Age-dependent doses to members of the public from intake of radionuclides Part 4: Inhalation dose coefficients

PLUTONIUM C-2 APPENDIX C D H H S D N A D O D D O E D O L D O T D O T / U N / N A / I M D G D W E L E C D E C G / E K G E E G E E G L E P A F F i F A O F D A F E M A F I F R A F P D f p m F R F S H g G C g d G L C G P C G S D G y H P L C H R G C H S D B I A R C I C R P I D L H I L O I R I S I T R I k B q K d k g k k g K o c K ow L L C L C 50 L C l o LD50 D e p a r t m e n t o f H e a l t h a n d H u m a n S e r v i c e s d e o x y r i b o n u c l e i c a c i d D e p a r t m e n t o f D e f e n s e D e p a r t m e n t o f E n e r g y D e p a r t m e n t o f L a b o r D e p a r t m e n t o f T r a n s p o r t a t i o n D e p a r t m e n t o f T r a n s p o r t a t i o n / U n i t e d N a t i o n s / N o r t h A m e r i c a / I n t e r g o v e r n m e n t a l M a r i t i m e D a n g e r o u s G o o d s C o d e d r i n k i n g w a t e r e x p o s u r e l e v e l e l e c t r o n c a p t u r e d e t e c t i o n e l e c t r o c a r d i o g r a m e l e c t r o e n c e p h a l o g r a m E m e r g e n c y E x p o s u r e G u i d a n c e L e v e l E n v i r o n m e n t a l P r o t e c t i o n A g e n c y F a h r e n h e i t f i r s t f i l i a l g e n e r a t i o n F o o d a n d A g r i c u l t u r a l O r g a n i z a t i o n o f t h e U n i t e d N a t i o n s F o o d a n d D r u g A d m i n i s t r a t i o n F e d e r a l E m e r g e n c y M a n a g e m e n t A g e n c y F e d e r a l I n s e c t i c i d e , F u n g i c i d e , a n d R o d e n t i c i d e A c t f l a m e p h o t o m e t r i c d e t e c t i o n f e e t p e r m i n u t e F e d e r a l R e g i s t e r f o l l i c l e s t i m u l a t i n g h o r m o n e g r a m g a s c h r o m a t o g r a p h y g e s t a t i o n a l d a y g a s l i q u i d c h r o m a t o g r a p h y g e l p e r m e a t i o n c h r o m a t o g r a p h y g e o m e t r i c s t a n d a r d d e v i a t i o n g r a y h i g h p e r f o r m a n c e l i q u i d c h r o m a t o g r a p h y h i g h r e s o l u t i o n g a s c h r o m a t o g r a p h y H a z a r d o u s S u b s t a n c e D a t a B a n k I n t e r n a t i o n a l A g e n c y f o r R e s e a r c h o n C a n c e r I n t e r n a t i o n a l C o m m i s s i o n o n R a d i o l o g i c a l P r o t e c t i o n i m m e d i a t e l y d a n g e r o u s t o l i f e a n d h e a l t h I n t e r n a t i o n a l L a b o r O r g a n i z a t i o n I n t e g r a t e d R i s k I n f o r m a t i o n S y s t e m I n h a l a t i o n T o x i c o l o g y R e s e a r c h I n s t i t u t e k i l o B e q u e r e l a d s o r p t i o n r a t i o k i l o g r a m m e t r i c t o n o r g a n i c c a r b o n p a r t i t i o n c o e f f i c i e n t o c t a n o l w a t e r p a r t i t i o n c o e f f i c i e n t l i t e r l i q u i d c h r o m a t o g r a p h y l e t h a l c o n c e n t r a t i o n , 5 0 % k i l l l e t h a l c o n c e n t r a t i o n , l o w l e t h a l d o s e , 5 0 % k