Bioassay Measurements of Individuals Living Near the U.s. Department of Energy's Hanford Site in Washington State - Fall 1985

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BIOASSAY MEASUREMENTS OF INDIVIDUALS LIVING NEAR THE U.S. DEPARTMENT OF ENERGY'S HANFORD SITE IN WASHINGTON the U.S. Department o f Energy Pacific Northwest Laboratory

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In October of 1985, the Department of Energy (DOE) conducted a workshop a t Edwin Markham School i n Franklin County on Hanford environmental monitorwas the uncertainty and concern on the part of many residents i n northwest Franklin County regarding potential health effects of past and ongoing Hanford One of the primary issues discussed during that workshop To provide those individuals w i t h additional information regarding potential Hanford impacts on their health, the Manager o f the DOE ' s Richland Operations Office announced during the workshop t h a t DOE's resources would be available t o residents o f northwest Franklin County for the evaluation of internally deposited radioactive materials. Following t h a t announcement, the Pacific Northwest Laboratory, operated by Battelle Memorial Institute under contract toDOE, provided whole body counts and analyses of urine samples on request t o the residents o f northwest Franklin data . T h i s report describes those measurements and summarizes the resulting

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In the fall of 1985, at the request of the U.S. Department o f Energy's Richland Operations Office (DOE-RL), the Pacific Northwest Laboratory provided special bioassay measurements to individuals living near the Hanford Site in The purpose of the bioassay measurements was to provide individuals, living within a specific area near the Hanford Site, information on the current levels of radionuclides in their bodies. The measurements included whole body counter ( i n vivo) examinations and urine sample analyses for detecting the presence of major radionuclides related to current and historical operations at Hanford. Notifications o f the special measurements were sent by letter to 515 residences in north Franklin County. 515 residences requested and received whole body counts. Of these, 32 also provided urine samples. Efghty-nine individuals from 52 of the The measurements gave no evidence of unusual levels o f radioact vity in o f radioactivity i n an individual following an exposure is dependent on the quality of the measurement and the nature of the exposure. This report includes a discussion of the capability, under various circumstances, of the measurements that were provided, The ability o f bioassay measurements to detect the presence

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DESCRIPTION OF PROGRAM . 2 WHOLE BODY COUNTING . 4 RESULTS OF MEASUREMENTS . 6 WHOLE BODY COUNTS . 6 EVALUATION OF THE CAPABILITY OF THE BIOASSAY MEASUREMENTS . 9

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Map o f Area Within Which Notification Letters Were Sent Battell e Mobi 1 e Who1 e Body Counter Summary o f Whole Body Count Spectra Comparison of Spectra Obtained From Individuals with Interfering Levels of Natural Radioactivity on Clothing Sensitivity of Whole Body Count . . Sensitivity of Urinalysis . Sensitivity o f Bioassay Measurements . Calibration Factors for BOMAB Phantom . Summary of Whole Body Count Spectrum Analyses Strontiurn-90 Results Uncorrected f o r Reagent Bias

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This report describes special pub1 ic bioassay measurements performed by the Pacific Northwest Laboratory, operated by Battelle Memorial Institute, in the fall of 1985 at the request o f the Manager of the Richland Operations Office (RL) of the Department of Energy (DOE). The purpose of the measurements was to provide information to individuals living within a specific area near the Hanford Site regarding the current levels of radionuclides in their bodies. Whole body counts were performed on 89 individuals. Thirty-two of these peopl e a1 so elected to provide samples for urinalysis. were designed to detect major radionuclides related to the current and historical operations at Hanford. BIOASSAY MONITORING FOR INTERNAL RADIOACTIVITY Bioassay monitoring is a common procedure for detecting the presence of Public familiarity with the use of bioassayforeign substances in the body. techniques has been recently heightened by news articles about the testing o f professional athletes for certain drugs. Bioassay measurements are equal ly useful for determining the presence of various radioactive materfals in the determine worker exposure to internal radioactivity. Such measurements are commonly performed in the nuclear industry to There are two general types of bioassay measurements: direct and body counter, to measure the radiations that are emitted by radioactive materials in the body. radioactivity in excreta from the body. presence of radioactive material in the body by inference from the presence of material in the excreta. with both the direct and the indirect bioassay methods. Direct methods use a sensitive radiation detector, called a whole Indirect measurements are performed by measuring the The indirect method indicates the There are advantages and limitations associated Di rect bioassay measurements are re1 ati vely easy to perform, are capabl e of detecting several radioactive materials from a single measurement, and provide a direct measure of the amount of the radioactive materials present

