December 23, 1999
- DRAFT -
NATIONAL ECONOMIC COUNCIL
OCCUPATIONAL ILLNESS COMPENSATION FOR
DEPARTMENT OF ENERGY CONTRACTOR PERSONNEL
REPORT OF TASK GROUP 1
January, 2000
CONTENTS
· EXECUTIVE SUMMARY
· BACKGROUND
· Nuclear Weapons Production and DOE Operations
· Radiation Exposures and Cancer Risk
· Chemical Exposures
· FINDINGS
· Summary of Major Findings from DOE Epidemiologic Studies
· Summary of Findings Related to Chemical Hazards at DOE Sites
· Summary of Findings from Special Radiation Workers Monitoring Programs:
Los Alamos Plutonium Workers
Rocky Flats High RAD Workers Program
US Transuranium and Uranium Registries
· Summary of Findings from Other Surveillance Programs:
Epidemiologic Surveillance Program
Computerized Accident/Incident Reporting System (CAIRS)
· Initial Results from the Former Workers Program
· REFERENCES
· APPENDICES
· APPENDIX 1: Summary of Epidemiologic Studies
· APPENDIX 2: References for the DOE Epidemiologic Studies
· APPENDIX 3: Chemical Contaminants at DOE
· APPENDIX 4: Radiation Workers Monitoring Programs
· APPENDIX 5: Epidemiologic Surveillance Program and CAIRS
· APPENDIX 6: Initial Results from Former Workers Studies
· APPENDIX 7: List of Panel Members
________________
EXECUTIVE SUMMARY
This report summarizes the activities and results of both completed health studies and ongoing health surveillance programs that are conducted at the US Department of Energy (DOE). The DOE is a government-owned, contractor-operated Federal government agency. Studies reviewed here focus on this contractor workforce during their work producing nuclear weapons.
Historically, the primary focus of DOE health studies was limited to health effects related to exposure to ionizing radiation. Toxic chemicals (other than radionuclides) have been studied only to a limited extent. This report does not postulate what diseases might result from these exposures. Rather, it relies solely on adverse health outcome information and radiation exposure data from peer-reviewed studies as well as technical government reports.
The panel did not consider nor evaluate other non-DOE populations with occupational radiation exposures such as shipyard workers, medical personnel, or atomic bomb survivors. Establishing and measuring causal links between exposures and illness was not considered to be within the scope of the mandate of this panel.
There is evidence that current and former contractor workers at DOE nuclear weapons production facilities are at increased risk of illness from occupational exposures associated with the production of nuclear weapons. The strength of the evidence varies with some evidence showing a strong association with employment in specific facilities while other evidence is at best suggestive of an occupational association.
The primary focus of the studies concerning the health status of these workers has been mortality studies. The evidence presented in the studies reviewed by the panel clearly provides strong evidence in the form of statistically significant excesses of specific cancers at a number of DOE facilities. In addition, a number of studies showed statistically significant positive trends by radiation dose. This evidence, considering that many studies identified excess cancers that did not reach the levels of statistical significance and that several studies did show statistically significant cancer excesses with extended follow-up periods, demonstrates a relationship of work at nuclear weapons facilities and illness. Cancers for which strong evidence exists include lung, brain, bladder, myeloma, leukemia and other lymphatic cancers, stomach, respiratory, laryngeal, and trachea. The identification of excess of some types of cancers at some facilities and other types of cancers at other facilities is not unexpected based on the vast differences in production processes and thus exposures at the various DOE facilities.
Information presented to the panel concerning morbidity studies and medical surveillance programs for current and former DOE contract workers also present significant evidence that these workers have suffered material impairment of health as a result of performing their duties in the production of nuclear weapons. This evidence must be viewed with caution for several reasons. The former worker medical surveillance program is in its initial phase with only preliminary results available. The participants are self selected and therefore caution must be exercised in drawing any conclusions as to the health status of the overall population of former workers. However, the results presented do provide strong evidence that participating former workers at some facilites have experienced significant health impairment in the form of nonmalignant lung diseases consistent with exposures to asbestos and silica, hearing impairment, and beryllium disease. The mortality studies have also show strong evidence that workers at several facilities have experienced nonmalignant lung diseases.
The strength of the evidence is limited by several factors. First and foremost are the limitations associated with most mortality studies such as difficulties in determining individual exposures, limited cohort size, and limited follow-up time. Population-based studies also have a number of inherent limitations including their inability to answer questions about the relationship between and individual's illness and the workers' occupational exposures. Another factor that limits the strength of the presented evidence is the numerous potentially confounding exposures and the lack of industrial hygiene data to account for these exposures. The scope of the available studies and information present significant limitations to the evidence. A number of DOE facilities have not been included in these studies and the available studies have not included all workers. Finally, since most of the studies were limited to the identification of the underlying cause of death, many cancers and other occupational diseases may not have been accounted for in the available information.
________________
BACKGROUND
On July 15, 1999, President Clinton issued a Memorandum to the Secretaries of Defense, Labor, and Energy, the Attorney General, the Director of the Office of Management and Budget, and the Assistant to the President for Economic Policy regarding occupational illness compensation for DOE contractor personnel. The Memorandum indicated the Administration's intent to submit legislation to create a program to give DOE contractor employees with chronic beryllium disease (CBD) and beryllium sensitivity compensation benefits similar to those available to Federal employees. Such legislation was submitted to Congress on November 17, 1999. In addition, the July 15th Memorandum established an interagency review led by the National Economic Council (NEC) to assess, by March 31, 2000, whether there are other illnesses that warrant inclusion in this program and how this should be accomplished.
In determining whether and how other illnesses should be included in this program, three tasks were designated. The first task (Task 1) is the subject of this report to the NEC.
From October 1999, through January, 2000, a panel of experts from a wide spectrum of federal agencies (Appendix 7) met to address the following questions:
What is the evidence that current and former contractor workers at DOE facilities are at increased risk of illness resulting from exposures to occupational hazards uniquely associated with nuclear weapons production?
How strong is this evidence?
To answer these questions, the federal expert panel examined and evaluated information and data from a variety of sources including current and historical exposure hazards at DOE facilities which are unique to nuclear weapons production, as well as epidemiologic, other health studies and surveillance activities conducted among DOE contractor workers. Although data from other radiation exposed cohorts, most notably shipyard workers, were presented to the panel, the results of these studies are not included in this report due primarily to the limited focus and charge of this panel.
