A True Measure of Exposure

234 Los Alamos Science Number 23 1995

A TRUE MEASURE OF EXPOSURE the human tissue analysis program at Los Alamos

by James F. McInroy

he human tissue analysis pro- postmortem analysis of tissues from oc- physics measures that are meant to gram, a 35-year-long research cupationally exposed individuals. Be- keep plutonium contamination to a Tprogram at Los Alamos, has cause the risk of cancer is highly de- minimum. been scrutinized by the local and na- pendent on not only the amount of tional news media and, more recently, plutonium retained in the body, but also The author (now retired from the Labo- by the President's Advisory Committee the fraction that goes to specific organs, ratory) hopes that the tissue results pre- on Human Radiation Experiments. Al- our discoveries on plutonium distribu- sented here, some of which are relative- though this program does not technical- tion have helped to clear away uncer- ly recent, will inspire rejuvenation of an ly fall under the description of "human tainties about the human metabolism effort that can continue to help elimi- experimentation," as defined by Secre- and potential health effects of this ra- nate the remaining uncertainties charac- tary of Energy Hazel O'Leary, charges dioactive substance. terizing plutonium dosimetry. by the news media of DOE's "body snatching," unethical procurement of The plutonium excretion models, which human tissues and organs, and hiding were the main product of the plutonium or withholding resulting data from the injection studies, provided an indirect Early Studies of Plutonium next-of-kin and their lawyers mandated means for estimating the amount of Metabolism that this program be included in the plutonium retained in the body of a liv- Advisory Committee's investigation ing person from the amount excreted in Bill Moss's article, "The Human Pluto- and that all documents and other infor- the urine. Those models were crucial nium Injection Experiments," reviews mation about the program be made because they were the most commonly the fact that, in 1944, when plutonium available. used means for estimating the body began to be produced in large quanti- burden and the ultimate risk from acci- ties, nothing was known about human As the leader of the Los Alamos tissue dental plutonium exposures, but they metabolism, retention, distribution, and project for 21 years, I will take this op- gave no information about the distribu- excretion of this manmade element. portunity to review the motivations, the tion of plutonium in the body, nor were The leading scientists and medical doc- manner of obtaining tissue samples, and there any independent means to check tors in the Manhattan Project, however, the most important findings of what the on their accuracy. The painstaking col- were well aware that working with plu- general public, including my wife, sees lection and analysis of tissues from de- tonium might pose a serious health haz- as a very ghoulish activity. Work on ceased individuals over the last 35 ard. They had done research on using cadavers has been at the heart of med- years has provided at least some of the radionuclides for medical diagnostics in ical discovery and medical education missing information, and that informa- the 1930s, and they knew that long- for hundreds if not thousands of years. tion now serves as a cornerstone of the lived radionuclides such as radium are This work is no exception—our pro- present models for determining the dangerous if they are retained inside the gram enabled us to quantify the pluto- doses and the risks from plutonium ex- body because they become a constant nium distribution in the body through posure. The early biokinetic models internal source of radiation. Biomed- used to estimate body burdens were ically, plutonium was assumed to be The image at left is an autoradiograph of based primarily on indirect measure- much like radium. Internal deposits of a tracheobronchial lymph node from a ments such as urinalysis, fecal analysis, radium had produced fatal anemias and former worker at the Laboratory. It external lung counting, and/or whole bone cancers in the radium dial painters shows alpha tracks radiating in a typical body counting. In contrast, the tissue of the 1920s, and there was great con- star pattern from tiny alpha-active data are direct and definitive. The tis- cern that internal exposure to plutonium clumps of matierial. Chemical analyses sue program has also provided an accu- and its compounds might be at least as of the radioisotopes in this individual’s rate measure of the general level of plu- dangerous. lungs and lymph nodes indicated that tonium exposure of Laboratory those clumps most likely consisted of an employees and thus a check on the effi- By January 29, 1944, 11 milligrams of aggregate of plutonium particles. cacy of industrial hygiene and health plutonium (a fair share of the world's

Number 23 1995 Los Alamos Science 235

A True Measure of Exposure

total supply at that time) had been allo- Lawrence of Los Alamos had modified baugh, who was also a research scien- cated for animal metabolic studies. The the Langham model to take into account tist at the Laboratory, decided to send results indicated that the skeleton was long-time excretion data from a selected several of the organs and bones to the the major deposition site, the retention group of Los Alamos workers who had Laboratory for radiochemical analysis time was long, and the liver had the experienced accidental intakes during to determine the plutonium content. highest concentration among the soft the Manhattan Project and who had tissues, followed by the kidneys and the been followed as part of an epidemio- Kelley had worked with plutonium for spleen. How appropriate were those logical study (some of those men tell a number of years prior to his death animal data for quantifying the distribu- their stories in the roundtable "On the and was carrying in his body a measur- tion and retention of plutonium in hu- Front Lines"). But many uncertainties able plutonium "burden," which pre- mans—and thus for determining the remained. Most worker exposures were sumably had been obtained mostly doses and the risks of plutonium the result of inhaling tiny airborne parti- through inhalation of moderate routine exposure? cles of plutonium into the lung. How airborne contamination. The estimated did that mode of exposure compare to whole-body content, based on urine ex- The human injection experiments were, the injection of plutonium directly into cretion data and the application of Jim in part, an effort to answer that ques- the bloodstream? It was suspected that Lawrence's PUQFUA (Plutonium Body tion. Excretion data were collected the patterns of retention, distribution, Burden (Q) From Urine Assays) code, from all subjects following injection of and excretion, and thus the dose to the was 18 nanocuries, a little less than half plutonium into the bloodstream, and body, would change depending on the maximum permissible body burden small tissue specimens from those sub- whether the intake was by inhalation, of 40 nanocuries. The tissue samples jects who were terminally ill were ana- ingestion, or a cut or puncture wound, represented the first opportunity to de- lyzed for plutonium following their but no human data were available to termine directly the plutonium burden death. A number of important observa- check the conjectures. It was also ex- carried in an individual who had been tions followed: 1) there were no major pected that the dose and the ultimate analyzed for plutonium content prior to differences between humans and the risk of exposure would be affected by death and thus to check the predictive common laboratory animals in the dis- the particular chemical form and particle power of the urine excretion models tribution in tissues with the exception of size of the material taken in, the time against real data. It was also an oppor- liver; 2) the liver of humans contained since exposure, the duration of expo- tunity to measure the real efficacy of 20 to 40 per cent of the total amount re- sure, and the effects of individual bio- the industrial hygiene and health tained versus 10 per cent or less for rats logical variation. physics measures that had been taken to when both received the same plutoni- reduce airborne plutonium contamina- um-citrate complex; 3) the retention tion in the work environment. Those half-time in liver was greater in hu- The Beginnings and the Philosophy responsible for industrial hygiene at mans; 4) the retention half-time for of the Los Alamos Tissue Program Los Alamos, including Wright Lang- whole body in humans was much longer ham, Donald Petersen, and Dr. Lush- than in laboratory animals; and 5) the Our human tissue analysis began spon- baugh, felt it was incumbent on them to excretion pattern in humans was differ- taneously following the accidental death take advantage of the availability of ent, especially that a much lower frac- of Cecil Kelley, a plutonium worker that information, even though it result- tion was eliminated in human feces here in Los Alamos. Kelley was expo- ed from the untimely and tragic death compared to animal feces. sure to a lethal dose of gamma and of a colleague. neutron radiation on December 30, Wright Langham, a radiobiologist in the 1958 and died 35 hours later. The radi- The Kelley data offered some surprises. Health Group at Los Alamos who had ation source was a plutonium collection Although the whole-body content was planned the analytical protocols for the vessel at DP Site that suddenly and un- found to be 19 nanocuries, in close human injection experiments, used the expectedly went critical during the agreement with the excretion model, excretion data to create a model relating year-end inventory (see "The Cecil Kel- that result was considered by Wright the amount of plutonium injected into ley Criticality Accident: The Origin of Langham to be "undoubtedly fortu- the bloodstream to the amount excreted the Los Alamos Human Tissue Analy- itous" because the fraction in the lung in the urine. Thus, the Langham model sis Program"). As a part of the medical and pulmonary lymph nodes was much became the first basis for estimating the autopsy, the local pathologist Dr. larger than predicted by the biokinetic amount of plutonium retained in the Clarence C. Lushbaugh collected tis- models of the day. That surprise led to body as a function of time following an sues to examine any physical changes the initiation of the tissue analysis pro- accidental intake of an unknown quanti- that might have been caused by the ex- gram at Los Alamos, a conserted effort ty. By the late 1950s, James N. P. treme radiation exposure. Dr. Lush- to collect and analyze tissues from

