Measurement of 212Pb loss rate from human lungs

Hursh, John B.; Mercer, T.T.

doi:10.1152/jappl.1970.28.3.268

Cited by 60 publications

(47 citation statements)

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“…Since lead absorbed into the systemic circulation would be expected to have similar biokinetics, regardless of the route of absorption, the concern resides in how well the model simulates deposition and absorption of lead in the respiratory tract. The respiratory tract portion of the ICRP model is empirically based on experimental observations from inhalation studies conducted in adults, which revealed multicompartmental absorption kinetics for deposited lead (Hursh and Mercer, 1970;Hursh et al, 1969;Wells et al, 1975;Chamberlain et al, 1978;Morrow et al, 1980 ). In these studies, exposures were to particles having mass median aerodynamic diameters below 1 m and, therefore, deposition of the inhaled lead particles can be assumed to have been primarily in the bronchiolar and alveolar regions of the respiratory tract (James et al, 1994 ) where transport of deposited lead to the gastrointestinal tract is likely to have been only a minor component of particle clearance ( Hursh et al, 1969 ).…”

Section: Discussionmentioning

confidence: 99%

Risks to children from exposure to lead in air during remedial or removal activities at Superfund sites: A case study of the RSR lead smelter Superfund site†

Khoury

Diamond

2003

J Expo Sci Environ Epidemiol

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Superfund sites that are contaminated with lead and undergoing remedial action generate lead -enriched dust that can be released into the air. Activities that can emit lead -enriched dust include demolition of lead smelter buildings, stacks, and baghouses; on -site traffic of heavy construction vehicles; and excavation of soil. Typically, air monitoring stations are placed around the perimeter of a site of an ongoing remediation to monitor air lead concentrations that might result from site emissions. The National Ambient Air Quality ( NAAQ ) standard, established in 1978 to be a quarterly average of 1.5 g / m 3 , is often used as a trigger level for corrective action to reduce emissions. This study explored modeling approaches for assessing potential risks to children from air lead emissions from the RSR Superfund site in West Dallas, TX, during demolition and removal of a smelter facility. The EPA Integrated Exposure Uptake Biokinetic ( IEUBK ) model and the International Commission of Radiologic Protection ( ICRP ) lead model were used to simulate blood lead concentrations in children, based on monitored air lead concentrations. Although air lead concentrations at monitoring stations located in the downwind community intermittently exceeded the NAAQ standard, both models indicated that exposures to children in the community areas did not pose a significant long -term or acute risk. Long -term risk was defined as greater than 5% probability of a child having a long -term blood lead concentration that exceeded 10 g / dl, which is the CDC and the EPA blood lead concern level. Short -term or acute risk was defined as greater than 5% probability of a child having a blood lead concentration on any given day that exceeded 20 g / dl, which is the CDC trigger level for medical evaluation ( this is not intended to imply that 20 g / dl is a threshold for health effects in children exposed acutely to airborne lead ). The estimated potential long -term and short -term exposures at the downwind West Dallas community did not result in more than 5% of children exceeding the target blood lead levels. The models were also used to estimate air lead levels for short -term and long -term exposures that would not exceed specified levels of risk ( risk -based concentrations, RBCs ). RBCs were derived for various daily exposure durations ( 3 or 8 h / day ) and frequencies ( 1 -7 days / week ). RBCs based on the ICRP model ranged from 0.3 ( 7 days / week, 8 h / day ) to 4.4 g / m 3 ( 1 day / week, 3 h / day ) for long -term exposures and were lower than those based on the IEUBK model. For short -term exposures, the RBCs ranged from 3.5 to 29.0 g / m 3 . Recontamination of remediated residential yards from deposition of air lead emitted during remedial activities at the RSR Superfund site was also examined. The predicted increase in soil concentration due to lead deposition at the monitoring station, which represented the community at large, was 3.0 mg / kg. This potential increase in soil lead concentration was insignificant, less th...

