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Power Functions Relating Excretion to Body Burden

Description: Formulae necessary to relate the quantity of radionuclides excreted to that assimilated in exposures that are acute and those that are multiple or continuous are derived from power function relationships. Particular attention is given to providing equations having variables for which the bioassayer can easily derive numerical values. This paper presents this data.
Date: February 21, 2003
Creator: Sanders, S.M. Jr.
Partner: UNT Libraries Government Documents Department

Historical Exposures to Chemicals at the Rocky Flats Nuclear Weapons Plant: A Pilot Retrospective Exposure Assessment

Description: In a mortality study of white males who had worked at the Rocky Flats Nuclear Weapons Plant between 1952 and 1979, an increased number of deaths from benign and unspecified intracranial neoplasms was found. A case-control study nested within this cohort investigated the hypothesis that an association existed between brain tumor death and exposure to either internally deposited plutonium or external ionizing radiation. There was no statistically significant association found between estimated radiation exposure from internally deposited plutonium and the development of brain tumors. Exposure by job or work area showed no significant difference between the cohort and the control groups. An update of the study found elevated risk estimates for (1) all lymphopoietic neoplasms, and (2) all causes of death in employees with body burdens greater than or equal to two nanocuries of plutonium. There was an excess of brain tumors for the entire cohort. Similar cohort studies conducted on worker populations from other plutonium handling facilities have not yet shown any elevated risks for brain tumors. Historically, the Rocky Flats Nuclear Weapons Plant used large quantities of chemicals in their production operations. The use of solvents, particularly carbon tetrachloride, was unique to Rocky Flats. No investigation of the possible confounding effects of chemical exposures was done in the initial studies. The objectives of the present study are to (1) investigate the history of chemical use at the Rocky Flats facility; (2) locate and analyze chemical monitoring information in order to assess employee exposure to the chemicals that were used in the highest volume; and (3) determine the feasibility of establishing a chemical exposure assessment model that could be used in future epidemiology studies.
Date: February 1, 1999
Creator: Robertson, Janeen Denise
Partner: UNT Libraries Government Documents Department

Toxicological Benchmarks for Wildlife

Description: Ecological risks of environmental contaminants are evaluated by using a two-tiered process. In the first tier, a screening assessment is performed where concentrations of contaminants in the environment are compared to no observed adverse effects level (NOAEL)-based toxicological benchmarks. These benchmarks represent concentrations of chemicals (i.e., concentrations presumed to be nonhazardous to the biota) in environmental media (water, sediment, soil, food, etc.). While exceedance of these benchmarks does not indicate any particular level or type of risk, concentrations below the benchmarks should not result in significant effects. In practice, when contaminant concentrations in food or water resources are less than these toxicological benchmarks, the contaminants may be excluded from further consideration. However, if the concentration of a contaminant exceeds a benchmark, that contaminant should be retained as a contaminant of potential concern (COPC) and investigated further. The second tier in ecological risk assessment, the baseline ecological risk assessment, may use toxicological benchmarks as part of a weight-of-evidence approach (Suter 1993). Under this approach, based toxicological benchmarks are one of several lines of evidence used to support or refute the presence of ecological effects. Other sources of evidence include media toxicity tests, surveys of biota (abundance and diversity), measures of contaminant body burdens, and biomarkers. This report presents NOAEL- and lowest observed adverse effects level (LOAEL)-based toxicological benchmarks for assessment of effects of 85 chemicals on 9 representative mammalian wildlife species (short-tailed shrew, little brown bat, meadow vole, white-footed mouse, cottontail rabbit, mink, red fox, and whitetail deer) or 11 avian wildlife species (American robin, rough-winged swallow, American woodcock, wild turkey, belted kingfisher, great blue heron, barred owl, barn owl, Cooper's hawk, and red-tailed hawk, osprey) (scientific names for both the mammalian and avian species are presented in Appendix B). [In this document, NOAEL refers to both dose (mg contaminant per ...
Date: January 1, 1993
Creator: Sample, B.E. Opresko, D.M. Suter, G.W.
Partner: UNT Libraries Government Documents Department

