Impact of altitude on the dosage of indoor particulates entering an individual's small airways

The complexity of indoor particulate exposure intensifies at higher altitudes owing to the increased lung capacity that residents develop to meet the higher oxygen demands. Altitude variations impact atmospheric pressure and alter particulate dynamics in ambient air and the human respiratory tract, complicating particulate inhalation. This study assessed the fraction of PM2.5 and PM10 entering small airways. This assessment covered an altitude range from 400 m above sea level to 3650 m, and an in vitro respiratory tract model was used. The experimental results confirmed that with increasing altitude, the penetration fractions of PM2.5 and PM10 significantly increased from 0.133 ± 0.031 and 0.141 ± 0.045 to 0.404 ± 0.159 and 0.353 ± 0.132, respectively. Additionally, the computational fluid dynamics simulation results revealed that among particles with sizes of 0.1 to 10 µm, the 7.5-μm particles exhibited the most substantial reduction in deposition in the upper airway, displaying a decrease of 6.27%. Our findings underscore the health risks faced by low-altitude residents during acclimatization to higher altitudes, as they experience heightened exposure to particulate matter sources.

Ferroptosis participated in inhaled polystyrene nanoplastics-induced liver injury and fibrosis

The emerging contaminant nanoplastics (NPs) have received considerable attention. Due to their tiny size and unique colloidal properties, NPs could more easily enter the body and cross biological barriers with inhalation exposure. While NPs-induced hepatotoxicity has been reported, the hepatic impact of inhaled NPs was still unknown. To close this gap, a 40 nm polystyrene NPs (PS-NPs) inhalation exposure mice model was developed to explore the hepatotoxicity during acute (1 week), subacute (4 weeks), and subchronic period (12 weeks), with four exposure doses (0, 16, 40, and 100 μg/day). Results showed that inhaled PS-NPs caused a remarkable increase of ALT, AST, and ALP with a decrease of CHE, indicating liver dysfunction. Various histological abnormalities and significantly higher levels of inflammation in a dose- and time-dependent manner were observed. Moreover, after 4 weeks and 12 weeks of exposure, Masson staining and upregulated expression of TGF-β, α-SMA, and Col1a1 identified that inhaled PS-NPs exposure triggered the progression of liver fibrosis with the exposure time prolonged. From the mechanistic perspective, transcriptome analysis revealed that ferroptosis was involved in PS-NPs-induced liver hepatotoxicity, and key features of ferroptosis were detected, including persistent oxidative stress, iron overload, increased LPO, mitochondria damage, and the expression changes of GPX4, TFRC, and Ferritin. And in vitro and in vivo recovery tests showed that ferroptosis inhibitor Fer-1 treatment alleviated liver injury and fibrosis. The above results confirmed the critical role of ferroptosis in PS-NPs-induced hepatotoxicity. Furthermore, to better conclude our findings and understand the mechanistic causality within it, an adverse outcome pathway (AOP) framework was established. In total, this present study conducted the first experimental assessment of inhalation exposure to PS-NPs on the liver, identified that continuous inhaled PS-NPs could cause liver injury and fibrosis, and PS-NPs- ferroptosis provided a novel mechanistic explanation.

Risk assessment of airborne agricultural pesticide exposure in humans in rural China

Continuous exposure to airborne pesticides causes their gradual accumulation in the human body, eventually posing a threat to human health. To the best of our knowledge, risk assessment study of pesticide non-occupational exposure to residents in agricultural areas has not been conducted in China. In this study, air samples (gas and dust) were collected from inside and outside residences of seven households and an area near the field in a grain-growing area (wheat and maize rotation) for eight months, and the pesticides present were examined both qualitatively and quantitatively. Using a 95% confidence interval, 9 out of 16 pesticides were detected, namely acetamiprid, acetochlor, atrazine, flucarbazone-sodium, imidacloprid, methyldisulfuron-methyl, nicosulfuron-methyl, pendimethalin, and beta-cyhalothrin, and their safety was subsequently evaluated. The results showed that the inhalation exposure of households to beta-cyhalothrin exceeded the acceptable range in the first residential, and the excess lifetime cancer risk of acetochlor inhalation exposure in six households and area around the field exceeds 1E-6, which highlights the need to strengthen preventive screening for cancer risk.

