude. It was not deleted, the option of the prime contractor. SENES also objected to some changes made in the report that were more than editorial, and made without contacting SENES.
Ms. Michell commented that since 1981, hospitals have been required to report to the state tumor registry, but the Oak Ridge hospital was the last to comply. She had heard of hundreds of thyroid cancers diagnosed and reported to the state Department of Health particularly in 1998 and 1999, but the I-131 report used the "last incidence data" from 1995. Those data after 1995 have been repeatedly requested, but never provided. Dr. Moore, the Tennessee State Epidemiologist, did not understand why she had not been provided with that information, albeit labeled "preliminary." He agreed to help her get it. However, he also pointed out that preliminary information is relatively worthless because of incomplete reporting and incomplete statistical analysis. He was currently analyzing state cancer sites through the end of 1996. The 1997 and '98 data are still too incomplete to be of any help to his studies.
Dr. Karl Markiewicz asked about the Tennessee gummed film network, which operated in Knoxville from 1956-57. Did the releases from Oak Ridge affect that film, or was there a contribution on that film? Dr. Hoffman answered that intuitively one would think so, but they did not measure radioactive iodine, but the non-volatile fallout. That was used in a mathematical model to calculate the iodine component. The Oak Ridge releases would not have affected the gummed film.
Ms. Jeanne Gardener, a former K-25 worker, advised ATSDR not only to do the surveys, but also to listen to the information of offsite residents. She noted the difficulty for an ill worker or a resident to have to wait all day for only two 15-minute public comment periods at this Subcommittee's meeting, and also asked if any sick workers or sick residents were members. Mr. Pereira responded that ATSDR has made strong attempts to have such representative persons. For many personal reasons, including financial issues and potential risk of their benefits, those people identified to date have chosen not to participate. ATSDR is again attempting to invite a sick worker's participation on the panel, which now has members who work or have worked at the facility. He encouraged applications from sick workers. Ms. Gardener reported that she herself is a good example of a person on disability who cannot receive any compensation for participating on a panel such as this. Knowing that, she wondered aloud why it was set up that way. Dr. Davidson noted that much of the Subcommittee's work is done through its work groups, whose meetings are generally short (~1½-2 hours), and encouraged public participation.
Ms. Michell acknowledged ORHASP's hard work, but reminded the committee that DOE had publicly admitted that their records are flawed and inaccurate. Much of the I-131 report is based on that unreliable data. She also asked that the committee over time address other toxicants that of concern that are not included in the report. She charged that the EPA used this report and the long time period of nine years to avoid the human health hazard evaluation that is required by law for Superfund sites. EPA needs to fulfil its obligations; this report does not take the place of a human health hazard evaluation. She noted that DOE this study and this Subcommittee. Dr. Davidson confirmed that other contaminants of concern will be addressed in future meetings.
Dr. Davidson read Mr. Napp's question to Dr. Peelle of why the Oak Ridge signature contaminants of nickel, strontium, cesium, and chromium, which are in residents' bodies, were not included in the Phase I evaluation, and why was it not peer reviewed? Dr. Peelle was not involved with ORHASP in Phase I. While he thought that some of those elements were reviewed, he recalled that some information could not be released during Phase I.
Mr. Napp: Does the resignation of Dr. Lands from the Subcommittee opened a seat that could be filled by a sick self-identified resident? Dr. Davidson said yes; that was to be considered on the following day by the Subcommittee.
Mr. Napp: Dr. Hoffman's analysis of the ORHASP I-131 report task seems to contradict Dr. Grayson's report, in which at least one reviewer found no health effects in the Oak Ridge area. Dr. Hoffman confirmed that. There are public health concerns, especially considering that the I-131 background was elevated over natural background, so he would not condone a lower bound set at zero. The ATSDR reviewers were also more restrained than he would be about the need for a public health response. But he noted that all four of them are health physicists, none are epidemiologists or chemical engineers; and the difficulty of doing such broad reviews.
Dr. Frome: Was thyroid cancer an underlying cause of death in the autopsy data, if not the underlying cause of metastasis? The under-ascertainment of thyroid cancer is unrelated to the causes of death on death certificates.
Dr. Brooks strongly took issue with the analysis related to the caustic scrubbers, found the design analysis of little value, and the assumptions improper. He cited the report's contradictions and lack of evidence for the scrubber, which for him called intot questioned the legitimacy of the study results. He asked if Dr. Hoffman wished to totally review the assumptions of the caustic scrubber, which the latter confirmed. Dr. Brooks and Dr. Widner debated the report until Mr. Pereira suggested they resolve those questions privately.
