Exhaled Breath Condensate Samples Research Articles

Metal and oxidative potential exposure through particle inhalation and oxidative stress biomarkers: a 2-week pilot prospective study among Parisian subway workers

ObjectiveIn this pilot study on subway workers, we explored the relationships between particle exposure and oxidative stress biomarkers in exhaled breath condensate (EBC) and urine to identify the most relevant biomarkers for a large-scale study in this field.MethodsWe constructed a comprehensive occupational exposure assessment among subway workers in three distinct jobs over 10 working days, measuring daily concentrations of particulate matter (PM), their metal content and oxidative potential (OP). Individual pre- and post-shift EBC and urine samples were collected daily. Three oxidative stress biomarkers were measured in these matrices: malondialdehyde (MDA), 8-hydroxy-2′deoxyguanosine (8-OHdG) and 8-isoprostane. The association between each effect biomarker and exposure variables was estimated by multivariable multilevel mixed-effect models with and without lag times.ResultsThe OP was positively associated with Fe and Mn, but not associated with any effect biomarkers. Concentration changes of effect biomarkers in EBC and urine were associated with transition metals in PM (Cu and Zn) and furthermore with specific metals in EBC (Ba, Co, Cr and Mn) and in urine (Ba, Cu, Co, Mo, Ni, Ti and Zn). The direction of these associations was both metal- and time-dependent. Associations between Cu or Zn and MDAEBC generally reached statistical significance after a delayed time of 12 or 24 h after exposure. Changes in metal concentrations in EBC and urine were associated with MDA and 8-OHdG concentrations the same day.ConclusionAssociations between MDA in both EBC and urine gave opposite response for subway particles containing Zn versus Cu. This diverting Zn and Cu pattern was also observed for 8-OHdG and urinary concentrations of these two metals. Overall, MDA and 8-OHdG responses were sensitive for same-day metal exposures in both matrices. We recommend MDA and 8-OHdG in large field studies to account for oxidative stress originating from metals in inhaled particulate matter.

Sensitive detection of exhaled breath condensate inflammation biomarkers using boron nitride nanosheet/gold nanoparticle hybrids

An ultrasensitive electrochemical immunosensor using boron nitride nanosheet/gold nanoparticle (BNNS/AuNP) hybrids was developed for exhaled breath condensate (EBC) interleukin-6 (IL-6) quantification. BNNS were synthesized by chemical vapor deposition and decorated with AuNPs. The BNNS/AuNP hybrids were characterized by SEM, TEM, XRD, Raman, XPS, etc., and deposited on screen-printed carbon electrodes. Anti-IL-6 antibodies were immobilized via EDC/NHS crosslinking. The immunosensor detected IL-6 by differential pulse voltammetry technique with a linear range of 0.01–200 ng/mL and a limit of detection of 5 pg/mL. The sensor showed high reproducibility and selectivity. Validation with spiked EBC samples demonstrated good accuracy (relative error <5%). The sensor was successfully applied to analyze IL-6 in EBC samples. The BNNS/AuNP hybrid immunosensor provides a sensitive platform for non-invasive EBC biomarker quantification in respiratory diseases.

Digital image colorimetry for determination of ethanol in exhaled breath condensate.

Aim: This study aimed to develop a colorimetric approach for quantifying ethanol using smartphone image analysis. Method: This research presents a straightforward smartphone-based colorimetric sensor that efficiently measures ethanol levels in exhaled breath condensate (EBC) samples. The process involved changing the acidic dichromate color in an ethanolic solution, followed by image analysis. Results: The results showed that this method was able to estimate ethanol concentrations in the range of 300-1500 and 1600-8000μg ml-1 in EBC. Conclusion: This study was a follow-up study on the previous work published for the determination of ethanol in EBC samples and highlights the potential benefits of using digital images and smartphone applications for ethanol determination in biological samples.

Advances in proteomics methods for the analysis of exhaled breath condensate.

