PUBLIC HEALTH ASSESSMENT

General Comments

1

ATSDR, an agency of the federal government, has a clear conflict of interest when it prepares health assessments on sites where the federal government itself is the primarily responsible party. This conflict is never clearer than today, when the federal government gives itself a high five for being such a good, clean citizen in Oak Ridge.

Either ATSDR's methodology is suspect, or their knowledge base is suspect, or their honesty is suspect. In either case, the public is ill served by false assurances.

The finding of the ATSDR that releases from the Oak Ridge National Laboratories over the past 60 years have posed no public health threat is unconscionable, unsupported by the scientific community, and flat-out false.

The declaration that Oak Ridge has never posed a health risk cannot be supported by science or by common sense. ATSDR's finding is either the result of half-hearted work or simple duplicity.

In 1980, Congress established the ATSDR to carry out the health-related responsibilities under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) commonly known as the Superfund Law. CERCLA charges the EPA to find and to clean up the most dangerous hazardous waste sites in the United States, and CERCLA charges ATSDR to determine the extent of human exposure to hazardous substances at those sites. In 1984, ATSDR's public health authority was extended to Solid Waste Disposal Act (SWDA) sites. The Superfund Amendments and Reauthorization Act of 1986 further extended ATSDR's authority to federal facilities. ATSDR has the following legislation authorities that pertain to its activities at DOE sites:

• Section 120 of CERCLA (42 USC 9620): concerns the application of CERCLA to federal facilities
• Section 104(i) of CERCLA: concerns ATSDR's authorities and responsibilities
• Section 107 of CERCLA: concerns liability
• Section 3019 of SWDA (42 USC 6939a): concerns exposure information and health assessments

As the lead public health agency responsible for implementing the health-related provisions of Superfund, ATSDR is charged with assessing health hazards at specific hazardous waste sites, helping to prevent or reduce exposure and the illnesses that result, and increasing knowledge and understanding of the health effects that may result from exposure to hazardous substances. As the potentially responsible party (PRP), DOE is required to fund cleanup and public health investigations, such as the ATSDR PHAs, for the Oak Ridge Reservation. ATSDR as an advisory, non-regulatory public health agency conducts independent public health assessments and provides recommended actions to protect public health. It makes health calls following an independent evaluation of data and exposure situations; it does not make any decisions based on who is funding its work.

ATSDR's mission is to serve the public by using the best science, taking responsive public health actions and providing trusted health information to prevent harmful exposures and disease related to toxic substances. The ATSDR public health assessment process serves as a mechanism to help ATSDR scientists sort through the many hazards at waste sites and determine when, where, and for whom public health actions should be taken. Through this process, ATSDR finds out whether people living near or at a hazardous waste site are exposed to toxic substances, whether that exposure is harmful, and what must be done to stop or reduce an exposure. ATSDR scientists use the detailed guidance in the updated ATSDR Public Health Assessment Guidance Manual to identify hazards and to recommend needed public health actions.

More information about the ATSDR evaluation process can be found in ATSDR's Public Health Assessment Guidance Manual at http://www.atsdr.cdc.gov/HAC/PHAManual/toc.html or by contacting ATSDR at 1-888-42-ATSDR. An interactive program that provides an overview of the process ATSDR uses to evaluate whether people will be harmed by hazardous materials is available at http://www.atsdr.cdc.gov/training/public-health-assessment-overview/html/index.html.

This public health assessment evaluates the releases of radionuclides to the Clinch River and the Lower Watts Bar Reservoir from the ORR via White Oak Creek; assesses past, current, and future exposure to radionuclide releases for people who use or live along the Clinch River; and addresses the community health concerns and issues associated with the radionuclide releases from White Oak Creek. ATSDR evaluated data and exposure situations to determine the public health implications of past, current, and future off-site exposures.

ATSDR concluded that past, current, and future exposures to radionuclides released from White Oak Creek to the Clinch River and Lower Watts Bar Reservoir are not a public health hazard. Though people might have or might yet come in contact with X-10 radionuclides that entered the Clinch River or Lower Watts Bar Reservoir via White Oak Creek, ATSDR's evaluation of data and exposure situations for users of these waterways indicates that the levels of radionuclides in the sediment, surface water, and biota are—and have been in the past—too low to cause observable health effects.

That said, however, please note that ATSDR never states nor implies in this PHA that, "...releases from the Oak Ridge National Laboratories over the past 60 years have posed no public health threat..." This PHA only evaluates off-site exposures to X-10 radionuclides released to White Oak Creek that entered the Clinch River and Lower Watts Bar Reservoir. The PHA does not evaluate any on-site exposures (these are handled by other agencies) or exposures to other contaminants released from this facility. In addition to this PHA, ATSDR is also conducting public health assessments on X-10 iodine 131 releases, Y-12 mercury releases, K-25 uranium and fluoride releases, PCB releases from X-10, Y-12, and K-25, and other topics such as the Toxic Substances Control Act (TSCA) incinerator and off-site groundwater. For copies of these other assessments, please contact ATSDR's Information Center toll-free at 1-888-422-8737.

2

It never ceases to amaze me how our government officials like to pronounce threats as totally harmless. Over the years it has been contaminated geese and frogs, air and water, yet the threat is always stated to be so innocuous that the animals or fish could be eaten, yet millions of dollars are being spent to clean it up and dispose of it. Is it me or is there a real large logic gap here?

What is wrong with this picture? If White Oak Creek Drainage Basin poses absolutely no threat, as the Agency for Toxic Substances and Disease Registry states, why are so many millions being spent to clean up and remediate the area by the Department of Energy? How can we find credibility amid the illogic of such duplicity?

Either there is a real threat here, even though it may be fairly minor — a few deaths per 100,000 — or a lot of money is being poured into the waste heap. This certainly seems to be the case with money for the agency efforts that are obviously purely palliatives without a shred of credibility.

It is time for real mortality-morbidity data to be placed on the table — no more empty pronouncements of complete safety. Only an idiot sees the world in such black-and-white contrast.

It is true that DOE has spent and continues to spend billions of dollars on environmental remediation at the Oak Ridge Reservation. As a result of past activities at the ORR, parts of the on-site facilities and lands have been contaminated with PCBs, radioactive elements, asbestos, mercury, and other industrial wastes. In November 1989, EPA listed the ORR on the final National Priorities List (NPL). DOE is performing remediation activities at the reservation under a Federal Facility Agreement (FFA), which is an interagency agreement between the DOE, EPA, and TDEC. EPA and TDEC, and the public help DOE select the details for remedial actions at the ORR. These stakeholders work collaboratively to ensure the remediation activities are adequate, and to ensure that hazardous waste related to previous and current ORR activities is completely studied and appropriate remedial action is taken. Environmental management is the largest program at Oak Ridge. Information on the program is available at http://www.oakridge.doe.gov/External/Default.aspx?tabid=42 .

Though DOE is remediating these wastes, it is extremely important to understand that the federal funding used to remediate these lands and facilities are only for contamination within the reservation—none of the funding is intended for clean up of off-site areas; the on-site areas currently undergoing remediation are not accessible to residents. Though costly, DOE is spending this money to prevent contamination from traveling off site, or at a minimum, to detect it in a timely manner before it affects off-site areas.

ATSDR's PHAs are evaluations of exposures to off-site populations. This PHA evaluates the releases of radionuclides to the Clinch River and the Lower Watts Bar Reservoir from the X-10 site via White Oak Creek; assesses past, current, and future exposure to radionuclide releases for people who use or live along the Clinch River from the Melton Hill Dam to the Watts Bar Dam; and addresses the community health concerns and issues associated with the radionuclide releases from White Oak Creek. It is not an evaluation of people who were exposed while working on-site at the reservation. Other agencies handle that responsibility.

ATSDR concluded that past, current, and future exposures to radionuclides released from White Oak Creek to the Clinch River and the Lower Watts Bar Reservoir are not a public health hazard. People who used or lived along the Clinch River or Lower Watts Bar Reservoir in the past, or who currently do so or will in the future, might have or might yet come in contact with X-10 radionuclides that entered the Clinch River or Lower Watts Bar Reservoir via White Oak Creek. ATSDR's evaluation of data and exposure situations for users of these waterways indicates, however, that the levels of radionuclides in the sediment, surface water, and biota are—and have been in the past—too low to cause observable health effects.

3

There is a need for an independent external peer review of this ATSDR PHA (from scientists who have not been selected by the ATSDR) to address issues of technical and public credibility. These reviewers should have independence from DOE and its contractors. They should also be free from local organizational and economic conflicts of interest.

He expressed concern that the data validation process and internal ATSDR review did not catch what he considered to be discrepancies. In his opinion, this report contained major technical errors that had implications in terms of how ATSDR conducts business.

In the past, CDC/NCEH relied on a standing committee of the NRC/NAS for peer reviews of CDC contractor dose reconstructions and risk evaluations. Such peer reviews by the NRC/NAS were conducted at Hanford, Fernald, INEL, and Savannah River. I recommend that consideration be given to the reactivation of this committee of the NRC/NAS for scientific peer review of the technical content of the ATSDR PHAs at Oak Ridge. In addition, such a peer review should address whether or not these PHAs have been responsive to community concerns.

