Potential Respiratory Hazards Research Articles

Respiratory and Other Hazard Characteristics of Substances in Cleaning Products Used in Healthcare Centres in England and Wales

Occupational use of cleaning products can cause asthma in healthcare workers but the cleaning agents responsible are not yet known. This study aimed to identify respiratory and other hazards in cleaning products on the National Health Service (NHS) supply chain online catalogue and used in the NHS. Information on cleaning products, their composition, and H-statements that identified hazard characteristics of chemical substances in them was obtained from chemical safety data sheets (SDSs). Furthermore, a quantitative structure-activity relationship model and a published asthmagen list were used to identify potential additional respiratory hazards. 473 cleaning products and 229 substances were identified. SDSs reported only 4 respiratory sensitizers but an additional 51 were suggested by the other 2 methods. In contrast, 25 respiratory irritants were identified using SDSs and only one from the asthmagen list. This comprehensive overview of cleaning agents' hazards has potential use in future risk assessment and epidemiological studies.

A numerical study on sedimentation effect of dust, smoke and traffic particle deposition in a realistic human lung

Inhalation of pollutants can be deadly for respiratory health, as toxic pollutants can penetrate the deep lungs which could occur severe respiratory infection and lead to life-threatening respiratory diseases. The excessive presence of pollutants in the environment increases the concern of potential respiratory health hazards. To date, a microscopic understanding of the sedimentation effect on dust, smoke and traffic (pollutant) particles transported to the airways is missing in the literature. This first-ever study aims to analyse the sedimentation effect in various directions of pollutant particle transport in airways. This study also quantitatively explains how particle size, density, and physical exercise impact pollutant particle transport and deposition (TD) in the human lung airways. The contribution of the sedimentation effect is largely independent of particle size. The sedimentation effect can also be found significant at the trachea region when the fluid flow is horizontal. Overall, traffic particles with large diameters and high flow rates are deposited in the upper lung, whereas dust particles with large diameters and high flow rates are deposited in the deep lung. It is expected that 79.1 % of the particles will reach the deep lung. The difference between the deposition rates of the horizontal and vertical lungs reduces if the particle size reduces, the flow rate increases or the particle density reduces. The deposition rate of a horizontal lung for the heaviest particles (traffic) at 15 L/min flow rate is about 4.5 % higher than that of a vertical lung with the same flow rate.

Respirable nano-particulate generations and their pathogenesis in mining workplaces: a review

There is a growing concern in mining community about the contribution of nano-particulates to miner’s health. Despite the health influence of respirable dusts and associated lung diseases have been recognized for decades in the mining industry, the nano-scale particulates accompanying with complicated physiochemical properties and their enormous contribution in quantity have been drawing attentions only in recent a few years because of the advancement of nano-science discipline. In this review, we examine the current regulations of dusts exposure and the dominant mass-based monitoring methods to point out the ignorance of nano-particulates in mining industry. The recognized mining-related nano-particulates sources are summarized to identify the mechanically generated finer particulates including particles and aerosols. In addition, the mechanism of adverse health impact on miner with exposure to nano-scale particulates is discussed in a detail to emphasize their substantial detriment as a potential respiratory hazard. Characterization of the complex physiochemical properties of nano-particulates are then summarized and discussed because these properties could be different from regular respirable dusts due to their dramatically increased surface area and particulate counts. The intent of this review is to demonstrate the potential of adverse health effect of nano-particulate on the mine personals throughout the mining cycle and to identify the research gaps of the mine nano-particulate characterization and quantification. We suggest that further understanding of the mining induced nano-particulate properties and their pathogenesis are critical for the future engineering control measure to mitigate the potential health threat for future miners.

Work-related asthma: A position paper from the Thoracic Society of Australia and New Zealand and the National Asthma Council Australia.

ABSTRACTWork‐related asthma (WRA) is one of the most common occupational respiratory conditions, and includes asthma specifically caused by occupational exposures (OA) and asthma that is worsened by conditions at work (WEA). WRA should be considered in all adults with asthma, but especially those with new‐onset or difficult to control asthma. Improvement in asthma symptoms when away from work is suggestive of WRA. Clinical history alone is insufficient to diagnose WRA; therefore, objective investigations are required to confirm the presence of asthma and the association of asthma with work activities. Management of WRA requires pharmacotherapy similar to that of non‐WRA, however, also needs to take into account control of the causative workplace exposure. Ongoing exposure will likely lead to decline in lung function and worsening asthma control. WRA is a preventable condition but this does rely on increased awareness of WRA and thorough identification and control of all potential occupational respiratory hazards.