A survey of radioactive fallout data in Alaska

Description: Considerable attention has been directed by the scientific community to assessing the levels and fate of radionuclides in Arctic ecosystems. The following text and tables present available data and discussion of radionuclide fallout in Alaska. A literature search of 23 on-line databases (Table 1) using Alaska, Strontium (Sr), Cesium (Cs), Plutonium (Pu) and Radionuclide as constraint terms responded with 177 possible citations. After eliminating duplicate citations, 31 articles were available: 17 were relevant to the subject matter; the remainder addressed geologic issues. All of the cited literature addressed {sup 137}Cs, {sup 90}Sr and {sup 239,240}Pu as a result of radionuclide fallout from nuclear testing or accidental release.
Date: October 23, 1995
Creator: DePhillips, M.P.
Partner: UNT Libraries Government Documents Department

FRAMES User Defined Body Burden Concentration File Module Documentation

Description: The Framework for Risk Analysis in Multimedia Environmental Systems (FRAMES) Body Burden Concentration File (BBF) contains time-varying, instantaneous, constituent concentrations for body burden by contaminant. This report contains the requirements for this file and will be used by software engineers and testers to ensure that the file inputs properly.
Date: June 1, 2001
Creator: Pelton, Mitchell A.; Rutz, Frederick C.; Eslinger, Melany A. & Gelston, Gariann M.
Partner: UNT Libraries Government Documents Department

Individual Dose Calculations with Use of the Revised Techa River Dosimetry System TRDS-2009D

Description: An updated deterministic version of the Techa River Dosimetry System (TRDS-2009D) has been developed to estimate individual doses from external exposure and intake of radionuclides for residents living on the Techa River contaminated as a result of radioactive releases from the Mayak plutonium facility in 1949–1956. The TRDS-2009D is designed as a flexible system that uses, depending on the input data for an individual, various elements of system databases to provide the dosimetric variables requested by the user. Several phases are included in the computation schedule. The first phase includes calculations with use of a common protocol for all cohort members based on village-average-intake functions and external dose rates; individual data on age, gender and history of residence are included in the first phase. This phase results in dose estimates similar to those obtained with system TRDS-2000 used previously to derive risks of health effects in the Techa River Cohort. The second phase includes refinement of individual internal doses for those persons who have had body-burden measurements or exposure parameters specific to the household where he/she lived on the Techa River. The third phase includes summation of individual doses from environmental exposure and from radiological examinations. The results of TRDS-2009D dose calculations have demonstrated for the ETRC members on average a moderate increase in RBM dose estimates (34%) and a minor increase (5%) in estimates of stomach dose. The calculations for the members of the ETROC indicated similar small changes for stomach, but significant increase in RBM doses (400%). Individual-dose assessments performed with use of TRDS-2009D have been provided to epidemiologists for exploratory risk analysis in the ETRC and ETROC. These data provide an opportunity to evaluate the possible impact on radiogenic risk of such factors as confounding exposure (environmental and medical), changes in the Techa River source-term data and ...
Date: October 23, 2009
Creator: Degteva, M. O.; Shagina, N. B.; Tolstykh, E. I.; Vorobiova, M. I.; Anspaugh, L. R. & Napier, Bruce A.
Partner: UNT Libraries Government Documents Department