236 Los Alamos Science Number 23 1995 A True Measure of Exposure

deceased occupationally exposed work- specimens from the lung, tracheo- Studies of Occupationally ers. The program also included some bronchial lymph nodes, liver, kidney Exposed Workers members of the general public as con- and bone specimens. Later, interest in trols. The hope was to quantify all the minor deposition sites and possible con- Los Alamos Donors. From 1959 to variables affecting the distribution and sequences, such as potential genetic ef- 1978 tissues from 116 former employ- retention of plutonium and then use the fects if the radioactive elements were to ees of the Laboratory were analyzed. data to improve the in vivo estimates of deposit in gonadal tissue, led to the col- Not all had been exposed to plutonium; internal plutonium exposures. lection of several additional tissues. many were support personnel such as secretaries, janitors, firemen, truck dri- The most important sources of tissues The ethics of our tissue collection vers, and others who had volunteered to were the many workers involved with process has commanded the most atten- be part of the program. the handling of plutonium in the 1940s tion during the recent re-examination of and 1950s when most of the serious ex- the tissue program by the President's Since our association with the USTUR posures occurred. Those individuals Advisory Committee. Our own exami- in 1971, tissues from 60 additional Los were fairly young at the time and nation of procedures has shown that for Alamos workers with known or sus- proved to be a very healthy group. As all normal deaths (that is, not involving pected exposure to plutonium have a result, the collection of human tissues accidents, suicide, homicide, and so been analyzed, including six whole from autopsy or surgery has proceeded forth), tissue collection was done only bodies. As of October 1995, there are slowly. after obtaining appropriate authority 42 living members of the Registry from through a written consent form. For Los Alamos who have given their con- The plan to include unexposed people example, during the 1950s and 1960s sent for radiochemical analyses follow- as controls eventually grew into a large consent for autopsy and tissue collec- ing death; seven of them are whole- study of the U.S. non-occupationally tion were obtained in writing from the body donors. A total of 25 highly exposed general population. The results next of kin by the floor nursing supervi- exposed workers from all over the have produced an accurate determina- sor or attending physician at the Los country are currently enrolled with the tion of the background levels of inter- Alamos Medical Center.* USTUR as whole-body donors follow- nally deposited plutonium from atmos- ing death. pheric fallout due to nuclear weapons Then in 1968 the Atomic Energy Com- testing and from accidental release to mission (AEC) sponsored the formation What has tissue analysis revealed about the environment from nuclear facilities. of a formal registry to collect medical, the effectiveness of the Laboratory's ef- The results from the general population exposure, and work histories of plutoni- forts to protect its workers from expo- study are presented in the last section um workers on a voluntary basis and to sure to plutonium? During the early of this article. request authority from the registrants days of the Laboratory's operation, par- for autopsy and tissue analysis at the ticularly during the war years, we know The tissue program has also included time of death. Originally called the that the containment and filtering sys- the study of americium, uranium, thori- National Plutonium Registry, it was tems were not available or were not um, and neptunium, however, the vast eventually expanded into two registries, used as efficiently as they are today. majority of the analyses performed on the U.S. Transuranium Registry and the The higher levels of contamination pre- tissues at Los Alamos were for plutoni- U.S. Uranium Registry. The two are sent at that time were clearly reflected um and americium. As mentioned now combined and referred to as the in the tissues we analyzed from a secre- above, plutonium in the bloodstream USTUR. They are administered at tary who worked in the original pluto- was found to be deposited preferentially Washington State University under the nium processing building known as "D" in the liver and skeleton. If the expo- sponsorship of the DOE's Office of building. Although she probably never sure was from inhalation, the lung and Health and Environmental Research. worked in a plutonium laboratory, her associated lymph nodes would also re- The accompanying box "Authority and lungs, liver, and skeleton contained tain deposited plutonium. If the expo- Collection of Tissues" outlines the pro- larger concentrations of plutonium than sure was through ingestion, the conse- cedures followed at Los Alamos in the the general public, undoubtedly from quences would be reduced because the early days and by the Registries in inhalation of airborne plutonium during gastrointestinal tract allows only about more recent times to obtain consent and her work hours. one plutonium atom out of ten thousand to collect tissues. to pass through the intestinal walls and To evaluate the overall exposure of the enter the blood stream. That knowl- * The Los Alamos Medical Center was operated Laboratory work force, a comparison of by the AEC until 1964, after which it was pur- edge of the primary deposition sites led chased by the Lutheran Health Systems of Fargo, concentrations of plutonium in the liver the early researchers to collect tissue North Dakota. was made between the worker popula- continued on page 241

Number 23 1995 Los Alamos Science 237

A True Measure of Exposure

Authorization and Collection of Tissues

he charge of “body snatching” by the news media opens up the issue of where Tand how the Los Alamos tissue analysis program obtained samples for study. During the first twelve years of the program, from 1959 to 1971, all samples were obtained from individuals who had died and/or were given autopsies at the Los Alamos Medical Center. As described in the main text, the first case was Cecil Kelley, who had worked with plutonium and died as a result of a criticality accident. His autopsy was authorized by the Los Alamos coroner, and then the pathologist at the Los Alamos Medical Center, Dr. Clarence C. Lushbaugh, decided to collect tissue samples from Kelley and have them analyzed for plutonium content by the bio- medical research group at the Laboratory (Lushbaugh had a joint appointment with that group). After the Kelley incident, Lushbaugh decided to make the collection of tissue specimens for plutonium analyses a routine part of all autopsies performed at the Medical Center. That practice was quite acceptable since, in those days, autopsies were considered a learning tool. They were used to confirm the accuracy of the physician’s diagnosis, to determine the effectiveness of certain medical treat- ments, and, of course, to determine the cause of death, especially in the cases of unattended deaths. Also, autopsy programs measuring plutonium in human tissues were being conducted at other sites in the U.S. and in foreign countries.

Perhaps the more unusual practice was Lushbaugh’s attempt to get permission to perform an autopsy on every person who died at the Los Alamos Medical Center— Laboratory employees, members of the general population from Los Alamos and surrounding areas, and transient visitors from other parts of the country. Of course autopsies had to be perfomed on a certain percentage of persons dying in the hospital each year in order to maintain the accreditation of the hospital and hospital staff. Also the members of the Los Alamos community were typically very interested in the science that could be learned from the autopsies and were willing to make this ﬁnal contribution of themselves in the interest of science.

For routine deaths, the floor nursing supervisor or the attending physician would ask the next of kin to sign the Medical Center's "Authority for Autopsy" form, which stated that the next of kin "authorize(d) a postmortem examination of the decedent, including removal and retention of such specimens and tissues, as the examining physician deems proper for therapeutic or scientific purposes". Few refused consent. Non-routine deaths (accidents, unattended deaths, suicides, homicides, and so on) fell under the authority of the coroner, and so the coroner was asked and would grant consent for the retention and analysis of tissues. In all the cases mentioned above, the next of kin were not necessarily made aware that tissues were being retained specifically for the analysis of plutonium content

Formal consent from occupationally exposed workers. Procedures for obtaining consent became more formal and more explicit in 1968 when the United States Atomic Energy Commission (AEC) established the National Plutonium Registry to function as a national center for the collection of medical, exposure, and work histories for the workers in the AEC nuclear complex. The Registry was an outgrowth of the postmortem tissue sampling program that had begun in 1949 at the AEC's Han- ford site near Richland, Washington and continued to collect tissues at autopsy provided permission was given in advance by the occupationally exposed individual. In the original request for funds, the primary purpose of the Registry was stated as "the protection of the interests of the workers, employees, and public by serving as a national focus for acquisition and dissemination of the newest and best information

238 Los Alamos Science Number 23 1995

A True Measure of Exposure

relative to the effects of the transuranium elements on people." In 1970, the name of the Registry was changed to the United States Transuranium Registry (USTR) but the mission did not change, and by June 1974, 5843 transuranium workers had been identiﬁed, of whom 3880 had signed release forms for their medical and health physics records and 819 had given authority for autopsy.

Initially, all tissues collected by the Registry, with the exception of cases originat- ing at Rocky Flats, were analyzed at the Battelle, Paciﬁc Northwest Laboratories, in Richland, Washington. In 1971, the Los Alamos Laboratory was added to the list of "approved" laboratories. The Battelle and Los Alamos laboratories submit- ted their own research proposals and were funded independently by the AEC for radiochemical analysis of the Registry tissues. In 1978, the Energy Research and Development Agency (ERDA), successor to the AEC, directed that the Los Alam- os tissue analyses laboratory become the lead laboratory for analysis of human tissues for the United States Transuranium Registry (USTR).*

Once the Registry was established, physicians in the Industrial Medicine Group at Los Alamos would use the periodic employee medical examinations as a time to introduce the Registry and its purpose to those Laboratory employees who were either known to have, or suspected of having, internal exposure to the transuranium elements. Individuals willing to release their medical, exposure, and work histories to the Registry and to donate tissues following their death were provided additional detailed information and appropriate consent forms. Those forms were generally signed prior to death by the donor, his spouse or nearest next of kin, and a non-related witness. The forms were kept on ﬁle and had to be renewed every ﬁve years to be valid. Also the next of kin could withdraw the consent for tissue donation at the time of death if they desired to do so.

Potential donors were provided with identification cards to carry on their person that notified the attending physician or hospital staff at the time of death of the individual's desire to donate tissues to the U.S. Transuranium Registry. The card gave a telephone number to be called if death was imminent or had occurred. Once the Registry was notified, they alerted our tissue analysis laboratory, and we sent instructions and shipping containers to the hospital where the autopsy was to take place. Following the autopsy, tissue specimens were individually packaged in plastic bags, frozen, packed in Dry Ice, and shipped to Los Alamos by overnight delivery.

In recent years, the Registry instituted a whole-body donation program in which all internal organs were removed, packaged as described above, and sent directly to Los Alamos, and the cadaver was shipped to Richland for complete dissection. The skin, muscle, and bones were then shipped to Los Alamos for analyses. Be- cause identiﬁcation cards in wallets were sometimes overlooked, whole-body donors had the additional option of carrying Medic Alert bracelets or medallions so that there would be no delay in notifying the Registry of their death. The fact that the Registry often knew of an individual's death within a matter of minutes following the event, or sometimes prior to death, has led some people to conclude that the Registry was in collusion with the pathologists or contractors for the DOE to obtain tissue specimens. Thus, the charge of "body snatching.” ■

*In 1978, the Energy Research and Development Agency funded the establishment of the United States Uranium Registry (USUR). In 1992, the USTR and USUR were combined to form the United States Transuranium and Uranium Registries (USTUR). An excellent summary of the history of the USTUR is given by R. L. Kathren et al in reference 12.

Number 23 1995 Los Alamos Science 239 A True Measure of Exposure

Layman’s View of An Autopsy

The author, during the course of his 21 years in the Tissue Analysis Pro- gram at Los Alamos, attended numerous autopsies. He is aware that many people do not know what happens at an autopsy, and thought it would be interesting to offer the following lay description.