Toxicological analysis of aerosols derived from three electronic nicotine delivery systems using normal human bronchial epithelial cells

Electronic nicotine delivery systems (ENDS) are a rapidly growing global market advertised as a safer alternative to combustible cigarettes. However, comprehensive investigations of END aerosol physicochemical and toxicological properties have not been fully explored across brands to assess relative safety. In this study, we evaluated aerosols collected from three ENDS – Juul Fruit Medley (5% nicotine), Logic Power (2.4% nicotine), and Mistic (1.8% nicotine). ENDS aerosols were generated using standard machine puffing regimen and collected with a novel fluoropolymer condensation trap. Triple quadrupole-inductively coupled plasma-mass determined the presence of heavy metals in collected aerosols. The toxicological effects of ENDS aerosols on normal human bronchial epithelial cells (NHBE) were investigated using cellular viability, reactive oxygen species, oxidative stress assays, along with DNA damage assessments using the CometChip©. Results indicated the total metal concentrations within collected ENDS aerosols were higher for Mistic and Logic compared to Juul. Logic Power aerosols elicited higher reactive oxygen species levels than Mistic and Juul in NHBE after 24-h exposure. Similar dose-dependent reductions of cellular viability and total glutathione were found for each exposure. However, Logic and Juul aerosols caused greater single stranded DNA damage compared to Mistic. Our study indicates that regardless of brand, ENDS aerosols are toxic to upper airway epithelial cells and may pose a potential respiratory hazard to occasional and frequent users.

Use of EpiAlveolar Lung Model to Predict Fibrotic Potential of Multiwalled Carbon Nanotubes.

Expansion in production and commercial use of nanomaterials increases the potential human exposure during the lifecycle of these materials (production, use, and disposal). Inhalation is a primary route of exposure to nanomaterials; therefore it is critical to assess their potential respiratory hazard. Herein, we developed a three-dimensional alveolar model (EpiAlveolar) consisting of human primary alveolar epithelial cells, fibroblasts, and endothelial cells, with or without macrophages for predicting long-term responses to aerosols. Following thorough characterization of the model, proinflammatory and profibrotic responses based on the adverse outcome pathway concept for lung fibrosis were assessed upon repeated subchronic exposures (up to 21 days) to two types of multiwalled carbon nanotubes (MWCNTs) and silica quartz particles. We simulate occupational exposure doses for the MWCNTs (1-30 μg/cm2) using an air-liquid interface exposure device (VITROCELL Cloud) with repeated exposures over 3 weeks. Specific key events leading to lung fibrosis, such as barrier integrity and release of proinflammatory and profibrotic markers, show the responsiveness of the model. Nanocyl induced, in general, a less pronounced reaction than Mitsui-7, and the cultures with human monocyte-derived macrophages (MDMs) showed the proinflammatory response at later time points than those without MDMs. In conclusion, we present a robust alveolar model to predict inflammatory and fibrotic responses upon exposure to MWCNTs.

Characterization of an aerosol generation system to assess inhalation risks of aerosolized nano-enabled consumer products

Objective: The aerosolization of common nano-enabled consumer products such as cosmetics has significantly increased engineered nanoparticle inhalation risks. While several studies have investigated the impact of cosmetic dermal exposures, inhalation hazards of aerosolized cosmetics are much less known but could pose considerable harm to users due to potential co-exposure of nanoparticles and other product components.Materials and Methods: In this study, we developed a fully automated aerosol generation system to examine the aerosol properties of four aerosolized nano-enabled cosmetics using real-time monitoring and sampling instrumentation. Physicochemical characterization of aerosols was conducted using scanning electron microscopy coupled with energy dispersive x-ray spectroscopy (SEM-EDX). Characterization and calibration of animal exposure pods coupled to the system were also performed by measuring and comparing particle concentrations between pods.Results and Discussion: Results show peak emissions are shade dependent and varied between 12,000–22,000 particles/cm3 with modal diameters ranging from 36 nm–1.3 µm. SEM-EDX analysis determined that the original products and collected aerosols have similar morphological features consisting of micron-sized particles decorated with nanoparticles and crystalline structures. Mean total particle concentration in pods at 5 and 10 mg/m3 target levels were 2.22E + 05 #/cm3 and 4.33E + 05 #/cm3, respectively, with <10% variability between pods.Conclusions: The fully automated exposure platform described herein provides reproducible aerosol generation, conforms to recommended guidelines on chemical testing, and therefore is suitable for future in vivo toxicological assessments to examine potential respiratory hazards of aerosolized nano-enabled consumer products.