NUCLEAR WEAPONS PRODUCTION & DOE OPERATIONS
The Department of Energy and its predecessor agencies, principally the Manhattan Engineering District and the Atomic Energy Commission, have been engaged primarily in an extensive industrial enterprise to build and test nuclear weapons. For more than half a century, DOE has owned and its contractors have operated a nationwide network of heavy industrial sites as well as research laboratories involved in every aspect of weapons production from the refining of raw materials to the eventual testing of the bombs, and ultimately to the management of the weapons stockpile and the environmental consequences of nuclear production and testing (Ref. 1). It has been estimated that 5.5 trillion dollars (in 1996 dollars) have been spent since 1940 on US nuclear weapons and weapons-related programs (Ref. 2) and that upwards of 600,000 workers were involved in the construction, maintenance, operations, and scientific activities at DOE-owned facilities.
Figure 2 (Appendix 3) summarizes the process used to produce nuclear weapons. At each stage of the nuclear weapons cycle, from refining the raw materials to weapons assembly and finishing, to waste management and disposal, the principal materials used and primary exposures are listed. This figure is by no means a complete inventory of the potential health hazards that exist during the complex process of producing a nuclear weapon. For a more complete understanding of the potential chemical hazards involved in its operations, DOE has published a description of chemical vulnerabilities at its sites (Ref. 3). In addressing its charge, the NEC Task 1 panel examined evidence of illnesses from two classes of exposure: radiation and chemicals.
RADIATION EXPOSURES & CANCER RISK
Throughout the history of weapons production, exposure to external ionizing radiation was viewed as the hazard of greatest concern to the health of the nuclear weapons workforce. Great effort and expense were devoted to assessing dose principally to external radiation, but also to internal doses and neutrons as well. The greatest body of radiation exposure data comes from the dosimeters worn by DOE employees to measure external ionizing radiation. These were primarily film badges until the early 1970s when solid state thermo-luminescent detectors (TLDs) were adopted. The time period between badge readings was largely determined by the occupational standards of the time. In the 1950s the occupational limit was a weekly limit, in the 1960s a quarterly limit was established and since the 1970s the primary limit is an annual limit. Each site has been expected to determine who needs to wear a dosimeter and how often to exchange dosimeters based on working conditions at that site.
Radiation measurements are converted to radiation dose through the application of correction and quality factors to approximate the biologic effect of external gamma radiation at a depth of 1 cm in tissue (deep dose equivalent [DDE]). Prior to 1993 DOE required that internal dose be reported as annual effective dose equivalent (AEDE), which is the summation for all tissues and organs of the products of the dose equivalent calculated to be received by each tissue or organ during the specified year from all internal depositions multiplied by the appropriate weighting factor. Since 1993 internal dose has been required to be reported as committed effective dose equivalent (CEDE), which is the sum of the dose equivalents to various tissues in the body, each multiplied by the appropriate weighting factor, that will be accumulated over the next 50 years.
Dose records go as far back as the establishment of the Manhattan Engineering District in late 1942. These records have been used in various contexts to assess exposures of the DOE workforce and to evaluate their health. Radiation protection and control programs constituted the main focus of worker safety and health efforts at DOE sites. Prior to 1974 annual doses of less than 10 mSv were not required to be reported to the AEC. These records are available at the sites and have been used in health studies at selected sites. Starting in 1974 the AEC began collecting data on the number of individuals with measurable exposure, which is the subset of all monitored individuals who receive a measurable exposure (greater than limit of detection for the monitoring system). Many personnel are monitored as a matter of prudence and may not receive a measurable exposure. The number of individuals with measurable exposure is a better indicator of the exposed workforce. Appendix 4 (Table 7) lists the results of radiation monitoring from 1974 through 1997.
The historic distribution of dose for the DOE workforce is shown in Figure 1. The decline in average dose between 1986 and 1991 was due to the cessation of nuclear weapons production and the shutdown of numerous reactors used in their production
Figure 1. Historic Dose Distribution for the DOE Workforce
Based on the estimates shown above, average dose from 1945 to 1997 was about 1 mSv per year. The BEIR V report of the National Research Council provides a model for estimating excess cancer mortality based on a continuous adult working lifetime (47 year) exposure of 10 mSv per year. Using this model with an estimated average annual exposure of 1 mSv for the DOE cohort of monitored workers, an excess of 288 cancers per 100,000 might be expected. This number could be as low as 215 or as high as 546 per 100,000 cancers in excess of the 20,560 cancer deaths per 100,000 population expected in the absence of occupational radiation exposures, a one to three percent excess.
Note: The BEIR model estimates 2,880 excess cancers for continuous exposure to 10 mSv/y from age 18 to age 65 for a population of 100,000 males. Applying this to the DOE work force being exposed to 1 mSv/y this converts to 2880/10 = 288 cancers per 100,000 exposed workers.
CHEMICAL EXPOSURES
It has been estimated that more than 40,000 different chemicals are present throughout the DOE complex, and some, such as solvents and degreasers, are used in vast quantities. Toxicological information is available on most of the major chemicals to which DOE workers are exposed; however, little is known about the actual levels of worker exposure to these materials. DOE does not maintain a centralized repository of information on exposures to individual chemicals.
To further complicate matters, exposures are often to mixtures of substances making a risk assessment based on the known toxicological profiles of these materials nearly impossible.
While chemical hazards have not been either well documented or studied at DOE, a number of reports suggest, either directly or indirectly, that chemical hazards pose a significant health risk to both current and former DOE workers (Ref. 4-6). These risks may exceed those posed by radionuclides.
An example of a non-radiogenic chemical exposure is beryllium, a hazard that is specifically excluded from this report (since it is already covered under separate legislation). Exposure by DOE contractor workers and the resulting health conditions associated with beryllium exposure (Ref. 7) served as a basis for the Presidential Memorandum of July 15, 1999, and as the origin of this report.
________________
FINDINGS
SECTION 1: SUMMARY OF MAJOR FINDINGS FROM DOE EPIDEMIOLOGIC STUDIES
Background
Mortality studies of DOE workers began in 1964 and have continued uninterrupted through the present. The patterns of mortality have been the primary focus of these studies, particularly cancers from ionizing radiation exposure. More than 40 studies of DOE contractor workers have been completed to date; there are more than 20 additional studies underway. The studies cover fourteen out of nineteen of the principal facilities of the US weapons complex but excludes dozens of private facilities that supplied DOE and the entire navy nuclear program (which is excluded by Executive Order). The studies concentrated primarily on production workers. At those sites where construction workers were employed as part of a prime contract, they would have been included in the site's study, but not analyzed as a separate group. Construction workers employed by the Zia Company at the Los Alamos National Laboratory were the one exception where a separate analysis of their mortality experience is reported. The studies include workers employed from 1944-86 with results emphasizing those employed during the period of greatest production activity across the DOE weapons complex between 1944 and 1979. Due to changes in the DOE's mission with the cessation of the nuclear arms race and various international arms limitations agreements, results of these historical studies no longer reflect current workplace conditions.