The White Oak Creek Radionuclide Releases PHA underwent an internal ATSDR review, a data validation review by other government agencies (i.e., the Department of Energy and the Tennessee Department of Environment and Conservation), and an external review. Through its external peer review process, ATSDR's Office of Science had three scientific experts review this public health assessment (see Appendix H for the peer reviewer comments and ATSDR's responses). The agency's peer review process provides an objective and thorough evaluation of this PHA by experts in the fields this assessment covers—specifically, health physics. Individuals within the agency who have the proper background (e.g., toxicology and health physics) also reviewed the document during the agency's internal review process. During the external review process, scientists not employed by ATSDR or the CDC independently reviewed this document and provided us with their unbiased, scientific opinions.

All peer reviewers approved of the assessment and found no major flaws that would invalidate ATSDR's conclusions and recommendations. In the words of one peer reviewer: "You [ATSDR] have done a good job under very difficult circumstances with a lot of unwanted publicity and carping. The science under the report is very good and the report is well written in a very good manner that is suitable for both an informed and interested public and the scientific community." Further, an external peer reviewer commented, "The study further addresses local concerns raised by the residents of the area even when it is doubtful that there is any validity to the concern raised."

4

Clearly define what is meant by a "public health hazard."

Clearly distinguish between the ability to observe health effects and the potential existence of health effects that cannot be detected at low doses. The inability to detect effects does not mean zero risk of radiation exposure, as is implied at several points in the current draft.

Public health hazard is now defined in the summary of the final PHA on page 2 as "a source of potential harm to human health as a result of past, current, or future exposures."

ATSDR recognizes that every radiation dose, action, or activity may have an associated risk. Given our evaluation in this public health assessment, ATSDR concludes that exposures to X-10 radionuclides released from White Oak Creek to the Clinch River and to the Lower Watts Bar Reservoir are not a health hazard. Past and current exposures are below levels associated with adverse health effects and regulatory limits. Adults or children who have used, or who might continue to use, the waterways for recreation, food, or drinking water are not expected to have adverse health effects due to exposure. ATSDR has categorized those situations as posing no apparent public health hazard from exposure to radionuclides related to X-10. This classification means that people could be or were exposed, but that the level of exposure would not likely result in any adverse health effects.

Contrary to this commenter's statement, the document does not imply that the inability to detect effects means no risk of exposure. This is clearly evident by the use of the no apparent public health hazard conclusion category in this public health assessment. ATSDR uses this category in situations in which human exposure to contaminated media might be occurring, might have occurred in the past, or might occur in the future, but where the exposure is not expected to cause any harmful health effects. Therefore, it is evident that ATSDR is not saying there is no risk of radiation exposure. On the contrary, we are saying that radiation exposure is possible, but that this exposure is not expected to result in observable health effects.

EPA-conducted risk assessments are useful in determining safe regulatory limits and in prioritizing sites for cleanup. These risk assessments provide estimates of theoretical risk from possible current or future exposures and consider all contaminated media regardless of whether exposures are occurring or are likely to occur. These quantitative risk estimates are not intended, however, to predict the incidence of disease or to measure the actual health effects in people caused by hazardous substances at a site. By design, these risk estimates are conservative predictions that generally overestimate risk. Risk assessments do not provide a perspective on what the risk estimates mean in the context of the site community and do not measure the actual health effects that hazardous substances have on people.

ATSDR uses the public health assessment process to evaluate the public health implications of exposure to environmental contamination and to identify the appropriate public health actions for particular communities. ATSDR scientists conduct a health effects evaluation by carefully examining site-specific exposure conditions about actual or likely exposures; conducting a critical review of available toxicological, medical, and epidemiologic information to ascertain the substance-specific toxicity characteristics (i.e., levels of significant human exposure), and comparing an estimate of the amount of chemical exposure (i.e., dose) to which people might frequently encounter at a site to situations that have been associated with disease and injury. This health effects evaluation involves a balanced review and integration of site-related environmental data, site-specific exposure factors, and toxicological, radiological, epidemiologic, medical, and health outcome data to help determine whether exposure to contaminant levels might result in harmful effects. The goal of the health effects evaluation is to decide whether harmful effects might be possible in the exposed population by weighing the scientific evidence and by keeping site-specific doses in perspective. The output is a qualitative description of whether site exposure doses are of sufficient nature and magnitude to trigger a public health action to limit or eliminate, or to study further any potentially harmful exposures. The PHA presents conclusions about the actual existence and level of the health threat (if any) posed by a site. It also recommends ways to stop or reduce exposures.

For detailed information on risk, please see Appendix F in the final PHA.

5

There are a lot of concerned individuals downwind and downstream of the Department of Energy Oak Ridge Reservation (DOE ORR). (Comment received on the initial release PHA dated December 2003.)

Thank you for your comment. Section VI. Community Health Concerns of the final PHA contains the public health concerns received from area residents, community groups, and other interested parties related to issues associated with radionuclide releases from White Oak Creek, as well as ATSDR's responses to these concerns. These concerns and responses are sorted by category (X-10 facility processes and exposure pathway concerns, concerns about radionuclides associated with X-10's releases to White Oak Creek, concerns about contaminants released from the Oak Ridge Reservation, and general concerns related to the Oak Ridge Reservation) and presented in tabular form in Section VI of the final PHA.

Also, ATSDR developed a Community Health Concerns Database to compile and track community health concerns related to the ORR. From 2001 to 2005, ATSDR compiled more than 3,000 community health concerns obtained from the ATSDR/ORRHES community health concerns comment sheets, written correspondence, telephone calls, newspapers, comments made at public meetings (e.g., ORRHES and work group meetings), and surveys conducted by other agencies and organizations. Further, within this section of the final PHA ATSDR provides responses to the comments received on the public comment version of the White Oak Creek Radionuclide Releases PHA.

During the PHA's external peer review process, a peer reviewer made the following comment regarding this issue: "The study further addresses local concerns raised by the residents of the area even when it is doubtful that there is any validity to the concern raised." Thus, as this reviewer points out, ATSDR is addressing all of the community concerns related to releases from X-10 to White Oak Creek.

6

According to the Final Report of the Oak Ridge Health Agreement Steering Panel titled: Releases of Contaminants from Oak Ridge Facilities and Risks to Public Health, December, 1999, ATSDR has not even scratched the surface of the bewildering array of public health concerns of the many communities downwind and downstream of DOE ORR. (Comment received on the initial release PHA dated December 2003.)

After reviewing the ORHASP report, it is unclear what concerns have not been addressed. ATSDR has reviewed this report and has an entire section (Section VI. Community Health Concerns) of the final PHA devoted to listing and addressing community concerns received about X-10 radionuclide releases to the Clinch River and the Lower Watts Bar Reservoir via White Oak Creek.

In fact, from 1991 to 2000 ATSDR completed the following public health activities to address specific current off-site public health concerns and issues not addressed by the Tennessee Department of Health's Oak Ridge Health Studies. These studies only evaluated whether off-site populations experienced past exposures to radiological and chemical releases from the ORR.

Review of Clinical Information on Persons Living in or near Oak Ridge, Tennessee dated September 10, 1992.

Health Consultation on Y-12 Weapon Plant Chemical Releases into East Fork Poplar Creek dated April 5, 1993. DOE implemented many of ATSDR's recommendations before finalizing the Remedial Investigation and Feasibility Study on Lower East Fork Poplar Creek and the 1995 Record of Decision for the Lower East Fork Poplar Creek.

Clinical Laboratory Support in 1994. ATSDR and the National Center for Environmental Health (NCEH) facilitated clinical laboratory support by the NCEH Environmental Health Laboratory for patients referred to the Emory University School of Public Health by an Oak Ridge physician.

ATSDR Science Panel on the Bioavailability of Inorganic Mercury in August 1995. Four papers were published by science panel members in Risk Analysis.17 (5), 527-569 (1996).

Health Consultation on DOE's Proposed Mercury Clean-up Level for the East Fork Poplar Creek Floodplain Soil dated January 1996. DOE cited the conclusions of this health consultation in the 1995 Record of Decision for the Lower East Fork Poplar Creek.

Health Consultation on Lower Watts Bar Reservoir dated February 1996. DOE cited this health consultation in the 1995 Record of Decision for the Lower Watts Bar Reservoir. The state of Tennessee followed up on the recommendation to analyze for PCBs in turtles.

Physician Health Education Program on Cyanide in August 1996. The physician education program supplied health care providers with information on health impacts of possible cyanide intoxication.

Community and Physician Education on PCBs in Fish in September 1996. ATSDR developed a community and physician education program on PCBs in Watts Bar Reservoir fish to follow up on recommendations contained in the ATSDR health consultation.

Watts Bar Reservoir Fish Advisory Pointers brochure dated 1997. ATSDR worked with the state of Tennessee and local community groups to develop the brochure as a follow up on recommendations contained in the ATSDR health consultation.

