Respiratory Tract Deposition Research Articles

An Aerosolized Fluorescent Microsphere Technique for Evaluating Particle Deposition in the Avian Respiratory Tract

The objective of this study was to examine the feasibility of using aerosolized fluorescent microspheres to examine particle distribution in the respiratory tract of birds following aerosol exposure. Adult domestic pigeons (Columbia livia domestica; n = 5 birds per microsphere size) were exposed to aerosolized monodispersed populations of various sized carboxylate microspheres (0.5, 1.0, 2.0, 3.0, 6.0, and 10.0 microm) for 30 min. For aerosol-exposure purposes, the birds were anesthetized with injectable anesthetics, intubated, and placed on positive-pressure ventilation using a mechanical ventilator. Immediately following aerosol exposure, the birds were euthanatized, and carcasses were preserved via intravenous infusion of modified paraformaldehyde/gluteraldehyde fixative (pH = 7.2 and 340 mOsm). Initial evaluation of microsphere distribution in air sacs (cranial and caudal thoracic and abdominal) and at the level of the ostia was performed using a stereoscopic microscope with an epifluorescent module. More detailed examination of the distribution of microspheres within the respiratory tract was achieved using a confocal scanning laser microscope with a krypton argon laser and a scanning electron microscope. The results from this study revealed that positive-pressure ventilation resulted in distribution of smaller sized fluorescent microspheres (sizes 1.0, 2.0, and 3.0 microm) throughout the pigeon's respiratory tracts, and these microspheres were in highest concentration in the secondary bronchi and ostia for all of the examined air sacs. The larger sized beads (6.0 and 10.0) were confined to the upper airway (trachea and primary bronchi). The results from this study allow for a better understanding of particle deposition following positive-pressure ventilation and aerosol exposure in birds.

Particle Deposition in Human Respiratory Tract: Effect of Water-Soluble Fraction

In the nearly saturated human respiratory tract, the presence of water-soluble substances in inhaled aerosols can cause change in the size distribution of particles. This consequently alters the lung deposition profiles of the inhaled airborne particles. The magnitude of particle deposition in the lung is affected by the soluble component present in the particle. This is estimated by a numerical model. The model solves the condensation growth equation to determine the size evolution of respirable particles within the human respiratory tract. The water uptake by the particles in the respiratory tract results in change of size and density of the particles, and these changes are incorporated for estimating the particle deposition efficiency. The model results are compared with experimental results of sodium chloride particles. The model reproduces the major features of the experimental data. The simulations indicate that the particle can grow up to two times or more of its original size due to water uptake, depending on the quantity of the soluble matter it carries and thus can have significant effect on particle deposition efficiency. The study investigated the effect of soluble compounds in estimating total and regional lung dose of ambient particulate matter measured in Mumbai, India. The particle mass size distribution and composition considered for the ambient particulate matter, the variation in the total mass dose due to the growth was modest. But, the regional lung dose was significantly affected by the hygroscopic growth.

A set-up for field studies of respiratory tract deposition of fine and ultrafine particles in humans

Respiratory tract deposition data of ultrafine aerosol particles, hygroscopic particles and ambient particles in general are scarce. Measurements are associated with several difficulties. The objective of this work was to design a method for fast determination of highly size-resolved fine and ultrafine particle deposition, to be used on larger groups of human subjects in exposure studies and in typical ambient and indoor environments. The particle size distributions in dried samples of the inhaled and exhaled air are characterised with an electrical mobility spectrometer. A particle counter desmearing procedure reduces the spectrometer scan time. The precision and sensitivity of the method was tested for hygroscopic sodium chloride (NaCl) and hydrophobic Di-Ethyl-Hexyl-Sebacate (DEHS) aerosols in repeated identical experiments and experiments with different breathing frequencies on a single subject. The accuracy of the method was estimated by comparing results from three subjects with previous data obtained with monodisperse particles and with the well-established International Commission on Radiological Protection model (1994). Potential errors due to size shifts between the inhaled and exhaled samples and coagulation were simulated. The system has low losses in the studied particle size range (10–475 nm), typically 10% or less of the fraction deposited in the respiratory tract. Coagulation is noticeable at 10 5 cm - 3 but can be corrected for up to 5 × 10 5 cm - 3 . The precision in the determined deposited fraction is 0.02–0.08. The method is sensitive enough to quantify differences between breathing patterns and differences between hygroscopic and hydrophobic aerosols. Our results for NaCl and DEHS are in agreement with the ICRP 66 model [International Commission on Radiological Protection. (1994). Human respiratory tract model for radiological protection (ICRP Publication 66). Oxford, UK: Elsevier Science], and also suggest that the relative humidity in the respiratory tract is close to 99.5%. A respiratory tract deposition measurement can be done in 15–30 min. Recommendations are given for field applications of the method.