Ms. Sonnenburg: The Oak Ridge dose reconstruction summary notes that airborne releases from Y-12 were independently estimated at 5-7 times those reported by DOE. Where did that came from, and did you use the DOE statistics or did you multiply it by some other number? Dr. Widner responded that the raw data from the stack sample measurements were used to independently calculate the releases. A lot of the depleted uranium was not tracked as carefully as the enriched ore, and some was not included in the official release totals, but the study did a more thorough accounting. The study's estimates of uranium release of Y-12 and K-25 released were seven higher than DOE's, and they used those numbers. The efficiency of the scrubber treatment is definitely an important part of this.
Mr. Hill: Please tell us more about the ability of workers to receive compensation. Are the Veterans Administration and the Labor Department using the probability of causation in their adjudication of claims for all cancers? Dr. Hoffman: Yes. A White House Order now requires the use of the 99th percentile to ensure that the exposed individual gets the benefit of the doubt. So, if the extreme upper end is 50%, current legislation makes that ineligible for compensation and medical care. He personally disliked using the upper 99th percentile because it is too unstable, but there seems to be no room for discussion on this, and it goes into effect in July for workers only. Mr. Bill Murray, of ATSDR, reported that Mr. Larry Elliott of NIOSH could provide more details about this, and offered to provide his e-mail address for any questions. Ms. Michell advised the workers not to get their hopes up; they must have one of only a few cancers, and be able to prove that it was caused only by those few DOE facilities covered.
Mr. Hill: In view of the fact that the government persisted that there was no risk from radiation even as the experts proved there was, and the public's distrust results from that, he advised that it would be unwise to use that term in this setting.
Ms. Kaplan drew the members' attention to related material that she had developed and distributed, announcing that the second report had been briefly reviewed by Dr. Hoffman, but not yet by the Local Oversight Committee.
Mr. Akin: Why are females and children aged 5 years more susceptible, and is that true for all cancers or only thyroid endpoints? Dr. Hoffman: For all thyroid endpoints, females have a higher background risk than males. The ability of radiation to induce an excess risk is well documented, but the actual underlying mechanism making the background risk for females and children higher than that for exposed males is unknown. While the endocrine systems of both sexes seem to be the same in childhood, something seems to happen later in life that changes that (i.e., precursive damage early in life to DNA that manifests itself later). But excess relative list (excess relative to background), if mathematically normalized to background, shows little difference between males and females.
Mr. Lewis: Since the past diagnosis of thyroid cancers may be underestimated, and cancer registries are of little help, is there enough present knowledge to extrapolate to what might have occurred in the past? Dr. Hoffman: The uncertainty is present, but is not infinite; some conclusions can be supported, and some not. Some of the report's elements such as the caustic scrubber, that may have been missed, can be re-evaluated. But disease registries did begin late, and the use of palpation rather than ultrasound to detect a thyroid nodule did lead to under-ascertainment. Even with ultrasound, a biopsy may be inconclusive, and some may have had surgery to be on the safe side. That is why mass screenings can be dangerous, potentially leading to many unnecessary surgeries due to false positive results. Some of the inconclusive studies in the past were so because they focused on incidence; only examination of national data on thyroid cancer mortality produced a statistical relationship between fallout and thyroid cancer.
Dr. Davidson read a public comment by a UT professor into the record: Why were only DOE-friendly people asked to review the I-121 study? Dr. Davidson also asked if there is information is available on the relative intake of I-131 and the uptake into the thyroid in children versus adults, and in girls versus boys, because differences and disease outcome can either be due to different amounts getting into the target tissue (the thyroid) or an inherent sensitivity in one or the other. Dr. Hoffman reiterated that there is little difference between boys and girls in terms of either milk consumption or transfer from milk to blood, and blood to the thyroid. In the earliest months of life such as the neonatal period, the uptake from blood to the thyroid would be high (~60%) versus ~20% normally. The biggest difference between children and adults is that children drink more milk and have smaller thyroids, which produces a difference of 10-20 times in the dose to the thyroid. But while there is no difference in dose between males and females on the NCI Website, there is a difference in risk.
- Ms. Kaplan stated, as a person who had a false positive result and had the surgery, that having a surgery and living for any length of time with the terror that one might have cancer is not a trivial thing; it is really life-altering experience.
Dr. Davidson mentioned that the iodine issue would be addressed in the ORRHES Work Group, and again invited any of the public wishing to become involved to attend the work group meetings. With no further comments, the meeting adjourned at 7:30 p.m.