Settled Dust Samples Research Articles

Six Feet under Microbiota: Microbiologic Contamination and Toxicity Profile in Three Urban Cemeteries from Lisbon, Portugal.

Cemeteries are potential environmental reservoirs of pathogenic microorganisms from organic matter decomposition. This study aimed to characterize the microbial contamination in three cemeteries, and more specifically in grave diggers’ facilities. One active sampling method (impingement method) and several passive sampling methods (swabs, settled dust, settled dust filters and electrostatic dust cloths—EDC) were employed. The molecular detection of Aspergillus sections and SARS-CoV-2, as well as mycotoxin analysis, screening of azole resistance, and cytotoxicity measurement were also conducted. Total bacteria contamination was 80 CFU·m−2 in settled dust samples, reached 849 CFU·m−2 in EDC and 20,000 CFU·m−2 in swabs, and ranged from 5000 to 10,000 CFU·m−2 in filters. Gram-negative bacteria (VRBA) were only observed in in settled dust samples (2.00 × 105 CFU·m−2). Regarding Aspergillus sp., the highest counts were obtained in DG18 (18.38%) and it was not observed in azole-supplemented SDA media. SARS-CoV-2 and the targeted Aspergillus sections were not detected. Mycophenolic acid was detected in one settled dust sample. Cytotoxic effects were observed for 94.4% filters and 5.6% EDC in A549 lung epithelial cells, and for 50.0% filters and 5.6% EDC in HepG2 cells. Future studies are needed in this occupational setting to implement more focused risk management measures.

Microbial contamination in waste collection: Unveiling this Portuguese occupational exposure scenario

Previous studies anticipated that microorganisms and their metabolites in waste will increase as a consequence of a decreased collection frequency and due to differences in what kind of waste is bagged before collection leading to an increased exposure of workers handling the waste. This study aim was to investigate the microbial contamination present in the waste collection trucks (WCT) and in the support facilities (waste collection station - WCS). It was applied a multi-approach protocol using active (air sampling by impingement and impaction) and passive (surface swabs, electrostatic dust cloths and settled dust) sampling methods. The screening of azole-resistance, the investigation of mycotoxins and the assessment of the elicited biological responses in vitro were also carried out aiming recognizing the possible health effects of waste collection drivers. SARS-CoV-2 detection was also performed. In WCS only air samples had contamination in all the four sampling sites (canteen, operational removal core, operational removal center, and administrative service). Among all the analyzed matrices from the WCT a higher percentage of total bacterial counts and Gram-was detected in swabs (66.93%; 99.36%). In WCS the most common species were Penicillium sp. (43.98%) and Cladosporium sp. (24.68%), while on WCT Aspergillus sp. (4.18%) was also one of the most found. In the azole resistance screening Aspergillus genera was not observed in the azole-supplemented media. SARS-CoV-2 was not detected in any of the environmental samples collected, but Aspergillus section Fumigati was detected in 5 samples. Mycotoxins were not detected in EDC from WCS, while in WCT they were detected in filters (N = 1) and in settled dust samples (N = 16). In conclusion, our study reveals that a comprehensive sampling approach using active and passive sampling (e.g. settled dust sampling for a representative mycotoxin evaluation) and combined analytic methods (i.e., culture-based and molecular) is an important asset in microbial exposure assessments. Concerning the waste collection exposure scenario, the results of this study unveiled a complex exposure, particularly to fungi and their metabolites. Aspergillus section Fumigati highlight the significance of targeting this section in the waste management industry as an indicator of occupational health risk.

Determination of Total Mercury and Carbon in a National Baseline Study of Urban House Dust

Mercury (Hg) is one of the top ten chemicals of concern for public health, according to the World Health Organization. This study investigates Hg concentrations in house dust collected from urban single family homes, to better understand typical indoor residential exposures. Using direct solid sample analysis, total Hg and carbon (TC) were determined in the <80 µm fraction of settled dust samples collected under the Canadian House Dust Study. Hg concentrations displayed a log-normal distribution with median/geomean of 0.68/0.70 mg/kg (n = 995). A small subset (<1%) of homes exhibited anomalously high dust Hg concentrations (>9.0 mg/kg). A comparison of Hg concentrations in fresh dust and household vacuum dust collected from the same homes indicated no significant difference in the two sampling methods. Total carbon concentrations displayed a median/geomean of 29.3/28.5% (n = 1011). A significant correlation between total Hg and TC in house dust (p < 0.00001) reflects the association between Hg and organic carbon previously observed in soil and sediments. The results of this study indicate a 10-fold enrichment in house dust compared with the average background concentrations reported for soil and sediments (0.07 mg/kg). The observed enrichment is attributable to Hg emissions from indoor sources and/or Hg carried home from occupational sources.