Exposure Investigation on Serum PCB and Blood Mercury Levels in Consumers of Fish and Turtles from Watts Bar Reservoir dated March 1998. This exposure investigation is a follow-up activity to the ATSDR Health Consultation on Lower Watts Bar Reservoir dated February 1996 and to respond specifically to an informal recommendation from the Oak Ridge Health Agreement Steering Panel, as well as respond to general community interest. This study was done to measure actual PCB and mercury levels in people who have eaten large amounts of Watts Bar Reservoir fish or turtles. ATSDR tested for PCBs because previous investigations estimated that people who eat certain fish or turtles might have higher than average levels of PCBs in their bodies and suggested that the levels of PCBs in fish were a public health concern. ATSDR tested the blood samples for mercury because mercury was a historic contaminant of concern. Recent studies, however, have not detected mercury at levels of health concern in surface water, sediments, or fish from the Watts Bar Reservoir.

Compendium of Public Health Activities at the U.S. Department of Energy Oak Ridge Reservation (updated version) dated November 2000. ATSDR initiated and coordinated the development of the compendium to outline the past and present strategies used to address and evaluate public health issues related to chemical and radioactive substances released from the Oak Ridge Reservation.

Copies of ATSDR documents are available on ATSDR's Oak Ridge Reservation Public Health Web site at http://www.atsdr.cdc.gov/HAC/oakridge/index.html. In addition, detailed summaries of the public health activities prior to 2000 are available in the Compendium of Public Health Activities at the U.S. Department of Energy dated November 2000 on the ATSDR's Oak Ridge Reservation Public Health Web site at http://www.atsdr.cdc.gov/HAC/oakridge/phact/c_toc.html.

In 2001, ATSDR scientists conducted a review and analysis of the Phase I and Phase II screening evaluations of the Tennessee Department of Health's Oak Ridge Health Studies to identify contaminants that required further public health evaluation. ATSDR staff presented this review and analysis of the Phase I and Phase II screening evaluations to the Oak Ridge Reservation Health Effects Subcommittee (ORRHES). Given ATSDR's review and the comments received from the ORRHES, ATSDR scientists decided to use the ATSDR public health assessment process to conduct chemical-specific and issue-specific public health assessments and to address issues and community health concerns related to the following:

• Past and current exposure to uranium released from the Y-12 Weapons Plant,
• Exposure to contaminants released from the Toxic Substances Control Act (TSCA) incinerator,
• Past and current exposure to radionuclides released from White Oak Creek,
• Exposure to contaminated off-site groundwater,
• Past exposure to radioactive iodine (I 131) released from X-10,
• Past and current exposure to mercury released from the Y-12 Weapons Plant,
• Past and current exposure to uranium and fluoride released from K-25,
• Past and current exposure to PCBs released from X-10, Y-12, and K-25
• Current (1990-2003) and future exposure to other chemicals near the reservation, and
• Overall summary on the screening process and exposures to a mixture of chemicals and radionuclides.

At the February 11, 2002 ORRHES meeting, the ORRHES approved a recommendation endorsing ATSDR's screening process to determine the list of contaminants for further evaluation using the ATSDR public health assessment process.

Evaluation of Additional Populations

7

Pp. i. Line 34, and ii. Line 5. Given the emphasis placed on consideration of children, it would be appropriate to add pregnant and lactating women to the list of high risk groups. This will cover the fetus and the breast-fed infant. It's also a nice thing to do for women of childbearing age given the potential adverse impact of radiation exposure on their reproductive experience.

The section referenced by the commenter is ATSDR's standard forward used in all public health assessments. This particular group is not being added to our standard forward because it is particular to this evaluation and not necessarily appropriate for all public health assessments. But a discussion of this group has been added to Section VII. Child Health Considerations in the final PHA.

8

Page 105, Line 29. Stakeholders believe that ATSDR is not taking into consideration subsistence fishers who will consume much more than the standard "reference man" that ATSDR is utilizing. Stakeholders believe that ATSDR is 'blowing off' the more significant hazard that these fish present to growing children and pregnant women by ingestion of fish. Of special concern is ingestion of fish contaminated with Sr-90 and Cs-137. These three exposure considerations were, in fact, the most important 'risk drivers' of exposure to the consumption of radioactively contaminated fish downstream from another DOE facility, the Savannah River Site, near Aiken, SC. (Comment received on the initial release PHA dated December 2003.)

To evaluate past, current, and future exposures to radionuclides in Clinch River and Lower Watts Bar Reservoir fish, average fish consumers were evaluated (detailed below). In its Exposure Factors Handbook (available at http://www.epa.gov/ncea/pdfs/efh/front.pdf ) that outlines factors commonly used in exposure assessments EPA recommends using an assumed average intake rate for fish consumption for the general population of 20.1 grams/day (140.7 grams/week) of total fish. Of this fish intake rate, however, only 6.0 grams/day (42 grams/week) is considered as an average intake rate for the general population consuming freshwater and estuarine fish. All of the exposure assumptions used by ATSDR for past, current, and future exposures to radionuclides in Clinch River and Lower Watts Bar Reservoir fish were at least five times more than this average intake for the general population eating freshwater and estuarine fish. As detailed below, even when evaluating fish consumption by using assumed intake rates significantly above these recommended assumptions, ATSDR's estimated doses for past, current, and future exposures were below health-based comparison values.

In the Task 4 of the Tennessee Department of Health's Reports of the Oak Ridge Dose Reconstruction (Task 4 report), past exposures to radionuclides in Clinch River fish were evaluated for high fish consumers. Reportedly, a maximum fish consumer in the east south central region of the country would eat about 2.4 fish meals per week (based on a 200 gram per meal fish portion) (Rupp et al. 1980. Age dependent values of dietary intake for assessing human exposures to environmental pollutants. Health Physics 39: 151-163. Cited in the Task 4 report). The Task 4 report evaluated high fish consumers, who were referred to as "Category I fish consumers" and were described as individuals who frequently (between 1 and 2.5 fish meals per week) ate fish.

To evaluate past exposure to radionuclides in the Clinch River, ATSDR summarized the Task 4 organ doses from the Task 4 report for the bone, lower large intestine, red bone marrow, breast, and skin locations using the 50^th percentile value of the uncertainty distribution. The 50^th percentile (central) values represent the medians of organ doses. The highest radiation doses were associated with eating fish taken from the Clinch River near Jones Island between 1944 and 1991. Doses were much lower for all other pathways (see Table 11 and Table 12 in the final PHA). The Task 4 report's estimated organ doses to the bone, lower large intestine, red bone marrow, breast, and skin from eating fish were at least six times greater than the radiation doses to these organs from ingesting meat and milk, drinking water, and external radiation (see Table 12 in the final PHA). Likewise, ATSDR's derived annual whole-body and committed equivalent doses from eating fish were at least 10 times more than any of the other exposure pathways (see Table 11 in the final PHA). As mentioned and shown in Table 11, radiation doses from eating fish were highest near Jones Island—these annual whole-body and lifetime (70-year) doses were more than eight times greater than for people consuming fish from the Clinch River further downstream near Kingston. The annual whole-body dose was less than 3.4 mrem/year for an individual ingesting fish near Jones Island more than 29 times less than the 100 mrem/year recommended dose limit for the public by the International Commission on Radiological Protection (ICRP), the U.S. Nuclear Regulatory Commission (NRC), and the National Council on Radiation Protection and Measurements (NCRP). The whole-body lifetime dose for an individual ingesting fish caught near Jones Island was 238.6 mrem over 70 years more than 20 times less than ATSDR's radiogenic cancer comparison value of 5,000 mrem over 70 years.

To evaluate current and future exposure to radionuclides in Lower Watts Bar Reservoir fish, this public health assessment used data from ATSDR's Health Consultation on the Lower Watts Bar Reservoir. The health consultation used worst-case scenarios to evaluate radiological exposure to fish, assuming adults and children consumed two 8-ounce fish meals per week (454 grams/week), which is 10 times the intake rate (42 grams/week) recommended by EPA for freshwater fish. Even using these conservative exposure assumptions, the estimated dose was 6 mrem per year or less than 420 mrem over 70 years for the committed effective dose. The annual whole-body dose of 6 mrem per year is more than 16 times less than the dose of 100 mrem/year recommended for the public by the NCRP, ICRP, and NRC. The committed effective dose of 420 mrem over 70 years is more than 11 times less than ATSDR's radiogenic cancer comparison value of 5,000 mrem over 70 years.

To evaluate current and future exposure to radionuclides in Clinch River fish, ATSDR assumed a child ate 4 ounces of fish per week (113.4 grams/week) and an adult ate 8 ounces of fish per week (227 grams/week). This fish intake rate is based on a survey of high to moderate fish consumers during the ATSDR Exposure Investigation on Serum PCB and Blood Mercury Levels in Consumers of Fish and Turtles from Watts Bar Reservoir dated March 1998. Based on this intake rate, the highest estimated whole-body dose of 89.3 mrem—calculated for a 20-year-old adult exposed over 50 years (to age 70)—is 55 times less than ATSDR's radiogenic cancer comparison value of 5,000 mrem over 70 years.

Further, the PHA evaluates childhood exposures within Section III. Evaluation of Environmental Contamination and Potential Exposure Pathways and in Section VII. Child Health Considerations of the final PHA. In addition, a discussion of pregnant women has been added to Section VII of the final document.