Generally, a medical assistant for the pathologist prepares the body by cutting a "Y" shaped incision in the skin and muscle covering the chest and abdomen. The skin is cut back to reveal the muscles and ribs of the thorax (chest) and the opening the abdomen. The cartilage connecting the ribs to the sternum (breastbone) is easily cut with a scalpel, and the sternum along with the connected costal cartilage from the ribs are removed to reveal the lungs and heart. The opening in the abdomen accesses the visceral organs, the liver, stomach, kidneys, small and large intestine, bladder, and so forth.

Pathologists generally remove each of these organs one at a time, begin- ning with the heart and lungs, and grossly examine them for obvious abnor- Lungs from an occupationally exposed malities. They then remove small sections of tissue from suspicious areas worker inﬂated with dry nitrogen to ap- and preserve them in a special ﬁxative so that the tissues can later be ex- proximately normal size found in the amined microscopically. To observe the interior of large organs such as human chest. The ratio of plutonium to the lungs and liver, they often "bread-board" them. That is, they make par- americium was measured in the Los allel slices about 1/2 inch thick throughout the organ and continually look Alamos lung counter and compared with for abnormalities. Any suspected areas are snipped out and preserved for measurements made before death. microscopic examination. In this manner, all internal organs are removed from the body and weighed, and appropriate sections are removed and preserved when, based on training and experience, the pathologist deems it necessary.

While the body cavity lies empty, a piece of the vertebrae is sliced off the interior side of the vetebral column with a special bone saw. This bone specimen, called a "vertebral wedge," consists of several vertebral bodies and associated disks. It protrudes into the cavity and is easily removed without destroying the continuity of the vertebral column. Likewise, at this time, a rib and/or piece of sternum can also be removed for examination.

At some hospitals, the organs that have been removed are placed in plastic bags and incinerated. Other hospitals return the organs to the body cavity. In either case, they surgically sew the skin of the abdomen and chest to- A cross section of a lung that had been gether to restore the body to its' "normal" shape so that the mortician can inﬂated with nitrogen and frozen to retain prepare the body for viewing and burial. When prepared by a competent its natural shape. The dark area in the mortician, persons viewing the body are completely unaware that an autop- center is an enlarged pulmonary lymph sy has been performed on the deceased. node. When special circumstances require, the brain is removed by ﬁrst cutting the scalp from ear to ear and turning back the skin and hair to reveal the top of the skull. A special bone saw cuts through the skull bone to remove the skull cap, without cutting into the brain, itself. The brain is then removed intact, and the bony skull cap placed back into position at the top of the head. The scalp is sutured together, and the sutures are seldom no- ticeable when the body is prepared for the funeral. The body is then released to the funeral home for embalming or cremation, as the family has directed. ■

240 Los Alamos Science Number 23 1995 continued from page 237 tion and the general population (see 70 Figure 1). The liver was selected be- Workers in range of general population cause it is a major deposition site for 60 plutonium once plutonium has entered 50 the blood stream and because all or a major portion of the liver could be easi- 40 ly obtained for analysis. Large tissue samples were especially important for 30 evaluating the extremely low levels of plutonium in the general population. 20 Two-thirds of the workers had liver concentrations that did not differ signif- 10 icantly from the general population, Percent of Los Alamos Workers who were exposed only to environmen- 0 tal sources of plutonium such as atmos- <5.1 5.3 - 80.1 215 - 702 2664 - 9835 pheric fallout from weapons testing. Pu-239 Concentrations in Liver (dpm/kg) The remaining third fell naturally into three distinct groups. The two groups ening are evaluated. However, we can Figure 1. Plutonium in Workers with the highest liver concentrations answer some of the questions and refer versus the General Population (above 80 disintegrations per minute to other related studies carried out at This bar chart shows the liver concentra- per kilogram) had well documented ex- Los Alamos for answers to some of the tions of former employees of the Los posures and consisted mostly of others. Alamos National Laboratory. Approxi- chemists, physicists, and laboratory mately two-thirds of all those employees technicians. Almost without exception, Until recently, radiation protection stan- measured had liver concentrations below the persons with those high exposures dards for internal exposures were given 5.1 disintegrations per minute per kilo- had received them during the earliest in terms of the recommended maximum gram (dpm/kg), which is within the range days of the Laboratory's existence. The permissible body burden (MPBB) spec- observed in the U.S. general population group with intermediate liver concentraFig 1 -(Tissue)ified in terms of mass (micrograms) or exposed only to fallout. Individuals hav- tions was made up of the same profes- activity (nanocuries). [1 nanocurie = ing liver concentrations ranging from 5.3 sions as above but also included fire- 2,220 disintegrations per minute (dpm)] to 80.1 dpm/kg included mainly support men, health physics monitors, health For plutonium, the MPBB for nuclear personnel (firemen, custodians, health physics laborers, plumbers, and so on. industry workers was 0.65 microgram physics monitors, security guards, and The latter were probably exposed while or 40 nanocuries. The MPBB for so forth) that may have received minor passing through or working in a conta- americium is also 40 nanocuries. The exposures incidental to their job assign- minated area for short times. Overall, highest depositions measured at the ments. Individuals with liver concentra- it is evident that the majority of Labo- time of death by our program was tions greater than 80 dpm/kg were physi- ratory workers have been adequately about 85 nanocuries of plutonium in a cists, chemists, health physics monitors, protected from exposure to plutonium. former Los Alamos worker, 120 and metallurgists, all of whom had well nanocuries of americium in a worker at documented plutonium exposures. One might wonder whether there have the Lawrence Livermore Laboratory been any Laboratory personnel who re- (the latter is thought to have received ceived really high plutonium exposures, his exposure while working as a gradu- and, if so, whether the exposures have ate student at the University of Califor- affected their lives or been life threat- nia at Berkeley) and 15 microcuries ening. These are questions frequently (more exactly 14,600 nanocuries) of asked by concerned workers and the americium in a Hanford Site worker. general public, alike. (For a discussion Did the exposures contribute to their of plutonium exposures and their ef- deaths? The Los Alamos worker died fects see “On the Front Lines.”) at the age of 78 from a heart attack. The Livermore worker died at age 49 Our study was not designed to answer of a malignant melanoma. However, it all these questions. It was not an epi- is not believed that americium exposure demiology study where frequency of results in melanoma. The individual disease, causes of death, and life short- from the Hanford Site died at age 76

Number 23 1995 Los Alamos Science 241 A True Measure of Exposure

chemically measuring the plutonium content in the major deposition sites, that is, the lungs and associated lymph nodes, the liver, and the skeleton. These three organs contain about 90 per Trabecula cent or more of the retained plutonium. Determining the lung, and liver content is straight forward, since these organs are easily obtained at autopsy and are Endosteal layer Periosteal layer small enough to be analyzed in total.

The skeletal content is much more diffi- cult to determine, but is a critical mea- Blood vessel surement since about half of the systemic burden (internal to the body and exclusive of the lungs) is in the skeleton. Obviously, the entire skeleton is Spongy bone not easily obtained at autopsy. A rib, a Compact bone vertebral wedge (a block of one to three vertebral bodies removed from within Figure 2. Spongy versus Compact from cardiovascular disease. Of all the the body cavity), and the sternum were Bone cases analyzed by this program and/or the bones most often removed by the This drawing shows a portion of a bone followed by the Los Alamos plutonium pathologist for our study. That choice from which the marrow has been re- epidemiology studies, only one is was dictated in part by aesthetics—removed. Bone is composed of two kinds thought to possibly have died from the moval of these specimens does not dis- of tissue. One is dense in texture like effects of their plutonium exposure. figure the body when it is prepared for ivory and is termed compact bone; the That individual, a chemist at Los Alam- a funeral and burial. In the early part other consists of slender spicules, tra- os during the Manhattan Project, died of the study, the bone specimens were beculae, and lamellae joined into a in 1990 at age 66 of an osteosarcoma analyzed for plutonium, and the results spongy structure, which is called cancel- (bone cancer). The primary site of the were extrapolated to represent the lous, or spongy, bone. The compact cancer was the sacrum. Osteosarcomas whole skeleton under the assumption bone is always on the exterior of the of the sacrum are not common in man that plutonium is uniformly distributed bone, the spongy bone on the interior. but have been observed in animals in all bones. The average weight of the The relative quantity of the two kinds of (beagle dogs) exposed to plutonium. skeleton in a young (25 to 35 years tissue varies in different bones and in Keep in mind, however, that this is a old), caucasian male weighing 70 kilo- different parts of the same bone, accord- single case and must be evaluated cau- grams is 10 kilograms, or about 14 per ing to functional requirements (see tiously. There seems to be scant hard cent of their body weight. The donors Gray's Anatomy, page 282). evidence that exposure to plutonium to our program were much older men in and/or americium at the levels reported their sixth or seventh decades. In the above has caused any significant life current enrollment of the USTUR, 69 shortening or disease. per cent of the donors are age 65 or older. (Eighty-five percent are older Quantitative results on plutonium de- than age 55.) Body weight proportions position and distribution. The data change significantly with age. The as- obtained from deceased occupationally sumption of a 10-kilogram skeleton, or exposed workers by the tissue analysis even a skeletal weight based upon 14 program has been used in many ways. per cent of the body weight, is there- One of the primary objectives of this fore very uncertain. study was to measure quantitatively the total body burden, or deposition, of plu- An even more important complication tonium in a person so that models pre- in estimating the skeletal content of plu- dicting this deposition from urine tonium was the discovery that, unlike analyses could be validated and im- radium, which is distributed somewhat proved. This can be accomplished by uniformly throughout the bone mineral,

242 Los Alamos Science Number 23 1995 A True Measure of Exposure

Cancellous bone Compact bone

100 2.5

80 2.

60 1.5

40 1.