Questioning the appropriateness of sieving for processing indoor settled dust samples

Dust is a widely-used matrix for estimating human exposure to chemicals or as a screening tool for the identification of indoor chemicals of concern. As dust sampling became more common in exposure assessment, techniques used in processing soil have been adapted to dust samples, and separation of dust particles by sieving is common practice. However, there are no defined pore sizes, which results in inconsistent or difficult data interpretation and exposure estimates. Moreover, dust consists of more particle types than soil, particularly fibers, which behave differently during the sieving process. In this study, composite samples from seven microenvironments (homes, apartments, kindergartens, schools, public spaces, offices, and cars) were used to investigate the impact of the separation of dust by sieving on the observed chemical distributions. Dust was sieved to four particle size fractions (1-2 mm, 0.5-1 mm, 0.25-0.5 mm, and < 0.25 mm) and each fraction was analyzed for organic carbon content and polycyclic aromatic hydrocarbons (PAHs), and images of dust samples were taken by optical microscope. We identified irregular distributions across size fractions for carbon and PAHs as well as for fibrous particles. Based on the combination of chemical analyses and microscopy, we recommend careful consideration of pre-processing of dust samples to limit bias in dust exposure assessments, and sieving should be used only when necessary.

Global Patterns and Climatic Controls of Dust-Associated Microbial Communities.

ABSTRACTThe ubiquity and long-range transport of the microorganisms inhabiting dust can pose a serious risk to human, animal, and plant health. The well-recognized importance of dust-associated microorganisms contrasts starkly with our limited understanding of the factors determining the variation in the composition of these communities at the global scale. Here, we provide the first insight into the global determinants of dust-associated microorganisms by quantifying the environmental factors shaping bacterial and fungal community composition in 467 outdoor settled dust samples collected from 33 countries and 6 continents. Our results show that the global variation in dust-associated bacterial and fungal community composition was, to some degree, predictable from mean annual precipitation and temperature. Notably, our results show that the fungal genera Alternaria and Aspergillus, which contain many species that can serve as triggers of allergenic disease in humans and as plant pathogens, were more abundant in drier regions. Collectively, these results highlight the key influence of climate on the global distribution of dust-associated microorganisms and provide the baseline information needed to build a more comprehensive understanding of how microbial exposures vary across the globe and in response to climate change.IMPORTANCE A broad diversity of microorganisms can be found in dust, with some of these microorganisms capable of causing allergenic disease in human via inhalation or affecting plant health by acting as plant pathogens. However, the spatial variation in dust microbiomes and the environmental factors associated with this variation have not been comprehensively assessed at the global scale. Here, we investigated the bacteria and fungi found in outdoor settled dust samples spanning 33 countries and 6 continents. Our results show that dust-associated bacteria and fungi exhibit climate-driven variability in community composition at the global scale. Our results call for the development of strategies to predict the geographic distribution of dust-associated microorganisms and to identify the potential associations between microbial exposures and the health of humans, animals, and plants.

Health Risk Assessment, Pollution Indices and Ecological Risk of Chemical Elements in Dust and Soils of Warri Metropolis, Southern Nigeria