When excess mortality was noted or a trend identified for a specific cause of death, special in-depth studies were undertaken. Specific exposures that have been studied include external ionizing radiation, internal ionizing radiation from plutonium and polonium, tritium and uranium dust. Additionally metallic mercury, nickel and nickel oxides, phosgene, and epoxy resins have also been studied. The nature and degree of exposures varied greatly from site to site depending on the operations and production at a given site. Historically, white males were the primary subjects of these studies. More recent studies and most new studies examine the impact of exposures to both non-white and female workers.
Human data on cancer induction by radiation are extensive. The most comprehensive studies involve the survivors of the atomic bombings of Hiroshima and Nagasaki, X-rayed tuberculosis patients, and persons exposed during treatment for ankylosing spondilitis, cervical cancer, and tinea capitis. Cancers either frequently or occasionally associated with radiation include leukemia, thyroid, female breast, lung, stomach, colon, esophagus, bladder, ovary and myeloma.
Other lifestyle factors (smoking and lung cancer, diet and colon cancer) and occupational exposures (leukemia and benzene, bladder cancer and dyes) are potential confounders for some of these cancers. Age at exposure, dose, dose rate and other factors may also influence the results of a particular population-based study as well as modify an individual's risk for disease.
Findings: (PANEL MEMBERS ARE WORKING ON THESE CONCLUSIONS)
· Overall, DOE production workers had significantly lower age-adjusted death rates compared to the U.S. general population for all causes of death combined; there were only two exceptions.
· The relationship between mortality and exposure to ionizing radiation has been investigated for some but not all of the DOE cohorts. An increase in the risk of dying from specific conditions has been associated with increased exposure to external radiation exposure in seven cohort studies and to internal exposure in two studies.
· When positive trends for mortality by level of ionizing radiation were observed, they were always based on small numbers of deaths (less than five) among workers with the highest lifetime radiation doses.
· There was no clear excess risk of mortality for any specific condition among the groups that were studied. The observed higher mortality rates for specific conditions were limited to specific facilities, subgroups of workers, and specific time periods of employment.
· Special studies of workers with brain cancer, multiple myeloma, malignant melanoma, non-malignant respiratory diseases, and malignant respiratory diseases were pursued. Except for non-malignant respiratory disease among Fernald workers, the special studies did not find specific occupational exposures associated with the conditions.
A summary of studies and findings by site is found in Appendix 1. Appendix 1 also includes a listing of the Standardized Mortality Ratios (SMRs) for all causes of death for US nuclear weapons workers (Table 1) as well as a summary of statistically significant elevated SMRs for selected causes of death for US nuclear weapons workers, by site (Table 2). Table 3 shows the statistically significant SMRs for each cause of death among DOE contractor employees.
A listing of both the peer-reviewed and other publications relating to epidemiologic studies of DOE workers is found in Appendix 2 of this report.
________________
SECTION 2: SUMMARY OF FINDINGS RELATED TO CHEMICAL HAZARDS AT DOE SITES
Background
Table 4 (Appendix 3) provides an overview of the chemical hazards that are commonly cited in either environmental studies around DOE sites and/or in health studies of DOE workers. Table 4 represents a very small fraction of the estimated 40,000 chemicals that have been used at DOE facilities. Only a very small proportion of these chemicals has been examined in health studies of DOE workers. Table 5 and Figure 2 (Appendix 3) provide a summary of the principal chemicals, processes and sites used in the production of nuclear weapons.
Findings from epidemiologic studies:
· Mercury workers - studies of exposure to metallic mercury were associated with clinical neurologic abnormalities in the most highly exposed group.
· Centrifuge workers - an incidence of bladder cancer was observed among gas centrifuge manufacturing workers. Although epoxy resins and solvents were commonly used in the gas centrifuge manufacturing process, the observed higher incidence of bladder cancer among gas centrifuge workers was not associated with exposure to these substances. In phase I, the incidence rate was 7 times that expected. In phase II it was not found to be greater than for a local comparison population.
· Welders - the most recent study of welders revealed higher risk of death from lung cancer, prostate cancer, and stomach ulcers. The risk for lung cancer was not related to nickel exposure. Thorium was not evaluated in the first Oak Ridge welders study. The welders updated study has been requested from CER and will be evaluated (it is cited in the reference list).
________________
SECTION 3: SUMMARY OF FINDINGS FROM SPECIAL RADIATION WORKERS MONITORING PROGRAMS
Background
DOE supports three specialized monitoring programs or studies of a relatively small number of workers with the highest exposures to ionizing radiation from radionuclides and/or external sources. These special programs include a tissue registry for post-mortem analyses of workers with known occupational exposure levels to radionuclides, periodic medical follow-up for plutonium-exposed workers (average dose 1,250 mSv), and a program of cancer screening for workers with the highest doses of external radiation (dose greater than 200 mSv). These specialized programs are described in Appendix 4.
Findings:
· Specialized radiation worker studies have generally not shown unusual numbers or types of illnesses commonly associated with radiation exposure, even among workers with known high body burdens of radionuclides.
· One case each of osteosarcoma and lung fibrosis have been diagnosed among workers exposed to plutonium. Osteosarcoma is a rare cancer and is of interest since plutonium is known to deposit in the bone.
· Among the 244 causes of death in the tissue registries, a number of cancer deaths from causes associated with radiation exposure were identified. In addition, six confirmed cases of mesothelioma among DOE workers exposed to asbestos have been documented. Table 6 (Appendix 4) provides a complete listing.
________________
SECTION 4: SUMMARY OF FINDINGS FROM OTHER SURVEILLANCE PROGRAMS
Background
DOE supports two injury and illness surveillance programs. The Epidemiologic Surveillance Program collects illness information from occupational medicine programs. The Computerized Accident/Incident Reporting System (CAIRS) is a centralized database that collects all contractor reports of injuries, illnesses, and other accidents. It is based on Department of Labor requirements for reporting these events. Data from DOE investigations of these reports are used to generate performance indicators used by the DOE to provide estimates of dollar loses due to work-related injuries, illnesses, and accidental property damage. Recent summaries of epidemiologic surveillance and CAIRS data are presented in Appendix 5.
Findings:
· CAIRS provides an enumeration of lost-time injuries and illnesses throughout the DOE system
· The Epidemiologic Surveillance Program reports cases of occupational illnesses among DOE workers that are consistent with Sentinel Health Events of Occupational origin [SHE(O)] reported in the medical literature.
· Both of these DOE-maintained surveillance systems allow for the identification of current illnesses and injuries in its workforce.
________________
SECTION 5: INITIAL RESULTS FROM THE FORMER WORKERS PROGRAM
Background
In response to a Congressional mandate, DOE recently initiated a medical surveillance program tailored specifically to examine former DOE workers felt to be at high risk for occupationally-related illnesses. Preliminary results from these studies are presented in Appendix 6.