The analysis of exhaled breath condensate (EBC) demonstrates a promising avenue of minimally invasive biopsies for diagnostics. EBC is obtained by cooling exhaled air and collecting the condensation to be utilized for downstream analysis using various analytical methods. The aqueous phase of breath contains a large variety of miscible small compounds including polar electrolytes, amino acids, cytokines, chemokines, peptides, small proteins, metabolites, nucleic acids, and lipids/eicosanoids-however, these analytes are typically present at minuscule levels in EBC, posing a considerable technical challenge. Along with recent improvements in devices for breath collection, the sensitivity and resolution of liquid chromatography coupled to online mass spectrometry-based proteomics has attained subfemtomole sensitivity, vastly enhancing the quality of EBC sample analysis. As a result, proteomics analysis of EBC has been expanding the field of breath biomarker research. We present an au courant overview of the achievements in proteomics of EBC, the advancement of EBC collection devices, and the current and future applications for EBC biomarker analysis.

Biosensor for Rapid Measurement of Lactate in Exhaled Breath Condensate

Lactate concentration plays an important role in disease diagnostics. Higher lactate concentrations are associated with sepsis and septic shock [2], trauma [3], tissue hypoxia due to acute lung injury [4], and respiratory diseases [5]. Lactate level is also widely used in monitoring athletes’ training and fitness as long-term exhausting exercise leads to a rapid increase in lactate level and result in muscle weakening and fatigue [6]. Compared with the traditional blood sample media which is invasive and capillary blood monitoring is not suitable for routine clinical use, the exhaled breath condensate (EBC) is simple and non-invasive method with no potential for adverse effects for lactate analysis.In this presentation, a point-of-care electrochemical biosensor is introduced for the EBC lactate analysis. This disposable and low-cost sensor is aimed to be inserted in an EBC collection device developed by our team that enables real-time monitoring and rapid measurements of EBC lactate level. The sensor measurement is done directly after EBC sample collection, that minimizes the risk of sample degradation and is cheaper than the traditional laboratory techniques such as fluorometry or mass spectrometry.The sensor is modified with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), Prussian blue (PB) and lactate oxidase (LOD) enzyme. Lactate concentration is measured from amperometric current response generated by the redox reactions on sensor surface. The enzyme gel formulation is optimized based on rotating disk electrode (RDE) experiments and kinetics analysis, investigating the effect of LOD concentration and gel thickness, and was then applied to disposable sensors.Finally, human EBC analysis is conducted on healthy subjects at rest and after 30 min of intense aerobic cycling exercise. Sensor’s results in real EBC lactate measurements demonstrate a good correlation with fluorometry and mass spectrometry calibrations and exhibit high stability and sensitivity in both short-term and long-term use. Mass production of the sensor is done by robotic gel dispensing using a Biodot aspirate dispensing machine.Note: This presentation is based on the corresponding author's recent publication ‘Rapid Measurement of Lactate in the Exhaled Breath Condensate: Biosensor Optimization and In-Human Proof of Concept’ in ACS Sensors (doi.10.1021/acssensors.2c01739) [1]

A clinical proteomics study of exhaled breath condensate and biomarkers for pulmonary embolism

Pulmonary embolism (PE) can be a diagnostic challenge. Current diagnostic markers for PE are unspecific and new diagnostic tools are needed. The air we exhale is a possible new source for biomarkers which can be tapped into by analysing the exhaled breath condensate (EBC). We analysed the EBC from patients with PE and controls to investigate if the EBC is a useful source for new diagnostic biomarkers of PE. We collected and analysed EBC samples from patients with suspected PE and controls matched on age and sex. Patients in whom PE was ruled out after diagnostic work-up were included in the control group to increase the sensitivity and generalizability of the identified markers. EBC samples were collected using an RTube™. The protein composition of the EBCs were analysed using data dependent label-free quantitative nano liquid chromatography–tandem mass spectrometry. EBC samples from 28 patients with confirmed PE, and 49 controls were analysed. A total of 928 EBC proteins were identified in the 77 EBC samples. As expected, a low protein concentration was determined which resulted in many proteins with unmeasurable levels in several samples. The levels of HSPA5, PEBP1 and SFTPA2 were higher and levels of POF1B, EPPK1, PSMA4, ALDOA, and CFL1 were lower in PE compared with controls. In conclusion, the human EBC contained a variety of endogenous proteins and may be a source for new diagnostic markers of PE and other diseases.