BACKGROUND AND AIM: Adverse health effects have been linked with human exposure to chemical contaminants via diverse environmental pathways. This study assessed pollution levels, ecological risk and health risk of chemical elements in dust and soils of Warri Metropolis, Southern Nigeria. METHODS: Forty topsoil and settled dust samples were collected from ten sampling sites and analysed for chemical elements using Inductively Coupled Plasma Mass Spectrophotometry. The results were subjected to descriptive and inferential statistical analysis. Pollution Index (PI), Ecological Risk Index (ERI), Nemerov Integrated Pollution Index (NIPI) and Health Risk [Hazard Quotient (HQ) and Cancer Risk (CR)] were also calculated. RESULTS:Results revealed high concentrations (mg/kg) of Cu (2.1-38.4), Zn (21.4-268.0), Ag (0.015-2.720), Hg (0.09-0.51), P (120-1230) and B (3.0-7.0) in dusts; and Cu (1.0-42.7), Zn (6.2-492.0), Ag (0.016-100), Hg (0.05-0.33), P (30-1960) and B (3.0-5.0) in soils. Cu, Zn, Hg and P concentrations were highest and exceeded permissible limits in poultry farm dusts and Pessu soils. PI indicated very strong pollution (P15) for Ag and low pollution (P11) for Zn and Pb. Heavy pollution (NIPI3) in Effurun-Sapele road and Ekpan dusts was attributed to heavy metals. ERI revealed moderate risk for heavy metals in Igbudu market dusts and Pessu soils while other locations had low risks. Non-carcinogenic health risk evaluation showed HQs greater than 1.0 for V, Cr, Mn, Fe, Co, Cu, Zn, Pb, As, Al and Ca, signifying adverse health effects. The CRs of As, Cr, Cd, Ni and Co for children and; Cr and Co for adults were higher than the acceptable limit of 1.0×10⁻⁴, suggesting probable development of cancer. CONCLUSIONS:This study established the occurrence of dust and soil pollution by chemical contaminants from industrial emissions, vehicular sources and open-dumping. The chemical element concentrations pose carcinogenic and non-carcinogenic risks to children and adult residents of the study area. KEYWORDS: Chemical exposures, Heavy metals, Risk assessment, Cancer and cancer precursors, Children's environmental health

Occupational exposure to anaerobic bacteria in a waste sorting plant

ABSTRACT The study focused on exposure assessment to bacterial aerosols and organic dust in waste sorting plant. Samples were collected at different workplaces of waste sorting cycle i.e.: waste press, reloading area, loading of conveyor belt, sorting cabin, sorting hall, and control room. A quantitative analysis of aerobic and anaerobic bacteria was supplemented by qualitative analysis of anaerobic biota with the use of culture-based methods and biochemical tests. In addition, inhalable dust concentrations were also evaluated. To confirm the presence of Clostridium genus, the PCR reaction with specific primers (Chis150f and ClostIr) was performed. The average concentration of total bacteria in waste sorting plant was 4347 CFU m−3 (SD = 2439), of which 66% were anaerobic strains (2852 CFU m−3; SD = 2127). It was found that about 24% of anaerobic bacteria belonged to Clostridium genus (682 CFU m−3; SD = 633). The highest contamination with anaerobic bacteria was observed near the waste reloading plant (3740 CFU m−3), and the lowest in the control room (850 CFU m−3). The average concentration of inhalable dust in the waste sorting plant was 0.81 mg m−3 (SD = 0.59). The correlation analysis showed that the presence of anaerobic bacteria, including clostridia was significantly determined by the microclimate parameters. Qualitative analysis showed the presence of 16 anaerobic species belonging to 9 genera, of which Actinomyces, Clostridium, and Gemella were present at all workplaces. The molecular analysis confirmed the presence of Clostridium genus in both bioaerosol and settled dust samples. Implications: The study showed that anaerobic bacteria should be taken into account as an important component of this microbiota when assessing the exposure of waste sorting workers to biological agents. However, future studies should investigate more precisely how the composition of sorted waste as well as the season can affect the diversity of anaerobic bacteria in this working environment. More attention should be paid to regular cleaning of equipment surfaces in the plant, as deposited organic dust is an important reservoir of anaerobic bacteria, including those of a potentially pathogenic nature.

Characterization of unsubstituted and methylated polycyclic aromatic hydrocarbons in settled dust: Combination of instrumental analysis and in vitro reporter gene assays and implications for cancer risk assessment

Concentrations of 34 unsubstituted and methylated polycyclic aromatic hydrocarbons (PAHs and Me-PAHs) and AhR-mediated activities in settled dust samples were determined by a combination of gas chromatography–mass spectrometry and an in vitro reporter gene assay (PAH-CALUX). The levels of Σ34PAHs and bioassay-derived benzo[a]pyrene equivalents (CALUX BaP-EQs) were significantly higher in workplace dust from informal end-of-life vehicle dismantling workshops than in common house dust and road dust. In all the samples, the theoretical BaP-EQs of PAHs (calculated using PAH-CALUX relative potencies) accounted for 28 ± 19% of the CALUX BaP-EQs, suggesting significant contribution of aryl hydrocarbon receptor (AhR) agonists and/or mixture effects. Interestingly, the bioassay-derived BaP-EQs in these samples were significantly correlated with not only unsubstituted PAHs with known carcinogenic potencies but also many Me-PAHs, which should be included in future monitoring and toxicity tests. The bioassay responses of many sample extracts were substantially reduced but not suppressed with sulfuric acid treatment, indicating contribution of persistent AhR agonists. Cancer risk assessment based on the CALUX BaP-EQs has revealed unacceptable level of risk in many cases. The application of bioassay-derived BaP-EQs may reduce underestimation in environmental management and risk evaluation regarding PAHs and their derivatives (notably Me-PAHs), suggesting a consideration of using in vitro toxic activity instead of conventional chemical-specific approach in such assessment practices.

