Estimation of the Personal Deposited Dose of Particulate Matter and Particle-Bound Metals Using Data from Selected European Cities

The present study focused on the estimation of the personal dose of airborne particles using an exposure dose model (ExDoM2). Input data from three European cities (Athens, Kuopio, Lisbon) were selected to implement the model that calculates the deposited dose and retention of particles in the respiratory tract, the mass transferred to the oesophagus and the absorption to blood as well as the dose for five particle-bound metals. Model results showed that after one day exposure higher deposited dose in the respiratory tract was obtained for Lisbon as a direct consequence of the higher PM concentration measured in this city. Moreover, the activity profile and the physical characteristics of the exposed subject had strong impact on the estimated deposited dose. Thus, light activity corresponded to higher deposited dose compared to no activity as well as an adult male exhibited higher dose, both findings associated with increased inhalation rate. Regarding the internal dose for particle-bound metals higher dose for four out of the five metals was obtained in lungs followed by the muscles for As, the gastrointestinal tract for Cr, the other tissues for Mn, the intestines for Cd and finally for Pb higher dose was found in bones and blood

Exposure and effects on human health in landfill sites from ambient particulate matter

The human exposure to particulate matter is a subject of increasing scientific interest due to the effects of particulate matter on human health. The high concentrations of particulate matter observed in landfills and the adverse health effects associated with high particulate matter concentrations make the study of personal exposure and consequent dose from particulate matter present in landfill sites necessary. The current study focus of workers in the waste management facility of the Prefecture of Chania. The waste management facility of the Prefecture of Chania consists of the landfill and the Mechanical Recycling and Composting Plant. For the calculation of the internal particle dose in the human body were performed particle mass concentrations measurements, particle mass size distributions measurements and chemical analyzes for the determination of the metal content in the particulate matter. In addition, indoor and outdoor particulate matter emission rates were estimated. Natural process (wind erosion) and anthropogenic process (movement of refuse trucks and manual sorting of waste) were also examined. The study of the different activities in the waste management facility of the Prefecture of Chania and their influence on the air pollution were examined in the current work. In particular, the outdoor emission rates were used as input parameter to a dispersion model in order to calculate the outdoor particulate matter concentrations. The most important source of particulate matter in the outdoor waste management facility of the Prefecture of Chania is the resuspension of dust due to refuse truck movement on roads. In addition, particulate matter emissions generated by wind erosion of compost piles and landfill cover.Particulate matter enters the human body mainly through the respiratory tract. The deposited particles in the respiratory tract transferred to the rest of the body. Simulation of the mechanisms through which the particulate matter entering the body, are deposited, accumulated and transferred to the rest of the body performed from