Potential occupational and respiratory hazards in a Minnesota cannabis cultivation and processing facility.

Cannabis has been legalized in some form for much of the United States. The National Institute for Occupational Safety and Health (NIOSH) received a health hazard evaluation request from a Minnesota cannabis facility and their union to undertake an evaluation. NIOSH representatives visited the facility in August 2016 and April 2017. Surface wipe samples were collected for analysis of delta-9 tetrahydrocannabinol (Δ9-THC), delta-9 tetrahydrocannabinol acid (Δ9-THCA), cannabidiol, and cannabinol. Environmental air samples were collected for volatile organic compounds (VOCs), endotoxins (limulus amebocyte lysate assay), and fungal diversity (NIOSH two-stage BC251 bioaerosol sampler with internal transcribed spacer region sequencing analysis). Surface wipe samples identified Δ9-THC throughout the facility. Diacetyl and 2,3-pentanedione were measured in initial VOC screening and subsequent sampling during tasks where heat transference was greatest, though levels were well below the NIOSH recommended exposure limits. Endotoxin concentrations were highest during processing activities, while internal transcribed spacer region sequencing revealed that the Basidiomycota genus, Wallemia, had the highest relative abundance. To the authors' knowledge, this is the first published report of potential diacetyl and 2,3-pentanedione exposure in the cannabis industry, most notably during cannabis decarboxylation. Endotoxin exposure was elevated during grinding, indicating that this is a potentially high-risk task. The findings indicate that potential health hazards of significance are present during cannabis processing, and employers should be aware of potential exposures to VOCs, endotoxin, and fungi. Further research into the degree of respiratory and dermal hazards and resulting health effects in this industry is recommended.

Update of occupational lung disease.

ObjectiveOccupational Lung Disease is an oldest but still a biggest problem in occupational health.MethodsSteering Committee members of the Japan Society for Occupational Health (JSOH) Occupational Lung Disease Study Group selected and summarized current topics on occupational lung diseases based on expert opinion, as informed by governmental regulation, public health concerns, and frequently discussed in related academic conferences.ResultsThe topics included in this review are professional education in medical screening skills, 2014 update of Helsinki Criteria, respiratory diseases found in the earthquake and tsunami affected regions, newly recognized occupational lung diseases, and potential respiratory health hazards.DiscussionsAlthough occupational lung diseases seem to stay as one of the major concerns in occupational health, screening tools and control measures are standardized for the better prevention of the diseases. As this health problem usually occurs in where the most actively economically developing area is, the patients tend to increase in emerging economic powers with huge population.

Assessment of the potential respiratory hazard of volcanic ash from future Icelandic eruptions: a study of archived basaltic to rhyolitic ash samples

BackgroundThe eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011), Iceland, triggered immediate, international consideration of the respiratory health hazard of inhaling volcanic ash, and prompted the need to estimate the potential hazard posed by future eruptions of Iceland’s volcanoes to Icelandic and Northern European populations.MethodsA physicochemical characterization and toxicological assessment was conducted on a suite of archived ash samples spanning the spectrum of past eruptions (basaltic to rhyolitic magmatic composition) of Icelandic volcanoes following a protocol specifically designed by the International Volcanic Health Hazard Network.ResultsIcelandic ash can be of a respirable size (up to 11.3 vol.% < 4 μm), but the samples did not display physicochemical characteristics of pathogenic particulate in terms of composition or morphology. Ash particles were generally angular, being composed of fragmented glass and crystals. Few fiber-like particles were observed, but those present comprised glass or sodium oxides, and are not related to pathogenic natural fibers, like asbestos or fibrous zeolites, thereby limiting concern of associated respiratory diseases. None of the samples contained cristobalite or tridymite, and only one sample contained quartz, minerals of interest due to the potential to cause silicosis. Sample surface areas are low, ranging from 0.4 to 1.6 m2 g−1, which aligns with analyses on ash from other eruptions worldwide. All samples generated a low level of hydroxyl radicals (HO•), a measure of surface reactivity, through the iron-catalyzed Fenton reaction compared to concurrently analyzed comparative samples. However, radical generation increased after ‘refreshing’ sample surfaces, indicating that newly erupted samples may display higher reactivity. A composition-dependent range of available surface iron was measured after a 7-day incubation, from 22.5 to 315.7 μmol m−2, with mafic samples releasing more iron than silicic samples. All samples were non-reactive in a test of red blood cell-membrane damage.ConclusionsThe primary particle-specific concern is the potential for future eruptions of Iceland’s volcanoes to generate fine, respirable material and, thus, to increase ambient PM concentrations. This particularly applies to highly explosive silicic eruptions, but can also hold true for explosive basaltic eruptions or discrete events associated with basaltic fissure eruptions.