Organophosphate Flame Retardants in Car Dust from Thailand and Implications for Human Exposure

Organophosphorus flame retardants (PFRs) are a group of compounds frequently detected in indoor dust that pose high health risks to exposure subjects. The present study reports on the investigation of the levels and profiles of seven target PFRs in car dust samples from Thailand. The samples were collected from the discarded air conditioning (AC) filter of 14 private cars (called AC dust samples) and from the bag filter installed in vacuum cleaners of 10 car washing services (called settled dust samples) in 2019. The concentrations of 7PFRs in AC dust samples were approximately 3,800-91,000 ng/g, whereas those from settled dust samples were about 11,000 to 15,000 ng/g. Tris (2-butoxyethyl) phosphate (TBEP) was found to be the most prominent of PFRs detected in both types of car dust with the highest concentration of 39,000 ng/g for AC filter dust and 10,000 ng/g for settled dust. The main PFR contributors in both dust types were TBEP (80%, 75%), followed by Tris (2-ethylhexyl) phosphate (TEHP) (9%, 5%) and tris(1-chloro-2-propyl)phosphate (TCPP) (7%, 4%), respectively. Tris(2-chloroethyl)phosphate (TCEP) and tri cresyl phosphate (TCP) were not detected in both types of car dust and tris(1,3-dichloro-2-propyl) phosphate (TDCPP) was found only in settled dust samples. According to the results of exposure assessment to PFRs in car dust, the human exposures via ingestion for adults and toddlers ranged from 1.69×10-2 to 2.67 and 10.6 to 2,360 ng/kg/day. The human exposures via inhalation for adults and toddlers ranged from 3.27×10-4 to 5.17x10-2 and 2.58×10-1 to 40.9 ng/kg/day. The highest exposure among PFRs corresponded to TBEP for both adults and toddlers and the risk through ingestion was higher than inhalation intake. Toddlers were more exposed to PFR contaminants in comparison to adults. When comparing the estimated average daily intake (ADI) values with the reference doses (RfDs) for PFRs, it was found that exposure to PFRs in car cabins via inhalation and dust ingestion is unlikely to have adverse human health effects.

On the question of studyng dust-like formations in urban ecosystems

According to the World Health Organization, more than 80% of urban residents are at risk due to unsatisfactory air quality and air pollution, which causes approximately 4.2 million deaths per year. The purpose of the work is to give an overview of scientific articles related to the dustiness of the city’s natural environments. The articles of foreign and Russian researchers were analyzed - the definition of urban road dust was given; the primary technogenic and natural sources of dust particle generation in the city, thephysical and chemical properties of road dust, their dependence on climate, the type of roads and city architecture, the effect of photolysis on physicalchemical characteristics of dust particles are reviewed as well. Particular attention is paid to the negative impact of dust particles PM2.5 and PM10 on human health and the environment. The question of the absence in Russian scientific practice an officially recognized methodology for the settled dust sampling with updating the regulatory documentation on the methodology for the sampling of fine particles suspended in the air is considered. Recommendations are given on the creation of the regulatory framework governing the sampling and analysis of road dust, which is confirmed by the numerous conclusions of both foreign and some domestic researchers as an environmental geo-indicator.

DNA Sequence-Based Approach for Classifying the Mold Status of Buildings.