Inflammatory markers in exhaled breath condensate in nonasthmatic children with food allergy

Allergy is a systemic inflammation; therefore, although the allergic symptom may be seen in a specific organ system, the effects of this inflammation may be seen in other organs. interleukin (IL) IL4, IL5 and IL13 are the major Th2 cytokines and e-cadherin is an epithelial barrier protein. The objective of this research was to assess indicators of inflammation specific to Th2 responses and proteins related to the protective barrier of the airway’s inner lining. These assessments were conducted using exhaled breath condensate (EBC), which provides insights into peripheral airway conditions of children suffering from food allergies. The study had 24 patients with food allergy and 24 control individuals younger than three years of age with no history of food reaction. The diagnosis of food allergy was based on food allergen-specific IgE and skin prick test positivity in our clinic and oral food testing in selected cases. EBC samples were obtained by Ecoscreen (Jaegar, Hoechberg, Germany). IL4, IL5, IL13 and E-cadherin levels were measured in these samples by enzyme linked immunoassay. The group of children with food allergies, consisting mainly of 14 girls, had a median age of 16 months, whereas the control group, which included 11 girls, had a median age of 15 months (p = 0.89). Comparing the two groups, children with food allergies exhibited notably lower levels of IL-13 in the EBC compared to the control group (median values of 59.14 and 76.36, respectively, p = 0.02). Conversely, the concentration of IL-4 in the EBC was significantly higher in children with food allergies (median values of 1.94 and 1.29, respectively, p = 0.003). However, the levels of IL-5 and e-cadherin showed no significant differences between the two groups (with p-values of 0.74 and 0.09, respectively) as shown in table . High level of IL-4 despite the low level of IL-13 in the EBC of children having food allergy may be indicative of an early inflammatory phase that is not yet in the effector phase. Studies about the evolution of this process later in life are needed to assess the role of airway inflammation in children with food allergy who develop asthma.

Carbonized aerogel/ZnO-based dispersive solid phase extraction of daclatasvir and sofosbuvir from biological samples prior to liquid chromatography–tandem mass spectrometry

Daclatasvir and sofosbuvir are antiviral medications utilized in the treatment of chronic hepatitis C virus (HCV) infection. Due to their low therapeutic index, careful monitoring is necessary to ensure that the optimal dose is administered. High-performance liquid chromatography-tandem mass spectrometry (HPLC–MS/MS) is an exceptionally sensitive and specific technique for quantifying these drugs within biological matrices. In this study, we developed a novel dispersive solid-phase extraction method employing a carbonized bio aerogel composite with ZnO for efficient extraction of daclatasvir and sofosbuvir from exhaled breath condensate, urine, and plasma samples. The extracted analytes were subsequently subjected to analysis using HPLC–MS/MS. Optimal parameters including pH adjustment, sorbent quantity variation, and elution solvent selection were fine-tuned to achieve maximum recovery efficiency while ensuring selectivity enhancements. The developed method demonstrated broad linearity ranging between 1.2 and 200 ng/mL along with good precision (relative standard deviations ≤6.2 %) and an acceptable coefficient of determination (r2 ≥0.994). These findings establish our proposed method as suitable for reliable drug quantification in clinical samples.

Effect of elexacaftor/tezacaftor/ivacaftor on mucus and mucociliary clearance in cystic fibrosis

BackgroundThe cystic fibrosis transmembrane conductance regulator (CFTR) modulator elexacaftor/tezacaftor/ivacaftor (E/T/I) is highly effective clinically for those with at least one F508del-CFTR allele. The effects of E/T/I on mucociliary clearance (MCC) and sputum properties are unknown. We, therefore, sought to characterize the effects of E/T/I on in vivo MCC and sputum characteristics hypothesized to impact mucus transport. MethodsForty-four participants ≥12 years of age were enrolled into this prospective, observational trial prior to initiation of E/T/I and had baseline measurement of MCC and characterization of induced sputum and exhaled breath condensate (EBC) samples. Study procedures were repeated after 1 month of E/T/I treatment. ResultsAverage age was 27.7 years with baseline forced expiratory volume in 1 second (FEV1) of 78.2 % predicted. 52 % of subjects had previously been treated with a 2-drug CFTR modulator combination. The average whole lung MCC rate measured over 60 min (WLAveClr60) significantly improved from baseline to post-E/T/I (14.8 vs. 22.8 %; p = 0.0002), as did other MCC indices. Sputum% solids also improved (modeled mean 3.4 vs. 2.2 %; p<0.0001), whereas non-significant reductions in sputum macrorheology (G’, G”) were observed. No meaningful changes in exhaled breath condensate endpoints (sialic acid:urea ratio, pH) were observed. ConclusionsE/T/I improved the hydration of respiratory secretions (% solids) and markedly accelerated MCC. These data confirm the link between CFTR function, mucus solid content, and MCC and help to define the utility of MCC and mucus-related bioassays in future efforts to restore CFTR function in all people with CF.