30 Activity (dpm per sample)

20 0.5 Concentration (dpm/gram ash)

0 0 Proximal end Proximal shaft Middle shaft Distal shaft Distal end

Plutonium content of sections of the femur

Activity per section Concentration (dpm) (dpm/gram ash)

Figure 3. Deposition of Plutonium in a Thigh Bone The bar chart shows the plutonium-239 content of different sections of a thigh bone (femur) in two ways, the total activity of each section and the concentration, or activity per gram. Plutonium deposits on the bone surface, and therefore, the concentration in- creases with the amount of surface area. Since the interior of the end sections of the femur contain spongy bone with a high de- gree of trabecularity and therefore a large surface area, the concentration of plutonium is higher at those ends. Fig 3 Tissue plutonium is deposited on the bone sur- blood cells. Red marrow is the site for two ends of the femur, which contain face. Autoradiographs made from ani- the production of the red blood cells most of the spongy tissue. mals given large injections of plutonium and the granular leukocytes. It is found citrate demonstrate that phenomenon in the spongy portions of the flat and Given this pattern of deposition, the pri- quite clearly. That means that the con- short bones, the ends of the long bones, mary carcinogenic risk from plutonium centration of plutonium is greatest the ribs, sternum, and vertebral bodies. in the skeleton is associated with the where there is a large amount of bone hematopoietic stem cells (blood-forming surface compared to bone volume. The relative quantity of compact versus cells) of the bone marrow, which fills spongy bone varies among different the spongy structure, and osteoblasts Figure 2 shows that the bone is com- bones, and in different parts of the same (bone-forming cells) close to the bone posed of two general types of structure: bone, according to functional require- surfaces. Plutonium in or near the bone a very dense structure like ivory on the ments. Because plutonium deposits on marrow might lead to leukemia, where- outside, termed "compact" bone; and a the bone surfaces, and spongy bone has as plutonium on the bone surface might spongy stucture on the inside consisting a high surface area, the distribution of lead to osteosarcoma. of slender spicules, trabeculae, and plutonium within a bone is proportional lamellae. The cavities of the bone are to the distribution of the spongy bone. Returning to the problem of estimating filled with bone marrow. Yellow mar- Figure 3, showing the distribution of the amount deposited in the skeleton row is found in the large cavities of the plutonium in the large thigh bone called from the samples taken during autopsy, long bones. It consists, for the most the femur, illustrates this very well. we note that the ribs, sternum, and ver- part, of fat cells and a few primitive Most of the plutonium is located at the tebral bodies usually sampled at autop-

Number 23 1995 Los Alamos Science 243 A True Measure of Exposure

For the inhalation cases, greater proportions of plutonium-239 and americium- 239 80 Pu 241 are found in the respiratory tract than are predicted by the International 241 70 Am Commission on Radiological Protection (ICRP publications 30 and 48). Early models based upon animal data had 60 proposed a 500-day half-time for the retention of plutonium in the lungs. 50 The data in Figure 4, derived from individuals who died approximately 30 years following their exposure, show 40 very clearly that the half-time in the lungs of humans is much longer. An- 30 other ﬁnding is that americium is cleared much more rapidly from the

Percent Whole Body Content 20 liver than is plutonium, whereas early models used the same clearance time for both elements. The liver-clearance 10 half-time for americium is two to three years whereas the liver-clearance half- 0 time for plutonium is 20 years (ICRP Respiratory Liver Skeleton Muscle Other Tract publication 48). After long-term exposure, signiﬁcant fractions of the sys- Figure 4. Whole-body Distibution of Plutonium and Americium temic plutonium-239 and americium- The bar chart shows the mean distributions of plutonium-239 and americium-241 in 241 are found in muscle and other soft four whole bodies donated to the U.S. Transuranium Registry. All were exposed pri- tissue, which suggests that those tissues marily by inhalation approximately 30 years prior to death. The error bars represent function as a long-term depot for those one standard deviation from the mean.Fig. 4The Tissue two elements differ most in the liver re- nuclides. tention time (plutonium has a residence half-time of 20 years compared to 2 to 3 years for americium). Also the fraction of americium found in the skeleton and mus- How do the body burdens measured cle is higher than that of plutonium. The large error bars are indicative of individual from our radiochemical analyses of biological variation and possible variation in exposure parameters. whole-bodies compare to the body burdens predicted by applying biokinetic sy have relatively high proportions of laboratory at Los Alamos for one or models to excretion data? Table 1 pre- spongy bone and therefore have a rela- more of the following elements: pluto- sents a comparison that Ron Kathren tively higher concentration of plutoni- nium, americium, uranium, and thori- and I published in 1991. Measurements um than the entire skeleton. Therefore um. Six of the twelve analyzed had of the systemic deposition (all organs early estimates of skeletal content de- worked and received their exposures at except the lung) and the whole-body rived from analyses of those bone types Los Alamos. Twenty-four donors are deposition of plutonium-239 in four could easily have overestimated the still living, and ten bodies are awaiting whole bodies are shown in red. Also skeletal content if uniform distribution analyses at the Registries' newly estab- listed are 13 different theoretical esti- had been assumed. lished laboratory at Washington State mates of the deposition. Each theoreti- University in Pullman,WA. One body cal estimate was calculated by applying Wisely, the USTUR instituted a whole- was not analyzed because the person a different biokinetic model to the uri- body donor program in 1979 so that the tested positive for hepatitus-B at the nary excretion data obtained during the distribution of the actinides could be time of death, and we did not want lives of those four individuals. determined for the entire skeleton and to expose our analysts to that deadly also for the less frequently sampled soft disease. Table 1 shows that the plutonium bur- tissues. As of October 1995, 47 indi- dens estimated from the older biokinet- viduals have since consented to become Detailed data from six whole bodies ic models were many times greater than whole body donors. To date, 23 of have been published. Figure 4 shows the measured values. The results of those individuals have died. Twelve the relative distributions of plutonium two models are within a factor of two whole bodies have been analyzed in our and americium in four of the bodies. of the tissue analysis results for all four

244 Los Alamos Science Number 23 1995 A True Measure of Exposure

Table 1. Tissue Results on Whole Bodies Compared with Estimates of Biokinetic Models

Systemic Burden of Plutonium-239* (nanocuries)

Biokinetic Model Date Case 193 Case 208 Case 213 Case 242

Langham 1950 27.0 56.5 55.9 94.6

Healy 1956 23.2 40.0 43.0 80.0

Durbin 1972 13.0 30.5 61.1 47.8

Rundo et. al. 1976 3.0 10.0 5.9 15.1

Parkinson & Henley 1981 8.9 31.6 17.8 42.4

Leggett 1984 3.8 4.0 11.6 29.7

Jones 1985 5.7 11.9 8.1 20.0

Leggett & Eckerman 1987 4.9 8.4 6.8 11.6

Revised Langham per Legett & Eckerman 1987 3.2 5.9 8.1 16.2

PUQFUA (7.3) (15.5) (13.5) (23.3)

Tissue Analysis 1988 3.1 3.8 6.7 24.3

Tissue Analysis (whole body) (6.6) (6.1) (8.2) (75.7)

*Systemic burdens refer to the content of all organs excluding the lungs, whereas whole-body burdens include the lung content. cases: the Langham power function the whole bodies was an investigation most of the skeletal plutonium was as- model as modified by Leggert and Eck- of the amount of plutonium in the bone sociated with the mineralized bone. erman and the two component exponen- marrow. Animal studies had shown Concentrations of plutonium were tial model proposed in ICRP publica- that myeloid leukemia as well as os- more than ten times greater in the min- tions 19 and 30. In all four cases in teosarcomas (bone cancer) can be in- eralized portions than in the organic Table 1, exposure was primarily by in- duced in laboratory animals by plutoni- fraction. Approximately 3 per cent of halation. Jim Lawrence’s PUQFUA um in bone given appropriate exposure the total skeletal plutonium was esti- code is also a modification of the Lang- conditions. As a result, there was some mated to be resident in the marrow, ham equation and was used at Los concern that a high bone marrow con- with the concentration in the red mar- Alamos for many years. The code esti- centration might increase the risk of row several times greater than the con- mated the whole-body deposition in- leukemia above that calculated by the centration in the yellow marrow. Our cluding the lung, and therefore, the ICRP bone model. result suggests that the radiation dose PUQFUA results should be compared to the mineralized portion of the bone with the radiochemical estimate of We attempted to evaluate the leukemia and to osteoblasts in the periosteal lay- whole-body contents shown in paren- risk from plutonium exposure in hu- ers andendosteal layers of the bone theses. Lawrence continuously used mans by separating the bone marrow (see Figure 2) may be an order of mag- the tissue analysis estimates of plutoni- from mineral bone. The separation nitude or more than the dose to the red um deposition in deceased workers over was accomplished by washing the mar- marrow. The implication of these find- the years to verify and improve his row out of the bone cavities with a jet ings is that the risk of bone tumors is model. of water and then measuring the pluto- several times greater risk than the risk nium in the bone-mineral and bone- of leukemia. One of the other new studies done on marrow components. As expected,