9

Page 124, Line 1. ATSDR has omitted the risk to unborn children sustained by their mothers consuming fish contaminated with radioactive cesium, strontium, and other radionuclides. This is especially important because there has never been a Tennessee fish advisory in place in any of these downstream communities to warn the public of the imminent and substantial hazard posed by consuming 'hot fish' downstream of DOE ORR. The only warning is the PCBs – radioactive contamination is never even mentioned once on any of the stream signage or in any of Tennessee's official fish advisories. (Comment received on the initial release PHA dated December 2003.)

A discussion of exposure in utero has been added to Section VII. Child Health Considerations in the final PHA. In the Task 4 of the Tennessee Department of Health's Reports of the Oak Ridge Dose Reconstruction (Task 4 report), the Task 4 team concluded that its estimated radiological doses and excess lifetime cancer risks were "incremental increases above those resulting from exposure to natural and other anthropogenic sources of radiation," but were "not large enough for a commensurate increase in health effects in the population to be detectable, even by the most thorough of epidemiological investigations." The Task 4 team noted that "in most cases, the estimated organ-specific doses are clearly below the limits of epidemiological detection (1 to 30 cSv [centisievert]) for radiation-induced health outcomes that have been observed following irradiation of large cohorts of individuals exposed either in utero (Doll and Wakeford 1997), as children, or as adults (NRC 1990; Thompson et al. 1994; Pierce et al. 1996)" (ChemRisk 1999a). Thus, because past radiation exposures—when doses were the highest—were not expected to cause harmful health effects in utero, in infants, and in children, adverse health effects would also not be expected to occur as a result of current and future radiation exposures to the Clinch River and Lower Watts Bar Reservoir. White Oak Creek radionuclide releases and contaminant concentrations have continued to decrease over time.

Regarding the fish advisories, the Tennessee Department of Environment and Conservation's (TDEC) Division of Water Control is responsible for issuing and posting fish advisories. Evaluating fish tissue problems in the state of Tennessee involves a multi-agency effort, comprised of DOE, EPA, TDEC, the Tennessee Wildlife Resources Agency (TWRA), and the Tennessee Valley Authority (TVA). An abundance of data are available on contaminants in fish in these systems, including data collected by TVA, DOE, TWRA, and TDEC. These agencies use Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) criteria to analyze fish tissue in these waterways, which applies EPA risk assessment to evaluating potential exposures to contaminants in fish. DOE, TDEC, and EPA have responsibilities under CERCLA, but the state has ultimate responsibility for the advisories. The state fish advisories are available at http://www.state.tn.us/twra/fish/contaminants.html .

It is important to understand that although radionuclides and other contaminants might be present in fish in the Clinch River and the Lower Watts Bar Reservoir, only PCBs have been found at levels in particular species of fish that could potentially cause adverse health effects. This is why radionuclides are not part of the advisories for these waterways—they have not been detected at harmful levels in these water systems. These agencies are basing their advisories on numerous data collected over several years by different entities, all of which show that radionuclides are not present in fish in the Lower Watts Bar Reservoir and the Clinch River at levels that could cause adverse health effects. ATSDR's evaluation in this public health assessment concurs with the findings of the state, EPA, and these other entities. In addition, ATSDR is preparing a public health assessment that will evaluate PCB releases from the three main ORR facilities: X-10, Y-12, and K-25. When available, copies of ATSDR's public health assessment on PCBs can be obtained by contacting ATSDR's Information Center toll-free at 1-888-422-8737.

Evaluation of Past Exposures

10

Page 4, lines 18–20: ATSDR should provide the rationale for the conclusion that "Because of conservative parameters used by the Task 4 team, the calculated risk and true exposure would not be underestimated for people who actually lived in the community." As currently presented, this is an opinion that is not supported either by the analysis of the Task 4 report in Sect. III.B or by the summary in Appendix D. It is an important conclusion that deserves to be fully documented.

The comment is noted. To align the text more with the statements in the Task 4 of the Tennessee Department of Health's Reports of the Oak Ridge Dose Reconstruction (Task 4 report), this text was changed to the following in the final PHA: "The Task 4 team used conservative screening parameters with the intention of calculating estimates of risk that are not likely to underestimate the actual risk to any exposed individual. Meaning, for each radionuclide and exposure pathway evaluated, the Task 4 team expected these calculated estimates to overestimate the risk for most or all real individuals."

11

There are several problems with the analysis, the first of which is that ATSDR ignored doses to organs/tissues other than bone surface, lower large intestine, red bone marrow, the female breast, and skin in calculating the effective dose (their whole-body dose).

ATSDR's approach to dose estimation was seriously flawed because it ignored dose contributions to organs and tissues other than those currently listed in Table 11. Thus, until those flaws are corrected, the above comments, which were based on the erroneous (incomplete) sets of doses, are superfluous.

They simply divide this value by 48 (number of years of exposure) to estimate an annual average dose to the whole body. Their approach yielded an annual average dose to the whole body of ~4 mrem/year (which is based primarily on the doses to a Category I fish eater who consumed fish caught near Jones Island). They then compare this value with the "100-mrem per year dose recommended for the public" by ATSDR, the ICRP, the NRC, and the NCRP, and reach the obvious conclusion that this annual dose is small in comparison to the recommended dose (limit).

However, doses for an essentially complete suite of organs/tissues were provided in Appendix 13A in the Task 4 report. When a complete accounting of organ/tissue doses is made using 50^th percentile estimates in conjunction with the tissue weighting factors given in Table 6 of the PHA, the average annual dose to male and female Category I fish eaters over the 1944–1991 exposure period increases to 9.4 mrem/year and 6.4 mrem/year, respectively, or, on average, about twice what ATSDR calculated.

The effective dose is the sum of the dose received by all organs of the body. The equivalent dose is the dose received by specific organs. This approach varied in the public health assessment depending on the specific radionuclides being evaluated. See Section III. Evaluation of Environmental Contamination and Potential Exposure Pathways in the final PHA for more specific information on this evaluation.

ATSDR uses the critical organ concept. The critical organ, as defined by the International Commission on Radiological Protection (ICRP), is the organ receiving the highest radiation dose following an intake of radioactive material. Basically, the critical organ is the organ or organ system most susceptible to radiation damage resulting from the specific exposure conditions being evaluated. This concept also takes into account the dose received by various parts of the body under these exposure conditions. For its public health evaluation of past exposures (those referenced by the commenter), ATSDR considered the contaminants of concern for X-10 radionuclide releases to White Oak Creek and chose the organ systems based on this critical organ concept. For the dose assessment, ATSDR looked at the following critical organs: bone, lower large intestine, red bone marrow, breast, and skin. For example, cesium 137 is a whole-body issue. It is distributed fairly uniformly throughout the body, with the intestines receiving the highest radiation dose. Strontium 90, however, is considered a bone-seeking radionuclide because while about 70-80% of the amount of ingested strontium 90 passes through the body, nearly all of the remaining 20–30% of strontium 90 is absorbed and deposited in the bone.

The method described by the commenter is used as a first approximation of the annual dose. This method is generally used by many agencies, including the U.S. Environmental Protection Agency (EPA), the U.S. Department of Energy (DOE), and the U.S. Nuclear Regulatory Commission (NRC) in determining the accumulated dose in the first year following an intake. This issue was discussed at several Exposure Evaluation Work Group meetings (EEWG, formerly known as the Public Health Assessment Work Group [PHAWG]) and at the Oak Ridge Reservation Health Effects Subcommittee (ORRHES) meetings where the screening process was discussed. The reason for dividing the total dose by 48 years (for certain exposure scenarios, ATSDR divided the total dose by a different number of years; see Table 10 in the final PHA for these specific scenarios) was to establish a first approximation of the dose, as this would allow for comparison to the 100 mrem/year dose limit recommended for the public by the ICRP, the National Council on Radiation Protection and Measurements (NCRP), the NRC, and ATSDR. ATSDR approximated the annual whole-body dose for each pathway by applying weighting factors to the Task 4's estimated 50^th percentile organ-specific doses, adjusting for a 1-year exposure, and summing the adjusted organ doses across each pathway. The first approximation value of 4.0-mrem/year for past exposures is 25 times less than the 100 mrem/year dose limit recommended for the public. Because this approximated value is so much lower than the dose limit recommended for the public during the screening-level evaluation, no further actions were necessary. Had the approximation shown an annual dose close to 100 mrem/year, ATSDR would have re-assessed the evaluation and conducted further investigation.

Yes, this is correct. Even when using different calculations and including all organs and tissues evaluated in the Task 4 of the Tennessee Department of Health's Reports of the Oak Ridge Dose Reconstruction (Task 4 report) to estimate doses for the worst-case exposure scenario (i.e., a Category I fish consumer near Jones Island), the annual doses would still be more than 10 times less than 100 mrem/year—the radiation dose limit recommended for the public by the NCRP, NRC, and ICRP. Thus, even when different calculations are applied, the commenter still calculated an estimated dose significantly below the 100 mrem/year recommended dose limit.

12

Page 5, paragraph 3: The authors focus exclusively on 50^th percentile estimates of "whole-body doses" and derived annual average dose, while their analysis of the Task 4 report in Sect. III.B covers critical, but incomplete, information on a suite of doses to individual organs/tissues. Furthermore, the summation of 50^th percentiles as point estimates will underestimate the median value for the total dose and risk.