Assessment of Dose to the Nursing Infant from Radionuclides in Breast Milk

Description: A computer software package was developed to predict tissue doses to an infant due to intake of radionuclides in breast milk based on bioassay measurements and exposure data for the mother. The package is intended mainly to aid in decisions regarding the safety of breast feeding by a mother who has been acutely exposed to a radionuclide during lactation or pregnancy, but it may be applied to previous intakes during the mother s adult life. The package includes biokinetic and dosimetric information needed to address intake of Co-60, Sr-90, Cs-134, Cs-137, Ir-192, Pu-238, Pu-239, Am-241, or Cf-252 by the mother. It has been designed so that the library of biokinetic and dosimetric files can be expanded to address a more comprehensive set of radionuclides without modifying the basic computational module. The methods and models build on the approach used in Publication 95 of the International Commission on Radiological Protection (ICRP 2004), Doses to Infants from Ingestion of Radionuclides in Mothers Milk . The software package allows input of case-specific information or judgments such as chemical form or particle size of an inhaled aerosol. The package is expected to be more suitable than ICRP Publication 95 for dose assessment for real events or realistic planning scenarios in which measurements of the mother s excretion or body burden are available.
Date: March 1, 2010
Creator: Leggett, Richard Wayne & Eckerman, Keith F
Partner: UNT Libraries Government Documents Department

Radium in humans: A review of U.S. studies

Description: This document was originally conceived as a description of the radium studies that took place at Argonne National Laboratory. It soon became evident, however, that to document the widespread use of radium, a brief review of the application of radium in medicine and in the US dial painting industry is required. Further, because the Argonne studies were not the only such efforts, brief overviews of the other radium programs are included. Even so, much material has been omitted. The extensive references included will allow the interested reader to find additional information. The effects of internally deposited radium in humans have been studied in this country for more than 75 years. Some 2,400 subjects have had their body contents of radium measured, and a majority of them have been followed for most of their adult lives, to understand and quantify the effects of radium. Many more individuals acquired radium internally but were never measured. Some of this group have been located and followed until death; in these cases the cause of death is known without a body content measurement. As a consequence of the efforts made to locate, measure, and follow exposed individuals, a great deal of information about the effects of radium is available. Nevertheless, great gaps remain in the knowledge of radium toxicity. The Argonne study is the largest every undertaken of the effects on humans of an internally deposited radioelement, in which the insult has been quantitated by actual measurements of the retained radioisotope. The study has now been terminated, even though more than 1,000 subjects with measured radium burdens are still alive. This document is written as a brief summary of current knowledge accumulated in this incomplete study.
Date: February 10, 1995
Creator: Rowland, R.E.
Partner: UNT Libraries Government Documents Department

Uncertainties in Organ Burdens Estimated from PAS

Description: To calculate committed effective dose equivalent, one needs to know the quantity of the radionuclide in all significantly irradiated organs (the organ burden) as a function of time following the intake. There are two major sources of uncertainty in an organ burden estimated from personal air sampling (PAS) data: (1) The uncertainty in going from the exposure measured with the PAS to the quantity of aerosol inhaled by the individual, and (2) The uncertainty in going from the intake to the organ burdens at any given time, taking into consideration the biological variability of the biokinetic models from person to person (interperson variability) and in one person over time (intra-person variability). We have been using biokinetic modeling methods developed by researchers at the University of Florida to explore the impact of inter-person variability on the uncertainty of organ burdens estimated from PAS data. These initial studies suggest that the uncertainties are so large that PAS might be considered to be a qualitative (rather than quantitative) technique. These results indicate that more studies should be performed to properly classify the reliability and usefulness of using PAS monitoring data to estimate organ burdens, organ dose, and ultimately CEDE.
Date: February 2, 2004
Creator: La Bone, T.R.
Partner: UNT Libraries Government Documents Department

The present status of polonium tolerance estimation. Biology seminar, February 1, 1949

Description: Despite the fact the adequate data from long-term, chronic experiments on the effects of Po{sup 210} are not available, some sort of a working figure for the maximum permissible body content of polonium is desirable. As described herein, calculations involved in determining the permissible body content of polonium generally fall into three classes. 1. Comparison of X-ray and polonium toxicity and application of an acceptable X-ray tolerance figure. 2. Assumption of a most sensitive organ and computation of the critical concentration of radioactive material present in this organ under conditions such that the organ received an assumed maximum permissible exposure over an indefinitely long period of time. 3. Comparison of radium and polonium toxicity with application of an acceptable maximal content of radium.
Date: February 16, 1949
Creator: Hackett, P. L.
Partner: UNT Libraries Government Documents Department