Number 23 1995 Los Alamos Science 245 A True Measure of Exposure

General Population Studies 10

Origin and procedures. From the be- 1 40 ginning in 1959 the tissue program in- 1 2 4 309 cluded non-occupationally exposed in- 1 8 2 45 dividuals who died at the Los Alamos 2 4 338 2 Medical Center. At first the collection 3 1 2 and analysis of tissues from that gener- 2 1 al-population sample was meant to de- 237 18 termine background levels for compari- 149 4 son with the levels found in plutonium 1 workers. The community and the Lab- oratory were also interested in determining whether or not any plutonium had been released from the Laboratory Distribution of U.S. general population cases and was causing internal exposure of Figure 5. Geographic Distribution of General Population Study people living in Los Alamos and near- The map shows the states of origin of the 1187 individuals from the general population by communities. from whom tissues were collected and analyzed over the course of the Los Alamos tissue analysis project. Major collection sites were near the DOE nuclear facilities at Los A more global concern was the impact Alamos, the Rocky Flats Facility in Colorado, the Savannah River Facility, and the Han- of the more than 320 kilocuries (ap- ford Facility in Washington State. Control populations were collected from areas not proximately 5,000 kilograms or 11,000 near nuclear facilities in Pennsylvania, Illinois, and New York. A few other individuals pounds) of plutonium-239 that had been from other states died in one of the participating hospitals and were included in the distributed worldwide, mostly in the sampling process. northern hemisphere, from atmospheric testing of nuclear weapons. Reliable Los Alamos analyze tissues from indi- in 1973 and the Pennsylvania-area in data were not available on how much viduals living in the Denver-Boulder 1974. had been deposited and retained in tis- area. Local hospitals collected the tissues of the general population, nor sues, which were then picked up and Before setting up those programs, we whether there were significant differ- sent to Los Alamos by personnel from investigated the legality of having ences in exposure depending on where the Colorado Department of Health. pathologists send tissues to Los Alamos a person lived. It was obvious even at Tissue collection from the Denver- and found it to be within the limitations the start of the tissue study that answer- Boulder area continued until 1985. included in the autopsy consent form ing those questions would be a natural used by most hospitals. Although con- and important extension of the research With the cooperation of the Medical sent forms vary from hospital to hospi- effort if and when the opportunity Director at the plutonium production tal, they are all similar. In particular, arose. plant at Savannah River Plant, contact the "Authorization for Autopsy" form was made with local pathologists and published by the American Medical As- The Los Alamos general population tissues were collected, from 1972 to sociation states in part, "I (we) autho- study expanded its borders somewhat 1979, from the areas around Augusta, rize the removal and retention or use accidentally when, in 1968, tissues Georgia and Aiken, South Carolina to for diagnostic, scientific, or therapeutic from 36 individuals from New York establish the background levels of envi- purposes of such organs, tissues, and City (unclaimed bodies) were sent to ronmental plutonium and evaluate the parts as such physicians and surgeons Los Alamos and, at the request of the possible release of plutonium from the deem proper."* This authority was AEC's Health and Safety Laboratory, Savannah River Plant. Realizing the granted subject to any special restric- analyzed for fallout plutonium. In samples collected from the Los Alam- tions by the next of kin, but it generally 1970, the Colorado Department of os, Rocky Flats, and Savannah River provides for the release of tissues for a Health wanted to evaluate the extent of areas may have been contaminated by scientific study such as ours. With a off-site plutonium contamination that local releases from these nuclear facili- few exceptions, individuals whose tis- was suspected to have occurred as the ties, we sought control populations sues were sent to us were not identified result of a major fire in 1969 at the from areas far away from existing nu- * Rocky Flats plutonium processing and clear facilities. As a result, we added Form 44 in "Medico-legal Forms with Legal Analysis" (American Medical Association, fabrication facility. They requested that the Illinois-area residents to the study Chicago, Illinois, 1961).

246 Los Alamos Science Number 23 1995 A True Measure of Exposure

Table 2. Results of Hypothesis Testing for Geographic Differences

The table summarizes the results of sta- 1974-75 tistical testing for geograhic differences in the plutonium content of different tis- Kidney PA LA CO GA NM sues. The two-letter abbrevations stand (0.114) (0.108) (0.081) (0.075) (0.063) for states, except for LA, which stands for Los Alamos. For each tissue listed, Liver LA NM GA IL PA CO the distribution from those states under- (2.399) (2.123) (1.942) (1.461) (1.398) (1.276) lined with the same line do not differ significantly. Median values in units of Lung NM LA GA CO PA IL disintegrations per minute (dpm) per (0.535) (0.447) (0.316) (0.301) (0.271) (0.104) kilogram are given in parentheses. Even where statistically significant differences Lymph Node LA NM CO PA exist from one state to the next (in (6.553) (6.500) (2.917) (1.923) which case the states fall on two different lines), the differences in median are Rib LA NM PA quite small, on the order of 1 dpm per (1.125) (0.966) (0.460) kilogram of tissue, so that the measured differences probably have no practical Vertebrae NM CO GA PA LA consequence. (0.673) (0.631) (0.400) (0.363) (0.213) In the analysis, we tried to eliminate the Female Gonad CO PA LA dependence on age at death and year of (2.769) (1.000) (0.667) death by considering only very short time segments, namely, the year of Male Gonad LA PA CO NM GA death, and subtracting out the age (0.568) (0.319) (0.063) (0.053) (0.042) trends found during those time periods. The two time periods chosen (1974-75 Spleen LA PA GA NM CO and 1967-68) were selected because they (0.350) (0.164) (0.160) (0.147) (0.101) included the major portion of the data and because they were the only periods Thyroid LA PA CO IL NM GA where data was available from certain (1.303) (0.749) (0.363) (0.286) (0.00) (-0.194) geographical locations. A Kruskal-Wal- lis non-parametric test of significance of 1967-68 among-region differences at the a = 0.05 level was used. If this test indicated Liver LA NM NY overall significance, Mann-Whitney tests (1.823) (1.730) (1.500) were performed for all pairwise comparisons of the geographic regions (at the Lung LA NM NY a = 0.05 level). If the Kruskal-Wallis test (1.272) (1.165) (0.668) was not significant, then all pairwise comparisons were declared not Vertebrae NM NY LA significant. (4.557) (1.539) (0.769)

by name, only by hospital identification determine if the next of kin were told ping charges for sending the tissues to number or autopsy number. We be- specifically about our plutonium analy- us by air freight). lieved that the standard autopsy clause ses of the donated tissues.) Patholo- was adequate to release tissues for our gists were generally reimbursed a small Between 1959 to 1985 samples were plutonium study, and we left it to the amount ($25 to $100) to cover their collected in that manner from 1848 in- discretion of the pathologist or their cost of collecting the tissues, packaging dividuals in seven geographic areas representative to do whatever additional each tissue individually, freezing them throughout the United States. Figure 5 explaining to the next of kin they for storage, packing them in Dry Ice, shows the number of individuals from deemed necessary and appropriate. and finally arranging to have them whom we analyzed tissue for each of (That means we did not follow up to shipped to us. (We also paid the ship- the 27 contributing states.

Number 23 1995 Los Alamos Science 247 A True Measure of Exposure

In 1978 Los Alamos was named the showed no geographic differences in plutonium in lung and liver. In the lead laboratory for analyzing tissues do- any of the tissue concentrations of plu- general conclusions of the above refer- nated by occupationally exposed work- tonium. For the time span 1974-75, the ence, they stated "...there is consider- ers to the U.S. Transuranium and Ura- data showed no regional differences in able evidence to suggest that both the nium Registries. At that time our plutonium concentrations in the verte- 40-year half-time for plutonium in liver general population study had to be dis- brae, kidney, spleen, and female go- and the 100-year half-time for plutoni- continued because of funding con- nads, but, as shown, there were small um in the skeleton recommended in straints. By then, one or more tissues regional differences in all other tissues ICRP Publication 19 (ICRP72) and em- had been analyzed from 1,254 of the (liver, lung, lymph node, rib, male ployed in ICRP Publication 30 (Part 1), individuals who had contributed autop- gonad and thyroid). (ICRP79), are too long. Values of 20- sy specimens. Results from approxi- and 50-years for retention times in liver mately 900 individuals (approximately How have the data been used? The and skeleton, respectively, now seem 4,400 tissues) were reported in the open 1981 report "Deposition and Retention more reasonable." The ICRP report literature through three major reports. of Plutonium in the United States Gen- stated further: "The more recent infor- Unfortunately, in 1990, a freezer failure eral Population" evaluated the data as a mation on the behavior of inhaled plu- resulted in the loss of the unanalyzed function of time and compared the re- tonium, or other actinide compounds, in tissues and they had to be destroyed by sults with the predicted organ concentra- animals, and on the behavior of inhaled cremation. tions estimated using the ICRP lung particles in man [from the Los Alamos model and the annual air concentrations Tissue Study], is not always consistent What has been learned? Most impor- of fallout plutonium measured by DOE's with the assumptions of the ICRP Lung tantly, the data showed that levels of Environmental Measurements Laborato- Model. These discrepancies are being plutonium in the U.S. general popula- ry in New York City (formerly AEC’s considered by the Task Group on Res- tion are small and that populations liv- Health and Safety Laboratory). Accord- piratory Tract Models." ing near major nuclear facilities did not ing to the ICRP Publication 48, "The have significantly higher plutonium lev- Metabolism of Plutonium and Related The ICRP further stated that "Since the els than those living far from such facil- Elements," those data showed "reason- appearance of ICRP Publication 19, ities. The analyses also confirmed that able agreement between computed and much more information on the tissue major deposition sites of fallout plutoni- measured values for lung. Computed contents and retention of plutonium and um were the respiratory tract, the liver values for skeleton were about three americium in humans has become and the skeleton. The measured deposi- times lower than measured values in available. Much additional information tion patterns and retention factors are vertebrae and rib. . . .The computed val- can be obtained from continuing the critical for identifying the level of haz- ues for liver were also somewhat lower measurements of fall-out plutonium in ard to the general population. than the measured values. . . .The com- autopsy material. . . .” ■ puted content of fallout plutonium-239 The data also show that liver concentra- in lung-associated lymph nodes is an tions increase slightly with age and order of magnitude higher than the mea- skeletal concentrations decrease. Evi- sured content. The half-time values Further Reading dently, as time passes a remobilization used in the [ICRP] model were based of the bone mineral releases plutonium upon data from beagles; monkeys, and Wright H. Langham. 1961. Special supplement: from the skeleton, which then deposits rodents accumulated less plutonium than acute radiation death resulting from an accidental nuclear critical excursion. Journal of Occupa- in the liver. beagles in their lymph nodes, and are tional Medicine 3, no. 3 Special Studies: 169- more consistent with human data. 177. No significant differences in tissue de- These findings emphasize the need for position of plutonium between males careful extrapolation of animal data to B. G. Bennett. 1974. Quarterly Summary Re- port, HASL-278, January 1974. New York: and females were evident. predict human metabolism." Fallout Program Health and Safety Laboratory.