The ATSDR PHA uses statistically inappropriate procedures for dose summation of annual doses. The original Task 4 report produced 95% credibility intervals for all dose and risk estimates. The central value of these intervals was the median, 50^th percentile of the underlying probability distribution or obtained from a quantitative uncertainty analysis. Using median values as point values to sum each annual dose to produce a lifetime cumulative dose will underestimate the median value of the cumulative dose.

When estimating risk for individuals exposed to radiation, the full credibility interval of dose is more scientifically appropriate than the central value. The arithmetic mean of that distribution is more appropriate than the median value for estimating the average dose and risk to a group of exposed individuals. The mean value of risk is the summarization of the full weight of evidence that cancer could be induced due to exposure.

There is the potential for substantial underestimation of annual doses and cumulative lifetime effective whole body doses to maximally exposed persons. This issue is exacerbated by ignoring 95% credibility intervals on the dose estimates reported in the original Task 4 report and by failure to sum across all of the organs irradiated through ingestion of Cs-137.

For most organs, the dose is the result of ingestion of Cs-137. Thus, the whole-body dose and the organ-specific doses are nearly identical. There is some additional dose to the bone and red bone marrow contributed by ingestion of Sr-90 and to the gastrointestinal tract from ingestion of Ru-106.

It is the range of doses (represented by the 95% credibility intervals provided in the Task 4 report) that should have been used in the ATSDR analysis. A value based solely on a 50^th percentile estimate is an insufficient estimator of true dose and subsequent risks. When the average annual effective doses are derived using the 95^th percentile estimates of doses over the 48-year exposure period, the values for both male and female Category I fish consumers fall in the 75–80 mrem/year range (or ~4 rem/40 mSv over 48 years). Although the average annual doses for female fish consumers based on the 50^th percentile dose estimates are lower than those for males, the ratios of the 95^th to the 50^th percentile significantly higher for females (cf. values in Table 13.A.1 and 13.A.4 in the Appendices to the Task 4 report). These 95^th percentile dose estimates are fairly close to the annual 100-mrem dose (limit) used as a Minimum Risk Level "Comparison Value" by the ATSDR.

The premise that best estimate (mean or median) values are inadequate for communicating with the general public is another statement based on facts not in evidence. The public has little appetite for statistics that they don't think they need. What they do want is straight answers, not maybes. Median values give the public what they want and expect.

Contrary to this commenter's opinion, using the full estimated interval of the dose is not more scientifically appropriate than the 50^th percentile estimate when evaluating health effects from exposure. Instead, use of the full interval of the dose or the central estimates depends on the realistic, site-specific exposure conditions about the actual or likely exposures evaluated. Further, use of the upper-bound value artificially increases the risk: the calculated uncertainty in many cases is at least an order of magnitude or greater than the 50^th percentile value. In this public health assessment ATSDR uses the central values because they provide the most realistic doses for potential exposures to radionuclides in the Clinch River and the Lower Watts Bar Reservoir. Central estimates describe the risk or dose for a typical, realistic individual. The goal of the health effects evaluation is to decide whether harmful health effects might be possible in the exposed population by weighing the scientific evidence and by keeping the site-specific doses in perspective. When considering central estimates, half of the potential doses will fall above and half will fall below the estimate. Therefore, an individual's actual dose would be most likely closer to the central value than near the high or low end of the dose estimate range. In fact, ATSDR's external reviewers who evaluated documents associated with the Oak Ridge Dose Reconstruction recommended emphasizing the central estimate rather than the upper and lower bounds of the dose distribution.

For its evaluation of past exposures to X-10 radionuclide releases via White Oak Creek, ATSDR used a dose methodology and considered the 50^th percentile estimates provided in the Task 4 report (available at http://www2.state.tn.us/health/CEDS/OakRidge/WOak1.pdf ). The Task 4 team, on the other hand, used a risk model and the upper 95^th percentile dose and risk levels. Nonetheless, even using different approaches, ATSDR came to the same basic conclusions as described below.

According to page 15-2 of the Task 4 report, "The highest exposures, doses, and estimated lifetime risks of excess cancer incidence were from the ingestion of contaminated fish. The most highly contaminated fish would have been harvested in the vicinity of CRM [Clinch River Mile] 20.5, near Jones Island." Further, according to page 13-18 of the Task 4 report, "For the Jones Island area (CRM 20.5), the large total risk from ingestion of fish for the Category I consumer is considered by the study team to be a conservative estimate, because the likelihood is small that someone consumed that mush fish from only the Jones Island area." On page 15-4 of the Task 4 report, the authors' state: that "The radiological doses and excess lifetime cancer risks estimated in this report are incremental increases above those resulting from exposure to natural and other anthropogenic sources of radiation. Nevertheless, for the exposure pathways considered in this task, the doses and risks are not large enough for a commensurate increase in health effects in the population to be detectable, even by the most thorough of epidemiological investigations. In most cases, the estimated organ-specific doses are clearly below the limits of epidemiological detection (1 to 30 cSv [centisievert]) for radiation-induced health outcomes that have been observed following irradiation of large cohorts of individuals exposed either in utero, as children, or as adults." "Even in the case of Category I consumers of fish, the upper confidence limits on the estimated organ-specific doses are below 10 cSv, and the central values are below 1 cSv. The lower confidence limits on these doses are well below levels that have been considered as limits of epidemiological detection in studies of cohorts of other exposed populations. The large uncertainty, combined with the small number of individuals comprising Category I consumers, diminishes the statistical power available to detect a dose response through epidemiological investigation. Therefore, it is unlikely that any observed trends in the incidence of disease in populations that utilized the Clinch River and Lower Watts Bar Reservoir after 1944 could be conclusively attributed to exposure to radionuclides released from the X-10 site, even though this present dose reconstruction study has potentially identified increased individual risks resulting from these exposures."

Also, the Task 4 report was reviewed by the Oak Ridge Health Agreement Steering Panel (ORHASP)—a panel of experts and local citizens appointed to direct and oversee the Oak Ridge Health Studies. On page 12 of the ORHASP's final report titled Releases of Contaminants from Oak Ridge Facilities and Risks to Public Health (available at http://www2.state.tn.us/health/CEDS/OakRidge/ORHASP.pdf ), the panel determined, "Although the White Oak Creek releases caused increases in radiation dose, the calculated exposures were small, and less than one excess cancer is expected." In addition, on page 38 of the ORHASP report regarding the number of health effects that would be expected from exposure to X-10 radionuclide releases via White Oak Creek, the panel estimates "less than one excess cancer case from 50 years of contaminated fish consumption" would result.

On page 147 of the final public health assessment, "ATSDR concludes that exposures to X-10 radionuclides released from White Oak Creek to the Clinch River and to the Lower Watts Bar Reservoir are not a health hazard. Past and current exposures are below levels associated with adverse health effects and regulatory limits. Adults or children who have used, or might continue to use, the waterways for recreation, food, or drinking water are not expected to have adverse health impacts due to exposure. ATSDR has categorized those situations as posing no apparent public health hazard from exposure to radionuclides related to X-10. This classification means that people could be or were exposed, but that their level of exposure would not likely result in adverse health effects."

Thus, even though ATSDR used a dose methodology and considered the 50^th percentile estimates, while the Task 4 team used a risk model and the upper 95^th percentile dose and risk levels, ATSDR came to the same basic conclusion. ORHASP found that less than one excess cancer case would be expected to occur as a result of exposure to X-10 radionuclide releases via White Oak Creek; ATSDR concluded that this exposure was not expected to cause adverse health effects.

Thank you for your comment. As described above, we agree that using the 50^th percentile estimates provide a much more realistic framework for evaluating exposures to the public.

13

The annual variation in risks from consumption of 1 lb of fish caught near Grassy Creek (CRM 14) from 1944–1991, given in Table 13.11 of the Task 4 report, can be used as a surrogate for the variation over time in doses resulting from consumption of fish caught near Jones Island. Doses (risks) estimated in this manner for the period 1944–1948 were three times greater than the average [which was estimated from the sum of risks for each year in the period given in the table (2.4 x 10^-6), divided by 48 years]. Thus, the upper credibility limits of doses to all Category I fish consumers of fish caught near Jones Island during 1944–1948 would be about 230 mrem/year, and thus well above the dose (limit) used for comparative purposes by the ATSDR. The upper credibility limits of the dose estimates calculated in this way fall to less than 100 mrem/year (averaging ~40 mrem/year) during the period from 1950–1953. They increase again during 1954–1959 to average levels that are nearly identical to those incurred during 1944–1949. Not surprisingly, the peak releases of Cs-137, which is the primary contributor to the dose from fish consumption and to the doses from several other pathways (see Tables 13.8 and 13.9 in the Task 4 report), took place during the years 1944–1949 and 1954–1959 (see Table 2 and Fig. 21 in the ATSDR PHA).

