Oak Ridge National Laboratory Worker Mortality Study

Page 1

Oak Ridge National Laboratory Worker Mortal i t y Study * I n August 1990, prior to briefings for contractor management and employee representatives,various Headquarters offices were advised by Oak Ridge Operations(ORO)ofthe results of a follow - u p epidemiology study of certain workers a t Oak Ridge National Laboratory(ORNL)which indicated a radiation dose - related increase risk of mortality due to all cancers and more than expected numbers of all types of leukemia. notifications were also made to the State of Tennessee. At that time, * The study results have now been accepted for publication in the Journal of the American Medical Association (March 1991 issue), and employee briefings for all OR NL employees are scheduled for the afternoon of January24. * The study was funded by DOE under its contract with Oak Ridge Associated Universities(ORAU)for work on the overall Health and Mortality Study of Workers employed by contractors to DOE and its predecessor agencies. * The study ' s principal investigator is Or. Steve Wing, School of Public Health, Department o f Epidemiology, University of North Carolina (UNC) a t Chapel Hi 11 incol 1a borat i on with ORAU researchers. * The study follows a 1985 study of the same population for which Dr. Harvey Checkoway of UNC was the principal investigator and which was published in the British Journal of Industrial Medicine. * The total worker population was comprised o f 17,517 individuals of all race and sex groups. From the total worker group, a subgroup o f 8,318 white males, who had only worked at OR NL (and no other DOE facility)for more than thirty days between 1943 and 1972 were studied. White males were studied because their larger numbers provide the best basis for

Page 2

statistically meaningful results. this subgroup from all causes. Through 1984, 1 , 5 2 4 deaths occurred in Mortality rates for most causes of death were generally lower among the total worker group and the white male subgroup, when compared to the U.S. general population, and were significantly lower for some categories of disease such as diseases of the heart and circulatory system, non-malignant diseases of the respiratory system, certain site specific cancers including 1 ung cancer, and a1 1 external causes (accidents). Total career doses of penetrating radiation from external sources (primat*ily gamma) a s recorded on personal dosimeters were generally 1 OW (average 1 . 7 rem); 638 o f t h e white male subgroup of 8,318 white males had a total career dose o f more than 5 rem, (5 rem is the annual radiation worker exposure limit.) Increased risks o f mortality due to all cancers combined in the subgroup of white males, who were compared to other plant workers, were found to be associated with external radiation dose. This association was found after controlling for age, date of birth, socioeconomic status and active work status. This effect was strongest among workers who were occupationally exposed to radiation 20 or more years before their deaths. unexplained by existing knowledge of radiation biology or epidemiology. The 1985 Checkoway study in which the same group of workers were followed through 1977, did not show any association between radiation dose and cancer mortality. Wing's study followed the workers through 1984, thus adding 7-years of follow-up to the previous study. The percentage of increase in cancer mortality reported in the Wing study--' 5% increase per rem o f radiation dose--is an order o f magnitude greater than mortality estimates derived from follow-up studies of A-bomb survivors and other populations exposed to radiation at high dose rates. A similar estimate of the cancer mortality risk association with radiation has been

Page 3

reported for atomic weapons plant workers at the Atomic Weapons Establishment i n the United Kingdom. More than the expected numbers of deaths from all types of leukemia combined were observed: among the 8,318 subgroup of white males studied (28 deaths; 17.2 were among the 3 , 7 6 3 white males who were ever monitored for internally deposited radionuclides (16 deaths; 7 . 2 expected). Most of the leukemia deaths occurred after 1960 among men hired in the 1940s and 1950s. Another analysis was performed excluding seven deaths from chronic lymphocytic leukemia, which is not considered to be associated with radiation dose, and similar results were obtained. ORAU recommends continued follow-up of this population and others exposed t o protracted low doses of radiation in order to evaluate their validity * Dr. Wing, accompanied by ORAU researchers, will summarize the study results in a general employee briefing at ORNL beginning at 2 : 4 5 p.m., January 2 4 . Union leadership has been kept advised of the study. * NE, ER, EH, the Office of the Under Secretary, Industrial Relations, the Office o f the Press Secretary and Congressional Relations are being provided with a copy of this fact sheet for information on the current * The news media will not be permitted to cover the employee briefings; however, the media will be offered the opportunity to discuss the study’ findings with the study investigators, following the employee briefings. No press release is planned at this time. The need for a press release will be reconsidered at the time of study’s publication in the Journal o f the American Medical Association in March.

Page 4

* Oak Ridge Operations’ staff will advise the State o f Tennessee officials and the City o f Oak Ridge Mayor and City Manager following the briefings. It is our understanding, based on conversations with Headquarters‘ Congressinal Affairs, that the Tennessee Congressional Delegation will be