The data were also examined for geo- Based to a large extent on the Los I. C. Nelson, K. R. Heid, P. A. Fuqua, and T. D. graphic differences (see Table 2). To Alamos general population tissue study Mohony. 1971. Plutonium in Autopsy Tissue eliminate any inﬂuence of the year of program (the ICRP referenced four Samples. Battelle-Northwest Paciﬁc Laboratory report BNWL-SA-4077. death, we examined tissues from indi- major Los Alamos reports and one per- viduals who died during a certain short sonal communication from me in their Y. Takizawa. 1970. Japanese hygienists points time period and we subtracted out the Publication 48), the ICRP has recom- out increase in plutonium in human body. Japan age trends found in that time period. mended changes in their lung model Society of Public Hygiene. Nagoya, Japan. Oc- tober 28, 1970. For the time span 1967-68, the data that reduce the retention parameters for

248 Los Alamos Science Number 23 1995 A True Measure of Exposure

P. W. Krey, D. Bogen, and E. French. 1962. in whole bodies donated to the United States Plutonium in man and his environment. Nature Transuranium Registry. Radiation Protection 195: 263-265. Dosimetry, 26, no. 1/4: 151-158.

C. R. Lagerquist, S. F. Hammond, D. L. Bokows- J. F. McInroy, R. L. Kathren, G. L. Voelz, and ki, and D. B. Hylton. 1973. Distribution of plu- M. J. Swint. 1991. U.S. Transuranium registry tonium and americium in occupationally exposed report on the 239plutonium distribution in a humans as found from autopsy samples. Health human body. Health Physics Journal 60, no. 3: Physics 25: 581-564. 307-333.

E. E. Campbell, M. F. Milligan, W. D. Moss, H. J. F. McInroy, E. R. Gonzales, and J. J. Miglio. F. Schulte, and J. F. McInroy. 1973. Plutonium 1992. Measurement of thorium isotopes and in autopsy tissue. Los Alamos Scientific Labora- 228Ra in soft tissues and bones of a deceased tory report, LA-4875. thorotrast patient. Health Physics Journal 63, no. 1: 54-71. J. F McInroy. 1975. The Los Alamos Scientific Laboratory's human autopsy tissue analysis study R. L. Kathren, and J. F. McInroy. 1991. Com- (Los Alamos Scientific Laboratory report LA- parison of systemic plutonium deposition esti- UR-85-2322). In The Health Effects of Plutoni- mates from urinalysis and autopsy data in five um and Radium: Proceedings of the University of whole-body donors. Health Physics Journal 60, James F. McInroy earned a M.Ed. in physical Utah's Workshop on the Biological Effects and no. 4: 481-488. science from Pennsylvania State University in Toxicity of 239Plutonium and 226Ra, Sun Valley, 1959. He taught chemistry and physics for ten Idaho, October 6-9, edited by W. S. S. Jee, 249- J. N. P. Lawrence. 1978. A History of PUQ- years in the public school system in Pennsylva- 270. FUA—plutonium body burden (Q) from urinaly- nia and New York with an additional five years sis Los Alamos, NM. Los Alamos National Lab- at Slippery Rock University, Slippery Rock, PA. J. F. McInroy, E. E. Campbell, W. D. Moss, G. oratory report LA-7403-H. McInroy earned a M.S. in 1969 and a Ph.D in L. Tietjen, B. C. Eutsler and H. A. Boyd. 1979. 1973 from Colorado State University in health Plutonium in autopsy tissue: a revision and up- E. R. Humphreys, J. F. Loutit, and V. A. Stones. physics and radiobiology. His doctoral research dating of data reported in LA-4875. Health 1985. The induction by 239plutonium of involved evaluation of possible exposures to the Physics 37: 1-136. myeloid leukemia and osteosarcoma in female general population via the food chain, should CBA mice (interim results). In Metals in Bone, there be an accidental release of polonium-210 J. F. McInroy, H. A. Boyd ,and B. C. Eutsler. edited by N. D. Priest, 342-352. Lancaster MTP during the launch of satellites containing nuclear 1981. Deposition and retention of plutonium in Press. powered electronic sources (SNAP devices). McInroy joined the Health Research Division of the United States general population. In Ac- the Laboratory as project leader in 1972 follow- tinides in Man and Animals, edited by M. E. International Commission on Radiological Protec- ing funding by the Atomic Energy Commission Wrenn. Salt Lake City, Utah: RD Press, 161- tion. 1979. Limits for Intakes of Radionuclides of the human tissue analysis program and re- 179. by Workers: ICRP Publication 30. Oxford: mained in that position until his retirement in Pergammon Press. 1993. From 1979 to 1984 he was deputy group Wendy Hoffman to J. F. McInroy. 1994. Los leader of Health Division’s Epidemiology Alamos Medical Center Authority for Autopsy J. F. McInroy and R. L. Kathren. 1990. Plutoni- Group. McInroy was instrumental in the organi- form. Los Alamos Medical Center, Los Alamos, um content in marrow and mineralized bone in an zation and establishment of the International New Mexico. occupationally exposed person. Radiation Pro- Conference on Low Level Measurements of Ac- tection Dosimetry 32, no. 4: 245-252. tinides and Long-Lived Radionuclides in Biolog- R. L. Kathren, L. A. Harwick, R. E. Toohey, J. J. ical and Environmental Samples, and was Chair- Russell, R. E. Filipy, S. E. Dietert, M. M. Hu- man of the Technical Planning Committee for nacek, and C. A. Hall. 1994. Annual report of their meetings in Sweden, Japan, India, and the United States transuranium and Uranium Reg- Brazil. He also played an instrumental role in istries: April 1992 - September 1993. Washing- the development of the National Bureau of Stan- ton State University report USTR-0015-94. dards (now NIST) natural matrix reference mate- rials containing metabolized actinide elements in J. N. Stannard. 1988. Radioactivity and Health: human tissues (lungs, liver, and bone). McInroy A History, edited by R. W. Baalman, Jr. Office has been a member of Sigma XI, the Health of Scientific and Technical Information, Battelle Physics Society, the Radiation Standards Com- Memorial Institute. mittee of the Health Physics Society, and the Bioassay, Analytical and Environmental Chem- G. T. Seaborg to R. S. Stone. January 5, 1944. istry Conference. McInroy became a member of Physiological Hazards of Working with Plutoni- the Human Studies Project in December 1993 and was responsible for making available all um. MUC-GTS-384. documents associated with the Human Tissue Study Project. J. F. McInroy, H. A. Boyd, B. C. Eutsler, and D. Romero. 1985. Part IV: Preparation and analysis of the tissues and bone. Health Physics Journal 49, no. 4: 587-621.

J. F. McInroy, R. L. Kathren, and M. J. Swint. 1989. Distribution of plutonium and americium

Number 23 1995 Los Alamos Science 249 A True Measure of Exposure

The Cecil Kelley Criticality Accident The origin of the Los Alamos Human Tissue Analysis Program

n December 30, 1958, an acci- two operators led Kelley to a shower. surrounded by hot water bottles. His dent occurred in the Los Alam- One operator turned the stirrer off as blood pressure and pulse were at first Oos plutonium-processing facili- they went by. unobtainable. He had shaking chills, ty, where plutonium was chemically and the uncontroled movement of his separated, or “recovered,” from various Within five or ten minutes, a nurse, su- extremities and torso necessitated re- compounds. In this facility, plutonium pervisors, and radiation monitoring staff straint by the nursing staff. Kelley’s compounds were dissolved and mixed were all on the scene. Kelley was evi- anxiety and restlessness were eased only in a large tank with chemical reagents dently in shock and virtually uncon- by Demerol. After about ten minutes, to concentrate and purify the plutonium. scious, but rather innocently, the nurse the nurses were able to measure Kel- On the day of the accident, Cecil Kel- noted that Kelley had “a nice pink ley’s pulse (160 beats per minute) and ley, an experienced chemical operator, skin.” Because the nature of the acci- his blood pressure (80/40). His body was working with the large mixing tank. dent was unknown at the time, it was emitted a small but measureable amount The solution in the tank was supposed not understood until later that Kelley’s of gamma rays, and his vomit and feces to be “lean,” typically less than 0.1 pink skin was erythema (a redness of were sufficiently radioactive to give a grams of plutonium per liter, but the the skin, like that from a sunburn) positive reading on the detector. concentration on that day was actually caused by his radiation exposure. 200 times higher. In fact, the tank con- One hour and forty minutes after the ac- tained enough plutonium (3.27 kilo- The possibility of a criticality accident cident, Kelley entered the third stage, grams) in an upper layer of organic sol- had been considered so remote that the which was both the longest and most vent to be very close to criticality—that radiation monitoring staff began their encouraging. Kelley regained coher- is, capable of sustaining a chain reac- investigation by searching for plutonium ence, and although he complained of se- tion. When Kelley switched on the stir- in the work environment with alpha de- vere abdominal cramps and occasionally rer, the liquid in the tank formed a vor- tectors. They found no widespread ac- retched and vomited, he seemed consid- tex, or whirlpool. The lower, aqueous tivity. It was only as Kelley was leav- erably improved overall. He was trans- layer was pushed outward and up the ing in an ambulance, eighteen ferred from the emergency room to a walls of the tank, as if forming a bowl; minutes after the accident, that the cir- private room, placed in a bed that was the upper, plutonium-containing layer cumstances of his accident became on “shock blocks,” and enclosed in an flowed into the center of this “bowl,” clear. The monitoring staff had just oxygen tent. Kelley’s first blood sam- which increased the thickness of the begun gamma radiation measurements. ples were drawn at this time. Because layer. In this new configuration, the When they saw the high level of gamma Kelley had been irradiated with neu- plutonium went critical, releasing a radiation in the vicinity of the large trons, the sodium and other light metals huge burst of neutrons and gamma radi- mixing tank (tens of rad per hour), the in his blood were “activated,” or trans- ation in a pulse that lasted a mere 200 investigators quickly realized what had formed into radioisotopes such as sodi- microseconds. happened. um-24. His average whole-body dose was first estimated by measuring the ra- Kelley, who had been standing on a foot The symptoms Kelley displayed at the dioactivity of his blood. It appeared to ladder peering into the tank through a plutonium-processing facility, character- have been massive—in the range of 900 viewing window, fell or was knocked to ized by collapse and mental incapacita- rad from fast neutrons and 2,700 rad the floor. Confused and disoriented, he tion, were the first stage of his clinical from gamma rays, giving a total of apparently turned the stirrer off and on course (what is now know as the most 3,600 rad—and certainly lethal.1 again, then ran out of the building. The severe form of acute radiation syn- two other operators on duty at the time drome). The second stage began when Six hours after the accident, the lym- saw a bright flash of light, like that of a he arrived in the emergency room of the phocytes virtually disappeared from flash bulb, and heard a dull thud. Los Alamos Medical Center. It was Kelley’s peripheral circulation, which Quickly, they rushed to help, and found dire. Kelley was semiconscious, retch- 1 After his death, Kelley’s radiation dose was bet- Kelley outdoors. He was ataxic (lack- ing, vomiting, and hyperventilating. His ter estimated, again using biological indicators of ing muscular coordination). All he skin was cold and dusky reddish-violet, the neutron dose and inferring the gamma dose. could say to the operators was, “I’m and his lips had a bluish color that indi- The results were somewhat greater than the estimate made during Kelley’s period at the hospital: burning up! I’m burning up!” Assum- cated poorly oxygenated blood. He was 900 rad from fast neutrons and 3,000 to 4,000 rad ing he’d had a chemical accident, the immediately wrapped in blankets and from gamma rays, giving 3,900 to 4,900 rad.