Based on the information presented in the SENES Oak Ridge, Inc., Task 4 Report, in Table 13.11 (Annual risk / lb of fish at CRM 14), Fig. 13.3 (Comparison of risks at different CRM), Table 12.11 (Risk coefficients), and Page 13-4 (fish consumption rates for different categories of people), I can state that the upper bound of doses from fish consumption at CRM 20.5 (Jones Island) and CRM 14.0 exceeded 100 mrem/yr in some years (e.g., 1946, 1956) for people in fish consumption Categories I (about 20 kg/yr) and II (10 kg/yr). Doses from drinking water or from external exposure to contaminated sediments are not included in these tables.

Using a nominal radiogenic lifetime risk of cancer incidence of 8% per Sv, and dividing into the reported upper bound risk levels (which are the result mostly of uncertainty associated with exposure to Cs-137) indicates that individual cumulative whole body doses could have been larger than the ATSDR whole body radiogenic cancer CV of 5000 mrem. Given that the peak exposures occurred within two five-year periods between 1944 and 1959, it can be shown that the maximum annual doses could have exceeded 100 mrem/y during these years. By contrast, the annual dose reported in the ATSDR PHA is 4 mrem.

ATSDR does not acknowledge that there are large uncertainties in these estimates, and that, because of large variations in releases from White Oak Creek over time, annual doses to individuals exposed in the 1940s and 1950s, when releases were at their highest levels, would have been significantly higher than values based on an average dose over 48 years.

In his opinion, inappropriate averages were being used to present a positive view of the results.

When the increased levels of annual releases and exposure (i.e., consumption of fish caught during the 1940s and 1950s when releases were much higher than the average) are factored into the analysis, effective doses exceed the 100-mrem per year dose limit at the upper limit of the 95% credibility interval of the annual dose received via all pathways of exposure.

Because the use of the upper bound value artificially increases the risk as the calculated uncertainty in many cases is at least an order of magnitude or greater than the 50^th percentile value, ATSDR used the 50^th percentile (central) value from the Task 4 of the Tennessee Department of Health's Reports of the Oak Ridge Dose Reconstruction (Task 4 report). The values calculated by ATSDR are in line and agree with the Task 4 values, even though the methods of analyses were different (see the response to comment 12 for more information on how these different methods were used to develop the same basic conclusions). ATSDR uses the central values in this public health assessment because they provide the most realistic doses for potential exposures to radionuclides in the Clinch River and the Lower Watts Bar Reservoir. Central estimates are used because they describe the risk or dose for a typical person. When considering central estimates, half of the potential doses will fall above and half will fall below the estimate. Therefore, a person's actual dose would most likely be closer to the central value than near the high or low end of the range of dose estimates. In fact, ATSDR's external reviewers who evaluated documents associated with the Oak Ridge Dose Reconstruction recommended emphasizing the central estimate rather than the upper and lower bounds of the dose distribution.

As noted above, the commenter is using the maximum annual dose calculated from the upper 95^th percent confidence level in the Task 4 Report. This unrealistic, upper-bound value artificially increases the doses. Although this method may be appropriate for regulatory matters, ATSDR uses the central values (50^th percent or mean value). The agency believes this is a more realistic expression of the potential for exposure and resulting dose. The scenarios associated with using the upper-bound (95% confidence level) to estimate the maximum annual dose would require over many years almost daily intakes of the maximum concentrations found in water and fish associated with a specific location around Jones Island.

The nominal cancer risk factor used by many regulatory agencies, including the U.S. Environmental Protection Agency (EPA), the U.S. Nuclear Regulatory Commission (NRC), and the U.S. Department of Energy (DOE), is 5%—not 8% as indicated by the commenter. The 8% includes cancer, hereditary effects, and other non-specific risks.

The method described by the commenter is used as a first approximation of the annual dose. The EPA, NRC, and DOE generally use this method in determining the accumulated dose in the first year following an intake. This issue was discussed at several Exposure Evaluation Work Group meetings (EEWG, formerly known as the Public Health Assessment Work Group [PHAWG]) and at the Oak Ridge Reservation Health Effects Subcommittee (ORRHES) meetings where the screening process was discussed. The reason for dividing the total dose by 48 years (for certain exposure scenarios, ATSDR divided the total dose by a different number of years; see Table 10 in the final PHA for these specific scenarios) was to establish a first approximation of the dose. This would allow for comparison to the 100 mrem/year dose limit recommended for the public by the International Commission on Radiological Protection (ICRP), the National Council on Radiation Protection and Measurements (NCRP), the NRC, and ATSDR's minimal risk level (MRL). Furthermore, as specified in ICRP Publication 60, "The limit should be expressed as an effective dose of 1mSv [millisievert] [100 millirem] in a year. However, in special circumstances a higher value of effective dose could be allowed in a single year, provided that the average over 5 years does not exceed 1 mSv per year."

ATSDR approximated the annual whole-body dose for each pathway by applying weighting factors to the Task 4's estimated 50^th percentile organ-specific doses, adjusting for a 1-year exposure, and summing the adjusted organ doses across each pathway. The first approximation value of 4.0 mrem/year for past exposures is 25 times less than the 100 mrem/year dose limit recommended for the public by the ICRP, NCRP, and NRC. Because this approximated value was so much lower than the dose limit recommended for the public during the screening-level evaluation, no further actions were necessary. Had the approximation shown an annual dose close to 100 mrem/year, ATSDR would have re-assessed the evaluation and conducted further investigation.

14

P. 57. Line 23 et seq. The quoted conclusion from the ORHASP report about past releases and harm need to be reconciled with the conclusions of this report.

The comment is noted. The following text was added to clarify that these risks were not associated with radionuclides from X-10, but with elevated mercury and PCB concentrations: "ORHASP noted, however, the Task 4 report determined that following exposure to fish contaminated with X-10 radionuclides via White Oak Creek, less than one excess cancer case was expected. Studies also indicate that elevated PCB concentrations drove the health risks associated with eating fish from the Clinch River and Watts Bar Reservoir."

15

Page 84, Table 9. Summary of Estimated Organ-Specific (Equivalent) Radiation Doses For Past Exposure Pathways. One more overly complex and undecipherable table. Stakeholders are wondering if this is intentional on ATSDR's part. Is ATSDR attempting to bury critical information in technical jargon and a cobbling of critical exposure information? If this is not, in fact intentional on ATSDR's part, it certainly is obscuring to the stakeholders.

Most stakeholders hold little hope that ATSDR can improve its public health practice without a sea change in both its cooperate attitude and its senior management. (Comment received on the initial release PHA dated December 2003.)

This table was changed in subsequent revisions and is presented in the final PHA as Table 11. Summary of Estimated Organ-Specific Doses and Whole-Body Doses for Each Past Radiation Exposure Pathway and the Estimated Lifetime Organ-Specific Doses and Lifetime Whole-Body Doses From All Past Radiation Exposure Pathways. This table provides the whole-body and organ-specific doses for all of the pathways of interest in the Task 4 of the Tennessee Department of Health's Reports of the Oak Ridge Dose Reconstruction (Task 4 report).

ATSDR is unclear on what information could be buried in this table and on what "technical jargon" is used. Without more information or specific details on what is undecipherable, ATSDR is not sure what changes could be made. But please note that the table has been completely modified since December 2003. It now consists of numbers (doses) only and provides footnotes to explain how the doses were calculated and where the information was obtained from (various tables in the Task 4 report). ATSDR believes that the table provides necessary information on these doses and how they were calculated.

For more information, please refer to the Task 4 report available online at http://www2.state.tn.us/health/CEDS/OakRidge/WOak1.pdf and see Appendix D for a brief on the 1999 Task 4 report. Copies of the Task 4 report are also available at the DOE Information Center located at 475 Oak Ridge Turnpike, Oak Ridge, Tennessee (telephone number: 1-865-241-4780).

16

P. 84. Table 11. A preliminary check of the organ doses, weighting factors, products, and sums (effective doses), between the Task 4 report and this report indicates that the numbers given in this report have been abbreviated with respect to those given in the Task 4 report. Therefore, it is not obvious that the numbers supposedly leading to the stated effective doses given in this report are numerically consistent, by themselves, with their stated relationship. Consequently, this will have to be demonstrated by a table of doses, weighting factors, products, and sums that, by calculation, actually agree with the results given on p.84. Otherwise, the stated results given in this report will have greatly diminished credibility.

The only difference between the tables is that Table 11 in the final PHA presents the doses in millirem, whereas the Task 4 of the Tennessee Department of Health's Reports of the Oak Ridge Dose Reconstruction (Task 4 report) uses centisieverts. For example, in Table 13.3 on page 13-6 of the Task 4 report, the Category I bone dose for male fish consumers is 0.81 centisieverts, which is 0.81 rem or 810 millirem—the value presented in Table 11 of the final PHA. Instead of creating another table, a footnote has been added to Table 11: "To compare the doses in the Task 4 report to the doses in this table, 1,000 mrem is equal to 1 centisievert (cSv). For example, 810 mrem (organ-specific radiation dose to the bone for fish ingestion at Jones Island) divided by 1,000 would equal 0.81 cSv—the same value presented in Table 13.3 of the Task 4 report."