Online preconcentration and chiral separation of ofloxacin in exhaled breath condensate by capillary electrophoresis

Breath analysis is an effective method of monitoring systemic or respiratory ailments. A simple chiral capillary electrophoresis method coupled with an online field-amplified sample injection stacking method is presented for ultratrace quantification of the enantiomers of ofloxacin in exhaled breath condensate (EBC). The study is focused on the use of EBC as an easily available biological sample to monitor ofloxacin’s enantiomers levels with good patient compliance. The proposed method was validated in accordance with FDA guidelines over the concentration range of 0.004–1.0 µg mL−1 of racemic ofloxacin. Inter- and intra-day precision and accuracy were within the acceptable limit (below 8.50 %). The method was specific for routine analysis of ofloxacin’s enantiomers. A small volume of EBC samples from seven patients under ofloxacin therapy was analyzed using the proposed method in which the concentrations of “R” and “S” enantiomers were between 0.0026 and 0.056 µg mL−1.

Oxylipin concentration shift in exhaled breath condensate (EBC) of SARS-CoV-2 infected patients

Infection of airway epithelial cells with severe acute respiratory coronavirus 2 (SARS-CoV-2) can lead to severe respiratory tract damage and lung injury with hypoxia. It is challenging to sample the lower airways non-invasively and the capability to identify a highly representative specimen that can be collected in a non-invasive way would provide opportunities to investigate metabolomic consequences of COVID-19 disease. In the present study, we performed a targeted metabolomic approach using liquid chromatography coupled with high resolution chromatography (LC-MS) on exhaled breath condensate (EBC) collected from hospitalized COVID-19 patients (COVID+) and negative controls, both non-hospitalized and hospitalized for other reasons (COVID−). We were able to noninvasively identify and quantify inflammatory oxylipin shifts and dysregulation that may ultimately be used to monitor COVID-19 disease progression or severity and response to therapy. We also expected EBC-based biochemical oxylipin changes associated with COVID-19 host response to infection. The results indicated ten targeted oxylipins showing significative differences between SAR-CoV-2 infected EBC samples and negative control subjects. These compounds were prostaglandins A2 and D2, LXA4, 5-HETE, 12-HETE, 15-HETE, 5-HEPE, 9-HODE, 13-oxoODE and 19(20)-EpDPA, which are associated with specific pathways (i.e. P450, COX, 15-LOX) related to inflammatory and oxidative stress processes. Moreover, all these compounds were up-regulated by COVID+, meaning their concentrations were higher in subjects with SAR-CoV-2 infection. Given that many COVID-19 symptoms are inflammatory in nature, this is interesting insight into the pathophysiology of the disease. Breath monitoring of these and other EBC metabolites presents an interesting opportunity to monitor key indicators of disease progression and severity.

Elevated leukotriene B4 and 8-isoprostane in exhaled breath condensate from preterm-born infants

BackgroundInflammation and oxidative stress play a key role in the development of bronchopulmonary dysplasia (BPD), possibly contributing to persistent respiratory morbidity after preterm birth. We aimed to assess if inflammatory markers were elevated in exhaled breath condensate (EBC) of infants born very prematurely (< 32 weeks gestation) at 12–16 corrected months of age, and if increased levels were associated with BPD diagnosis and respiratory morbidity.MethodsEBC samples and respiratory questionnaires were collected from 15 term-born infants and 33 preterm-born infants, 12 with a neonatal BPD diagnosis. EBC samples were analysed for leukotriene B4 (inflammation) and 8-isoprostane (oxidative stress) concentrations using enzyme-linked immune-assays. Differences between groups were analysed by Kruskal-Wallis Test with post-hoc comparisons, independent samples t-test or Mann-Whitney U test depending on normality of the data.ResultsLeukotriene B4 and 8-isoprostane levels were elevated in exhaled breath condensate of preterm-born infants compared to those born at term (mean difference [95% CI]; 1.52 [0.45, 2.59], p = 0.02; 0.77 [0.52, 1.02], p < 0.001, respectively). Leukotriene B4 and 8-isoprostane levels were independent of BPD diagnosis and respiratory morbidity over the first year of life.ConclusionsInfants born very prematurely exhibit elevated markers of airway neutrophilic inflammation and oxidative stress beyond the first year of life, regardless of a neonatal diagnosis of chronic lung disease or respiratory morbidity during infancy. These findings may have implications for future lung health.Trial RegistrationN/A.