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in the body. that can escape from the body and enter the detector of the whole body counter and 2) the radiation detector must be sensitive to the incomfng radiations. The capability for detecting a particular type of radioactive material thus depends on the properties of the material and the properties o f the radiation ruthenium-106. However, the Hanford Mobile Whole Body Counter cannot be used for the detection of some radionuclides, including plutonium, radiostrontium, To detect a specific radioactive material, two criteria must be 1) the radioactive material present i n the body must emit radiations The Hanford Mobile Whole Body Counter can detect gamma-ray-emi tting The indirect bioassay method is potentially effective for measuring all Theradioactive materials including plutonium, radiostrontium, and tritium. criterion for indirect bioassay is only that the material in the body is excreted via the pathway measured. However, the disadvantages of the indirect method are that a separate test must be performed for each type of material and the amount of the material in the body must be inferred based on the quantity measured in the excreta. These inferences are made using mathematical models that describe the excretion of materials following their intake into DESCRIPTION OF PROGRAM Bioassay measurements were performed on individuals 1 iving near the in November and December of 1985, included both whole body counting and The measurements, performed by the Pacific Northwest Laboratory Recipients of the measurements were individuals living in Frank1 in County near the eastern boundary of the Hanford Site as defined by an arc of radius ten miles from the Washington Public Power Supply System's WNP-2 plant (Figure 1). This area was designated by the Department of Energy.

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Invitation letters were sent'by DOE-RL to 515 residences in the desigbody counts. Of these, 3 2 also requested the urine analyses. of the individuals requesting the measurements are summarized in Appendix A. Eighty-nine individuals from 5 2 of the residences requested whole WHOLE BODY COUNTING The whole body counting was performed using the Battelle Mobile Whole Body Grange Hall located on Taylor Flats Road about 0.1 mile south of Mathews Corner The tests were conducted from November 12-27, 1985, at the Chiawana The Battelle Mobile Whole Body Counter is a truck-mounted in vivo radioassay facility. The facility consists of a shielded 12-inch diameter by 4-inch deep cy1 indrical sodium iodide radiation detector positioned above a sliding pad on which the examinee lies during the test (Figure 2). During the examination, the pad slowly moves underneath the detector so that the entire length of the examinee is scanned. This traverse requires about ten minutes. The detector is sensitive to photons in the energy range o f 150 to 5000 keV. Table 1 shows the sensitivity of the procedure for several radionuclides. TABLE 1. Sensitivity of Whole Body Count Radionuclide Detectable Level (pCi) Appendix B describes the techniques used to calibrate the detector and to evaluate the measurements,

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Indirect bioassay monitoring was performed using urine as the excreta medium. The urine samples were collected in late November and early December 1985 using sampling kits that were dellvered to the participants' residences. Sample analyses were performed by U.S. Testing Company at their Richland, strontium-90, and tritium. Analyses were performed on 500 mL aliquots of urine. Table 2 shows the detection levels for the analyses. Appendix 0 descri bes the radiochemi cal procedures used to process the samples e TABLE 2. Sensitivity of Urinalysis RESULTS OF MEASUREMENTS WHOLE BODY COUNTS ' Whole body counts were performed on 89 persons. One individual's examination was invalid because of interferences from naturally occurring Nine of the 89 persons examined had naturally occurring radioactivity on This radioactivity is associated with radioactive gases their clothing during their initial examination that interfered with the in the atmosphere that are produced by naturally occurring uranium and thorium in the earth. radioactive decay products. radiation inhibits the detection of low levels of radioactivity in the body. The radioactive gases are radon and thoron, and they produce If present at sufficient levels, this background