The risk factors and threshold level of subchronic inhalation exposure of reclaimed water

Inhalation of reclaimed water is known to cause lung inflammation, and free endotoxins have been shown to be a major risk factor for acute exposure. Subchronic exposure has also been shown to induce inflammatory responses with visible tissue damage. However, subchronic risk factors have yet to be identified, and a threshold for the protection of occupational populations during urban reuse is necessary. In this study, potential risk factors in reclaimed water were examined by subchronic exposure with fractionated reclaimed water, and the health risk threshold was tested with a series of diluted reclaimed water. Accordingly, following a 12-week exposure, macromolecules and microorganisms were found to be two major risk factors in reclaimed water that could cause pulmonary inflammation, including increased proportion of polymorphonuclear leukocytes in bronchoalveolar fluid, formation of inducible bronchus-associated lymphoid tissue, and elevation of Immunoglobulin A levels. Moreover, inflammation persisted after a 4-week recovery period. The calculated threshold of reclaimed water exposure for mice was 31.8 Endotoxin Unit (EU)/(kg·day) under when exposed to 50% additional relative humidity from reclaimed water at 25°C for 2 hr/day. Meanwhile, the subchronic threshold estimate for humans under the same exposure conditions was found to be 12.2 EU/(kg·day), corresponding to endotoxin levels of 61.7 EU/mL in reclaimed water. The threshold level of endotoxin was lower than that in most non-potable reclaimed water. The findings of this study suggest that occupational exposure of reclaimed water can serve as a potential risk to workers.

High-solution emission characters and health risks of volatile organic compounds for sprayers in automobile repair industries

The increasing automobile repair industries (ARIs) with spray facilities have become an important volatile organic compound (VOC) pollution source in China. However, the VOC health risk assessment for long-term exposure in ARIs has not been well characterized. In this study, though sampled VOCs from 51 typical ARIs in Beijing, the relationship between emission patterns, average daily exposure concentrations (EC), and health risks was comprehensively analyzed with the health assessment method. Results showed that concentrations of 117 VOCs from the samples ranged from 68.53 to 19863.32 μg·m-3, while the ARI operator's daily VOC inhalation EC was 11.24-1460.70 μg·m-3. The organic VOC (OVOC) concentration accounted for 73.16 ~ 94.52% in the solvent-based paint workshops, while aromatics were the main VOC component in water-based paint spraying (WPS) workshops, accounting for 70.08%, respectively. And the method of inhalation exposure health risk assessment was firstly used to evaluate carcinogenicity and non-carcinogenicity risk for sprayers in ARIs. The cumulative lifetime carcinogenic risk (LCR) for 24 sampled VOCs were within acceptable ranges, while the mean hazard index (HI) for 1 year with 44 sampled VOCs was over 1. Among them, ethyl alcohol had a high carcinogenic risk in both mixed water-based paint (MP) and solvent-based paint workshops. The mean HI associated with aromatics were 2.88E - 3 and 4.30E - 3 for 1 h in MP and WPS workshops. O-ethyl toluene and acetone are VOC components that need to be paid attention to in future paint raw materials and spraying operations. Our study will provide the important references for the standard of VOC occupational exposure health limits in ARIs.