A computer program for the simulation of fiber deposition in the human respiratory tract

As inhaled fibers may lead to a variety of lung diseases, detailed information on their deposition in the human respiratory tract is an indispensable requirement in medical science. In the work presented here, a Visual Basic ® computer program, termed FIBROS, is described which enables the simulation of fibrous particle deposition in both the extrathoracic region and different parts of the lung itself, including the results of published numerical studies on inertial/interceptional as well as diffusional and gravitational deposition. The input window of FIBROS includes the selection of specific breathing conditions by variation of the tidal volume and breathing cycle. Furthermore, the user is able to determine fiber properties such as diameter, aspect ratio, specific weight, and fiber orientation with respect to the air stream in the upper and lower airways of the lungs. Besides the offer of various deposition formulae for each region of the respiratory tract, thereby also allowing a distinction between mouth and nose breathing, the user may select between different morphometric datasets of the lung and respective airway scaling procedures. Analysis routines of FIBROS include the estimation of regional deposition fractions, thereby distinguishing between extrathoracic, bronchial, and acinar compartments, and a calculation of generation-by-generation deposition probabilities within tubular and alveolar structures. Preliminary results presented here should demonstrate the effects on fiber deposition due to variations of the breathing behaviour and the particle properties.

Aerosol Deposition in the Human Respiratory Tract Breathing Air and 80:20 Heliox

Aerosol mixing resulting from turbulent flows is thought to be an important mechanism of deposition in the upper respiratory tract (URT). Since turbulence levels are a function of gas density, the use of a low density carrier gas would be expected to reduce deposition in the URT. We measured aerosol deposition in the respiratory tract of 8 healthy subjects using both air and heliox, a low density gas mixture containing 80% helium and 20% oxygen, as the carrier gas. The subjects breathed 0.5, 1, and 2 microm-diameter monodisperse polystyrene latex particles from a reservoir at a constant flow rate (approximately 450 mL/sec) and tidal volume (approximately 900 mL). Aerosol concentration and flow rate were measured at the mouth using a photometer and a pneumotachograph, respectively. Deposition was 17.0%, 20.3%, and 38.9% in air and 16.8%, 18.5%, and 36.9% in heliox for 0.5; 1, and 2 microm-diameter particles, respectively. There was a small but statistically significant decrease in deposition when using heliox compared to air for 1 and 2 microm-diameter particles (p < 0.05). While it could not be directly measured from these data, it is likely that when breathing heliox instead of air, deposition is reduced in the URT and increased in the small airways and alveoli.

Analysis of Total Respiratory Deposition of Inhaled Ultrafine Particles in Adult Subjects at Various Breathing Patterns

Ultrafine particles are ubiquitous in the ambient air, and their unique physicochemical characteristics may pose a potential health hazard. Accurate lung dose information is essential to assess a potential health risk from exposure to these particles. In the present study, we measured total respiratory tract deposition fraction (TDF) of inert ultrafine aerosols (NMD = 0.04, 0.06, 0.08, and 0.10 μm and σg 1.3) in a group of young healthy adults (11 males and 11 females). A fast-response ultrafine condensation particle counter was used for continuous monitoring of inhaling aerosols breath by breath. Six different breathing patterns were used: three different tidal volumes (Vt = 500, 750, and 1000 ml) and two different flow rates for each Vt. The mean respiratory time (Tm) ranged from 2 to 4 s. The measured data showed that TDF increased with a decrease in particle size, thereby an increase in diffusion coefficient (D), and with an increase in Tm and Vt. For a given particle size both Tm and Vt were almost e...