dosimetry models. In the current study developed a dosimetry model (ExDoM2) for calculating internal dose of particles in the human body. The ExDoM2 model consists of a revised respiratory tract deposition/clearance model (updated version of the ExDoM) and a pharmacokinetic (PBPK) model. The revised respiratory tract deposition/clearance model incorporating new particle clearance mechanisms in the respiratory tract and was used to calculate the deposited dose of particles in the respiratory tract, the retention of particles in the respiratory tract, the transport of particles to the oesophagus (gastrointestinal tract) and lymph nodes, and the absorption to blood. The PBPK model was used for the transport of metals (As, Pb, Cd, Cr and Mn) from the blood in the human body (e.g. liver, heart, kidneys, brain, gastrointestinal tract).The major difference in the ExDoM2 model developed in the current study compared to other models (e.g. ExDoM, MPPD) in the scientific literature is that it incorporates a PBPK module for specific metals (As, Pb, Cd, Cr and Mn) of particles. In addition, the respiratory tract deposition/clearance model of the ExDoM2 incorporating new particle clearance mechanisms in the respiratory tract based on the revised model of the ICRP and also allows the user to enter different particle size distribution measurements (per hour) for determining realistic human exposure at different microenvironments during the day.The input data for the model implementation were derived from field measurements in the waste management facility of the Prefecture of Chania. They were selected four categories of exposed individuals: (a) workers at the outdoor weighing facility, (b) workers at the indoor site of manual waste sorting (first shift), (c) workers at the indoor site of manual waste sorting (second shift) and (d) non-workers in the waste management facility of the Prefecture of Chania. The objective of using different exposure scenarios is to determine whether the particulate matter dose of workers in the waste management facility of the Prefecture of Chania is increased compared to that of the general population in the area.Η έκθεση των ανθρώπων σε αιωρούμενα σωματίδια αποτελεί αντικείμενο έντονου επιστημονικού ενδιαφέροντος λόγω των επιπτώσεων τους στην ανθρώπινη υγεία. Οι υψηλές συγκεντρώσεις αιωρούμενων σωματιδίων που καταγράφονται σε Χώρους Υγειονομικής Ταφής Απορριμμάτων (ΧΥΤΑ), καθώς και η συσχέτιση που αυτές παρουσιάζουν με αρνητικά συμπτώματα στην ανθρώπινη υγεία, ανέδειξαν την ανάγκη μελέτης της προσωπικής έκθεσης και δόσης σε αιωρούμενα σωματίδια που προέρχονται από ΧΥΤΑ. Η παρούσα εργασία επικεντρώνεται στους εργαζόμενους της μονάδας διαχείρισης απορριμμάτων του Νομού Χανίων. Η μονάδα διαχείρισης απορριμμάτων του Νομού Χανίων αποτελείται από τον Χώρο Υγειονομικής Ταφής (ΧΥΤ) και από το Εργοστάσιο Μηχανικής Ανακύκλωσης και Κομποστοποίησης (ΕΜΑΚ). Για τον υπολογισμό της εσωτερικής δόσης αιωρούμενων σωματιδίων στο ανθρώπινο σώμα πραγματοποιήθηκαν μετρήσεις συγκεντρώσεων μάζας αιωρούμενων σωματιδίων, μετρήσεις κατανομής μεγέθους της μάζας των αιωρούμενων σωματιδίων και χημικές αναλύσεις για την περιεκτικότητα των αιωρούμενων σωματιδίων σε μέταλλα. Επίσης, υπολογίστηκαν οι ρυθμοί εκπομπής αιωρούμενων σωματιδίων σε εσωτερικούς και εξωτερικούς χώρους της μονάδας. Φυσικές διεργασίες (αιολική διάβρωση) και ανθρώπινες δραστηριότητες (κίνηση των απορριμματοφόρων και χειροδιαλογή απορριμμάτων) επίσης εξετάστηκαν. Η μελέτη διαφόρων δραστηριοτήτων στη μονάδα διαχείρισης απορριμμάτων του