250 Los Alamos Science Number 23 1995 A True Measure of Exposure

The origin of the Los Alamos Human Tissue Analysis Program was taken as a grave sign. Twenty-four Kelley’s exposure record included 18 termine relative timescales for the move- hours after the accident, a sternal bone instances of high nose-swipe counts and ment of plutonium through the body and marrow biopsy was performed. The 10 instances of minor exposures, such within organs. This was possible be- marrow appeared watery, rather than as being involved in the cleanup of a cause changes in plutonium production bloody, and no excessive bleeding oc- plutonium spill or getting a slight lacer- methods between Kelley’s first and sec- curred. The marrow was almost com- ation. Urine assays taken during that ond stints as a plutonium worker had pletely acellular, edematous, hemorrhag- period usually showed slight amounts of considerably increased the ratio of pluto- ic fatty tissue. From that observation, plutonium. Analysis of those assays in- nium-238 to plutonium-239 in the mater- along with the rapid onset of lymphope- dicated that Kelley’s plutonium body ial being handled. This fact, coupled nia (depression of the lymphocytes in burden was 19 nanocuries (see “The with the record of nose counts and expo- the bloodstream overall), it was clear Human Plutonium Injection Experi- sures, enabled them to distinguish the that Kelley would not survive long. ments”). Kelley’s records showed that “early” plutonium from the “late” pluto- all of his exposures occurred during his nium and, thus, to trace qualitatively the During the second evening after the ac- early plutonium work (1946-1949) and movement of plutonium from the lungs cident, Kelley entered the fourth stage. it was very likely that most of his pluto- to other organs. They found that pluto- The pain in his abdomen became diffi- nium burden was accumulated during nium cleared relatively rapidly from the cult to control. He became increasingly this period from chronic inhalation ex- lungs compared with the clearance from restless despite medication—so much so posure to low-level airborne plutonium. the bone and lymph nodes. Much of the that the intravenous infusions were inad- plutonium in the lungs migrated to the vertantly interrupted. He began to Autopsy samples were taken from liver whereas only a small percentage sweat profusely, his color became throughout Kelley’s body to measure migrated to the bone and lymph nodes. ashen, and his pulse irregular. About plutonium concentrations. (The acci- Finally, the rate of clearance from the 35 hours after the accident, Kelley died. dent itself, an exposure to neutrons and lungs to the liver must be relatively fast gamma rays, had no impact on the and the retention time in the liver must Kelley had spent about half of his 11.5 amount or distribution of plutonium in be longer than in the lungs. years at Los Alamos as a plutonium- his body.) The tissue analysis showed processing operator (from 1946 to 1949 that Kelley’s total plutonium body bur- A memorandum written by Jean Mc- and, again, from 1955 through 1958). den was 18 nanocuries. This compared Clelland and Bill Moss, chemists in the During that time, he underwent several extremely well with the value of 19 Health Division, presented the results of minor exposures to plutonium, including nanocuries determined from urinalysis. Kelley’s tissue analysis. Those results regular exposure to moderate levels of Wright Langham stated that the above showed that plutonium was retained in airborne plutonium in various chemical agreement “was so very satisfactory that the lungs and pulmonary lymph nodes forms. Therefore, his tragic death be- it is undoubtedly fortuitous.” In addi- much, much longer than contemporary came an opportunity to determine cer- tion, it was found that about 50 per cent models had predicted. Because this was tain factors crucial to the protection of of the plutonium was in the liver, 36 per unexpected, it was decided to collect tis- workers. By analyzing the tissues of his cent in the skeleton, 10 per cent in the sues from other exposed individuals to body, researchers could determine Kel- lungs, and 3 per cent in the respiratory confirm this phenomenon. They also ley’s total plutonium body burden and lymph nodes. Plutonium Injection Ex- stated that tissues from non-occupation- compare it with the result obtained from periments in humans had shown a ally exposed individuals would be col- periodic urine assays during his life. somewhat different distribution: 65 per lected as controls. Thus, the Los Alam- Furthermore, they could determine the cent in the skeleton and 22 per cent in os tissue analysis program was begun. ■ distribution of the plutonium in Kelley’s the liver, for example, most likely the body. Because certain tissues are more result of differences in the chemical and sensitive to radioactivity than others, the physical nature of the plutonium (the Further Readings distribution of the plutonium was im- experiments used a soluble salt of pluto- portant in determining the effective nium whereas Kelley inhaled plutonium T. L. Shipman, C. C. Lushbaugh, D. F. Petersen, dose. That result could be applied dust particles). W. H. Langham, P. S. Harris, and J. N. P. Lawrence. 1961. Acute radiation death resulting broadly to other individuals who were from an accidental nuclear critical excursion. exposed to plutonium largely by inhala- Another interesting factor in Kelley’s Journal of Occupational Medicine: Special Sup- tion over a prolonged period. analysis was that they were able to de- plement. (March 1961): 145-192.

Number 23 1995 Los Alamos Science 251 A True Measure of Exposure

The Karen Silkwood Story what we know at Los Alamos

aren Silkwood died on November 13, 1974 in a fatal one-car crash. Since then, her story has acheived worldwide fame as the subject of many Kbooks, magazine and newspaper articles, and even a major motion picture. Silkwood was a chemical technician at the Kerr-McGee’s plutonium fuels production plant in Crescent, Oklahoma, and a member of the Oil, Chemical, and Atom- ic Workers’ Union. She was also an activist who was critical of plant safety. During the week prior to her death, Silkwood was reportedly gathering evidence for the Union to support her claim that Kerr-McGee was negligent in maintaining plant safety, and at the same time, was involved in a number of unexplained ex- After her death, posures to plutonium. The circumstances of her death have been the subject of organs from Silkwood’s great speculation. body were analysed as After her death, organs from Silkwood’s body were analysed as part of the Los part of the Los Alamos Alamos Tissue Analysis Program at the request of the Atomic Energy Commis- sion (AEC) and the Oklahoma City Medical Examiner. Silkwood’s case was im- Tissue Analysis Program. portant to the program because it was one of very few cases involving recent ex- Silkwood’s case was posure to plutonium. It also served to confirm the contemporary techniques for important to the program the measurement of plutonium body burdens and lung burdens. The following account is a summary of Silkwood’s exposure to plutonium at the Kerr-McGee plant because it was one of and the subsequent analysis of her tissues at Los Alamos. very few cases involving In the evening of November 5, plutonium-239 was found on Karen Silkwood’s recent exposure to pluto- hands. Silkwood had been working in a glovebox in the metallography laboratory nium. It also served to where she was grinding and polishing plutonium pellets that would be used in fuel confirm the contemporary rods. At 6:30 P.M., she decided to monitor herself for alpha activity with the detector that was mounted on the glove box. The right side of her body read 20,000 techniques for the mea- disintegrations per minute, or about 9 nanocuries,1 mostly on the right sleeve and surement of plutonium shoulder of her coveralls. She was taken to the plant's Health Physics Office where she was given a test called a “nasal swipe.” This test measures a person’s body burdens and lung exposure to airborne plutonium, but might also measure plutonium that got on the burdens. person’s nose from their hands. The swipe showed an activity of 160 disintegrations per minute, a modest positive result.

The two gloves in the glovebox Silkwood had been using were replaced. Strange- ly, the gloves were found to have plutonium on the “outside” surfaces that were in contact with Silkwood’s hands; no leaks were found in the gloves. No plutonium was found on the surfaces in the room where she had been working and filter pa- pers from the two air monitors in the room showed that there was no significant plutonium in the air. By 9:00 P.M., Silkwood's cleanup had been completed, and as a precautionary measure, Silkwood was put on a program in which her total urine and feces were collected for five days for plutonium measurements. She returned to the laboratory and worked until 1:10 A.M., but did no further work in the glove boxes. As she left the plant, she monitored herself and found nothing.

Silkwood arrived at work at 7:30 A.M. on November 6. She examined metallo- graphic prints and performed paperwork for one hour, then monitored herself as she left the laboratory to attend a meeting. Although she had not worked at the glovebox that morning, the detector registered alpha activity on her hands. Health

1 1 nanocurie = 2,220 disintegrations per minute

252 Los Alamos Science Number 23 1995 A True Measure of Exposure what we know at Los Alamos

physics staff members found further activity on her right forearm and the right side of her neck and face, and proceeded to decontaminate her. At her request, a technician checked her locker and automobile with an alpha detector, but no activity was found.