Dampness or water damage in buildings and human exposure to the resultant mold growth is an ever-present public health concern. This study provides quantitative evidence that the airborne fungal ecology of homes with known mold growth ("moldy") differs from the normal airborne fungal ecology of homes with no history of dampness, water damage, or visible mold ("no mold"). Settled dust from indoor air and outdoor air and direct samples from building materials with mold growth were examined in homes from 11 cities across dry, temperate, and continental climate regions within the United States. Community analysis based on the sequence of the internal transcribed spacer region of fungal ribosomal RNA encoding genes demonstrated consistent and quantifiable differences between the fungal ecology of settled dust in homes with inspector-verified water damage and visible mold versus the settled dust of homes with no history of dampness, water damage, or visible mold. These differences include lower community richness (padj = 0.01) in the settled dust of moldy homes versus no mold homes, as well as distinct community taxonomic structures between moldy and no mold homes (ANOSIM, R = 0.15, p = 0.001). We identified 11 Ascomycota taxa that were more highly enriched in moldy homes and 14 taxa from Ascomycota, Basidiomycota, and Zygomycota that were more highly enriched in no mold homes. The indoor air differences between moldy versus no mold homes were significant for all three climate regions considered. These distinct but complex differences between settled dust samples from moldy and no homes were used to train a machine learning-based model to classify the mold status of a home. The model was able to accurately classify 100% of moldy homes and 90% of no mold homes. The integration of DNA-based fungal ecology with advanced computational approaches can be used to accurately classify the presence of mold growth in homes, assist with inspection and remediation decisions, and potentially lead to reduced exposure to hazardous microbes indoors.

Trace metals in indoor dust from a university campus in Northeast India: implication for health risk.

This study reports concentrations of trace metals and the associated health risks in settled dust of different microenvironments of a university in Northeast India. Settled dust samples were collected from the most accessible indoor locations by the students of Tezpur University, a rural-residential university of mid Brahmaputra Valley of Assam. Collected samples were digested in an aqua regia-assisted microwave digestion system and analyzed for iron (Fe), nickel (Ni), zinc (Zn), cadmium (Cd), and lead (Pb) using atomic absorption spectroscopy (AAS). The highest concentration was obtained for Fe with a mean value of 1353.51 ± 123mg/kg. Cadmium showed the lowest concentration with a mean value of 0.75 ± 0.57mg/kg. Cadmium was the highly enriched element followed by Pb, Zn, and Ni. The metals mostly fall in the "extremely high enrichment" category. The study revealed that infiltrated soil or street dust, eroding wall paints, and automotive sources were the main contributing sources of the metals. The calculated Hazard Index (HI) value, 0.39, was lower than the acceptable HI value of 1 indicating no significant non-cancer risk to the students from exposure to these heavy metals at present. The study also found no carcinogenic risk on exposure to the metals present in the indoor dust samples.

Contamination Status and Emission Sources of Polychlorinated Biphenyls in Settled Dust from End-of-life Vehicle Processing and Urban Areas, Northern Vietnam

Concentrations of polychlorinated biphenyls (PCBs) including 43 congeners of 10 homologs were determined in settled dust samples collected from urban houses and end-of-life vehicle (ELV) processing workshops in northern Vietnam. Concentrations of total 43 PCBs (ΣPCBs), 7 indicator PCBs (IN-PCBs), and 12 dioxin-like PCBs (DL-PCBs) in the ELV workshop dusts were significantly higher than those measured in the urban house dusts, suggesting ELV processing activities as potential sources of PCBs. However, concentrations of PCB-11 (3,3’-dichlorobiphenyl) in the urban house dusts (mean 4.5; range 1.2–8.7 ng/g) were markedly higher than levels found in the ELV workshop dusts (1.6; 0.46–5.4 ng/g). PCB-11 is a novel congener because it is only a trace component of technical PCB mixtures but identified as a major impurity of many organic pigments, especially diarylide yellow pigments. PCB patterns of the ELV workshop dusts were dominated by penta- and hexa-PCBs with major congeners as PCB-118, -138, -153, -110, and -101, which were also principal components of technical formulations such as Aroclor 1254, Kanechlor 500, and Sovol. Meanwhile, PCB-11 served as the most predominant congener detected in the urban house dusts, implying current emissions from paints and pigmented products; however, this point should be confirmed by further studies on the occurrence of PCBs in Vietnamese commercial products. Apart from PCB-11, the urban house dusts also contained elevated proportions of penta- and hexa-PCBs, suggesting residues from electrical equipment application in the past. Our results indicate that even though PCBs are legacy and banned chemicals, their presence has been observed in indoor environments due to their persistent nature and novel emission sources. Further studies on the occurrence and emission behavior of these pollutants should be conducted, including not only congeners in technical mixtures but also unintentionally produced compounds.