Evaluating the Effects of the Kingston Fly Ash Release on Fish Reproduction: Spring 2009 - 2010 Studies

Description: On December 22, 2008, a dike containing fly ash and bottom ash at the Tennessee Valley Authority's (TVA) Kingston Fossil Plant in East Tennessee failed and released a large quantity of ash into the adjacent Emory River. Ash deposits from the spill extended 4 miles upstream of the facility to Emory River mile 6 and downstream to Tennessee River mile 564 ({approx}8.5 miles downstream of the confluence of the Emory River with the Clinch River, and {approx}4 miles downstream of the confluence of the Clinch River with the Tennessee River). A byproduct of coal combustion, fly ash contains a variety of metals and other elements which, at sufficient concentrations and in specific forms, can be harmful to biological systems. The ecological effects of fly ash contamination on exposed fish populations depend on the magnitude and duration of exposure, with the most significant risk considered to come from elevated levels of certain metals in the ash, particularly selenium, on fish reproduction and fish early life stages (Lemly 1993; Besser and others 1996). The ovaries of adult female fish in a lake contaminated by coal ash were reported to have an increased frequency of atretic oocytes (dead or damaged immature eggs) and reductions in the overall numbers of developing oocytes (Sorensen 1988) associated with elevated body burdens of selenium. Larval fish exposed to selenium through maternal transfer of contaminants to developing eggs in either contaminated bodies of water (Lemly 1999) or in experimental laboratory exposures (Woock and others 1987, Jezierska and others 2009) have significantly increased incidences of developmental abnormalities. Contact of fertilized eggs and developing embryos to ash in water and sediments may also pose an additional risk to the early life stages of exposed fish populations through direct uptake of metals and other ash constituents (Jezierska and others 2009). The ...
Date: May 1, 2012
Creator: Greeley Jr, Mark Stephen; Adams, Marshall & McCracken, Kitty
Partner: UNT Libraries Government Documents Department

Individual Radiological Protection Monitoring of Utrok Atoll Residents Based on Whole Body Counting of Cesium-137 (137Cs) and Plutonium Bioassay

Description: This report contains individual radiological protection surveillance data developed during 2006 for adult members of a select group of families living on Utrok Atoll. These Group I volunteers all underwent a whole-body count to determine levels of internally deposited cesium-137 ({sup 137}Cs) and supplied a bioassay sample for analysis of plutonium isotopes. Measurement data were obtained and the results compared with an equivalent set of measurement data for {sup 137}Cs and plutonium isotopes from a second group of adult volunteers (Group II) who were long-term residents of Utrok Atoll. For the purposes of this comparison, Group II volunteers were considered representative of the general population on Utrok Atoll. The general aim of the study was to determine residual systemic burdens of fallout radionuclides in each volunteer group, develop data in response to addressing some specific concerns about the preferential uptake and potential health consequences of residual fallout radionuclides in Group I volunteers, and generally provide some perspective on the significance of radiation doses delivered to volunteers (and the general Utrok Atoll resident population) in terms of radiological protection standards and health risks. Based on dose estimates from measurements of internally deposited {sup 137}Cs and plutonium isotopes, the data and information developed in this report clearly show that neither volunteer group has acquired levels of internally deposited fallout radionuclides specific to nuclear weapons testing in the Marshall Islands that are likely to have any consequence on human health. Moreover, the dose estimates are well below radiological protection standards as prescribed by U.S. regulators and international agencies, and are very small when compared to doses from natural sources of radiation in the Marshall Islands and the threshold where radiation health effects could be either medically diagnosed in an individual or epidemiologically discerned in a group of people. In general, the results from ...
Date: June 8, 2007
Creator: Hamilton, T; Kehl, S; Brown, T; Martinelli, R; Hickman, D; Jue, T et al.
Partner: UNT Libraries Government Documents Department

INTERIM RESULTS FROM A STUDY OF THE IMPACTS OF TIN(II) BASED MERCURY TREATMENT IN A SMALL STREAM ECOSYSTEM: TIMS BRANCH, SAVANNAH RIVER SITE