Findings:
· Initially medical screening has found a relatively high proportion of abnormalities on chest X-ray among selected groups of former workers.
· Of the 882 individuals screened to date, 148 (17%) have ILO category 1/0 or greater perfusion on their chest X-ray indicating the presence of a pneumoconiosis.
· There were other findings but data were too preliminary to include. Conditions that are being studied include exposures to heavy metals, hearing loss, beryllium exposure and exposures to solvents and mixed chemicals.
______________
REFERENCES
Ref. 1 Linking Legacies. Connecting the Cold War Nuclear Weapons Production Processes to their Environmental Consequences. DOE/EM-0319 US Department of Energy. January 1997.
Ref. 2 Atomic Audit, the Costs and Consequences of U.S. Nuclear Weapons since 1940. S.I. Schwartz, editor. The Brookings Institution, Washington, D.C. 1998.
Ref. 3 Chemical Safety Vulnerability Working Group Report, 1994, U.S. Department of Energy, DOE/EH-0396P; DOE/EH-0398P
Ref. 4 Hazards Ahead: Managing Cleanup Worker Health and Safety at the Nuclear Weapons Complex. US Congress. Office of Technology Assessment. OTA-BP-O-85. Washington, D.C.: U.S. Government Printing Office, February 1993.
Ref. 5 Comparative Carcinogenicity of Ionizing Radiation and Chemicals. National Council on Radiation Protection and Measurements. NCRP Report No 96. Bethesda, MD. March 1, 1989.
Ref. 6 Radiation Protection in the Mineral Extraction Industry. National Council on Radiation Protection and Measurements. NCRP Report No 118. Bethesda, MD November 30, 1993.
Ref. 7 Beryllium Biomarkers: Application of Immunologic, Inflammatory, and Genetic Tools. Lee S. Newman. Pages 285-300 in Biomarkers: Medical and Workplace Applications. Joseph Henry Press. 1998, Washington D.C.
________________
APPENDIX 1
Background
Epidemiology is the study of the distribution and determinants of disease in human populations. The distribution of disease is considered in relation to time, place, and person. Relevant population characteristics include the age, race, and sex distribution of a population, as well as other characteristics related to health, such as social characteristics (e.g., income and education), occupation, susceptibility to disease, and exposure to specific agents. Determinants of disease include the causes of disease, as well as factors that influence the risk of disease. There are three major study designs that are used in studies of workers and communities.
Study Designs
Cohort Studies. The cohort study design is a type of epidemiologic study frequently used to examine occupational exposures within a defined workforce. A cohort study requires a defined population that can be classified as being exposed or not exposed to an agent of interest, such as radiation or chemicals that influence the probability of occurrence of a given disease. Characterization of the exposure may be qualitative (e.g., high, low, or no exposure) or very quantitative (e.g., radiation measured in Sieverts (Sv), chemicals in parts per million [ppm]). Surrogates for exposure, such as job titles, are frequently used in the absence of quantitative exposure data.
Individuals enumerated in the study population are tracked for a period of time, their vital status (dead or alive) is determined at the time of the study, and cause of death is sought for the deceased member of the study population. In general, overall rates of death and cause-specific rates of death have been assessed for workers at DOE sites. Death rates for the exposed worker population are compared with death rates of workers who did not have the exposure (internal comparison), or compared with expected death rates based on the U.S. population or state death rates (external comparison). If the rates of death differ from what is expected, an explanation is sought to account for the differences such as exposure to a carcinogen at work. In cohorts where the exposure has not been characterized, excess mortality can be identified, but these deaths cannot be attributed to a specific exposure, and additional studies may be warranted. More recent studies have looked at disease endpoints other than death, such as overall and cause-specific cancer incidence (newly diagnosed) rates.
Most cohort studies at DOE sites have been historical cohort studies, that is, the exposure occurred some time in the distant past. These studies rely on past records to document exposure. This type of study can be problematic if exposure records are incomplete or were destroyed. Cohort studies require populations that have been followed for many (20 to 30) years. They are generally difficult to conduct and are very expensive. These studies are not well suited to studying diseases that are rare. Cohort studies do, however, provide a direct estimate of the risk of death from a specific disease, and allow an investigator to look at many disease end points.
Case-Control Studies. The case-control study design starts with the identification of persons with the disease of interest (case) and a suitable comparison (control) population of persons without the disease. Controls must be persons who are at risk for the disease and are representative of the population that generated the cases. The selection of an appropriate control group is often quite problematic. Cases and controls are then compared with respect to the proportion of individuals exposed to the agent of interest. Case-control studies require fewer persons than cohort studies, and therefore, are usually less costly and less time consuming, but are limited to the study of one disease (or cause of death). These types of studies are well suited for the study of rare diseases and are generally used to examine the relationship between a specific disease and exposure.
Proportionate Mortality Studies. In situations where the total worker population at risk has not been identified, mortality rates cannot be calculated and risk cannot be estimated. When only deaths or illnesses are known there is an alternative approach. The approach is to examine the proportional distribution of deaths from specific conditions in the study group relative to the same condition in the U.S. general or regional population. The resulting index is the Proportional Mortality Ratio (PMR). This approach is not powerful although it is useful in rapidly screening worker populations to identify conditions that may reflect occupational exposures.
Standardized Mortality Ratio: The standardized mortality rate (SMR) is the ratio of the number of deaths observed in the study population to the number of expected deaths. The expected number of deaths is based on a reference (or comparison population). Death rates for the U.S. (or state) population are most frequently used as the comparison to obtain expected rates. An SMR of 100 indicates a similar risk of disease in the study population compared with the reference population. An SMR greater than 100 indicates excess risk of disease in the study population compared with the reference group, and an SMR less than 100 indicates a deficit of disease.
MAJOR FINDINGS
Because of the large number of studies and the many comparisons involved, only statistically significant higher rates and positive dose-response trends are reported. They are shown below in italics. Statistical significance reflects estimates that are based on a sufficient number of deaths to be judged reliable. Statistical significance by itself is not proof that the condition is due partly or in entirely to workplace exposures. Special studies were identified with a bold type face.
Fernald "Feed Materials Production Center" (Reference prefix - FMPC)
From 1951 to 1989 Fernald processed uranium and thorium into fabricated metal products for use in the defense programs. There were 4,014 white male employees included in the single cohort mortality study. For deaths through 1989, the death rate for stomach cancer among salaried white males was higher than the rate for the U.S. population. Hourly males had higher rates for all cancer combined, lung cancer, and motor vehicle accidents.
For all males there was a positive association between chronic respiratory disease mortality, excluding respiratory cancers, and internal dose equivalent. An independent study of the same population reported positive trends for both acute and chronic respiratory disease illness. Acute respiratory illness include influenza and pneumonia; chronic illnesses include emphysema and bronchitis.