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Except for one case, the interferences were reduced to within acceptable levels by having the individual change to cotton coveralls that were provided for this purpose. clothing made o f synthetic materials, static charge that attracts dust particles in the atmosphere. of the naturally occurring radioactive gases are attached to the dust particles. In the one uncorrected case, the individual did not wish a reexamination. A review of that individual's measurement result showed the characteristic interferences of the naturally occurring radioactivity. The interferences precluded an effective determination o f the presence or absence of Hanford-related radionucl ides. In all of these cases, the individual had arrived wearing Synthetic materials can generate a Individually, none of the 88 Val id examinations showed detectable levels o f internal radioactivity except for naturally occurring potassium-40. Potassium-40 levels in the subjects ranged from 0.048 PCi in a 4-year-old child to 0.16 vCi in an adult male. be expected In the U.S. population (UNSCEAR 1972). These levels are in the range that would Analysis of grouped data can sometimes enable detection of small amounts of radioactivity present in a study group at levels below that which can be detected in a single individual. Therefore, spectra for the 88 measurements were summed and visually inspected for indications of apparent radioactivity. No indications of such activity from radionuclides o f potential Hanford origin prevalence of lo; levels of naturally occurring radionuclides in the study group. The summed spectrum is shown in Figure C.l of Appendix C. The sensitivity o f the procedure could be improved by having each subject shower thoroughly and change to clean cotton clothing just before the examination. However, the sensitivity of the analysis was limited by the Participants in the urine testing program were a subset of the group that received whole body counts, provided a urine sample. No measurement result for an individual exceeded its corresponding analytical detection 1imit. Thirty-two of the 35 persons requesting the test

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The data for individual sample analyses are listed in Appendlx E. These data are the products o f the analytical process in which the activity indicated by the measurement is reported along with the uncertainty associated with the The analytical results for the strontium-90 and plutonium analyses were compared to the results obtained from performing the analytical procedure without any urine ({.e., a reagent blank). significance level, the urine data were tested to determine if there was a statistically significant difference in the analytical results obtained from the samples compared to the reagent blanks, This test showed that, for all three radionuclides, the urine analyses and the reagent blank analyses were not statistically different. Appendix F provides additional detail on the statistical tests that were performed. Using a one-tailed test at the 95% The tritium data could not be tested the same way because the analytical procedure was based on a comparison to a reagent blank. were therefore tested against the hypothesis that the samples actually contained a n d standard error o f the mean for the grouped tritium data were 240t110 picocuries per liter. Since tritium is a naturally occurring radionuclide and was introduced into the environment during the atmospheric nuclear testing of the 1960s, its presence i n environmental and biological media is expected. The amount of tritium excreted daily from the body is nearly the same as the amount taken daily into the body. i s thus about the same as its concentration in the water taken into the body. The bias observed for tritium in the grouped samples can thus be compared to levels of tritium in the environment to determine if the levels are within the range that would be predicted by environmental samples. Based on the results of environmental samples collected in the Hanford environs during 1984 (Price et al. 1985), the observed concentration bias for tritium in urine i s similar to the concentrations observed in various environmental media i n The tritium data The test was performed using a one-tailed t-test at the 95% This test indicated a slightly positive bias. The mean The concentration of tritium i n urine

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the vicinity of as well as away from the Hanford Site. observed range for tritium in drinking water across the United States as measured by the Environmental Protection Agency (1985) ranges from 100-400 picocuries per liter. are not considered unusual. Thus, tritium levels from the analysis of grouped data 'EVALUATION OF THE CAPABILITY OF THE BIOASSAY MEASUREMENTS Bioassay measurements readily provide a qualitative indication of the presence of radioactive materials in the body. However, in order to evaluate the significance o f the presence of the material i n terms of potential health impact, additional information is necessary. Specifically, the consequence of radioactive material in the body is a function of the amount of energy deposited i n body tissues by the radiations emitted from the material. measurements do not provide a direct measure of the total amount o f energy deposited i n tissues following internal exposure to radioactive material. However, mathematical models can be used to predict the relationship between a bioassay measurement and a corresponding total energy deposition for given Estimates of the sensitivity of the bioassay measurements were made by using the mathematical models to predict, under various circumstances, the amount o f exposure that could have been detected. The models and parameters for radionucl idelretention and excretion were those recommended by the International Commission on Radiological Protection (ICRP) as described in their ingestion were considered, and the time from the initial intake to the bioassay measurement was varied over 40 years. Both chronic and acute intakes via inhalation and The effective dose equivalent that would be received by an individual over a 50-year period following an intake (or the onset of intake in the case o f chronic exposures) detectable by a bioassay measurement, was calculated. To simplify their presentation, these doses are expressed i n terms o f multiples of the 5 rem whole body dose that i s received from the natural radiation background during a 50-year period. The results of the calculations are summarized

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TABLE 3. Sensitivity of Bioassay Measurements Years After Initial Intake Chronic Inhalation Tritium …