Νομού Χανίων και η επίδραση τους στην ατμοσφαιρική ρύπανση εξετάστηκε στο πλαίσιο της παρούσας εργασίας. Συγκεκριμένα, οι ρυθμοί εκπομπής των εξωτερικών χώρων χρησιμοποιήθηκαν ως παράμετροι εισόδου σε μοντέλο διασποράς για τον υπολογισμό των συγκεντρώσεων των αιωρούμενων σωματιδίων σε εξωτερικούς χώρους. Η σημαντικότερη πηγή αιωρούμενων σωματιδίων στους εξωτερικούς χώρους της μονάδας διαχείρισης απορριμμάτων του Νομού Χανίων είναι η επαναιώρηση σκόνης λόγω της κίνησης των απορριμματοφόρων σε δρόμους. Επιπλέον, εκπομπές αιωρούμενων σωματιδίων δημιουργούνται από την αιολική διάβρωση των σωρών του κομπόστ και της χωματοκάλυψης του ΧΥΤ (landfill cover).Τα αιωρούμενα σωματίδια εισέρχονται στον ανθρώπινο οργανισμό κυρίως μέσω της αναπνευστικής οδού. Τα σωματίδια που εναποτίθενται στο αναπνευστικό σύστημα μεταφέρονται στη συνέχεια στο υπόλοιπο σώμα. Η προσομοίωση των μηχανισμών με τους οποίους τα αιωρούμενα σωματίδια εισέρχονται στον οργανισμό, εναποτίθενται, συσσωρεύονται και μεταφέρονται στη συνέχεια στο υπόλοιπο σώμα πραγματοποιείται με μοντέλα δοσιμετρίας. Στο πλαίσιο της παρούσας εργασίας αναπτύχθηκε ένα μοντέλο δοσιμετρίας (ExDoM2) για τον υπολογισμό της εσωτερικής δόσης των αιωρούμενων σωματιδίων στο ανθρώπινο σώμα. Το μοντέλο ExDoM2 αποτελείται από ένα αναθεωρημένο μοντέλο εναπόθεσης/απομάκρυνσης σωματιδίων από το αναπνευστικό σύστημα (αναβαθμισμένη έκδοση του ExDoM) και από ένα φαρμακοκινητικό (PBPK) μοντέλο. Το αναθεωρημένο μοντέλο εναπόθεσης/απομάκρυνσης σωματιδίων ενσωματώνει νέους μηχανισμούς καθαρισμού σωματιδίων από το αναπνευστικό σύστημα και χρησιμοποιήθηκε για την εκτίμηση της εναποτιθέμενης δόσης σωματιδίων στο αναπνευστικό σύστημα, την κατακράτηση/συσσώρευση (retention) τους σε αυτό, τη μεταφορά τους στον οισοφάγο (γαστρεντερικό σύστημα) και στους λεμφαδένες και την απορρόφηση τους στο αίμα. Το PBPK μοντέλο χρησιμοποιήθηκε για τη μεταφορά των μετάλλων (As, Pb, Cd, Cr και Mn) που περιέχουν τα αιωρούμενα σωματίδια από το αίμα στο ανθρώπινο σώμα (π.χ. συκώτι, καρδιά, νεφροί, εγκέφαλος, γαστρεντερικό σύστημα). Η σημαντικότερη διαφορά στο μοντέλο ExDoM2 που αναπτύχθηκε στο πλαίσιο της παρούσας εργασίας από τα υπόλοιπα μοντέλα (π.χ. ExDoM, MPPD) που έχουν αναπτυχθεί στη διεθνή βιβλιογραφία είναι ότι ενσωματώνει ένα PBPK μοντέλο για συγκεκριμένα μέταλλα (As, Pb, Cd, Cr και Mn) που περιέχουν τα αιωρούμενα σωματίδια. Επιπλέον, το μοντέλο εναπόθεσης/απομάκρυνσης σωματιδίων από το αναπνευστικό σύστημα του ΕxDoM2 ενσωματώνει νέους μηχανισμούς καθαρισμού σωματιδίων από το αναπνευστικό σύστημα με βάση το αναθεωρημένο μοντέλο της Διεθνούς Επιτροπής Ακτινοπροστασίας (ICRP) και επιπλέον επιτρέπει στο χρήστη να εισάγει διαφορετικές μετρήσεις κατανομής μεγέθους σωματιδίων (ανά ώρα) για τον καθορισμό ρεαλιστικού σεναρίου έκθεσης του ανθρώπου σε διαφορετικά μικροπεριβάλλοντα κατά τη διάρκεια της ημέρας. Τα δεδομένα εισόδου που χρησιμοποιήθηκαν κατά την εφαρμογή του μοντέλου ExDoM2 προήλθαν από μετρήσεις πεδίου στη μονάδα διαχείρισης απορριμμάτων του Νομού Χανίων. Επιλέχθηκαν προς μελέτη τέσσερις κατηγορίες ατόμων: (α) εργαζόμενοι στον εξωτερικό χώρο του ζυγιστηρίου (β) εργαζόμενοι στον εσωτερικό χώρο χειροδιαλογής (πρώτη βάρδια), (γ) εργαζόμενοι στον εσωτερικό χώρο χειροδιαλογής (δεύτερη βάρδια) και (δ) μη- εργαζόμενοι στη μονάδα διαχείρισης απορριμμάτων του Νομού Χανίων. Ο σκοπός της χρήσης διαφορετικών σεναρίων έκθεσης είναι να καθορίσει εάν η δόση σωματιδίων των εργαζομένων στη μονάδα διαχείρισης απορριμμάτων του Νομού Χανίων είναι αυξημένη σε σύγκριση με εκείνη του γενικού πληθυσμού της περιοχής