The Fernald study will be updated with new deaths through 1997. It will also include additional workers as well as an in-depth assessment of radiation, chemical exposures, and cigarette smoking.
Hanford Site (Reference prefix - HAN)
The Hanford Site produced reactor fuel, operated nine reactors and five chemical separation facilities, and fabricated plutonium components for the weapons program. Hanford site workers have been the subjects of numerous mortality studies beginning in 1964. The first study compared longevity of workers with that of their brothers and sisters. No differences were seen among radiation exposed and non-exposed workers. Within Washington state for the period 1950-1971, atomic workers, presumed to be Hanford site workers, were reported to have higher proportions of death due to multiple myeloma, cancer of the pancreas, and cancer of the colon than were seen in the general population of Washington. A similar proportional analysis that included the average lifetime occupational dose of ionizing radiation found that the dose was higher than expected for multiple myeloma, cancer of the pancreas, cancer of the brain and central nervous system, kidney cancer, lung cancer, colon cancer, myeloid leukemia and lymphoma. In addition to the specific cancers, three broad categories: "all cancer combined," "bone marrow cancers," and "reticuloendothelial cancers" were identified as radiation sensitive cancers. This method of analysis was questioned because it included only deceased workers in the comparison group. Several independent reviewers of the average lifetime dose methodology concluded that the method was inappropriate although the data did support a conclusion that radiation was associated with cancer of the pancreas and multiple myeloma. These early studies were not based on mortality rates and were used as the basis for more formal, in-depth cohort studies.
The earliest cohort studies reported on about 13,000 white males who were employed two or more years at Hanford with deaths through 1974, 1977 and 1978. Gradually the study population increased to include all workers without regard to length of employment at Hanford, about 44,000 employees with deaths through 1981 and 1986. Over time, Hanford workers have had mortality rates substantially below the general U.S. population rates with the following exceptions: Among female workers not monitored for external radiation, accidents, poisonings, and violence are greater than expected. Monitored females had a higher rate of death from diseases of the musculoskeletal system and connective tissues than expected. Unmonitored males had higher death rates for cancer of the pancreas and miscellaneous solid tumors than expected.
Among the Hanford workers, the relationship between the death rate and the external radiation dose has been studied repeatedly. Positive trends in the death rate with increasing exposure have been reported for white males and for white males and females combined. These trends were for deaths due to cancer of the liver, cancer of the pancreas, Hodgkin's disease, and multiple myeloma. In one study a positive trend for female genital cancers was noted.
In the early 1980s white males with a lifetime occupational dose of 20 mSv or more were known to have a small excess risk from lung cancer. A study of tobacco use in this group determined that the excess could not explained by smoking cigarettes.
Estimates of the increased risk of death per unit radiation exposure were made to test whether or not the radiation protection standards of the past adequately protected workers. One approach was to look at the upper limit of the risk per unit radiation and compare it to that for other populations. The absolute excess risk for leukemia per million person-years per 10 mSv, based on atomic bomb survivor data, as calculated by ICRP and BEIR committees, is approximately 1-2 deaths. For Hanford, the 95% upper confidence limit is about 4-5 deaths.
Age-at-exposure effect. The idea of sensitive age-at -exposure groups first appeared in 1977. Examination of the average lifetime dose equivalent for specific cancers compared to non-cancer deaths supported two sensitive age-at-exposure groups; under age 25 years and over age 45 years. Three subsequent analyses by the same research team reported this age sensitivity. It was variously reported as over age 58 years, over age 62 years, and age 55-65 years. A recent analysis reported a significant positive trend for all cancer combined by level of cumulative dose equivalent for monitored workers age 75 years and older who were born before 1905. A special case-control study of multiple myeloma at four DOE facilities reported that the most sensitive age-at-exposure group was age 45 years and older.
From 1981 through 1993 a number of models were proposed to estimate the cancers among Hanford workers that could be attributed to ionizing radiation. The attributable proportions from the modeling ranged from 5% to 50%.
Lawrence Livermore National Laboratory (Reference prefix - LLNL)
Lawrence Livermore National Laboratory (LLNL) is a multi-purpose laboratory that conducts research and development for the weapons program and for stockpile stewardship. The incidence rate of malignant melanoma was higher for 5,100 LLNL employees than for the population of the region based on 19 cases diagnosed from 1972-77. Work involving exposure to ionizing radiation was not associated with a diagnosis of melanoma; working as a chemist was. In 1984, based on a review of records for persons with and without melanoma, occupational factors were reaffirmed as being associated with melanoma risk. Later, when the incidence rates for LLNL workers were recalculated for the period 1969-80, higher rates were found for some cancers in addition to malignant melanoma. The incidence rates for salivary gland cancer and rectal cancer, among female Laboratory workers, were above the rates for the region. For male laboratory workers, other nervous system tumors, excluding brain tumors, were higher than expected.
Thirty one laboratory workers with malignant melanoma and a control group were interviewed about personal and occupational factors that might be associated with the disease. Five factors were more common than expected among persons with malignant melanoma. These were judged to contribute independently to a persons risk of melanoma. They were exposure to radioactive materials, work at Site 300, exposure to volatile photographic chemicals, participant at the Pacific Test Site, and chemist duties. The most recent interview study of 69 cases and an equal number of controls found that differences in personal factors, genetics, and recreational use of the outdoors were consistent with what is known about malignant melanoma of the skin. Only occupational exposure to alcohols, out of 39 industrial exposures examined, was more common among persons with melanoma.
Several special studies of the microscopic features of the melanoma tumors indicated that the tumor thickness among laboratory workers was significantly less than for individuals that did not work at LLNL, at least up to the time when the concern became public in 1977. These data on microscopic features were taken as evidence of medical over diagnosis of tumors at LLNL. A greater proportion of workers hired before 1962, who were engineers, particularly electrical engineers, had dark moles or pigmented nevi that are associated with a high risk of malignant melanoma.
Linde Air Products (Reference prefix - LIND)
Linde Air Products processed the highest grade Belgian Congo pitchblende and domestic uranium ores into uranium compounds from 1943 through 1949. Mortality rates through 1979 for the 995 white males were compared to U.S. rates and regional mortality rates. The results for the U.S. and region were similar. The rates for six cause of death categories were higher than expected: all causes of death combined, cancer of the larynx, all circulatory diseases, arteriosclerotic heart disease, respiratory diseases, and in particular, pneumonia.
Los Alamos National Laboratory (Reference prefix - LANL)
Los Alamos National Laboratory (LANL) is a multi-purpose laboratory where nuclear weapons were designed, developed and tested; and small quantities of plutonium metal were produced. The first and longest running study at LANL was for two groups of workers with the highest exposures to plutonium. The two groups are 224 white males within the Manhattan Project and 26 workers with plutonium depositions in 1944-45. Deaths rates have been analyzed at various points in time. The study of 224 males reported that no death rate was greater than expected for deaths through 1980. For the 26, the overall mortality rate and all causes of cancer rate were below what was expected based on the U.S. general population through 1987.