The mediating role of exhaled breath condensate metabolites in the effect of particulate matter on pulmonary function in schoolchildren: A crossover intervention study

The role played by metabolites in exhaled breath condensate (EBC) in the effect of PM on schoolchildren's pulmonary function has received little attention. Accordingly, we examined whether metabolites in EBC mediated the effect of PM10, PM2.5, and PM1 on the pulmonary function of schoolchildren at a residential primary school who had received an air-cleaner cross-over intervention. Samples of EBC were collected from a total of 60 schoolchildren and subjected to metabolomics analysis. We found that the effect of PM on six pulmonary function indicators was mediated by the following nine lipid peroxidation-related and energy metabolism-related metabolites present in EBC: 4-hydroxynonenal, arachidoyl ethanolamide, dl-pyroglutamic acid, 5-deoxy-d-glucose, myristic acid, lauric acid, linoleic acid, l-proline, and palmitic acid. However, while all nine of these metabolites mediated the effects of PM on boys' pulmonary function, only 4-hydroxynonenal, arachidoyl ethanolamide, and dl-pyroglutamic acid mediated the effects of PM on girls' pulmonary function. Overall, our results show that (1) short-term exposure to PM affected the schoolchildren's pulmonary function by causing an imbalance between lipid peroxidation and glutathione-based antioxidant activity and by perturbing energy metabolism in respiratory system and (2) there was a sex-dependent antioxidant response to PM exposure, with boys being less resistant than girls.

Conversion of specific lncRNAs to biomarkers in exhaled breath condensate samples of patients with advanced stage non-small-cell lung cancer.

Objectives: Lung cancer (LC) is one of the most prevalent cancers with the highest fatality rate worldwide. Long noncoding RNAs (lncRNAs) are being considered potential new molecular targets for early diagnosis, follow-up, and individual treatment decisions in LC. Therefore, this study evaluated whether lncRNA expression levels obtained from exhaled breath condensate (EBC) samples play a role in the occurrence of metastasis in the diagnosis and follow-up of patients with advanced lung adenocarcinoma (LA). Methods: A total of 40 patients with advanced primary LA and 20 healthy controls participated in the study. EBC samples were collected from patients (during diagnosis and follow-up) and healthy individuals for molecular analysis. Liquid biopsy samples were also randomly obtained from 10 patients with LA and 10 healthy people. The expression of lncRNA genes, such as MALAT1, HOTAIR, PVT1, NEAT1, ANRIL, and SPRY4-IT1 was analyzed using cfRNA extracted from all clinical samples. Results: In the diagnosis and follow-up of patients with LA, lncRNA HOTAIR (5-fold), PVT1 (7.9-fold), and NEAT1 (12.8-fold), PVT1 (6.8-fold), MALAT1 (8.4-fold) expression levels were significantly higher than those in healthy controls, respectively. Additionally, the distinct lncRNA expression profiles identified in EBC samples imply that decreased ANRIL-NEAT1 and increased ANRIL gene expression levels can be used as biomarkers to predict the development of bone and lung metastases, respectively. Conclusion: EBC is an innovative, easily reproducible approach for predicting the development of metastases, molecular diagnosis, and follow-up of LC. EBC has shown potential in elucidating the molecular structure of LC, monitoring changes, and discovering novel biomarkers.