i l l PLUTONIUM C-3 APPENDIX C LDl o lethal dose, low LDH lactic dehydrogenase LH luteinizing hormone LOAEL lowest-observed-adverse-effect level LSE Levels o f Significant Exposure LT5 0 lethal time, 50% kill m meter MA trans,trans'-muconic acid MAL maximum allowable level mCi millicurie MCL maximum contaminant level MCLG maximum contaminant level goal MF modifying factor MFO mixed function oxidase mg milligram mL milliliter mm millimeter MMD mass median diameter mmHg millimeters o f mercury mmol millimole mppcf millions o f particles per cubic foot MRL Minimal Risk Level MS mass spectrometry NAAQS National Ambient Air Quality Standard NAS National Academy of Science NATICH National Air Toxics Information Clearinghouse NATO North Atlantic Treaty Organization NCE normochromatic erythrocytes NCEH National Center for Environmental Health NCI National Cancer Institute NCRP National Council on Radiation Protection ND not detected NFPA National Fire Protection Association ng nanogram NHANES National Health and Nutrition Examination Survey NIEHS National Institute of Environmental Health Sciences NIOSH National Institute for Occupational Safety and Health NIOSHTIC NIOSH's Computerized Information Retrieval System NLM National Library of Medicine nm nanometer nmol nanomole NOAEL no-observed-adverse-effect level NOES National Occupational Exposure Survey NOHS National Occupational Hazard Survey NPD nitrogen phosphorus detection NPDES National Pollutant Discharge Elimination System NPL National Priorities List NR not reported NRC National Research Council NS not specified NSPS New Source Performance Standards PLUTONIUM C-4 APPENDIX C N T I S N a t i o n a l T e c h n i c a l I n f o r m a t i o n S e r v i c e N T P N a t i o n a l T o x i c o l o g y P r o g r a m O D W O f f i c e o f D r i n k i n g W a t e r , E P A O E R R O f f i c e o f E m e r g e n c y a n d R e m e d i a l R e s p o n s e , E P A O H M / T A D S O i l a n d H a z a r d o u s M a t e r i a l s / T e c h n i c a l A s s i s t a n c e D a t a S y s t O P P O f f i c e o f P e s t i c i d e P r o g r a m s , E P A O P P T O f f i c e o f P o l l u t i o n P r e v e n t i o n a n d T o x i c s , E P A O P P T S O f f i c e o f P r e v e n t i o n , P e s t i c i d e s a n d T o x i c S u b s t a n c e s , E P A O R o d d s r a t i o O S H A O c c u p a t i o n a l S a f e t y a n d H e a l t h A d m i n i s t r a t i o n O S W O f f i c e o f S o l i d W a s t e , E P A O T S O f f i c e o f T o x i c S u b s t a n c e s O W O f f i c e o f W a t e r O W R S O f f i c e o f W a t e r R e g u l a t i o n s a n d S t a n d a r d s , E P A P A H p o l y c y c l i c a r o m a t i c h y d r o c a r b o n P B B K p h y s i o l o g i c a l l y b a s e d b i o k i n e t i c P B P D p h y s i o l o g i c a l l y b a s e d p h a r m a c o d y n a m i c P B P K p h y s i o l o g i c a l l y b a s e d p h a r m a c o k i n e t i c P C E p o l y c h r o m a t i c e r y t h r o c y t e s P