Among 6,970 LANL females, those classified as radiation workers had a high death rate for suicide through 1981. This was not related to duration of employment, plutonium exposure, or marital status.
A special study of malignant melanoma cases between 1969 and 1978 revealed that the rate of newly diagnosed melanomas was similar to that for New Mexico in general. Detailed review of work histories for 15 cases did not reveal any important characteristics of workplace exposures that differed from a comparison group.
The Los Alamos Zia Company was the construction contractor at LANL. The Zia study included 5,424 workers who were monitored for exposure to either plutonium or external ionizing radiation. For all workers combined, the mortality rates through 1984 were greater than the U.S. rates for stomach cancer, senility and ill-defined conditions, all injuries, all accidents, and in particular, motor vehicle accidents. Hispanic males did not share the high rate for senility and ill-defined conditions. Non-Hispanic males had higher rates for deaths from all causes, all cancers, lung cancer, all circulatory diseases, and all non malignant respiratory diseases.
No cause of death was reported with a positive trend for radiation exposure in the Zia Company study group.
In the most recent LANL study, based on 15,727 white males, no cause of death was higher than the U.S. rates through 1990.
Within the most recent LANL study, positive trends have been reported for external ionizing radiation and cancers of the brain and central nervous system, cancer of the esophagus, and Hodgkin's disease. Among workers not exposed to plutonium two additional positive trends were detected for kidney cancer and lymphocytic leukemia.
Mallinckrodt Chemical Works (Reference prefix - MCW)
The Uranium Division of Mallinckrodt Chemical Works (MCW) processed uranium ore and concentrate to pure uranium oxide and uranium metal from 1942 to 1966. The MCW study included 2,514 white males. No death rates were greater than the U.S. rates through 1993.
A positive trend was found for kidney cancer by level of exposure to cumulative external radiation.
Mound Facility (Reference prefix - MND)
Mound was the site for the development of non-nuclear and nuclear components for weapons using polonium and beryllium, and for recycling tritium. Mound also produced plutonium-238 electric generators for spacecraft. Three mortality studies of white males have been conducted at Mound. A preliminary study examined the mortality of 4,697 white male employees of the Mound Facility through 1979. Overall, no death rate was higher than expected based on US general population rates. Among men first hired between 1943 and 1945, the rates for all causes of death combined, all cancers combined, cancer of the rectum, lung cancer, all respiratory diseases, and all injuries were higher than expected. The higher rates for all causes of death combined and lung cancer were reported for men who worked less than two years at Mound. Among men hired through 1959, cancer of the prostate was high among those who worked more than 5 years. In the first published study of 4,182 white males, no death rates were higher than the U.S. rates through 1979. Analysis of deaths through 1983 for 4,402 white males reported that the rates for all cancers combined, cancer of the lung, and cancer of the rectum were high only among workers hired in1944 through 1945 (World War II hires). The higher death rates in World War II hires did not appear to be due to radiation exposure.
Workers who were monitored for external exposure to ionizing radiation had a positive trend for cancer of the lymphopoietic and hematopoietic system due primarily to the individual positive trends for all leukemia combined, particularly for lymphatic and myeloid leukemia that make up the larger category. Males monitored for polonium uptake did not have positive trends for any cause of death through 1983.
Oak Ridge Reservation (Reference prefix - OR)
Oak Ridge Reservation (ORR combined). There have been several studies that considered Oak Ridge workers as a single entity. The first study looked at the mortality experience of 28,008 white male World War II workers employed at three ORR facilities. Compared to the rates for the U.S. population through 1980, the workers had higher rates for all causes of death combined; lung cancer; tuberculosis; mental, psychoneurotic, and personality disorders; cerebrovascular disease; diseases of the respiratory system, particularly emphysema; and all accidents, particularly motor vehicle accidents. Because these workers were not engaged in military service during wartime, it is not possible to know whether or not these conditions reflect occupational exposures or underlying health conditions that would have excluded them from military service.
The second study updated mortality through 1984 and broadened the base of the first study to include 106,020 workers at all four ORR facilities. Mortality from all causes of death combined and all cancers combined were in close agreement with U.S. rates. There were substantial differences in death rates among workers at the various Oak Ridge plants, particularly the rates for lung cancer, leukemia and other lymphatic cancer that are discussed below.
Within the second study, data for 28,374 workers at X-10 and Y-12 were analyzed for trends. Positive trends were reported with increasing external radiation dose for all causes of death combined and all cancers combined.
There have been three published studies of brain cancer across the four ORR facilities. Of 26 chemicals included in the exposure analysis, none were positively associated with brain cancer. There were no positive trends for brain cancer with increasing external radiation dose and internal dose as measured by the lung dose. Although workers with brain cancer were more likely than other workers to have worked at ORR more than 20 years, there was no trend with years worked. A medical history of epilepsy or head injury was not associated with brain cancer.
Mortality data through 1974 and through 1989 were analyzed for about 1,059 white male welders at the Oak Ridge Reservation. No death rate was higher than the U.S. rate through 1974. When deaths through 1989 were considered, welders had more lung cancer, cancer of the prostate, and gastric ulcers. The risk of each cause was different among the facilities. The risk of lung cancer among welders exposed to nickel oxides did not differ from non-exposed welders.
Oak Ridge National Laboratory - (Reference prefix - ORX). The Oak Ridge National Laboratory (ORNL) is a multi-purpose laboratory that was involved in reactor operations, chemical separations, and research. The first cohort study of ORNL considered 8,375 white males and deaths through 1977. No cause of death was greater than expected based on the U.S. general population. A follow up study reported that the death rate from leukemia was greater than the U.S. rate through 1984, particularly among workers monitored for internal radiation contamination. In the most recent study of death rates through 1990, none of the four causes of death reported: all causes of death combined, all cancers combined, lung cancer, and leukemia, were higher than the U.S. rate.
Although the leukemia rate through 1984 was high, there was no positive trend in the death rate by level of cumulative external ionizing radiation dose. A positive trend was reported for all cancers combined by level of cumulative external dose.
A recent study of deaths through 1990 reported that radiation doses received after age 45 years predicts the all cancers combined mortality rate; another study notes this finding for those who were age 65 years and older at exposure.
Oak Ridge Y-12 Plant (Reference prefix - ORY). Y-12 was involved in uranium enrichment and fabrication of nuclear weapons components. The original Y-12 mortality study was updated twice. The first study included 18,869 white males who ever worked at the plant and mortality through 1974. The second study was restricted to 6,781 men who worked at least 30 days with mortality through 1979. The most recent study was expanded to include 10,597 nonwhite workers and females with deaths through 1990.