17

Page 84, table 11: The values given in Columns 2–6 in the last row of the table bear little or no relationship to the information upon which they were reportedly based. For example, if we apply ATSDR's formula to estimate a 70-year organ/tissue dose for bone (surface), we get a value of 1181 mrem from ingestion of fish caught near Jones Island alone. If we include the lowest estimates of doses to bone from the other exposure pathways, we obtain an additional dose of ~24 mrem. The sum of these two doses exceeds 1200 mrem. If we perform the same exercise for the data in Columns 3 and 4, the totals are <900 mrem. The values in Columns 5 and 6 in the last row of the table would make sense if they were reversed.

As a conservative measure, ATSDR recalculated the estimated committed equivalent doses presented in Table 11 to account for individuals who could have been exposed via all of the pathways and at all of the locations presented in the table. To approximate a committed equivalent dose to an organ over 70 years, ATSDR summed the organ-specific radiation doses from the Task 4 of the Tennessee Department of Health's Reports of the Oak Ridge Dose Reconstruction (Task 4 report) based on up to 48 years of exposure (for certain exposure scenarios, the dose was based on a different number of years; see Table 10 in the final PHA for these specific scenarios)—divided by 48, multiplied by 70 years, and rounded up.

18

Page 85, lines 8–9 (also Page 5, line 9), 11: The statement needs to be revised to say "at least 6 times greater ... from drinking water ingestion, eating meat and milk, and via external radiation." The doses to both the breast and the skin from external radiation at Kingston were about 6.5 times those from eating fish (Table 12), and drinking water ingestion was omitted from the original listing of pathways.

The table reference in line 11 should have been to Table 11, and not to Table 10.

Once the worst-case drinking water ingestion dose at K-25/Grassy Creek is incorporated into this statement, it would be "6 times greater." The change was made in the final PHA. Also, we believe the commenter meant to say "about 6.5 times less than those from eating fish."

Thank you for the comment. The change was made in the final PHA.

19

Page 87, paragraph 3: Where are the data for the dose calculations to Happy Valley residents presented? Based on what is said, it is clear that the 50^th percentile estimates of annual doses from fish consumption would have been about 35 mrem/year. By analogy with the comments on the material in paragraph 3 on page 5, 95^th percentile estimates of the effective doses would have exceeded the 100 mrem/year criterion and the 95^th percentile estimates of the organ/tissue doses would undoubtedly have exceeded the 5000 mrem total dose criterion as well (see results for the Grassy Creek Area, Clinch River Mile 14, in Table 13.A).

As a note of clarification, the commenter is making statements regarding "fish consumption" related to ATSDR's evaluation of Happy Valley residents in the PHA. To clarify, this part of Section III in the PHA refers to drinking water ingestion for Happy Valley residents, not fish consumption. Consequently, the commenter's statements do not apply to the referenced section of the document.

Regarding this drinking water evaluation, the Task 4 of the Tennessee Department of Health's Reports of the Oak Ridge Dose Reconstruction (Task 4 report) conducted an analysis of exposure to X-10 contaminants via the K-25 water intake, but not a separate analysis for residents living in the Happy Valley settlement such as ATSDR conducted in this public health assessment (described on pages 90–91 of the final PHA). ATSDR used the 50^th percentile of the modeled radioactivity concentrations in the Grassy Creek area of the Clinch River from the Task 4 report. Given ATSDR's derived annual whole-body doses for these residents, the highest annual radiological dose to a hypothetical Happy Valley resident (residing there from 1944 to 1950) from drinking water from the K-25 water intake was 14 mrem or 98 mrem over the 7-year period. This annual dose is at least seven times less than the 100 mrem/year dose recommended for the public by the International Commission on Radiological Protection (ICRP), the National Council on Radiation Protection and Measurements (NCRP), and the U.S. Nuclear Regulatory Commission (NRC). See Sections III.B.2. and IV.B. in the final PHA for more details.

20

Page 111, table 22: This table presents the summed doses from Table 11, which are erroneous as discussed above, in Column 3; the ATSDR criteria used to assess whether the doses represent a health hazard in Column 4; the results of the comparison (Column 5); and the conclusion that these (1) are not likely to cause adverse health effects and (2) that releases from White Oak Creek were not a public health hazard. Because the doses are in error, for reasons given above, all of the comparisons and the conclusions need to be revised. In addition, the implication that these releases could not have caused any adverse health effects in at least some exposed individuals is improper, and should be purged from the document, along with other such statements, for reasons discussed earlier.

As a conservative measure, ATSDR recalculated the estimated committed equivalent doses presented in Table 11 to account for individuals who could have been exposed via all of the pathways and at all of the locations presented in the table. To approximate a committed equivalent dose to an organ over 70 years, ATSDR summed the organ-specific radiation doses from the Task 4 of the Tennessee Department of Health's Reports of the Oak Ridge Dose Reconstruction (Task 4 report)—based on up to 48 years of exposure (except where noted in Table 10 of the final PHA)—divided by 48, multiplied by 70 years, and rounded up. These changes have been reflected in Table 22. Still, even with considering potential exposures via all of the pathways and at all of the locations presented in Table 11, all estimated doses are below levels shown to cause adverse health effects.

Based on our evaluation in this public health assessment, ATSDR concludes that exposures to X-10 radionuclides released from White Oak Creek to the Clinch River and to the Lower Watts Bar Reservoir are not a health hazard. Past and current exposures are below levels associated with adverse health effects and regulatory limits. Adults or children who have used, or might continue to use, the waterways for recreation, food, or drinking water are not expected to have adverse health impacts due to exposure. ATSDR has categorized those situations as posing no apparent public health hazard from exposure to radionuclides related to X-10. This classification means that people could be or were exposed, but that their level of exposure would not likely result in any adverse health effects.

This commenter is incorrect in implying that the document states "these releases could not have caused any adverse health effects." This is clearly evident by the use of the no apparent public health hazard conclusion category in this public health assessment. ATSDR uses this category in situations in which human exposure to contaminated media might be occurring, might have occurred in the past, or might occur in the future, but where the exposure is not expected to cause any harmful health effects. Therefore, ATSDR is not saying that these releases could not have caused any health effects. On the contrary, we are saying that radiation exposure is possible, but that this exposure is not expected to result in adverse health effects.

21

The ATSDR PHA states that dose estimates in the original Task 4 report of the Oak Ridge Dose Reconstruction were conservative (i.e., likely to overstate true doses to real persons). This conclusion is not true. The Task 4 report was specifically designed to produce realistic dose and risk results for reference individuals, fully accounting for the presence of multiple sources of uncertainty. The uncertainty about central values of dose is substantial, approaching a factor of 10 or more about the 50^th percentile value.

It has published the conclusion that our past work produced "conservative" estimates of dose without justification. Our estimates of doses to representative individuals as the result of past operations at ORNL were made without the intent to bias the conclusions in a manner that would overestimate the true exposure. This is precisely why we embraced the application of quantitative methods of uncertainty analysis.

The summary document indicated that the Task 4 Report was inherently conservative. In his opinion, he said, this means that there is an inherent bias towards overstating the truth of unknown exposure or risk, which according to him, was not true and was the reason quantitative uncertainty analysis was used in the approach.

In the Task 4 of the Tennessee Department of Health's Reports of the Oak Ridge Dose Reconstruction (Task 4 report), the authors state that they used measured concentrations when available. But if these data were not available, estimations were made via the use of modeled parameters. These estimations were subjective probability distributions as discussed in Chapter 4 of the task report. Given the nature of the subjective analyses, ATSDR believes these to be appropriately conservative in nature and application.

As discussed in NCRP Commentary 14 entitled A Guide for Uncertainty Analysis in Dose and Risk Assessments Related To Environmental Contamination, a quantitative uncertainty analysis, "usually requires that the state of knowledge about the uncertain components of the mathematical model be described by probability distributions." If this knowledge is unavailable, then professional judgment is used to evaluate the site-specific parameters. NCRP Commentary 14 also states that if the results of an assessment indicate that doses are below regulatory limits, then a quantitative uncertainty analysis may not be necessary. The Task 4 report used conservative parameters to estimate a 95% confidence interval for risks and doses from past exposures to X-10 radionuclides released to White Oak Creek. ATSDR calculated doses using the findings of the Task 4 report, and obtained estimated doses that were well below very conservative, regulatory limits.

In developing their conclusions, the Task 4 authors used a worst-case scenario considering the upper confidence limits for the highest fish consumers ingesting fish caught near Jones Island (the study area with the highest detected radionuclide concentrations). Even using this worst-case scenario, the Task 4 authors concluded that "the upper confidence limits on the estimated organ-specific doses are below 10 cSv [centisievert]...," which lies in the range that the authors describe as "clearly below the limits of epidemiological detection (1 to 30 cSv) for radiation-induced health outcomes that have been observed following irradiation of large cohorts of individuals..." Therefore, even considering this worst-case scenario, the Task 4 authors found that "...for the exposure pathways considered in this task, the doses and risks are not large enough for a commensurate increase in health effects in the population to be detectable, even by the most thorough of epidemiological investigations."

NCRP Commentary 14 also states that, following an uncertainty analysis, if the 95th percentile exceeds a standard or regulatory limit and the 50th percentile is less than the standard or regulatory limit, then additional evaluations may be recommended (page 23). ATSDR performed this additional evaluation and concluded that the more reasonable result was that the doses received from the intake of potentially contaminated foods (the pathway yielding the highest doses) were below regulatory limits and levels of a public health hazard. Even if doses from all other pathways evaluated were combined with the ingestion pathway, the doses were still sufficiently low and below levels where tolerable and observable adverse health effects would be expected.