Occurrence of extended-spectrum beta-lactamase-producing Enterobacteriaceae, microbial loads, and endotoxin levels in dust from laying hen houses in Egypt

BackgroundPoultry houses are often highly contaminated with dust, which might contain considerable amounts of microorganisms and endotoxins. The concentrations of microorganisms and endotoxins in dust from laying hen houses in Egypt are unknown. However, to estimate the risks for birds, the environment, and people working in laying hen houses, it is important to gather information about the composition of these dusts. Here we report the microbial loads, the occurrence of antimicrobial-resistant bacteria, and endotoxin concentrations in dust samples from 28 laying hen farms in Dakahliya Governorate, Egypt, and discuss the results relevant to the literature.ResultsPooled settled dust samples (n = 28) were analyzed for total viable counts of bacteria and fungi (CFU/g), the occurrence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, Salmonella spp., and methicillin-resistant Staphylococcus aureus (MRSA), and endotoxin concentrations (ng/g). The means and standard deviations of total viable counts were 7.10 × 108 ± 2.55 × 109 CFU/g for bacteria and 5.37 × 106 ± 7.26 × 106 CFU/g for fungi. Endotoxin levels varied from 2.9 × 104 to 6.27 × 105 ng/g. None of the tested samples contained Salmonella spp. or MRSA. In contrast, by direct plating, Enterobacteriaceae were found frequently (57%; n = 16), and suspected ESBL-producing Enterobacteriaceae occurred in 21% (n = 6) of the sampled barns. Using an enrichment method, the detection of Enterobacteriaceae and suspected ESBL-producing Enterobacteriaceae increased to 20 and 16 positive barns, respectively. Taking results from both methods into account, Enterobacteriaceae and suspected ESBL-producing Enterobacteriaceae were detected in 23 barns Overall, 100 ESBL suspected isolates (Escherichia coli, n = 64; Enterobacter cloacae, n = 20; and Klebsiella pneumoniae n = 16) were identified to species level by MALDI-TOF MS. Isolates from 20 barns (71% positive barns) were confirmed as ESBL producing Enterobacteriaceae by the broth microdilution test.ConclusionsDust in Egyptian laying hen houses contains high concentrations of microorganisms and endotoxins, which might impair the health of birds and farmers when inhaled. Furthermore, laying hens in Egypt seem to be a reservoir for ESBL-producing Enterobacteriaceae. Thus, farmers are at risk of exposure to ESBL-producing bacteria, and colonized hens might transmit these bacteria into the food chain.

Polychlorinated biphenyls in settled dusts from an end-of-life vehicle processing area and normal house dusts in northern Vietnam: Occurrence, potential sources, and risk assessment

Concentrations and congener-specific profiles of total 209 polychlorinated biphenyls (PCBs) were investigated in settled dust samples collected from end-of-life vehicle (ELV) processing, urban, and rural areas in northern Vietnam. Concentrations of total 209 PCBs, seven indicator congeners, and twelve dioxin-like PCBs decreased in the order: ELV working > ELV living ≈ urban > rural dusts. Penta- and hexa-CBs dominated the homolog patterns in all the samples with higher proportions in the ELV dusts compared to the urban and rural house dusts. The abundance and pattern of PCBs in the ELV dusts suggest on-going emissions of these compounds related to processing of vehicular oils and lubricants containing PCBs, whereas the presence of PCBs in the urban and rural house dusts indicate long-time releases. However, levels of some PCBs identified as by-products of pigment manufacturing (e.g., PCB-11 and PCB-209) were higher in the urban house dusts than those from other locations, resulting from human activities utilizing paints and pigments. Daily intake doses (ID), non-carcinogenic hazard quotient (HQ), and lifetime cancer risk (CR) of PCBs through dust ingestion were estimated for ELV workers and residents in the studied areas. The workers and children in the ELV sites were estimated to be at higher risk of PCB exposure, however almost all of the HQ < 1 and CR < 10−4 indicate no serious risk related to dust-bound PCBs.