04/01556 Energy and environmental conservation in Slovakia and institutional support: Rousek, J. International Journal of Risk Assessment and Management, 2003, 4, (2/3), 158–166

Fine particulate matter (PM2.5) contributes to the risk of cardiovascular events, partially owing to its deposition in the human respiratory tract. To investigate short-term effects of ambient PM2.5 exposure on alternation of blood pressure (BP), this study was conducted during the winter-summer period between 2014 and 2015. The study included 106 community residents in Wuhan city, China. We repeatedly monitored the household and outdoor PM2.5 concentrations as well as individual-level PM2.5 in each season, and then assessed personal PM2.5 exposure (including deposited doses of PM2.5 in the human respiratory tract) by using different methodology (such as using a dosimetry model). All participants took part in the physical examination, including the inflammatory indicators, BP and lung function parameters measurements. Subsequently, we assessed the health damage of exposure to PM2.5 using generalized additive models. We observed increased BP at 2-day lag for an interquartile range increase in ambient fixed-site, households, individual-level PM2.5 exposure and the corresponding lung deposited doses of each exposure concentration (p < 0.05), decreased BP at 3-day lag for an interquartile range increase in ambient fixed-site, households PM2.5 and the corresponding lung deposited doses of each exposure concentration (p < 0.05). The estimated deposited doses of PM2.5 by the deposition fractions in this study and the referenced deposition fractions by previous reported method were equivalent associated with alternation in BP. In conclusion, lung deposited dose of PM2.5 as a quantitative indicator may be used to assess adverse cardiovascular effects following the systemic inflammation. However, we require careful assessment of acute adverse cardiovascular effects using ambient fixed-site PM2.5 after short-term PM2.5 exposure.

Nasal and Lung Deposition of Fine and Coarse Particles in Rats

Deposition of particles in rat airways was measured using two methods. In method 1, a controlled flow of monodisperse particles was passed directly through the nasal airways of an anesthetized rat and nasal deposition efficiency was determined for particles with aerodynamic diameters between 0.5 and 4 μm. In method 2, upper respiratory tract (URT) and lung deposition fractions for unanesthetized rats exposed to radiolabeled particles in head-only units and anesthetized rats exposed in whole-body units were determined for particles with aerodynamic diameters between 0.9 and 3 μm. Animal breathing parameters were measured for method 2 exposures. Nasal deposition efficiency was greater for pulsatile flows than steady state (method 1). Nasal deposition was distinctly higher for method 1 exposures than those using method 2 because particles were 100% inhalable in method 1 and <100% inhalable in the head-only and whole body exposures of method 2. Similarly, deposition was greater in head-only than wholebody exposures because particle inhalability was greater in head-only exposures.

Respiratory Tract Deposition Efficiencies: Evaluation of Effects from Smoke Released in the Cerro Grande Forest Fire

Forest-fire smoke inhaled by humans can cause various health effects. This smoke contains toxic chemicals and naturally occurring radionuclides. In northern New Mexico, a large wildfire occurred in May 2000. Known as the Cerro Grande Fire, it devastated the town of Los Alamos and damaged Los Alamos National Laboratory (LANL). Residents were concerned about the possible dissemination of radionuclides from LANL via smoke from the fire. To evaluate potential health effects of inhaling radionuclides contained in the smoke from the Cerro Grande Fire, it was first necessary to evaluate how much smoke would deposit in the human respiratory tract. The purpose of this study was to evaluate respiratory-tract deposition efficiencies of airborne forest-fire smoke for persons of different ages exposed while inside their homes. Potential non-radiological health effects of a forest fire are reviewed. The deposition efficiencies presented can be used to evaluate in-home smoke deposition in the respiratory tract and expected radionuclide intake related to forest fires. The impact of smoke exposure on firemen fighting a forest fire is quantitatively discussed and compared. They primarily inhaled forest-fire smoke while outdoors where the smoke concentration was much higher than inside. Radionuclides released at the LANL site via the Cerro Grande Fire were restricted to naturally occurring radionuclides from burning trees and vegetation. Radiation doses from inhaled airborne radionuclides to individuals inside and outside the Los Alamos area were likely very small.

Radiological imaging as the basis for a simulation software of ventilation in the tracheo-bronchial tree.

The inhaled route is a promising new way for administering drugs to the human body. Flow and particle deposition in the human respiratory tract depends on the individual's anatomy as well as on the drug composition. A European Framework V Program supported project is currently developing a simulation tool for assessment of drug distribution and deposition. This tool relies heavily on the input of radiological data sets, which are obtained in humans. Both high temporal and spatial resolutions are required, and CT and MRI (including hyperpolarized helium-3 MRI) are applied. The radiological data are integrated into computation fluid dynamics software, which is capable of assessing air-flow profiles and compartmental behaviours. This is complemented by pharmacokinetic models, which should result in a simulation tool that will be of use for the theoretical design of new inhaled therapies. This article describes the special imaging requirements of each region of the respiratory tract and the feasibility of these sophisticated radiological techniques with a view of using these data in a simulation model of the lung.