Regional deposited dose in the human respiratory tract using different particulate metrics

The objective of the current study was to calculate the deposited dose rate in the human respiratory tract arising from particle number (PN) and particle mass (PM) measurements. A main objective was the investigation of deposition pattern and characteristics of the two metrics in the human respiratory tract. The dose rate was estimated for residents at a suburban background location (Chania, Greece). The total dose rate showed two peaks, one in the morning (1.6 × 109 particles/h at 7:00-8:00) and the other one at night (2.1 × 109 particles/h at 21:00-22:00), during the warm period, while the cold period showed two peaks, morning (2.0 × 109 particles/h at 9:00-10:00) and afternoon (3.6 × 109 particles/h at 18:00-19:00). The peaks during the warm period were associated with traffic emissions, whereas the peaks during the cold period were associated with both heating and traffic emissions. A higher dose rate of PN10 was found in the alveolar region while for PM10 it was found in the extrathoracic region. These findings are linked with increased contribution of ultrafine and coarse particles to PN10 (65%-78% and 54%-62% for cold and warm periods, respectively) and PM10 (63% and 55% for cold and warm periods, respectively) concentrations, respectively. The current study showed the importance to use both number and mass aerosol metrics for determining the human exposure and regional dose and their related health effects. The novelty of the current study is the simultaneous measurements of the two particles metrics and the full particle size distributions to make accurate estimates of regional deposited dose

The Representativeness of Outdoor Particulate Matter Concentrations for Estimating Personal Dose and Health Risk Assessment of School Children in Lisbon

This study investigated the suitability of outdoor particulate matter data obtained from a fixed monitoring station in estimating the personal deposited dose. Outdoor data were retrieved from a station located within the urban area of Lisbon and simulations were performed involving school children. Two scenarios were applied: one where only outdoor data were used assuming an outdoor exposure scenario, and a second one where an actual exposure scenario was adopted using the actual microenvironment during typical school days. Personal PM10 and PM2.5 dose (actual exposure scenario) was 23.4% and 20.2% higher than the ambient (outdoor exposure scenario) PM10 and PM2.5 doses, respectively. The incorporation of the hygroscopic growth in the calculations increased the ambient dose of PM10 and PM2.5 by 8.8% and 21.7%, respectively. Regression analysis between the ambient and personal dose showed no linearity with R2 at 0.07 for PM10 and 0.22 for PM2.5. On the other hand, linear regression between the ambient and school indoor dose showed no linearity (R2 = 0.01) for PM10 but moderate (R2 = 0.48) for PM2.5. These results demonstrate that ambient data must be used with caution for the representativeness of a realistic personal dose of PM2.5 while for PM10 the ambient data cannot be used as a surrogate of a realistic personal dose of school children

Characterization of Human Health Risks from Particulate Air Pollution in Selected European Cities

The objective of the current study was to estimate health risk indexes caused by the inhalation of particulate matter (PM) by adult males and children using data sampled in three European cities (Athens, Kuopio, Lisbon). Accordingly, the cancer risk (CR) and the hazard quotient (HQ) were estimated from particle-bound metal concentrations whilst the epidemiology-based excess risk (ER), the attributable fraction (AF), and the mortality cases were obtained due to exposure to PM10 and PM2.5. CR and HQ were estimated using two methodologies: the first methodology incorporated the particle-bound metal concentrations (As, Cd, Co, Cr, Mn, Ni, Pb) whereas the second methodology used the deposited dose rate of particle-bound metals in the respiratory tract. The indoor concentration accounts for 70% infiltration from outdoor air for the time activity periods allocated to indoor environments. HQ was lower than 1 and the cumulative CR was lower than the acceptable level (10−4), although individual CR for some metals exceeded the acceptable limit (10−6). In a lifetime the estimated number of attributable cancer cases was 74, 0.107, and 217 in Athens, Kuopio, and Lisbon, respectively. Excess risk-based mortality estimates (due to outdoor pollution) for fine particles were 3930, 44.1, and 2820 attributable deaths in Athens, Kuopio, and Lisbon, respectively