Description: Mercury (Hg) has been identified as a 'persistent, bioaccumulative and toxic' pollutant with widespread impacts throughout North America and the world (EPA. 1997a, 1997b, 1998a, 1998b, 2000). Although most of the mercury in the environment is inorganic Hg, a small proportion of total Hg is transformed through the actions of aquatic microbes into methylmercury (MeHg). In contrast to virtually all other metals, MeHg biomagnifies or becomes increasingly concentrated as it is transferred through aquatic food chains so that the consumption of mercury contaminated fish is the primary route of this toxin to humans. For this reason, the ambient water quality criterion (AWQC) for mercury is based on a fish tissue endpoint rather than an aqueous Hg concentration, as the tissue concentration (e.g., < 0.3 {mu}g/g fillet) is considered to be a more consistent indicator of exposure and risk (EPA, 2001). Effective mercury remediation at point-source contaminated sites requires an understanding of the nature and magnitude of mercury inputs, and also knowledge of how these inputs must be controlled in order to achieve the desired reduction of mercury contamination in biota necessary for compliance with AWQC targets. One of the challenges to remediation is that mercury body burdens in fish are more closely linked to aqueous MeHg than to inorganic Hg concentrations (Sveinsdottir and Mason 2005), but MeHg production is not easily predicted or controlled. At point-source contaminated sites, mercury methylation is not only affected by the absolute mercury load, but also by the form of mercury loaded. In addition, once MeHg is formed, the hydrology, trophic structure, and water chemistry of a given system affect how it is transformed and transferred through the food chain to fish. Decreasing inorganic Hg concentrations and loading may often therefore be a more achievable remediation goal, but has led to mixed results in terms ...
Date: March 30, 2012
Creator: Looney, B.; Bryan, L. & Mathews, T.
Partner: UNT Libraries Government Documents Department

Radiation exposures in reprocessing facilities at the Savannah River Plant

Description: Two large reprocessing facilities have been operating at the Savannah River Plant since 1955. The plant, which is near Aiken, South Carolina, is operated for the U.S. Department of Energy by the Du Pont Company. The reprocessing facilities have a work force of approximately 1,800. The major processes in the facilities are chemical separations of irradiated material, plutonium finishing, and waste management. This paper presents the annual radiation exposure for the reprocessing work force, particularly during the period 1965 through 1978. It also presents the collective and average individual annual exposures for various occupations including operators, mechanics, electricians, control laboratory technicians, and health physicists. Periodic and repetitive work activities that result in the highest radiation exposures are also described. The assimilation of radionuclides, particularly plutonium, by the work force is reviewed. Methods that have been developed to minimize the exposure of reprocessing personnel are described. The success of these methods is illustrated by experience - there has been no individual worker exposure of greater than 3.1 rems per year and only one plutonium assimilation greater than the maximum permissible body burden during the 24 years of operation of the facilities.
Date: June 1, 1979
Creator: Hayes, G.; Caldwell, R.D. & Hall, R.M.
Partner: UNT Libraries Government Documents Department