E L p e r m i s s i b l e e x p o s u r e l i m i t p g p i c o g r a m P H S P u b l i c H e a l t h S e r v i c e P I D p h o t o i o n i z a t i o n d e t e c t o r p m o l p i c o m o l e P M R p r o p o r t i o n a t e m o r t a l i t y r a t i o P N L P a c i f i c N o r t h w e s t L a b o r a t o r y p p b p a r t s p e r b i l l i o n p p m p a r t s p e r m i l l i o n p p t p a r t s p e r t r i l l i o n P S N S p r e t r e a t m e n t s t a n d a r d s f o r n e w s o u r c e s R B C r e d b l o o d c e l l R E L r e c o m m e n d e d e x p o s u r e l e v e l / l i m i t R f C r e f e r e n c e c o n c e n t r a t i o n R f D r e f e r e n c e d o s e R N A r i b o n u c l e i c a c i d R Q r e p o r t a b l e q u a n t i t y R T E C S R e g i s t r y o f T o x i c E f f e c t s o f C h e m i c a l S u b s t a n c e s S A R A S u p e r f u n d A m e n d m e n t s a n d R e a u t h o r i z a t i o n A c t S C E s i s t e r c h r o m a t i d e x c h a n g e S D s t a n d a r d d e v i a t i o n S E s t a n d a r d e r r o r S G O T s e r u m g l u t a m i c o x a l o a c e t i c t r a n s a m i n a s e S G P T s e r u m g l u t a m i c p y r u v i c t r a n s a m i n a s e S I C s t a n d a r d i n d u s t r i a l c l a s s i f i c a t i o n S I M s e l e c t e d i o n m o n i t o r i n g S M C L s e c o n d a r y m a x i m u m c o n t a m i n a n t l e v e l S M R s t a n d a r d i z e d m o r t a l i t y r a t i o S N A R L s u g g e s t e d n o a d v e r s e r e s p o n s e l e v e l S P E G L S h o r t T e r m P u b l i c E m e r g e n c y G u i d a n c e L e v e l S T E L s h o r t t e r m e x p o s u r e l i m i t S T O R E T S t o r a g e a n d R e t r i e v a l PLUTONIUM C-5 APPENDIX C S v s i e v e r t T D 5 0 t o x i c d o s e , 5 0 % s p e c i f i c t o x i c e f f e c t T L V t h r e s h o l d l i m i t v a l u e T O C t o t a l o r g a n i c c a r b o n T P Q t h r e s h o l d p l a n n i n g q u a n t i t y T R I T o x i c s R e l e a s e I n v e n t o r y T S C A T o x i c S u b s t a n c e s C o n t r o l A c t T W A t i m e w e i g h t e d a v e r a g e U F u n c e r t a i n t y f a c t o r U . S . U n i t e d S t a t e s U S D A U n i t e d S t a t e s D e p a r t m e n t o f A g r i c u l t u r e U S G S U n i t e d S t a t e s G e o l o g i c a l S u r v e y U S N R C U n i t e d S t a t e s N u c l e a r R e g u l a t o r y C o m m i s s i o n V O C v o l a t i l e o r g a n i c c o m p o u n d W B C w h i t e b l o o d c e l l W H O W o r l d H e a l t h O r g a n i z a t i o n PLUTONIUM C-6 APPENDIX C > g r e a t e r t h a n > g r e a t e r t h a n o r e q u a l t o = e q u a l t o < l e s s t h a n < l e s s t h a n o r e q u a l t o % p e r c e n t a a l p h a ß b e t a Y g a m m a 5 d e l t a ^ m m i c r o m e t e r M g, m i c r o g r a m q i * c a n c e r s l o p e f a c t o r n e g a t i v e + p o s i t i v e ( + ) w e a k l y p o s i t i v e r e s u l t ( ) w e a k l y n e g a t i v e r e s u l t