In vitro neurotoxicity of particles from diesel and biodiesel fueled engines following direct and simulated inhalation exposure

Combustion-derived particulate matter (PM) is a major source of air pollution. Efforts to reduce diesel engine emission include the application of biodiesel. However, while urban PM exposure has been linked to adverse brain effects, little is known about the direct effects of PM from regular fossil diesel (PMDEP) and biodiesel (PMBIO) on neuronal function. Furthermore, it is unknown to what extent the PM-induced effects in the lung (e.g., inflammation) affect the brain. This in vitro study investigates direct and indirect toxicity of PMDEP and PMBIO on the lung and brain and compared it with effects of clean carbon particles (CP). PM were generated using a common rail diesel engine. CP was sampled from a spark generator. First, effects of 48 h exposure to PM and CP (1.2-3.9 µg/cm2) were assessed in an in vitro lung model (air-liquid interface co-culture of Calu-3 and THP1 cells) by measuring cell viability, cytotoxicity, barrier function, inflammation, and oxidative and cell stress. None of the exposures caused clear adverse effects and only minor changes in gene expression were observed. Next, the basal medium was collected for subsequent simulated inhalation exposure of rat primary cortical cells. Neuronal activity, recorded using microelectrode arrays (MEA), was increased after acute (0.5 h) simulated inhalation exposure. In contrast, direct exposure to PMDEP and PMBIO (1-100 µg/mL; 1.2-119 µg/cm2) reduced neuronal activity after 24 h with lowest observed effect levels of respectively 10 µg/mL and 30 µg/mL, indicating higher neurotoxic potency of PMDEP, whereas neuronal activity remained unaffected following CP exposure. These findings indicate that combustion-derived PM potently inhibit neuronal function following direct exposure, while the lung serves as a protective barrier. Furthermore, PMDEP exhibit a higher direct neurotoxic potency than PMBIO, and the data suggest that the neurotoxic effects is caused by adsorbed chemicals rather than the pure carbon core.

Copper oxide particle emission and the spread in a public washroom from a high-speed jet air dryer

The high-speed jet discharged by hand dryers with brushed motors may release hazardous particles. In this study, the particles released from the hand dryer were trapped using high-efficiency particulate air filters for chemical composition analysis in a small test room. A manikin was placed to mimic a user standing in front of the dryer. Number and mass concentrations of the released particles were measured to estimate the particle emission rates and inhalation exposure. The particle emission rate reached 2.64 × 106 particles/s when starting the dryer. The released particles were found to contain a copper element, subsequently extrapolated to copper oxide. Secondly, in the large test room, jet airflows were measured using a three-dimensional ultrasonic anemometer. The results revealed that the horizontally placed palms caused the discharged jets to bend toward the human body, resulting in an upward motion of the air into the breathing zone. After running the dryer for 30 s, the peak mass concentration in the breathing zone for particles with a less than 2.5-μm diameter was 13.1 µg/m3. Installing high-efficiency particulate air filters to the air outlets of hand dryers was found to be effective in minimizing the exposure to CuO.

Serum PCDD/F levels in metropolitan populations living near a municipal solid waste incinerator in Eastern China

Ambient exposure to polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) is suspected to cause adverse human health outcomes. Herein, serum samples from 40 residents in the neighborhood of a municipal solid waste incinerator (MSWI) in the metropolitan area were measured for PCDD/Fs. The mean toxic equivalent (TEQ) concentration of total PCDD/Fs in human serum samples was 16.8 pg TEQ/g lipid. Serum PCDD/F levels were significantly higher in residents adjacent to the MSWI than in those from areas far from the emission source (p < 0.01). In addition, there were no significant associations between serum PCDD/Fs levels and factors, such as gender, age, and BMI in donors. For non-occupationally exposed populations, OCDD and 1,2,3,7,8-PeCDD in serum are available as indicators of total PCDD/Fs and total TEQ, respectively. The atmospheric PCDD/Fs levels were within a relatively low range in areas upwind and downwind of the MSWI. The results of the principal component analysis showed a distinct difference in PCDD/F congener patterns between air and serum samples, suggesting inhalation exposure could have a limited influence on the human body burden. Our findings will deepen the current knowledge of endogenous PCDD/F exposure in urban populations, and also facilitate public health protection strategies near MSWIs.