Study of respiratory status in young male automobile painters: A cross sectional study

Background: Painters are exposed to solvent fumes and aerosols containing various concentrations of pigments, binders, fillers (talc), and chemically reactive monomers. Specific components in paint, such as isocyanates and dimethyl ethanolamine, are capable of inducing acute and chronic forms of airflow obstruction. Our study aims to establish the hypothesis that even young male painters may be at an increased risk of developing respiratory impairment. We studied the respiratory status of young male painters exposed to paints for more than 5 years and compared their pulmonary functions to a group of age- and sex-matched controls. Aims: To compare various parameters of lung functions in young male automobile spray painters with age- and sex-matched controls. Materials and Methods: This cross sectional study was conducted in the department of physiology and medicine. Fifty-eight young male spray painters who attended the medical outpatient department of our college were selected. Fifty-two age- and sex-matched controls were also selected from subjects who attended the medical outpatient department for routine medical checkup for recruitment in the same automobile company. After history and routine examinations, the patients were subjected to pulmonary function tests. Schiller's spirovit SP-1 was used. The data were analysed using Student's t test. Results: Significantly reduced forced expiratory volume in 1 s (FEV1)/slow vital capacity (SVC) (P Conclusions: Potential respiratory health hazard exists in automobile painters and exposure to organic solvents should be prevented in order to improve their health status.

Flavorings in electronic cigarettes: an unrecognized respiratory health hazard?

Flavorings in electronic cigarettes: an unrecognized respiratory health hazard?

In vivo approaches to assessing the toxicity of quantum dots.

The small size and heavy metal composition of quantum dots (QDs) combined with their growing consumer product and biomedical research applications have generated concern over their safety. In an occupational setting where QD-enabled products are being manufactured, inhalation is a likely route of exposure. Since current research indicates that QDs could cause inflammation and toxicity in the respiratory tract, it is important that a variety of methods be available to further characterize this potential respiratory hazard. This chapter focuses primarily on in vivo methods for modeling the inhalation and assessing the pulmonary toxicity of QDs.

Physicochemical and toxicological profiling of ash from the 2010 and 2011 eruptions of Eyjafjallajökull and Grímsvötn volcanoes, Iceland using a rapid respiratory hazard assessment protocol

The six week eruption of Eyjafjallajökull volcano in 2010 produced heavy ash fall in a sparsely populated area of southern and south eastern Iceland and disrupted European commercial flights for at least 6 days. We adopted a protocol for the rapid analysis of volcanic ash particles, for the purpose of informing respiratory health risk assessments. Ash collected from deposits underwent a multi-laboratory physicochemical and toxicological investigation of their mineralogical parameters associated with bio-reactivity, and selected in vitro toxicology assays related to pulmonary inflammatory responses. Ash from the eruption of Grímsvötn, Iceland, in 2011 was also studied. The results were benchmarked against ash from Soufrière Hills volcano, Montserrat, which has been extensively studied since the onset of eruptive activity in 1995.For Eyjafjallajökull, the grain size distributions were variable: 2–13vol% of the bulk samples were <4µm, with the most explosive phases of the eruption generating abundant respirable particulate matter. In contrast, the Grímsvötn ash was almost uniformly coarse (<3.5vol%<4µm material). Surface area ranged from 0.3 to 7.7m2g−1 for Eyjafjallajökull but was very low for Grímsvötn (<0.6m2g−1). There were few fibre-like particles (which were unrelated to asbestos) and the crystalline silica content was negligible in both eruptions, whereas Soufrière Hills ash was cristobalite-rich with a known potential to cause silicosis. All samples displayed a low ability to deplete lung antioxidant defences, showed little haemolysis and low acute cytotoxicity in human alveolar type-1 like epithelial cells (TT1). However, cell-free tests showed substantial hydroxyl radical generation in the presence of hydrogen peroxide for Grímsvötn samples, as expected for basaltic, Fe-rich ash. Cellular mediators MCP-1, IL-6, and IL-8 showed chronic pro-inflammatory responses in Eyjafjallajökull, Grímsvötn and Soufrière Hills samples, despite substantial differences in the sample mineralogy and eruptive styles.The value of the pro-inflammatory profiles in differentiating the potential respiratory health hazard of volcanic ashes remains uncertain in a protocol designed to inform public health risk assessment, and further research on their role in volcanic crises is warranted.