Development of a web screening interface to calculate aerosol deposition in the human respiratory tract

Development of a web screening interface to calculate aerosol deposition in the human respiratory tract

Biphasic culture of rat lung slices for pharmacotoxicological evaluation of complex atmospheres.

The relevance to the in vivo situation of in vitro toxicity studies of complex atmospheres has frequently been limited by the procedures used for the exposure of the biological samples. We have evaluated from on-road measurements the size distribution pattern and the subsequent respiratory tract deposition rates of particulate matter from urban atmospheric aerosols, which are in the range of 110 and 3 pg/cm2 per min for tracheobronchial and alveolar areas, respectively. Continuous flow-through rotating chambers and a specific design for exhaust sampling and dilution with controlled adjustment of pO2 and pCO2 to 20% and 5%, respectively, have been developed to expose biphasic air/liquid organotypic cultures of rat lung slices to continuous flows of diluted exhausts from diesel engines with preservation of the physicochemical properties of the exhaust. The size distribution of the particulate matter and the bioavailability of pollutants were preserved, thus allowing us to closely mimic in vitro the in vivo atmosphere/tissue interactions that occur mainly through diffusion mechanisms. The toxicity response profile has been assessed in terms of tissue viability, oxidative stress, DNA injury, and the early phase of inflammatory reaction. Exhaust filtration, addition to fuel of rapeseed methyl ester, and preincubation of lung tissue with soy isoflavones modulated the toxicity response profile of exhausts. The importance of preserving both particulate matter size distribution and adsorbed pollutant bioavailability, which could not be ascertained using more classical in vitro approaches, is discussed and should be considered a prerequisite for further developments of in vitro studies to modelize in vivo inhalation of complex atmospheres.

A consideration of the role of gas/particle partitioning in the deposition of nicotine and other tobacco smoke compounds in the respiratory tract.

Tobacco smoke is an aerosol that contains both gaseous and suspended particulate material (PM). The particles are largely liquid droplets containing a wide variety of condensed organic compounds. Each compound in the smoke will partition between the gas and PM phases and will always seek a state of gas/particle equilibrium. When tobacco smoke is inhaled, a compound such as nicotine can deposit in the respiratory tract (RT) by four different mechanisms: (1) direct gas deposition (DGD) of the portion of the compound that is initially in the gas phase of the inhaled smoke; (2) evaporative gas deposition (EGD) of PM-phase compound by evaporation to the gas phase, then deposition; (3) particle deposition, evaporation from the deposited particle, then deposition from the gas phase (PDE); and (4) particle deposition with diffusion (PDD) into RT tissue. Three of the mechanisms (DGD, EGD, and PDE) involve volatilization from the PM phase. The relative importance of all the mechanisms is therefore greatly affected by the volatility of the compound from the PM phase as it is set by the compound's gas/particle partitioning constant K(p) through the compound's vapor pressure. For a largely nonvolatile compound such as benzo[a]pyrene, only PDD will likely be important. For a semivolatile compound such as nicotine, all four mechanisms can be important. Because tobacco smoke alkaloids such as nicotine can exist in protonated as well as free-base form, the fraction alpha(fb) of the compound that is in the neutral free-base form in the PM phase plays a critical, pH-dependent role in determining the relative importance of the four mechanisms. Equations are developed that can be used to ascertain the importance of the DGD and EGD mechanisms. The value of alpha(fb) for nicotine in a tobacco smoke PM is set by pH(eff), the effective pH of the PM phase. Historically, a primary method for measuring "smoke pH" has involved the direct exposure of a pH electrode to tobacco smoke. This method cannot yield direct insight into pH(eff) or alpha(fb) values because (1) problems exist in using such an electrode to measure smoke PM-phase pH, and (2) by itself, a measurement of the pH of tobacco smoke PM says nothing about the effects of PM-phase activity coefficients of protonated and free-base nicotine on the nicotine species distribution. The "acidic" values that have typically been measured for cigarette "smoke pH" by the direct pH electrode method are therefore neither reliable nor useful in determining the relative distribution of PM-phase nicotine among the protonated and free-base forms. The dependence of the volatility of nicotine from tobacco smoke PM on alpha(fb) means that measuring the gas/particle distribution of nicotine under equilibrium conditions in a tobacco smoke by denuder samplers (or by another method) can yield information about the nicotine K(p) for that smoke. Knowledge of K(p,fb), the partitioning constant for nicotine in the free-base form, then allows calculation of alpha(fb) through the relation K(p) = K(p,fb)/alpha(fb). The available data suggest that the smoke PM from some commercial cigarettes can be characterized by alpha(fb) > or = 0.4, i.e., 40% or more of the nicotine in the free-base form. This conclusion is consistent with (1) the gas-sampling denuder results obtained by Philip Morris in which significant tobacco smoke nicotine was observed to deposit in acid-coated denuder tubes, with more depositing when the cigarette tobacco blend was treated with ammonia; (2) the view that the sensory "impact" exhibited by some tobacco smokes is caused by the deposition of gaseous nicotine in the pharynx; (3) the observed throat irritation caused by nicotine inhalers; and (4) the high overall respiratory tract deposition efficiencies for nicotine of 0.9 and greater that have been reported for some cigarette smokes. The available information combines to create a picture of nicotine in cigarette smoke that contradicts the traditional view that cigarette smoke PM is typically acidic, with little free-base nicotine typically present in the smoke PM phase. Government agencies interested in establishing a framework for the testing and monitoring of nicotine delivery may wish to consider requiring the measurement and publication of the PM-phase alpha(fb) values for the cigars and cigarettes marketed in their jurisdictions.