Exhaled breath condensate profiles of U.S. Navy divers following prolonged hyperbaric oxygen (HBO) and nitrogen-oxygen (Nitrox) chamber exposures

Prolonged exposure to hyperbaric hyperoxia can lead to pulmonary oxygen toxicity (PO2tox). PO2tox is a mission limiting factor for special operations forces divers using closed-circuit rebreathing apparatus and a potential side effect for patients undergoing hyperbaric oxygen (HBO) treatment. In this study, we aim to determine if there is a specific breath profile of compounds in exhaled breath condensate (EBC) that is indicative of the early stages of pulmonary hyperoxic stress/PO2tox. Using a double-blind, randomized ‘sham’ controlled, cross-over design 14 U.S. Navy trained diver volunteers breathed two different gas mixtures at an ambient pressure of 2 ATA (33 fsw, 10 msw) for 6.5 h. One test gas consisted of 100% O2 (HBO) and the other was a gas mixture containing 30.6% O2 with the balance N2 (Nitrox). The high O2 stress dive (HBO) and low O2 stress dive (Nitrox) were separated by at least seven days and were conducted dry and at rest inside a hyperbaric chamber. EBC samples were taken immediately before and after each dive and subsequently underwent a targeted and untargeted metabolomics analysis using liquid chromatography coupled to mass spectrometry (LC-MS). Following the HBO dive, 10 out of 14 subjects reported symptoms of the early stages of PO2tox and one subject terminated the dive early due to severe symptoms of PO2tox. No symptoms of PO2tox were reported following the nitrox dive. A partial least-squares discriminant analysis of the normalized (relative to pre-dive) untargeted data gave good classification abilities between the HBO and nitrox EBC with an AUC of 0.99 (±2%) and sensitivity and specificity of 0.93 (±10%) and 0.94 (±10%), respectively. The resulting classifications identified specific biomarkers that included human metabolites and lipids and their derivatives from different metabolic pathways that may explain metabolomic changes resulting from prolonged HBO exposure.

Biomarkers of nitrosative stress in exhaled breath condensate and serum among patients with cystic fibrosis

PurposeThe measurement of biomarkers in exhaled breath condensate (EBC) offers a non-invasive way to assess airway disease and can be easily done in a clinical setting among patients with cystic fibrosis (CF). The role of oxidative and nitrosative stress in the complex pathophysiology of CF is widely accepted and biomarkers of oxidative and nitrosative stress can be measured in the serum and EBC. To our knowledge, this is the first study to assess markers of nitrosative stress in EBC and serum, collected simultaneously from the CF patients. Patients and methodsPaired EBC and serum samples were collected from 36 stable patients with CF and 14 healthy controls. Markers of nitrosative stress ‒ 3-nitrotyrosine and nitrate/nitrite were measured in the EBC and serum using an enzyme-linked immunosorbent assay. ResultsWe found no differences in 3-nitrotyrosine and nitrate/nitrite in the EBC of patients with CF as compared to healthy controls (125.37 ​± ​3.29 vs. 126.24 ​± ​2.21 ​nmol/L, p ​= ​0.218; 12.66 ​± ​7.23 vs. 8.79 ​± ​4.83 ​μmol/L, p ​= ​0.133, respectively). Furthermore, 3-nitrotyrosine and nitrate/nitrite were significantly higher in the serum of patients with CF as compared to the healthy controls (0.13 ​± ​0.02 vs. 0.11 ​± ​0.01 ​nmol/mg protein, p ​= ​0.003; 70.78 ​± ​22.55 vs. 53.08 ​± ​8.5 ​μmol/L, p ​= ​0.009, respectively). No correlations were found between the markers determined in the EBC and serum. ConclusionsThe results of the EBC nitrosative stress biomarkers should be interpreted with caution, especially in patients with stable disease, as the EBC values may be independent on levels of circulating markers that are elevated in the serum of patients with stable CF.

A new method for investigating bioequivalence of inhaled formulations: A pilot study on salbutamol.

Purpose: An efficient, cost-effective and non-invasive test is required to overcome the challenges faced in the process of bioequivalence (BE) studies of various orally inhaled drug formulations. Two different types of pressurized meter dose inhalers (MDI-1 and MDI-2) were used in this study to test the practical applicability of a previously proposed hypothesis on the BE of inhaled salbutamol formulations. Methods: Salbutamol concentration profiles of the exhaled breath condensate (EBC) samples collected from volunteers receiving two inhaled formulations were compared employing BE criteria. In addition, the aerodynamic particle size distribution of the inhalers was determined by employing next generation impactor. Salbutamol concentrations in the samples were determined using liquid and gas chromatographic methods. Results: The MDI-1 inhaler induced slightly higher EBC concentrations of salbutamol when compared with MDI-2. The geometric MDI-2/MDI-1 mean ratios (confidence intervals) were 0.937 (0.721-1.22) for maximum concentration and 0.841 (0.592-1.20) for area under the EBC-time profile, indicating a lack of BE between the two formulations. In agreement with the in vivo data, the in vitro data indicated that the fine particle dose (FPD) of MDI-1 was slightly higher than that for the MDI-2 formulation. However, the FPD differences between the two formulations were not statistically significant. Conclusion: EBC data of the present work may be considered as a reliable source for assessment of the BE studies of orally inhaled drug formulations. However, more detailed investigations employing larger sample sizes and more formulations are required to provide more evidence for the proposed method of BE assay.