Toxicological profile for plutonium

Quantifying radiological risk following the inhalation of radioactive aerosols entails not only an assessment of particle deposition within respiratory tract regions but a full accounting of clearance mechanisms whereby particles may be translocated to adjacent respiratory tissue regions, absorbed to blood, or released to the gastrointestinal tract. The model outlined in ICRP Publication 66 represents to date one of the most complete overall descriptions of particle deposition and clearance, as well as localized radiation dosimetry, within the respiratory tract. In this study, a previous review of the ICRP-66 deposition model is extended to the study of the subsequent clearance model. A systematic review of the clearance component within the ICRP 66 respiratory tract model was conducted in which probability density functions were assigned to all input parameters for both 239PuO2 and 238UO2/238U3O8. These distributions were subsequently incorporated within a computer code LUDUC (Lung Dose Uncertainty Code) in which Latin hypercube sampling techniques are used to generate multiple (e.g., 1,000) sets of input vectors (i.e., trials) for all model parameters needed to assess mechanical clearance and particle dissolution/absorption. Integral numbers of nuclear disintegrations, U(s), in various lung regions were shown to be well-described by lognormal probability distributions. Of the four extrathoracic clearance compartments of the respiratory tract, uncertainties in U(s), expressed as the ratio of its 95% to 5% confidence levels, were highest within the LN(ET) tissues for 239PuO2 (ratio of 50 to 130) and within the ET(seq) tissues for 238UO2/238U3O8 (ratio of 12 to 50). Peak uncertainties in U(s) in these respiratory regions occurred at particle sizes of approximately 0.5-0.6 microm where uncertainties in ET2 particle deposition fractions accounted for only approximately 10% of the total U(s) uncertainty for 239PuO2, and only approximately 30% of the total U(s) uncertainty for 238UO2/238U3O8 (the remainder is attributed to the clearance model alone). Of the eight clearance compartments within the thoracic regions of the respiratory tract, and for particle sizes below approximately 5 microm, uncertainties in U(s) were highest within the LN(TH) tissues for 239PuO2 (ratio of 60 to 80) and within the BB(seq) tissues for 238UO2/238U3O8 (ratio of 20 and 60). At particle sizes exceeding approximately 5 microm in aerodynamic diameter, peak uncertainties in U(s) are noted for the AI, bb(seq), and bb1 clearance compartments. As the particle size approaches 10 microm in size, uncertainties in U(s) within these three thoracic tissue regions approach a factor of 1,000 and are dominated by corresponding uncertainties in particle deposition.

Influences of parameter uncertainties within the ICRP 66 respiratory tract model: particle deposition.

The 2007 Recommendations (ICRP, 2007) introduced changes that affect the calculation of effective dose, and implied a revision of the dose coefficients for internal exposure, published previously in the Publication 30 series (ICRP, 1979a,b, 1980a, 1981, 1988) and Publication 68 (ICRP, 1994b). In addition, new data are now available that support an update of the radionuclide-specific information given in Publications 54 and 78 (ICRP, 1989a, 1997) for the design of monitoring programmes and retrospective assessment of occupational internal doses. Provision of new biokinetic models, dose coefficients, monitoring methods, and bioassay data was performed by Committee 2 and its task groups. A new series, the Occupational Intakes of Radionuclides (OIR) series, will replace the Publication 30 series and Publications 54, 68, and 78. OIR Part 1 (ICRP, 2015) describes the assessment of internal occupational exposure to radionuclides, biokinetic and dosimetric models, methods of individual and workplace monitoring, and general aspects of retrospective dose assessment. OIR Part 2 (ICRP, 2016), OIR Part 3 (ICRP, 2017), this current publication, and the final publication in the OIR series (OIR Part 5) provide data on individual elements and their radioisotopes, including information on chemical forms encountered in the workplace; a list of principal radioisotopes and their physical half-lives and decay modes; the parameter values of the reference biokinetic models; and data on monitoring techniques for the radioisotopes most commonly encountered in workplaces. Reviews of data on inhalation, ingestion, and systemic biokinetics are also provided for most of the elements. Dosimetric data provided in the printed publications of the OIR series include tables of committed effective dose per intake (Sv per Bq intake) for inhalation and ingestion, tables of committed effective dose per content (Sv per Bq measurement) for inhalation, and graphs of retention and excretion data per Bq intake for inhalation. These data are provided for all absorption types and for the most common isotope(s) of each element. The online electronic files that accompany the OIR series of publications contains a comprehensive set of committed effective and equivalent dose coefficients, committed effective dose per content functions, and reference bioassay functions. Data are provided for inhalation, ingestion, and direct input to blood. This fourth publication in the OIR series provides the above data for the following elements: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), actinium (Ac), protactinium (Pa), neptunium (Np), plutonium (Pu), americium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), and fermium (Fm).