Airborne Endotoxin from Indoor and Outdoor Environments: Effect of Sample Dilution on the Kinetic Limulus Amebocyte Lysate (LAL) Assay

Airborne endotoxins in occupational environments are a potential respiratory hazard to individuals. In this study, airborne endotoxins were collected using open-face and button aerosol samplers from inside animal housing units and downwind from agricultural production sites and a wastewater treatment plant. Filter extracts were then diluted to examine the effect of interfering substances on the kinetic Limulus amebocyte lysate (LAL) assay. In most cases, the overall endotoxin concentration was shown to decrease with increasing dilution up to 1000-fold, suggesting the presence of enhancing substances in the filter extracts. This dilution-dependent effect was most prominent in the open-face endotoxin samples, while button samples displayed little effect. Using a joinpoint regression model, it was determined that a dilution factor of 50 to 100 was generally sufficient to eliminate the presence of enhancing substances. After screening the data for dilution dependent effects, the airborne endotoxin concentrations were determined. The highest endotoxin concentrations, ranging from 2841 to 49,066 endotoxin units m−3 of air, were found inside swine farrowing and finishing barns. Airborne endotoxin concentrations were 10- to 100-fold lower inside a dairy barn and downwind of other agricultural production sites and the wastewater treatment plant. Examination of dilution-dependent effects should be considered essential when utilizing the LAL assay, especially if values are to be used for regulatory purposes.

A physico-chemical assessment of the health hazard of Mt. Vesuvius volcanic ash

Mt. Vesuvius, Italy, is regarded as one of the world's most dangerous volcanoes because of the potential for vast numbers of people to be affected by the renewal of volcanic activity; more than 600 000 people live within 10 km of the summit alone. Vesuvius has been quiescent since 1944 and with continued dormancy, the more likely it is that the next eruption will be explosive. At that point, wide-spread concern is likely over the potential health hazard of the ash, away from the zone of primary volcanic hazards. Analyses of the mineralogical and geochemical characteristics of ash provide us with critical information on the potential toxicity of the particles, for example, whether particles are sufficiently small to enter the lungs and whether the particles have reactive properties which could trigger disease. Rapid assessment of these characteristics allows real-time decision making on hazard mitigation issues (e.g. distribution of dust masks) and allows considered judgement on whether to embark on major medical/toxicological studies. The study presented here is the first time that the potential respiratory health hazard of ash from Vesuvius volcano has been considered and allows planning for future eruption scenarios. Twenty-one ash samples, representing the range of eruption styles at Vesuvius, were collected and analysed. The results demonstrate that the physical processes of fragmentation play an important role in determining the grain size and, therefore, hazard, of the ash. Here, the finest samples derive from the interaction of magma and water during the final, phreatomagmatic phases of plinian and subplinian eruptions (∼ 16 vol.% <4 µm material), while the low-intensity explosivity activity, associated with lava effusion, produces coarse ash posing a lesser hazard. The quantity of material found in the different health-pertinent fractions is strongly correlated, allowing prediction of these fractions where only coarser sieve data are available. Since Vesuvius produces silica under-saturated products, ‘free’ crystalline silica in the ash does not pose a significant health hazard (< 2 wt.% cristobalite and <3 wt.% quartz). Surface tests showed that the capability of the ash to generate the highly-reactive hydroxyl free radical varies considerably amongst samples, with available surface iron correlating well with reactivity potential.