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Section: Discussionmentioning

confidence: 99%

Risks to children from exposure to lead in air during remedial or removal activities at Superfund sites: A case study of the RSR lead smelter Superfund site†

Khoury

Diamond

2003

J Expo Sci Environ Epidemiol

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“…The respiratory tract deposition and clearance from the respiratory tract have been measured in adult humans (Chamberlain et al 1978;Hursh and Mercer 1970;Hursh et al 1969;Wells et al 1975). In these studies, exposures were to lead-bearing particles having mass median aerodynamic diameters (MMAD) below 1 μm and, therefore, deposition of the inhaled lead particles can be assumed to have been primarily in the bronchiolar and alveolar regions of the respiratory tract (James et al 1994) where transport of deposited lead to the gastrointestinal tract is likely to have been only a minor component of particle clearance (Hursh et al 1969).…”

Section: Inhalation Exposurementioning

confidence: 99%

“…Four percent of the inhaled lead is assumed to be transferred to the gastrointestinal tract. These parameter values reflect the data on which the model was based, which were derived from studies in which human subjects inhaled submicron leadbearing particles (Chamberlain et al 1978;Hursh and Mercer 1970;Hursh et al 1969;Wells et al 1975). These assumptions would not necessarily apply to exposures to large airborne particles (see Section 3.3.1.1).…”

Section: Leggett Modelmentioning

confidence: 99%

Characterizing Golden Eagle Risk to Lead and Anticoagulant Rodenticide Exposure: A Review

Herring

Eagles‐Smith

Buck

2017

Journal of Raptor Research

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“…Theoretical and experimental results for fractional pulmonary deposition of the total inhaled aerosol are shown in (39). They found 30% total deposition for the larger aerosol and 50-60% deposition for the smaller aerosol.…”

Section: Pulmonary Deposition Patternsmentioning

confidence: 99%

Deposition and clearance of inhaled particles.

Stuart¹

1984

Environ Health Perspect

157

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Theoretical models of respiratory tract deposition of inhaled particles are compared to experimental studies of deposition patterns in humans and animals, as determined principally by particle size, density, respiratory rate and flow parameters. Various models of inhaled particle deposition make use of convenient approximations of the respiratory tract to predict tractional deposition according to fundamental physical processes of impaction, sedimentation, and difussion. These theoretical models for both total deposition and regional Inasopharyngeal, tracheobronchial, and pulmonary) deposition are compared with experimental studies of inhaled dusts in humans or experimental animals that have been performed in many laboratories over several decades. Reasonable correlation has been obtained between theoretical and experimental studies, but the behavior of very fine (<0.01 inn) particles requires further refinement. Properties of particle shape, charge, and hygroscopicity as well as the degree of respiratory tract pathology also influence deposition patterns and further experimental work is urgently needed in these areas. The influence upon deposition patterns of dynamic alterations in inspiratory flow profiles caused by a variety of breathing patterns also requires further study, and the use of such techniques with selected inhaled particle size holds promise in possible diagnostic aid in diagnosis of normal versus disease conditions. Mechanisms of conducting airway and alveolar clearance processes involving mucociliary clearance, dissolution, transport to systemic circulation, and translocation via regional lymphatic clearance are discussed. The roles of the pulmonary macrophage in airway and alveolar clearance are described, and the applicability of recent solubility models for translocation or deposited materials to liver, skeleton, or other systemic organs is discussed.

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Measurement of 212Pb loss rate from human lungs

Cited by 60 publications

References 0 publications

Risks to children from exposure to lead in air during remedial or removal activities at Superfund sites: A case study of the RSR lead smelter Superfund site†

Risks to children from exposure to lead in air during remedial or removal activities at Superfund sites: A case study of the RSR lead smelter Superfund site†

Characterizing Golden Eagle Risk to Lead and Anticoagulant Rodenticide Exposure: A Review

Deposition and clearance of inhaled particles.

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