ICRP Publication 141: Occupational Intakes of Radionuclides: Part 4.

This study was conducted to determine the biological effects of inhaled 238PuO2 over the life spans of 144 beagle dogs. The dogs inhaled one of two sizes of monodisperse aerosols of 238PuO2 to achieve graded levels of initial lung burden (ILB). The aerosols also contained 169Yb to provide a gamma-ray-emitting label for the 238Pu inhaled by each dog. Excreta were collected periodically over each dog's life span to estimate plutonium excretion; at death, the tissues were analyzed radiochemically for plutonium activity. The tissue content and the amount of plutonium excreted were used to estimate the ILB. These data for each dog were used in a dosimetry model to estimate tissue doses. The lung, skeleton and liver received the highest alpha-particle doses, ranging from 0.16-68 Gy for the lung, 0.08-8.7 Gy for the skeleton and 0.18-19 for the liver. At death all dogs were necropsied, and all organs and lesions were sampled and examined by histopathology. Findings of non-neoplastic changes included neutropenia and lymphopenia that developed in a dose-related fashion soon after inhalation exposure. These effects persisted for up to 5 years in some animals, but no other health effects could be related to the blood changes observed. Radiation pneumonitis was observed among the dogs with the highest ILBs. Deaths from radiation pneumonitis occurred from 1.5 to 5.4 years after exposure. Tumors of the lung, skeleton and liver occurred beginning at about 3 years after exposure. Bone tumors found in 93 dogs were the most common cause of death. Lung tumors found in 46 dogs were the second most common cause of death. Liver tumors, which were found in 20 dogs but were the cause of death in only two dogs, occurred later than the tumors in bone and lung. Tumors in these three organs often occurred in the same animal and were competing causes of death. These findings in dogs suggest that similar dose-related biological effects could be expected in humans accidentally exposed to 238PuO2.

Toxicity of inhaled plutonium dioxide in beagle dogs

Associated with the use of 238Pu in thermoelectric power sources for space probes is the potential for human exposure, primarily by inhalation and most likely as 238PuO2. Several models have been developed for assessing the level of intake and predicting the resulting radiation dose following human exposure to 239Pu. However, there are indications that existing models do not adequately describe the disposition and dosimetry of 238Pu following human exposure. In this study, a canine model that accounts for these differences has been adapted for use with human excretion data. The model is based on existing knowledge about organ retention of plutonium. An analysis of the sensitivity of the model to changes in aerosol-associated properties indicated that predictions of urinary excretion are most sensitive to changes in particle solubility and diameter and in the ratio of fragment:particle surface area. Application of the model to urinary excretion data from seven workers exposed to a 238Pu ceramic aerosol gave estimated intakes of 390-8,200 Bq and associated initial pulmonary burdens of 80-1,700 Bq. The resulting 50-y dose commitments to critical organs per Bq of 238Pu intake were estimated to be 0.5 mSv for the thoracic region, 0.2 mSv for the liver, and 1 mSv for the bone surfaces.

Application of a canine 238Pu biokinetics/dosimetry model to human bioassay data.

Biokinetic data from published animal studies have indicated that there are significant differences in the radiation dose patterns resulting from the inhalation of 238 Pu oxide rather than 239 Pu oxide aerosols. Although less frequent than for 239 Pu, several exposures to 238 Pu have been documented in the USA. A 238 Pu biokinetic and dosimetry model developed by Mewhinney and Diel, which was based on the results of animal studies, was applied to urinary bioassay data from workers who inhaled 238 Pu aerosols at three different 238 Pu processing facilities. Although all the exposures were purportedly to « 238 Pu ceramic» or 238 Pu oxide particles, the temporal features of the observed urinary excretion patterns differed among the cases from the various facilities

A.W. Hickman

Papers

Application of a canine 238Pu biokinetics/dosimetry model to human bioassay data.

Intake Assessment for Workers Who Have Inhaled 238Pu Aerosols