A Validated High-Let Radiation Specific Biomarker in the Mayak Worker Cohort

Description: Our goal (see Project Objectives) is to deliver a dosimetry system which will enable both a Pu body burden of 0.3 kBq, and a 30 cGy {gamma} ray dose, to be separately estimated with a confidence limit of {+-}30%. In terms of the numbers analyzed and the data we have accrued, we have direct quantitative evidence that we are on track to providing such a comprehensive independent dosimetry system for Mayak workers. We had previously demonstrated that intra-chromosomal aberrations measured in peripheral blood lymphocytes can be used as a sensitive long-lived low-background quantitative biomarker of densely-ionizing radiation dose in individuals exposed many years ago. We propose to calibrate the system such that it can be used to estimate both the densely-ionizing internal plutonium exposure and the sparsely-ionizing external exposure in Mayak workers exposed to different combinations of these over a prolonged period, mostly many years ago. Our objective is to deliver a dosimetry system (set of calibration parameters) which will enable both a comparatively low Pu body burden of 0.3 kBq, and a comparatively low 30 cGy {gamma} ray dose (one of these or both of these) to be estimated with a confidence limit of {+-}30% (higher doses will of course be estimated with smaller confidence intervals and still lower doses with larger confidence intervals). (1) Draw blood, make metaphase slides and measure numbers of intra- and inter-chromosome aberrations (using the mBAND and mFISH techniques) in - (A) 255 healthy former Mayak workers who were exposed various combinations of internal and external exposures. The individuals were chosen from the data base of healthy former workers through computer simulation to optimize estimates of the dosimetry parameters. The individuals have both internal and external dose estimates from the SUBI Doses-99 system. (B) 85 healthy non-exposed controls with ages, gender, and smoking status, ...
Date: December 11, 2006
Creator: David J. Brenner, Ph.D., D.Sc. & Tamara Azizova, M.D.
Partner: UNT Libraries Government Documents Department

Comparison of organochlorine chemical body burdens of female breast cancer cases with cancer free women in Rio Grande do Sul, Brazil--Pilot Study

Description: This pilot study collected preliminary data to examine known and suspected breast cancer risk factors among women living in rural and urban areas in the state of Rio Grande do Sul, Brazil by questionnaire. In addition, the body burden levels of a panel of organochlorines was measured in a small clinic-based prospective sample.
Date: December 1999
Creator: Erdmann, C. A.; Petreas, M. X.; Caleffi, M.; Barbosa, F. S. & Goth-Goldstein, R.
Partner: UNT Libraries Government Documents Department

Present status of polonium tolerance estimations

Description: This report contains a summary of biological information on distribution, excretion, and toxicity of polonium; a comparison of results obtained when maximum permissible exposure rates for man are calculated from available data by different methods; and a critical evaluation of the present status of Po tolerance estimates. A maximum permissible body content of the order of 0.2 {mu}c/70 Kg man is obtained by two methods. Applying an urinary excretion rate of 0.1% of body content/day, effective half-life of 34 days, and certain corrections for the non-exponential nature of Pb excretion, maximum permissible air and water concentrations and urinary excretion rates have been computed. Extrapolation from present data to calculations of tolerance levels in man is still difficult, and there appears to be no substitute for actual long term experiments. On the other hand, permissible exposure levels quoted herein appear to be, to a large extent, consistent with conservative practice.
Date: October 14, 1948
Creator: Hursh, J.B. & Stannard, J.N.
Partner: UNT Libraries Government Documents Department

Application of Snyder's method for estimation of body burden and intake to blood to uranium bioassay data

Description: The problem of estimating internal exposure from the intake of uranium is discussed. Excreta samples are routinely taken from workers at regular intervals during normal operations and/or after an accidental release of radioactive substances to the immediate environment of the worker. Data on the activity excreted per day is analyzed to estimate the intake of uranium into the blood and the body. (ACR)
Date: January 1, 1983
Creator: Bernard, S.R.
Partner: UNT Libraries Government Documents Department

Contributions of occupational epidemiologic studies to radiation protection

Description: Early evidence of health effects of occupational radiation exposure contributed importantly to the establishment of exposure standards, especially for internal emitters. Standards derived in this manner for radium body burdens and for air concentrations of radon and its daughters were especially influential. The body burden limits for plutonium and other bone-seeking radionuclides were based upon the radium standard. The exposure controls instituted as a consequence of those early limits have reduced the exposure of worker populations to the extent that the current, more sophisticated epidemiologic studies will probably not influence the revision of existing standards. The justification for conducting such studies is discussed.
Date: January 1, 1982
Creator: Marks, S.
Partner: UNT Libraries Government Documents Department