The impact of ventilation rate on the fungal and bacterial ecology of home indoor air

The following study explores how measured ventilation rates influence bacterial and fungal community structure and concentrations in the indoor air of homes ventilated by leakage-based airflow. The dynamics of bacterial and fungal communities were quantified from homes within the Cherokee Nation in North Eastern, Oklahoma, USA, where seasonal air exchange rates (AERs) were measured, and seasonal outdoor and indoor air, floor dust, and settled dust samples were collected. Quantitative PCR (qPCR) and DNA amplicon sequencing were paired with a mass balance model to determine if high and low ventilation rate regimes impacted bacterial and fungal concentration and community structure, and to estimate the relative contributions of microbiota to indoor air from infiltration of outdoor air (ventilation) versus indoor emissions. For indoor PM10 and settled dusts samples, comparative analyses of microbial communities revealed no significant bacterial or fungal community differences between samples taken from homes dichotomized into high (average high AER = 0.56 hr−1) and low (average low AER = 0.16 hr−1) AER regimes (p > 0.1 for all), suggesting that ventilation was not a significant factor controlling bacterial and fungal concentrations and ecologies in the indoor air of these homes. A comparison between indoor emissions (typically due to occupancy and resuspension) and ventilation (infiltration of outdoor air) as a source of bacteria and fungi indicates that indoor emissions are the dominant source of particulate matter, bacteria, and fungi, accounting for ~94% indoor air PM10, ~97% of indoor air bacteria, and ~91% of indoor air fungi. Thus, indoor emission sources must be controlled to significantly impact human bacterial and fungal (allergen) exposure in the indoor air of these residential environments.

Occupational Exposures to Organic Dust in Irish Bakeries and a Pizzeria Restaurant.

For decades, occupational exposure to flour dust has been linked to a range of respiratory diseases, including occupational asthma, thought to result from exposure to fungi present in the flour. Antifungal resistance is of increasing prevalence in clinical settings, and the role of occupational and environmental exposures, particularly for specific fungal species, is of concern. Occupational exposure to flour dust can occur in a range of occupational settings, however, few studies have focused on restaurant workers. The objective of this study was to measure occupational exposure to flour and microbial contamination, including azole resistance screening, in two small commercial bakeries and in a pizzeria. Personal full shift inhalable dust measurements were collected from workers, and were analyzed for inhalable dust and fungi, bacteria, azole resistance, and mycotoxins. Samples of settled dust were collected, and electrostatic dust cloths (EDC) were deployed and analyzed for microbial contamination, including azole resistance screening, and mycotoxins. Geometric mean exposures of 6.5 mg m−3 were calculated for inhalable dust, however, exposures of up to 18.30 mg m−3 were measured—70% of personal exposure measurements exceeded the occupational exposure limit for flour dust of 1.0 mg m−3. The air and EDC fungal counts were similar to those reported in previous studies for similar occupational environments. The fungi were dominated by Penicillium genera, however Aspergillus genera, including Fumigati and Flavi sections, were observed using culture-based methods, and the Fumigati section was also observed by molecular tools. Both Aspergillus sections were identified on the azole resistance screening. Mycotoxins were also detected in the settled dust samples, dominated by deoxynivalenol (DON). The role of environmental exposure in both the development of antimicrobial resistance and the total mycotoxin body burden is a growing concern; therefore, the presence of azole-resistant fungi and mycotoxin contamination, although low in magnitude, is of concern and warrants further investigation.

On-line coupling of thermal extraction with gas chromatography / tandem mass spectrometry for the analysis of semivolatile organic compounds in a few milligrams of indoor dust

An original multiresidue method based on thermal extraction (TE) and gas chromatography/tandem mass spectrometry (GC/MS/MS) was developed to simultaneously quantify, from a very small amount of sample (a few milligrams), a wide range of concerning SVOCs, including polycyclic musks, organochlorines (OCs), organophosphates (OPs), oxadiazolones, polycyclic aromatic hydrocarbons (PAHs), polybromodiphenylethers (PBDEs), polychlorobiphenyls (PCBs), phthalates and pyrethroids, in indoor settled dust. Method limits of quantification (LOQs) ranged from 5 ng g−1 for PCBs, oxadiazon, 4,4′-DDE and 4,4′-DDT to 2000 ng g−1 for DEHP for a 2 mg sample of sieved dust. The proposed method was successfully validated in terms of accuracy and precision via replicate analysis of four different standard reference materials (SRMs 1649b (Urban Dust), 2585 (Organic Contaminants in House Dust), 2786 and 2787 (Fine Atmospheric Particulate Matter)) supplied by the National Institute of Standards and Technology (NIST) and was applied to five real indoor settled dust samples collected in French schools. In addition, its performance was compared to that of a previously published method based on pressurized liquid extraction (PLE) and GC/MS/MS. The different results obtained demonstrate the advantages of the proposed method over conventional methods and illustrate its two main features: i) its ease of use and very rapid implementation in only three steps (sieving, weighing and analysis), which make it particularly appropriate for environmental monitoring programs and large-scale studies, and ii) its ability to precisely and accurately quantify a wide range of SVOCs from trace (a few ng g−1) to highly concentrated (several mg g−1) compounds from only 2 mg of sieved dust.