Α dosimetry model of hygroscopic particle growth in the human respiratory tract

Summarization: The objective of the current study was to determine the growth and deposition of hygroscopic aerosol particles in the human respiratory tract. A hygroscopic particle growth methodology was incorporated into an existing particle dosimetry model (Exposure Dose Model 2, ExDoM2) using the κ-Köhler theory, the International Commission on Radiological Protection (ICRP) formulation for hygroscopic growth and mathematical formulations for taking into account the residence time, the influence of hygroscopicity on the particle’s density, and hygroscopic growth at 99.5% relative humidity. In order to validate ExDoM2, the results of the model were compared with experimental total deposition data for NaCl particles. The incorporation of the hygroscopic growth resulted in predictions closer to the experimental data than to model results without the use of a hygroscopic model formulation. The hygroscopicity plays a more significant role in the lower regions (tracheobronchial (TB) and alveolar-interstitial (AI) regions) of the respiratory tract. In particular, the hygroscopicity of NaCl particles decreases the deposition in the AI region for particles in the size range 0.03 μm ≤ aerodynamic diameter (dae) ≤ 0.2 μm while for the size range 0.3 μm ≤ dae ≤ 3 μm, the hygroscopicity increases the deposition in the AI region. In addition, it is observed that the deposition of (NH4)2SO4 and NH4NO3 particles with dae ≥ 0.30 μm is higher when the hygroscopic properties of the particles are taken into consideration. However, the particle deposition in the range 0.02 μm ≤ dae ≤ 0.25 μm is decreased due to hygroscopicity.Παρουσιάστηκε στο: Air Quality, Atmosphere and Healt

Size distribution and metal composition of airborne particles in a waste management facility

Summarization: The objective of the current study was to measure the particle mass concentration, mass size distribution, and metal composition of airborne particles in a waste management facility located at Chania (Crete, Greece). Measurements were performed at two locations of the waste management facility. High particulate matter (PM10) concentrations were observed at the indoor site of manual waste sorting. In particular, the average concentration of PM10 was equal to 217 μg/m3 during working hours, while during non-working hours was equal to 60 μg/ m3. The particle mass size distributions were unimodal reflecting the resuspension of coarse particles. Furthermore, the deposited dose of particles and particle-bound metals and their retention in the human respiratory tract was determined using a dosimetry model (ExDoM2). The ExDoM2 model was applied for an adult male worker (06:30–14:30) at the indoor site of a manual waste sorting. The daily working deposited dose of PM10 ranged from 1677 to 3028 μg, while the daily working deposited dose of particle-bound metals ranged from 22 to 39 μg. The highest daily working deposited dose in the respiratory tract is calculated for iron mass (PΜFe) and the daily working deposited dose for PΜFe ranged from 18 to 33 μg.Παρουσιάστηκε στο: Journal of Material Cycles and Waste Managemen

Simulations of the deposition of pharmaceutical aerosols in the human respiratory tract by dry powder inhalers (DPIs)

Summarization: Investigation of pharmaceutical aerosol deposition in the human respiratory tract is an important topic because it enhances knowledge regarding the effective treatment of lung diseases. Herein, deposition in the human respiratory tract produced by the use of Dry Powder Inhalers (DPIs) was modeled for an adult male. A modified version of the model named Exposure Dose Model 2 (ExDoM2) was used where simulations incorporated both monodisperse and polydisperse aerosols. The impact of breath holding and mouthpiece diameter was also examined. The results revealed that the larger the aerodynamic diameter, the greater the deposition in the extrathoracic region. On the contrary, higher deposition of polydisperse particles in the tracheobronchial and alveolar-interstitial region was observed for particles with aerodynamic diameter 2–4 μm. In the extrathoracic region, deposition increased with a decrease in the mouthpiece diameter. However, its effect is negligible for particles approximately <1 μm in the tracheobronchial and alveolar-interstitial regions. For bigger particles, an increase in mouthpiece diameter resulted in an increase of the deposition. Similar findings were obtained for monodisperse particles. In addition, the results showed that breath holding increases the deposition in the lungs for all mouthpiece diameters and Mass Median Aerodynamic Diameters (MMADs), which confirms the medical recommendations of breath holding after inhalation of pharmaceutical aerosols through DPIs for more effective treatment of lung diseases. Finally, the user of the modified version of ExDoM2 has the capability to modify the parameters of the model for a more representative/realistic scenario. Future objectives include simulations that adopt the effect of particle properties (density and shape factor) and other parameters (such as the tidal volume), as well as simulations incorporating deposition using realistic input data (MMAD and standard deviation sg).Presented on: Journal of Drug Delivery Science and Technolog