Deposition and clearance: unique problems in the proximal airways and oral cavity in the young and elderly

Prospective longitudinal studies measuring aerosol behavior in the respiratory tract as humans age have not been performed. The present paper reviews observations related to aging of the respiratory tract and other effects more likely due primarily to disease and iatrogenic causes. Upper airway deposition was found to approximate 50% in children during inhalation of drugs thought to be designed primarily for deposition in the lower respiratory tract. In older subjects, aging per se did not have a major impact on the deposition of aerosols. Disease processes that develop with age were shown to be the primary cause of deposition abnormalities. Flow-limitation in central airways was proposed as a major factor responsible for central airway deposition as well as abnormal clearance in common obstructive lung diseases. The oral cavity, a source of pathogenic organisms causing pneumonia, was also studied in the elderly. Salivary clearance, often abnormal in the aged, was related to colonization with pathogenic bacteria. Salivary clearance was not obviously reduced by aging per se but by iatrogenic sources such as drug therapy for other diseases.

Improved respiratory delivery of the anticancer drugs, camptothecin and paclitaxel, with 5% CO2-enriched air: pharmacokinetic studies.

To increase pulmonary deposition of anticancer liposome aerosols in mice by modulation of respiratory physiology through the addition of 5% CO2 to the air source used to generate the aerosols. Breathing CO2-enriched aerosol increases pulmonary ventilation with concurrent increased deposition of inhaled particles. Dilauroylphosphatidylcholine liposome formulations of two anticancer drugs, paclitaxel (PTX) and camptothecin (CPT), were investigated. The aerosol droplet size was measured using an Andersen cascade impactor. Drug concentrations in aerosol droplet fractions and tissues were determined by HPLC analysis. ICR mice were exposed to each liposome aerosol for 30 min. For each drug, one group of mice inhaled the drug-liposome aerosol generated with a mixture of 5% CO2 in air and another group inhaled the drug-liposome aerosols produced with normal air. Tissue distribution and pharmacokinetics were determined for both drug delivery systems. Significantly higher concentrations of PTX and CPT were found in organs of mice exposed to 5% CO2-air aerosols compared to organs of mice exposed to normal air aerosols. The highest concentrations of drug were detected in the lungs and were two- to fourfold higher with 5% CO2-air aerosols than with aerosols generated with normal air. Higher concentrations were also detected in liver, spleen, kidneys, blood, and brain. 5% CO2 enrichment of air increased respiratory tract deposition of inhaled aerosol particles containing PTX and CPT.

Regional lung deposition of a technetium 99m-labeled formulation of mometasone furoate administered by hydrofluoroalkane 227 metered-dose inhaler