Exposure assessment in one central hospital: A multi-approach protocol to achieve an accurate risk characterization

The bioburden in a Hospital building originates not only from patients, visitors and staff, but is also disseminated by several indoor hospital characteristics and outdoor environmental sources. This study intends to assess the exposure to bioburden in one central Hospital with a multi-approach protocol using active and passive sampling methods. The microbial contamination was also characterized through molecular tools for toxigenic species, antifungal resistance and mycotoxins and endotoxins profile. Two cytotoxicity assays (MTT and resazurin) were conducted with two cell lines (Calu-3 and THP-1), and in vitro pro-inflammatory potential was assessed in THP-1 cell line. Out of the 15 sampling locations 33.3% did not comply with Portuguese legislation regarding bacterial contamination, whereas concerning fungal contamination 60% presented I/O > 1. Toxigenic fungal species were observed in 27% of the sampled rooms (4 out of 15) and qPCR analysis successfully amplified DNA from the Aspergillus sections Flavi and Fumigati, although mycotoxins were not detected. Growth of distinct fungal species was observed on Sabouraud dextrose agar with triazole drugs, such as Aspergillus section Versicolores on 1 mg/L VORI. The highest concentrations of endotoxins were found in settled dust samples and ranged from 5.72 to 23.0 EU.mg−1. While a considerable cytotoxic effect (cell viability < 30%) was observed in one HVAC filter sample with Calu-3 cell line, it was not observed with THP-1 cell line. In air samples a medium cytotoxic effect (61–68% cell viability) was observed in 3 out of 15 samples. The cytokine responses produced a more potent average cell response (46.8 ± 12.3 ρg/mL IL-1β; 90.8 ± 58.5 ρg/mL TNF-α) on passive samples than air samples (25.5 ± 5.2 ρg/mL IL-1β and of 19.4 ± 5.2 ρg/mL TNF-α).A multi-approach regarding parameters to assess, sampling and analysis methods should be followed to characterize the biorburden in the Hospital indoor environment. This study supports the importance of considering exposure to complex mixtures in indoor environments.

Characterization of Occupational Exposure To Fungal Burden in Portuguese Bakeries.

Several studies reported adverse respiratory health effects in workers exposed to ambient contaminants in bakeries. The aim of this study was to examine worker exposure to fungi and mycotoxins in Portuguese bakeries in order to develop new policies in occupational health. Environmental samples such as air, surfaces, settled dust and electrostatic dust collector (EDC) were collected in 13 bakeries for fungal and mycotoxins assessment. Air samples obtained by impaction were performed applying malt extract agar (MEA) supplemented with chloramphenicol (0.05%) and dichloran glycerol (DG18) agar-based media. Air samples collected through impinger method were determined as well for fungal detection by molecular tools of Aspergillus sections and mycotoxins. The highest median value for fungal load was 1053 CFU·m−3 and 65.3% (32 out of 49) of the sampling sites displayed higher fungal load than limits imposed by the World Health Organization. Aspergillus genera was found in air, surface swabs and EDC. Molecular tools were effective in measuring Aspergillus section Fumigati in 22.4% on air, 27.8% on surface swabs and in 7.4% in EDC and Aspergillus section Versicolores in one air sample. All settled dust samples showed contamination with six to eight mycotoxins in each sample. The mycotoxins detected were deoxynivalenol-3-glucoside, deoxynivalenol, zearalenone, 15-acetyldeoxynivalenol, monoacetoxyscirpenol, diacetoxyscirpenol, fumonisin B1, fumonisin B2, griseofulvin, HT2, ochratoxin A, ochratoxin B and mycophenolic acid. Industrial hygienists and exposure assessors should rely on different sampling methods (active and passive) and different assays (culture based and molecular methods) to obtain an accurate risk characterization regarding fungal burden (fungi and mycotoxins). Additionally, the awareness for the raw material as a potential mycotoxins indoor contamination source is important.