The death rate for lung cancer was higher than the U.S. rate in the most recent two studies. An elevated lung cancer death rate was first evident for deaths occurring between 1955 and 1964. The rate continued to increase for deaths occurring between 1975 and 1979 followed by a declining rate.
Analysis of deaths through 1979 did not reveal positive trends for any cause of death with either external or internal exposure to ionizing radiation. The most recent study did not include radiation measurements.
Between 1953 and 1963 the Y-12 Plant used metallic mercury in a process to produce large quantities of enriched lithium. There were 5,663 workers categorized by exposure based on results of urinalysis data. Analysis of deaths through 1978 revealed no differences in the mortality patterns for mercury exposed workers as a whole, workers with the highest mercury exposures, and workers employed more than a year in a mercury process. There were 502 mercury workers involved in a clinical study. Clinical measurements revealed some deficiencies in neurological function particularly among those workers with the highest exposures, but not with the duration of exposure. A follow up study of 219 of the original subjects in the 1990s revealed that some neurologic effects were still detectable.
During the early operation of the Y-12 plant from 1942-1947, a group of 694 male workers was exposed to phosgene gas on a chronic basis and 106 males received acute exposures along with 91 females. A control group of 9,280 workers who also worked at Y-12 during the same era, but who did not have phosgene exposure, was also described. All groups were followed through the end of 1978 with particular interest in respiratory diseases and lung cancer. There was no evidence for increased mortality from respiratory diseases in this group.
Oak Ridge K-25 Gaseous Diffusion Plant (Reference prefix - ORK). The K-25 plant was a center for uranium enrichment for nuclear weapons and commercial uranium fuel. The death rates through 1989 for 35,712 workers were the focus of the study. White male workers had high rates relative to U.S. general population rates for all causes of death combined; cancer of the respiratory system, particularly lung cancer; bone cancer; mental disorders, all respiratory diseases, particularly pneumonia; symptoms, senility, and ill-defined conditions; all external causes of death, particularly accidents and specifically motor vehicle accidents. White females had a high rate for symptoms, senility, and ill-defined conditions.
Powdered nickel was used at the Oak Ridge K-25 gaseous diffusion plant in the production of the barrier material used to separate and enrich uranium. Death rates for 814 nickel workers who fabricated the barriers were compared to 1,600 controls. There were no differences in the death rates for the exposed and non exposed workers by cause of death through 1972. A later study compared the mortality through 1977 of the nickel workers and 7,552 non exposed workers. There were no causes of death with a rate higher than the U.S. rate and no differences between exposed and non exposed workers.
Epoxy resins and solvents were common exposures among K-25 gas centrifuge workers. A total of 263 workers with the most exposure were compared with 271 employees with no exposure at the plant during the same time period. The centrifuge workers reported five incident bladder cancers versus none reported by the non-centrifuge group. A specific causative agent for the increase in bladder cancer was not identified. The centrifuge workers are in a medical monitoring program
Pantex Plant (Reference prefix - PTX)
Pantex is the center for high-explosives component fabrication for nuclear weapons and for nuclear weapons disassembly and storage. The cohort mortality study of the Pantex Plant included mortality through 1978 among 3,564 white male employees. There were no causes of death with rates greater than those seen in the U.S. general population.
Portsmouth Gaseous Diffusion Plant (Reference prefix - PTS)
Mortality among 5,733 white male employees at the Portsmouth Gaseous Diffusion Plant was studied through 1982. No cause-specific death rate was greater than expected based on the U.S. general population rates. Based on urinalysis data for uranium content, two groups of workers were identified with relatively higher potential for exposure to uranium compounds. The mortality experience of these two groups was essentially the same as the total population of workers. This study was expanded to include all workers employed through 1991. The study included 8,877 employees and their mortality was studied through 1991. In September 1999, the study investigators reported that the death rates for various cancers did not exceed those for the U.S. population. Among the 6,827 workers exposed to uranium hexafluoride, special emphasis was on the death rates for all causes of death combined, all cancers combined, stomach cancer, hematopoietic cancer, and lung cancer. The rate for each of these was no larger than the comparable U.S. rate. There were no positive trends for these four cause of death groups by increasing urine counts. Among 1,446 workers exposed to fluorine or fluoride, and 465 exposed to nickel; the rate for all causes of death combined and all cancers combined did not exceed the U.S. rates.
Rocketdyne/Atomics International workers (Reference prefix - RAI)
The Rocketdyne/Atomics International radiation study included 4,563 employees monitored for exposure to external ionizing radiation. The mortality study considered external exposure to ionizing radiation and internal deposition of radioactive materials. Compared to U.S. general population through 1994, no cause of death rates were greater than expected.
Positive trends in the rates by level of exposure to external radiation were reported for all cancers combined, cancers of the blood and blood forming tissues, and lung cancer. In the Rocketdyne/Atomics International chemical study they found no relationship between asbestos exposure and lung cancer mortality among the radiation-monitored workers.
Positive trends in the rates by level of internal radiation dose were reported for cancers of the blood and blood forming tissues, and cancers of the upper aerodigestive tract.
Rocky Flats (Reference prefix - RFP)
For the 7,112 white males who ever worked at Rocky Flats, only the death rate for benign and unspecified neoplasm of the brain was greater than in the U.S. rate. Among the 5,413 Rocky Flats white males who worked at the site for at least 2 years, there was a higher rate of benign tumors and tumors of unspecified nature when comparing them with the U.S. general population through 1979; these were brain tumors. A study of 16 of the 22 known brain tumor cases through 1977 found no associations with exposure to internally deposited plutonium, external ionizing radiation or occupation. Independent review of occupational dosimetry records and pathologic examination of tissues from six of these workers led to the conclusion that none were radiation-related.
There were no positive trends for any cause of death by level of external or internal radiation exposure, although workers with a higher body burden (internal deposition) of plutonium had a higher rate for all causes of death combined and for all lymphopoietic cancers combined when compared to those with a smaller burden.
A subsequent reanalysis of the data for the 5,413 Rocky Flats workers found a positive trend for all non-cancers across external exposure groups due to a strong positive trend for circulatory diseases.
Savannah River Site (Reference prefix - SRS)
The Savannah River Site produced, purified and processed plutonium, tritium, and other radioisotopes for the nuclear weapons program. Three cancer incidence studies were conducted among active workers beginning with new cancer cases diagnosed in 1956 and ending in 1974, 1980, and 1983 respectively. There were no overall cancer incidence rates or rates by radiation exposure group that were higher than U.S. rates. Special investigations were conducted for (1) leukemia, and later for (2) leukemia, prostate cancer, and lung cancer. Preliminary results from the later study indicate that radiation monitored workers in the higher exposed group had a higher death rate for chronic lymphocytic leukemia than expected.