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The belief that the contents of the Task 4 report have not been considered is not accurate, certainly with respect to the Exposure Evaluation Work Group (EEWG). I presented the chain of logic used to develop best estimate (median) values of dose and risk in the Task 4 report to the then Public Health Work Group (PHAWG) on July 19, 2004. This information was supplementary to the attention given to the Task 4 report by the authors of the White Oak Creek PHA. The work of the EEWG is a team effort. Individuals do not seek credit for their comments on the draft PHAs.

Thank you for your comment.

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There are major technical inaccuracies, misinterpretations, and omissions in the dose and risk information obtained from the original Oak Ridge Dose Reconstruction (Task 4) reports. The most serious of these issues involve the lack of consideration of information on uncertainty in dose and risk, the failure to report individual risk estimates, the failure to report the 95% credibility intervals on dose and risk, and lifetime averaging of doses over the entire period of release, obscuring the relatively high annual doses for the early years of release (1944-1949, 1954-1959) to give the impression that annual doses were acceptably small.

ATSDR did not omit, misrepresent, or have technical inaccuracies in the information used from the Task 4 of the Tennessee Department of Health's Reports of the Oak Ridge Dose Reconstruction (Task 4 report) for the evaluation in this public health assessment. The dose information obtained from the Task 4 report was accurate and data relevant to this evaluation were not omitted.

ATSDR evaluated the need for an uncertainty analysis as outlined in NCRP Commentary 14 titled A Guide for Uncertainty Analysis in Dose and Risk Assessments Related to Environmental Contamination. In essence, the use of conservative and biased screening calculations indicated the possible resulting dose would be clearly below a regulatory limit. "Conservative screening calculations are designed to provide a risk estimate that is highly unlikely to underestimate the true dose or risk. Therefore, a more detailed analysis will likely demonstrate that the true risk is even less."

The document states that screening can be considered among the first steps in conducting an uncertainty analysis as this roughly defines the upper and lower bounds of a distribution of exposed populations or individuals. If these screening calculations are to be used successfully, a decision point has to be determined to establish the boundary at which no further analyses are necessary. According to NCRP Commentary 14, "For example, for dose reconstruction, the National Academy of Sciences has suggested that an individual lifetime dose of 0.07 Sv [sievert] be used as a decision criterion for establishing the need for more detailed investigation (NAS/NRC 1995 [National Research Council. 1995. Radiation dose reconstruction for epidemiologic uses. Committee on an assessment of CDC radiation studies. Board on Radiation Effects Research, Commission on Life Sciences. Washington, DC: National Academy of Sciences.])." A value of 0.07 Sv is equivalent to 7 rem or 7,000 mrem—a value that is 40% higher than ATSDR's radiogenic cancer comparison value of 5,000 mrem over 70 years. Thus, ATSDR's screening value is more conservative than the criteria suggested by the National Academy of Sciences as reported by the NCRP.

Regarding risk estimates, please see Appendix F in the final PHA and the response to comment 44 within this appendix.

ATSDR uses the central values—not the upper-bound value of the dose estimates— because these provide the most realistic doses for potential exposures to radionuclides in the Clinch River and the Lower Watts Bar Reservoir. Central estimates are used because they describe the risk or dose for a typical, realistic individual. When considering central estimates, half of the potential doses will fall above and half will fall below the estimate. Therefore, an individual's actual dose would most likely be closer to the central value than near the high or low end of the range of dose estimates. In fact, ATSDR's external reviewers who evaluated documents associated with the Oak Ridge Dose Reconstruction recommended emphasizing the central estimate rather than the upper and lower bounds of the dose distribution.

The method described by the commenter is used as a first approximation of the annual dose. This method is generally used by many agencies, including the U.S. Environmental Protection Agency (EPA), the U.S. Department of Energy (DOE), and the U.S. Nuclear Regulatory Commission (NRC) in determining the accumulated dose in the first year following an intake. This issue was discussed at several Exposure Evaluation Work Group meetings (EEWG, formerly known as the Public Health Assessment Work Group [PHAWG]) and at the Oak Ridge Reservation Health Effects Subcommittee (ORRHES) meetings where the screening process was discussed. The reason for dividing the total dose by 48 years (for certain exposure scenarios, ATSDR divided the total dose by a different number of years; see Table 10 in the final PHA for these specific scenarios) was to establish a first approximation of the dose, as this would allow for comparison to the 100 mrem/year dose limit recommended for the public by the International Commission on Radiological Protection (ICRP), the National Council on Radiation Protection and Measurements (NCRP), the NRC, and ATSDR. ATSDR approximated the annual whole-body dose for each pathway by applying weighting factors to the Task 4's estimated 50^th percentile organ-specific doses, adjusting for a 1-year exposure, and summing the adjusted organ doses across each pathway. The first approximation value of 4.0 mrem/year for past exposures is 25 times less than the 100 mrem/year dose limit recommended for the public. Because this approximated value is so much lower than the dose limit recommended for the public during the screening-level evaluation, no further actions were necessary. Had the approximation shown an annual dose close to 100 mrem/year, ATSDR would have reassessed the evaluation and conducted further investigation.

Evaluation of Current and Future Exposures

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Page 6, Line 17: ATSDR has determined that exposure to the current levels of radionuclides in the surface water, sediment, fish, and game are not expected to cause any harmful health effects in the present and future. Therefore, ATSDR concluded that current and future off-site exposure to radionuclides in the Clinch River and the LWBR via White Oak Creek is not a public health hazard.

The statement seems to assume conditions on the ORR will remain static in the future. This does not seem likely, given the longevity (e.g., millions of years) and dynamics associated with many of the contaminants that will be left in place, as well as the complexity of the site as whole. To a large degree, assurance that the health of the public and environment will be protected in the future appears to rely on the demonstrated success of current remedial activities and DOE's commitment to providing perpetual support of a comprehensive system of monitoring, maintenance, and institutional controls.

To support that contention that there will be no detectable public health effects from exposures to future WOC radionuclide releases, wording should be added that current remediations and engineering controls at existing operable units in the White Oak Creek watershed must be maintained for the foreseeable future.

The future safety of the public is dependent upon a continuing long term stewardship program which will ensure the integrity of the engineering controls that are being installed upstream in Melton Valley and elsewhere.

P. 7. Line 4. Concerning future exposures, has ATSDR evaluated the effects of current environmental restoration activities at ORNL?

Thank you for your comment. Text in Section I. Summary of the final PHA was changed to the following: "ATSDR's review of environmental data collected in and around the Clinch River and LWBR areas shows that the following practices

• annual environmental monitoring,
• institutional controls intended to prevent disruption of sediment,
• on-site engineering controls to prevent off-site contaminant releases, and
• DOE continuing its expected appropriate and comprehensive system of monitoring (e.g., of remedial activities and contaminant levels in media), maintenance, and institutional and engineering controls,

have limited exposure to the current levels of radionuclides in surface water, sediment, fish, and game to the point that radionuclides are not expected to cause any current or future harmful health effects. Given this evaluation, ATSDR concludes that current and future off-site exposure to radionuclides in the Clinch River and the LWBR via White Oak Creek is not a public health hazard." Similar text was also added to Section IV. Public Health Implications and Section VIII. Conclusions of the final PHA regarding future exposures.

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P. 34. The conclusions of the baseline risk assessment (Jacobs EM Team 1997b) appear to imply that consuming any fish taken from Poplar Creek, or bass from the Clinch River below Melton Hill Dam, pose a health risk. CRM 20.5 at Jones Island is only about three miles below Melton Hill Dam. How are the Jacobs conclusions to be reconciled with the final conclusions of this report?

Your comment is noted. The text has been clarified to explain that primary risks in DOE's risk assessment were not associated with radionuclides in fish: "The assessment also determined that because of PCB and mercury contamination, the consumption of any type of fish in Poplar Creek posed a health risk. Similarly, consumption of bass from the Clinch River below Melton Hill Dam posed a health risk due to PCB contamination. Still, no primary risks were associated with exposure to radionuclides in fish from the Clinch River or from Poplar Creek."

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The document should explain why some past waste-disposal sites, which are not current public health concerns, are now subject to remediation. Though expensive, this ensures that long-term safety is maintained and that catastrophic or chronic releases are prevented, or at minimum, detected in a timely manner. It may also be necessary to meet environmental contamination standards which are often more stringent than human health criteria.

The rationale of spending money now on currently satisfactory waste disposal scenarios in order to maintain their long-term safety should be explained. How can a responsible party recommend putting off necessary maintenance until after the disaster has occurred? An ounce of prevention is worth a pound of cure.

The following text was added to the introductory portion of Section II.C. Remedial and Regulatory History: "Although not current public health concerns, some of these former waste disposal sites are nonetheless subject to remediation. DOE is remediating these sites to ensure long-term safety is and to prevent off-site releases. More information on DOE's environmental management program can be obtained at http://www.oakridge.doe.gov/External/Default.aspx?tabid=42 ."