106 Investigation of Workplace Silica Exposures Using Novel Samplers and Methods

Abstract Scientists from the Health and Safety Executive visited a manufacturing workplace where coatings are prepared by loading powders, frit and water into various sized mills. The aim of the visit was to determine potential worker exposures to dust and respirable crystalline silica by static air monitoring and exhaled breath condensate. Low-cost particle monitors were deployed alongside more established scientific equipment. Airborne dust concentrations were measured at three site locations using two photometers, an optical particle counter (OPC) and a respirable cyclone. The size distribution was measured in real-time using a low-cost OPC and by offline analysis of a polycarbonate membrane filter housed inside an inhalable sampler. Pre and post shift samples of exhaled breath condensate were collected from 6 workers, with samples analysed by single particle inductively coupled plasma mass spectrometry to measure the number and size of silicon containing particles present. The real-time air monitoring data at all three locations showed peaks in airborne concentrations corresponding to the loading activities and indicating the tasks most likely to contribute to worker exposure. The average concentration of respirable dust measured closest to the process was 0.13 mg.m-3 for the 8-hour shift. The low-cost monitors provided good information about the changes in concentration over time relating to worker activities.

15 Biomonitoring for Respirable Crystalline Silica: Determination of Si-Containing Particles in Exhaled Breath Condensate Using Single Particle Inductively Coupled Mass Spectrometry

Abstract Biological monitoring is a useful way of determining overall exposures to chemical substances; however, in the case of respirable crystalline silica (RCS), this has not been possible in conventional biological matrices.  Previous research at HSE has shown that it was possible to detect silicon-containing particles in exhaled breath condensate (EBC) samples using single particle inductively coupled mass spectrometry (spICPMS) in a small number of quarry workers, and at that time the method had a particle size detection limit of around 300 nm.  In more recent work presented here we will describe the advances in the methodology and the results from exhaled breath condensate samples collected from a range of UK workers with potential RCS exposures.  Control samples were also collected for comparison. Static air/bulk samples were also collected to allow the size distribution and concentration of RCS to be determined in each workplace. The analytical advances include moving to using an ICP tandem MS for better specificity with an improved sample introduction system.  This has increased the size range detection of silicon-containing particles, allowing measurements in the size range of 100-2000 nm, in a one minute acquisition.  We have also standardised the EBC sampling by collecting the same volume of exhaled air (50L) from each volunteer. This improved methodology offers a viable biomonitoring method for a range of workplaces and has the potential to inform information about the efficacy of respiratory protective equipment and control measures in the workplace, complementing occupational hygiene. 

39 Investigation of Workplace Silica Exposures Using Novel Samplers and Methods

Abstract Scientists from the Health and Safety Executive visited a range of workplaces where there was the potential for exposure to silica. The aim of the visits was to determine potential worker exposures to dust and respirable crystalline silica by static air monitoring and exhaled breath condensate (EBC). To evaluate potential airborne exposures low-cost particle monitors were deployed alongside more established scientific equipment.  On site airborne dust concentrations were measured at different locations using two photometers, an optical particle counter (OPC) and a respirable cyclone. The size distribution was measured in real-time using a low-cost OPC and by offline analysis of a polycarbonate membrane filter housed inside an inhalable sampler using a Coulter Counter III. Pre and post shift samples of EBC were taken from 29 workers, with samples analysed by single particle inductively coupled plasma tandem mass spectrometry to measure Si-containing particles.  The real-time air monitoring data showed sustained increased concentrations or peaks corresponding to specific areas or activities, therefore indicating the tasks and/or locations most likely to contribute to worker exposure. The low-cost instruments were also effective in highlighting site locations and tasks most likely to contribute to worker exposure. An approach combining multiple sampling techniques provided a good characterisation of airborne, silica containing dusts. The EBC results consistently showed increased numbers of silicon containing particles post-shift compared with pre-shift.