On November 7, Silkwood reported to the Health Physics Office at about 7:50 in the morning with her bioassay kit containing four urine samples and one fecal sample. A nasal swipe was taken and significant levels of alpha activity were de- tected (about 45,000 disintegrations per minute (dpm) in each nostril and 40,000 dpm on and around her nose). This was especially surprising because her left Dr. Voelz reassured nostril had been almost completely blocked since a childhood accident. Other Silkwood that, based parts of her body also showed significant alpha activity (1,000 to 4,000 dpm on her hands, arm, chest, neck, and right ear). A preliminary examination of her upon his experience with bioassay samples showed extremely high levels of activity (30,000 to 40,000 workers that had much counts per minute in the fecal sample). Her locker and automobile were checked again, and essentially no alpha activity was found. larger amounts of plutonium in their bodies, she Following her cleanup, the Kerr-McGee health physicists accompanied her to her should not be concerned apartment, which she shared with another laboratory analyst, Sherri Ellis. The apartment was surveyed. Significant levels of activity were found in the bath- about developing cancer room and kitchen, and lower levels of activity were found in other rooms. In the or dying from radiation bathroom, 100,000 dpm were found on the toilet seat, 40,000 dpm on the floor mat, and 20,000 dpm on the floor. In the kitchen, they found 400,000 dpm on a poisoning. Silkwood package of bologna and cheese in the refrigerator, 20,000 dpm on the cabinet wondered whether the top, 20,000 dpm on the floor, 25,000 dpm on the stove sides, and 6,000 dpm on plutonium would affect a package of chicken. In the bedroom, between 500 and 1000 dpm were detect- ed on the pillow cases and between 500 and 2,000 dpm on the bed sheets. How- her ability to have ever, the AEC estimated that the total amount of plutonium in Silkwood’s apart- children or cause her ment was no more than 300 micrograms. No plutonium was found outside the apartment. Ellis was found to have two areas of low level activity on her, so children to be deformed. Silkwood and Ellis returned to the plant where Ellis was cleaned up. Dr. Voelz reassured her that she could have When asked how the alpha activity got into her apartment, Silkwood said that when she produced a urine sample that morning, she had spilled some of the normal children. urine. She wiped off the container and the bathroom floor with tissue and dis- posed of the tissue in the commode. Furthermore, she had taken a package of bologna from the refrigerator, intending to make a sandwich for her lunch, but then carried the bologna into the bathroom and laid it on the closed toilet seat. She remembered that she had part of her lunch from November 5 in the refrigerator at work and decided not to make the sandwich, so she returned the bologna to the refrigerator. Between October 22 and November 6, high levels of activity had been found in four of the urine samples that Silkwood had collected at home (33,000 to 1,600,000 dpm), whereas those that were collected at the Kerr-McGee plant or Los Alamos contained very small amounts of plutonium if any at all.

The amount of plutonium at Silkwood’s apartment raised concern. Therefore, Kerr-McGee arranged for Silkwood, Ellis, and Silkwood’s boyfriend, Drew Stephens, who had spent time at their apartment, to go to Los Alamos for testing. On Monday, November 11, the trio met with Dr. George Voelz, the leader of the Laboratory Health Division. He explained that all of their urine and feces would

Number 23 1995 Los Alamos Science 253 A True Measure of Exposure

be collected and that several whole body and lung counts would be taken. They would also be monitored for external activity.

The next day, Dr. Voelz informed Ellis and Stephens that their tests showed a small but insigniﬁcant amount of plutonium in their bodies. Silkwood, on the other hand, had 0.34 nanocuries of americium-241 (a gamma-emitting daughter of plutonium-241) in her lungs. Based on the amount of americium, Dr. Voelz estimated that Silkwood had about 6 or 7 nanocuries of plutonium-239 in her lungs, or less than half the maximum permissible lung burden (16 nanocuries) for workers. Dr. Voelz reassured Silkwood that, based upon his experience with workers that had much larger amounts of plutonium in their bodies, she should not be concerned about developing cancer or dying from radiation poisoning. Silkwood wondered whether the plutonium would affect her ability to have children or At the request cause her children to be deformed. Dr. Voelz reassured her that she could have normal children. of the AEC and the Oklahoma State Silkwood, Ellis, and Stephens returned to the Oklahoma City on November 12. Silkwood and Ellis reported for work the next day, but they were restricted from Medical Examiner, further radiation work. After work that night, Silkwood went to a union meeting Dr. A. Jay Chapman, in Crescent, Oklahoma. At the end of the meeting, at about 7 P.M., she left alone who was concerned about in her car. At 8:05, the Oklahoma State Highway Patrol was notiﬁed of a single car accident 7 miles south of Cresent. The driver, Karen Silkwood, was dead at performing an autopsy the scene from multiple injuries. An Oklahoma State Trooper who investigated on someone reportedly the accident reported that Silkwood's death was the result of a classic, one-car, sleeping-driver accident. Later, blood tests performed as part of the autopsy contaminated with showed that Silkwood had 0.35 milligram of methaqualone (Quaalude) per 100 plutonium, a team from milliliters of blood at the time of her death. That amount is almost twice the rec- Los Alamos was sent ommended dosage for inducing drowsiness. About 50 milligrams of undissolved to make radiation methaqualone remained in her stomach. measurements and assist At the request of the AEC and the Oklahoma State Medical Examiner, Dr. A. Jay in the autopsy. Chapman, who was concerned about performing an autopsy on someone reportedly contaminated with plutonium, a team from Los Alamos was sent to make radiation measurements and assist in the autopsy. Dr. Voelz, Dr. Michael Stewart, Alan Valentine, and James Lawrence comprised the team. Because Silkwood’s death was an accident, the coroner did not legally need consent from the next of kin to perform the autopsy. However, Silkwood’s father was contacted, and he gave permission for the autopsy over the telephone. The autopsy was performed November 14, 1974, at the University Hospital in Oklahoma City, Oklahoma.

Appropriate specimens were collected, preserved, and retained by Dr. Chapman for his pathological and toxicological examination. At the request of the coroner and the AEC, certain organs and bone specimens were removed, packaged, frozen, and brought back to Los Alamos for analysis of their plutonium content. Because Silkwood had been exposed to plutonium and had undergone in vivo plutonium measurements, her tissue was also used in the Los Alamos Tissue Analy- sis Program to determine her actual plutonium body burden, the distribution of the plutonium between different organs of her body, and the distribution within her lung. On November 15, small samples of the liver, lung, stomach, gastrointestinal tract, and bone were selected and analysed. The data, shown in Table 1, indicated clearly that there were 3.2 nanocuries in the liver, 4.5 nanocuries in the lungs, and a little more than 7.7 nanocuries in her whole body. These measurements agreed well with the in vivo measurements made before Silkwood’s death (6 or 7 nanocuries in the lung and a little more than 7 nanocuries in the whole body).

254 Los Alamos Science Number 23 1995 A True Measure of Exposure

There was no signiﬁcant deposition of plutonium in any other tissues, including the skeleton. The highest concentrations measured were in the contents of the gastrointestinal tract (0.05 nanocurie/gram in the duodenum and 0.02 nanocurie/gram in a small fecal sample taken from the large intestine). This demonstrated that she had ingested plutonium prior to her death.

With the exception of the left lung, the remaining unanalyzed tissues were repack- aged and kept frozen until it was determined whether or not additional analyses were required. The left lung was thawed, inﬂated with dry nitrogen until it was approximately the size that it would have been in the chest, and re-frozen in that conﬁguration. It was packed in an insulated shipping container in dry ice and sent to the lung counting facility at the Los Alamos Health Research Laboratory. The data were then compared with the in vivo measurements made prior to her death. As expected, without the ribs and associated muscle attenuating the x rays Table 1. Amounts of Plutonium-239 in the Organs of Silkwood from the americium-241, the results for the left lung measured postmortem were about 50 per cent higher, but not incon- Organ Plutonium-239 Concentrations sistent with the in vivo result. (nanocuries) (picocuries/gram) lung (whole) 4.5 4.6 Some of the most interesting observa- parenchyma 4.5 4.6 tions made during Silkwood’s tissue pleura 0.01 0.004 analysis were: 1) the distribution of plu- liver 3.2 2.4 tonium-239 within her lung and 2) the concentration of plutonium in the lung lymph nodes (TBLN) 0.02 0.80 relative to that in the tracheobronchial bone ~ 0 ~ 0 lymph nodes (TBLN). After the frozen left lung was returned to the Tissue Analysis Laboratory, the superior lobe was divided horizontally into sections. Those sections were further divided into two parts: the outer layer of the lung (pleura and sub-pleural tissue) and the inner soft tissue of the lung (parenchyma). The plutonium concentrations in the inner and outer parts of Silkwood’s lung were about equal, in stark contrast with another case examined under the Tissue Analy- sis Program in which the concentration in the outer part of the lung was 22.5 times higher than that in the inner part. That difference was an indication that Silkwood had probably been exposed within 30 days prior to her death, whereas the other case had been exposed years prior to death. Furthermore, the concentration of plutonium in Silkwood’s lung was about 6 times greater than that in the lymph nodes, whereas in typical cases that ratio would be about 0.1. Both of those results indicated that Silkwood had received very recent exposure and sup- ported the view that the plutonium tends to migrate from the inner part to the outer part of the lung and to the lymph nodes over time.

The saga of Karen Silkwood continued for years after her death. Her estate filed a civil suit against Kerr-McGee for alleged inadequate health and safety program that led to Silkwood’s exposure. The first trial ended in 1979, with the jury awarding the estate of Silkwood $10.5 million for personal injury and punitive damages. This was reversed later by the Federal Court of Appeals, Denver, Col- orado, which awarded $5000 for the personal property she lost during the cleanup of her apartment. In 1986, twelve years after Silkwood’s death, the suit was head- ed for retrial when it was finally settled out of court for $1.3 million. The Kerr- McGee nuclear fuels plant closed in 1975. ■

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