Dose-response relationships for female radium dial workers: A new look

Description: The values of initial systemic intake and of skeletal dose for all of the U.S. radium cases have recently been revised. This revision was required following the demonstrations by Rundo and by Keane that humans who were exposed to radium as adults lost radium at a rate that depended on the quantity of radium originally deposited within their bodies. These new values have been used to define new dose-response relationships for both the bone sarcomas and the carcinomas arising in the paranasal sinuses and mastoid air cells induced by internally deposited radium. The population examined was employed in the U.S. dial painting industry prior to 1950 and consisted of 1530 female dial workers for whom radium body burden measurements were available. By the end of 1990, 46 cases of bone sarcomas and 19 cases of head carcinomas had been diagnosed in this cohort. The head carcinoma incidence can be adequately fitted by a simple linear function, as was found in previous analyses. The bone sarcoma cases were previously fitted by a dose-squared-exponential function. With the revised values of systemic intake, the sarcoma results could not be satisfactorily fitted with this expression. When the exponent on D was increased to larger values, excellent fits were obtained.
Date: May 1, 1994
Creator: Rowland, R. E.
Partner: UNT Libraries Government Documents Department

DM-CSF stimulated proliferation of rat alveolar macrophages and the effects of differing particulate burden levels in alveolar macrophages on the proliferative response

Description: Particles are gradually redistributed among the lung`s population of alveolar macrophages (AM) at times well after they were originally deposited in the lung. One mechanism that may underlie this ``particle redistribution phenomenon`` is the in situ replication of particle-containing AM and the allocation of particles from dividing AM to daughter cells. Little is known about how the abilities of AM to proliferate may be affected by the containment of particles; conceivably, AM proliferation may be a particle burden-dependent process. In this study, we assessed the proliferative abilities of AM that contain differing burdens of phagocytized particles. Rats were intratracheally instilled with 2 {times} 10{sup 8} fluorescent, polystyrene microspheres ({approximately}2 {mu}M diam.), and several days thereafter their lungs were lavaged. The lavaged AM were analyzed using a multiparameter flow cytometer, and the AM were sorted according to their relative burdens of microspheres, i.e., low burdens, medium burdens, high burdens, based on their levels of fluorescence intensities. Control cells consisted of AM that were lavaged from the lungs of untreated animals and also passed through the flow cytometer. The sorted AM were then cultured in the presence of 0.3 ng/ml Granulocyte/Macrophage Colony-Stimulating Factor and cultured for up to 15 days. Control cells and the sorted AM all replicated similarly; no evidence was found to indicate that AM proliferation is either stimulated or decreased. Evidence was also obtained that indicated that when particle-containing AM divide, the particles they originally contained are distributed to their offspring.
Date: May 1, 1993
Creator: Pendergrass, D.; Valdez, Y. E. & Lehnert, B. E.
Partner: UNT Libraries Government Documents Department

Current concepts on airborne particles and health

Description: Epidemiological evidence of associations between environmental particulate concentrations and both acute and chronic health effects has grown with numerous recent studies conducted in the US and other countries. An association between short-term changes in particulate levels and acute mortality now seems certain. The association is consistent among studies and coherent among indicators of mortality and morbidity. Effects observed at surprisingly low pollution levels have raised concern for current exposures even in modestly polluted cities. Toxicology did not predict the acute mortality effect, and causal mechanisms are difficult to rationalize. Present data suggest that the fine fraction of particulate pollution is more toxic than larger particles, but the contribution of specific particulate species is poorly understood.
Date: November 1, 1994
Creator: Mauderly, J. L.
Partner: UNT Libraries Government Documents Department

Tabulation of dose equivalent per microcurie-day for source and target organs of an adult for various radionuclides

Description: Data are tabulated on the radiation dose equivalent per microcurie-day for source and target organs of a human adult for 100 radionuclides. These are listed at the end of the volume. Included are several radionuclides where the parent has a daughter radionuclide of physical half-life less than five minutes. In such cases separate S tables are given for the parent and for the daughter as well as a composite table which contains S values for the parent plus S values for the daughter weighted according to the percent decay via the daughter. (CH)
Date: November 1, 1975
Creator: Snyder, W.S.; Ford, M.R.; Warner, G.G. & Watson, S.B.
Partner: UNT Libraries Government Documents Department