The first complete mortality study included 9,860 white male Savannah River workers. A higher rate of leukemia than the U.S. general population through 1980 was reported. This was concentrated among hourly workers employed before 1955 who worked from 5 to 15 years. Review of the plant records and job duties of all workers who died from leukemia indicated that seven, half of the leukemia deaths, had the potential for some exposure to industrial solvents. The leukemia death rate through 1986 was higher than expected only for those deaths occurring from 1965 through 1969. Preliminary findings from the most recent study of a larger group of workers reported that the leukemia mortality rate was not higher than the U.S. rate through 1995.
A positive trend was seen for leukemia mortality and external dose for deaths through 1986.
Multi-Site study: All Department of Energy facilities (Greater than 5 rem Study) (Reference - MULTI96)
This is a study of 1,404 DOE and DOE contractor employees who received 50 mSv or more external radiation dose in any calendar year during employment at the facilities. Within this special group of workers, no causes of death were above that expected based on the U.S. general population. The addition of Navy nuclear shipyard workers to the study did not change the findings.
Multi-Site study: Multiple Myeloma (Reference - MULTI98b)
The study included 98 cases of multiple myeloma and 391 controls from the populations of the Hanford Site, Los Alamos National Laboratory, Oak Ridge National Laboratory, and the Savannah River Plant. The risk of multiple myeloma was linked to external ionizing radiation exposure after age 45 years.
Multi-Site study: Uranium dust study (Reference - MULTI95b)
This special study of uranium dust exposure and lung cancer among workers employed between 1943 and 1947 was conducted at the Tennessee Eastman, Y-12, Fernald, and Mallinckrodt facilities. There were 787 cases of lung cancer in the study. The risk of lung cancer did not increase with increasing radiation dose. The authors did suggest that there was a trend in risk for worker exposure after age 45 years. Analysis by external radiation dose and exposure to thorium, radium, and radon were uninformative.
Multi-Site study: Uranium Millers (Reference prefix - MULTI83)
The front end of the uranium fuel cycle includes the milling of uranium ore. The most recent National Institute for Occupational Safety and Health study of uranium millers included 2,002 males from seven plants on the Colorado Plateau. These men worked at least one year since 1940 and had never worked in uranium mining. Compared to the U.S. population through 1977, there were only two causes of death that had higher rates: non malignant respiratory diseases, particularly the chronic respiratory conditions, and miscellaneous accidents.
________________
Table 1. SMRs for all Causes of Death for US Nuclear Weapons Workers
Table 2. Statistically Significant Elevated SMRs for Selected Causes of Death for US
Nuclear Weapons Workers, by Site
Table 3
Statistically Significant Standardized Mortality Ratios (SMR) for Each Cause of
Death Among DOE Contractor Employees
APPENDIX 2
MORBIDITY AND MORTALITY STUDIES AT THE NUCLEAR WEAPONS COMPLEX
FMPC83. Wilson J. An epidemiological investigation of non-malignant respiratory disease among workers at a uranium mill. Doctoral Dissertation, University of North Carolina, Chapel Hill, School of Public Health, 1983.
FMPC96. Cragle DL, Watkins JP, Ingle JN, Robertson-DeMers K, Tankersley WG, West CM. Mortality among a cohort of white male workers at a uranium processing plant: Fernald Feed Materials Production Center, 1951-1989. Center for Epidemiologic Research, Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee, 1996.
FMPC99. Ritz B. Radiation exposure and cancer mortality in uranium processing workers. Epidemiology 1999; 10:531-538.
HAN71. Mancuso TF, Sanders BS, Brodsky A. Study of the lifetime health and mortality experience of employees of AEC contractors, Part I. Methodology and some preliminary findings limited to mortality for Hanford employees. Volume III of the proceedings of the sixth annual Health Physics Society topical symposium, Richland, Washington November 25, 1971.
HAN77. Mancuso TF, Stewart A, Kneale GW. Radiation exposures of Hanford workers dying from cancer and other causes. Health Physics 1977; 33:369-385.
HAN78a. Anderson TW. Radiation exposures of the Hanford workers: A critique of the Mancuso, Stewart and Kneale report. Health Physics 1978; 35:743-750.
HAN78b. Kneale GW, Stewart A, Mancuso TF. Reanalysis of data relating to the Hanford study of the cancer risks of radiation workers. Proceedings of the IAEA symposium on late biological effects of ionizing radiation, Volume 1; Vienna, Austria; March 13-17, 1978:387-412.
HAN78c. Reissland JA. An assessment of the Mancuso study. National Radiological Protection Board document NRPB R79; September 1978.
HAN78d. Sanders BS. Low-level radiation and cancer deaths. Health Physics 1978; 34:521-538.
HAN79a. Gilbert ES, Marks S. An Analysis of the Mortality of Workers in a Nuclear Facility. Radiation Research 1979; 79:122-148.
HAN79b. Gofman J. Question of radiation causation of cancer in Hanford workers. Health Physics 1979; 37:617-639.
HAN79c. Hutchison GB, Jablon S, Land CE, MacMahon B. Review of report by Mancuso, Stewart, and Kneale of radiation exposure of Hanford workers, draft report. Health Physics 1979; 37:207-220.
HAN80a. Gilbert ES, Marks S. An Updated Analysis of Mortality of Workers in a Nuclear Facility. Radiation Research 1980; 83:740-741.
HAN80b. Stewart A, Kneale G, Mancuso T. The Hanford data - A reply to recent criticisms. Ambio 1980; 9:67-73.
HAN81a. Darby SC, Reissland JA. Hanford radiation study. British Journal of Industrial Medicine 1981; 38:202-203.
HAN81b. Kneale GW, Mancuso TF, Stewart AM. Hanford radiation study III: a cohort study of the cancer risks from radiation to workers at Hanford (1944-77 deaths) by the method of regression models in life tables. British Journal of Industrial Medicine 1981; 38:156-166.
HAN82. Mole RH. Hanford radiation study. British Journal of Industrial Medicine 1982;39:200-202.
HAN83a. Baverstock KF. Hanford radiation study. British Journal of Industrial Medicine 1983;40:115.
HAN83b. Milham S. Occupational mortality in Washington state, 1950-1979. National Institute for Occupational Safety and Health; DHHS (NIOSH) Publication No. 83-116. (Microfiche tables describing Atomic Workers).
HAN83c. Savitz DA. A critical review of the Hanford worker studies: Cancer risk and low-level radiation. In: Proceedings of the 16th Mid-Year Topical Meeting: Epidemiology Applied to Health Physics, CONF-830101, pp 495-503, January 9-13, 1983, Albuquerque, New Mexico.
HAN83d. Tolley HD, Marks S, Buchanan JA, Gilbert ES. A Further update of the Analysis of mortality of workers in a nuclear facility.