Background: A new inhaled suspension formulation of mometasone furoate (MF), a potent corticosteroid with minimal systemic availability, has been developed for the treatment of asthma. This formulation is delivered by metered-dose inhaler (MDI) using the nonchlorofluorocarbon propellant hydrofluoroalkane 227 (HFA-227). Objective: The primary goal of this study was to determine the respiratory tract deposition of this formulation of MF. A secondary objective was to measure plasma concentrations of MF and a putative metabolite, 6-β-OH MF, to determine the systemic exposure to corticosteroid. Methods: This was a single-dose, open-label study in which 200 μg of technetium 99m ( 99mTc)-radiolabeled MF was administered to patients with asthma. Gamma scintigraphy was used to quantify lung, oropharyngeal, stomach, and MDI mouthpiece deposition patterns of MF. Results: Eleven patients, aged 21 to 47 years, with a history of asthma were enrolled in and completed the study. The mean (± SD) whole lung deposition of MF was 13.9% ± 5.7% of the metered (ex-valve) dose. The central lung zone received 5.3% ± 2.8% of the dose; the intermediate zone received 4.7% ± 1.9%; and peripheral lung deposition was 4.0% ± 1.5%. The mean (± SD) ratio of periphera to central lung deposition was 0.8 ± 0.2. Oropharyngeal deposition was 79.1% ± 8.7% of the ex-valve dose, with 6.3% ± 7.8% deposited on the MDI mouthpiece and 0.7% ± 0.5% exhaled. The majority of plasma samples taken for analysis of MF and 6-β-OH MF concentrations were below the limit of quantification (50 pg/mL) in all patients after inhalation of 200 μg 99mTc-labeled MF. Conclusion: The lung deposition of MF when administered via HFA-227 MDI is comparable to the 10% to 20% lung deposition seen with other corticosteroid suspension formulations administered by MDI that have demonstrated effectiveness in the treatment of asthma.

Probabilistic Accident Consequence Uncertainty Analysis of the Dose Calculations Module in the COSYMA Package

Uncertainty analysis of the dose calculation module of the COSYMA accident consequence assessment code has been undertaken, involving the following steps: (1) Expert judgement techniques were applied to assess uncertainties in measurable parameters determining external and internal doses. (2) The data obtained were used to calculate distributions on the dose quantities required as code input parameters. (3) The effect of uncertainties in dose quantities was analysed for a range of COSYMA end points, including the extent of countermeasures and incidences of early and late health effects, and the most important uncertainties were identified for inclusion in an overall uncertainty analysis of COSYMA. Parameters identified as making the largest contributions to uncertainty included external doses and location factors, residence times of materials on skin, breathing rates, and respiratory tract deposition and retention parameters, for the extent of countermeasures and early health effects, and caesium and iodine retention parameters for late effects.

Inhaled Drug Therapy During Mechanical Ventilation

In mechanically ventilated patients, drug delivery by inhalation is a common route of administration for an increasing number of pharmacologic agents. Inhalation of a therapeutic aerosol has advantages compared with other routes of drug administration with respect to convenience, ease of delivery, and safety. As with any drug, administration of an inhaled agent to a targeted site in an appropriate amount is essential for a therapeutic effect. Drug delivery is influenced by the physicochemical properties of the aerosolized drug, characteristics of the aerosol-generating device, technique of aerosol delivery, mechanical ventilator parameters, and airway anatomy. Lower respiratory tract deposition is diminished in ventilator-dependent patients due to losses arising from aerosol impaction on the ventilator circuit and endotracheal tube. For optimal drug delivery, the clinician should be familiar with the aerosol-generating device and technique of delivery, including mechanical ventilator parameters. Therapeutic gases such as nitric oxide and helium have been used as pharmacologic adjuncts during mechanical ventilation. Lower respiratory tract delivery of a therapeutic gas is influenced simply by gas diffusion. However, delivery of such agents to the mechanically ventilated patient is complicated by the requirement for specialized gas blenders and monitoring equipment. Inhaled drug delivery has the potential to modify the underlying respiratory pathophysiology while producing few systemic effects. In the future, the number of agents that can be administered by the inhalation route to mechanically ventilated patients will continue to expand. Clin Pulm Med 2000;7(3):140-146

Soot particle deposition in the human respiratory tract

Soot particle deposition in the human respiratory tract

The IMBA Suite: Integrated Modules for Bioassay Analysis

The increasing complexity of models representing the biokinetic behaviour of radionuclides in the body following intake poses problems for people who are required to implement these models. The problem is exacerbated by the current paucity of suitable software. In order to remedy this situation, a collaboration between British Nuclear Fuels, Westlakes Research Institute and the National Radiological Protection Board has started with the aim of producing a suite of modules for estimating intakes and doses from bioassay measurements using the new ICRP models. Each module will have a single purpose (e.g. to calculate respiratory tract deposition) and will interface with other software using data files. The elements to be implemented initially are plutonium, uranium, caesium, iodine and tritium. It is intended to make the software available to other parties under terms yet to be decided. This paper describes the proposed suite of integrated modules for bioassay analysis, IMBA.