An examination of interventions to reduce respiratory health and injury hazards in homes of low-income families

We evaluated whether combining asthma trigger reduction with housing structural repairs, device disbursement and education in low-income households with children would improve self-reported respiratory health and reduce housing-related respiratory health and injury hazards (convenience sample of n=67 homes with 63 asthmatic and 121 non-asthmatic children). At baseline, a visual assessment of the home environment and a structured occupant interview were used to examine 29 potential injury hazards and 7 potential respiratory health hazards. A home-specific intervention was designed to provide the children's parents or caretakers with the knowledge, skills, motivation, supplies, equipment, and minimum housing conditions necessary for a healthy and safe home. The enrolled households were primarily Hispanic and owned their homes. On average, 8 injury hazards were observed in the homes at baseline. Four months following intervention, the average declined to 2.2 hazards per home ( p<0.001), with 97% of the parents reporting that their homes were safer following the interventions. An average of 3.3 respiratory health hazards were observed in the homes at baseline. Four months following intervention, the average declined to 0.9 hazards per home ( p<0.001), with 96% of parents reporting that the respiratory health of their asthmatic children improved. A tailored healthy homes improvement package significantly improves self-reported respiratory health and safety, reduces respiratory health and injury hazards, and can be implemented in concert with a mobile clinical setting.

Evaluation of Worker Exposure to Airborne Dust in Cotton Ginneries

Airborne dust in cotton ginneries is a nuisance as well as a potential respiratory hazard. The workers in ginneries are subjected to vagaries of airborne dust pollution. Exposure to dust causes cough, cold, fever, breathing difficulties and may even lead to lung disorders if exposed for long term. Dust concentration in mg! m3 of PM 2.5 11m and PM 10 11m was measured at different workstations. Time weighed average (TWA) of airborne dust of PM 2.5 and PM10 was found up to 2.30 and 3.75 mg/m3 respectively in conventional ginneries. In automatic ginneries, workers are exposed to TWA of airborne dust levels of PM 2.5 and PM 10 up to 0.20 and 0.58 mg/m3 , respectively. The workers in all types of ginneries are exposed to dust concentrations above the permissible limits in all workstations. The thoracic dust and respirable dust concentration levels were observed above the permissible limits in all the workstations. Workers employed in automatic ginneries are comparatively less exposed to airborne dust than conventional and semi-automatic ginneries. Workers stationed at press house, pala house and at lint opener are subjected to higher levels of airborne dust.

Chlorine-related Inhalation Injury from a Swimming Pool Disinfectant in a 9-year-old Girl

Chlorine is a potential respiratory hazard in both occupational and household settings. The clinical sequelae of inhalation are variable in severity and timing, and subacute presentation is a concern. We report the case of a 9-year-old girl who developed dyspnea, hypoxemia, and pneumonitis approximately 12 hours after exposure to chlorine released from aerosolized swimming pool purification tablets. Her course was characterized by improvement with supplemental oxygen and bronchodilator therapy. Follow-up pulmonary testing at 4 months after the episode revealed the presence of mild obstructive reactivity of the airways, but she was able to perform normal activities without requiring medications. We discuss the pathophysiology, symptoms, therapy, and long-term follow-up of chlorine inhalation injuries.

History and results of the two inter‐laboratory round robin endotoxin assay studies on cotton dust

In the US cotton industry, airborne cotton dust levels are regulated, and other countries are moving to specify safety limits for airborne endotoxins. There is concern about potential respiratory health hazards associated with agricultural and other organic dusts. In laboratories, ranking which samples have high and low levels of endotoxin is usually in good agreement between laboratories. When different laboratories assay identical samples, the levels differ. The objective of this research was to evaluate the intra- and inter-laboratory variability for 13 laboratories measuring endotoxin in cotton dust. Two inter-laboratory round robin endotoxin assay studies were conducted using cotton dust. In the first round robin, each laboratory used their normal in-house assay method and then used a common extraction protocol. In the second round robin, a common extraction protocol and endotoxin assay kit was used. The intra-laboratory results had small variations but inter-laboratory results had very high variations. The inter-laboratory results using a common extraction protocol showed reduced differences. Using the same extraction protocol and endotoxin assay kit, the intra-laboratory variation was small and inter-laboratory variation was reduced but not enough for inter-laboratory agreement. Most of the laboratories were able to discern between the high and low endotoxin concentration dusts. Standardization has reduced the differences in results between laboratories and possibly further standardization may bring closer inter-laboratory agreement.