Occupational inhalation exposure during surface disinfection-exposure assessment based on exposure models compared with measurement data

BACKGROUND

For healthcare workers, surface disinfections are daily routine tasks. An assessment of the inhalation exposure to hazardous substances, in this case the disinfectant´s active ingredients, is necessary to ensure workers safety. However, deciding which exposure model is best for exposure assessment remains difficult.

OBJECTIVE

The aim of the study was to evaluate the applicability of different exposure models for disinfection of small surfaces in healthcare settings.

METHODS

Measurements of the air concentration of active ingredients in disinfectants (ethanol, formaldehyde, glutaraldehyde, hydrogen peroxide, peroxyacetic acid) together with other exposure parameters were recorded in a test chamber. The measurements were performed using personal and stationary air sampling. In addition, exposure modelling was performed using three deterministic models (unsteady 1-zone, ConsExpo and 2-component) and one modifying-factor model (Stoffenmanager®). Their estimates were compared with the measured values using various methods to assess model quality (like accuracy and level of conservatism).

RESULTS

The deterministic models showed overestimation predominantly in the range of two- to fivefold relative to the measured data and high conservatism for all active ingredients of disinfectants with the exception of ethanol. With Stoffenmanager® an exposure distribution was estimated for ethanol, which was in good accordance with the measured data.

IMPACT STATEMENT

To date, workplace exposure assessments often involve expensive and time consuming air measurements. Reliable exposure models can be used to assess occupational inhalation exposure to hazardous substances, in this case surface disinfectants. This study describes the applicability of three deterministic and one modifying-factor model for disinfection of small surfaces in healthcare settings, in direct comparison to measurements performed and will facilitate future exposure assessments at these workplaces.

Contamination of surfaces in children's homes with nicotine and the potent carcinogenic tobacco-specific nitrosamine NNK

BACKGROUND

Tobacco smoke exposure (TSE) through secondhand and thirdhand smoke is a modifiable risk factor that contributes to childhood morbidity. Limited research has assessed surface TSE pollution in children's environments as a potential source of thirdhand smoke exposure, and none have examined levels of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) on surfaces.

OBJECTIVE

This study measured surface NNK and nicotine in children's homes and associations with sociodemographics and parent-reported TSE behaviors. We assessed correlations of surface NNK and nicotine with dust NNK, dust nicotine, and child cotinine.

METHODS

Home surface wipe NNK and nicotine data from 84 children who lived with smokers were analyzed. Tobit and simple linear regression analyses were conducted to assess associations of surface NNK and nicotine with child characteristics. Spearman's (ρ) correlations assessed the strength of associations between environmental markers and child cotinine.

RESULTS

Nearly half (48.8%) of children's home surfaces had detectable NNK and 100% had detectable nicotine. The respective geometric means (GMs) of surface NNK and nicotine loadings were 14.0 ng/m2 and 16.4 µg/m2. Surface NNK positively correlated with surface nicotine (ρ = 0.54, p < 0.001) and dust NNK (ρ = 0.30, p = 0.020). Surface nicotine positively correlated with dust NNK (ρ = 0.42, p < 0.001) and dust nicotine (ρ = 0.24, p = 0.041). Children with household incomes ≤$15,000 had higher surface NNK levels (GM = 18.7 ng/m2, p = 0.017) compared to children with household incomes >$15,000 (GM = 7.1 ng/m2). Children with no home smoking bans had higher surface NNK (GM = 18.1 ng/m2, p = 0.020) and surface nicotine (GM = 17.7 µg/m2, p = 0.019) levels compared to children with smoking bans (GM = 7.5 ng/m2, 4.8 µg/m2, respectively).

IMPACT

Although nicotine on surfaces is an established marker of thirdhand smoke pollution, other thirdhand smoke contaminants have not been measured on surfaces in the homes of children living with smokers. We provide evidence that the potent carcinogenic tobacco-specific nitrosamine NNK was detectable on surfaces in nearly half of children's homes, and nicotine was detectable on all surfaces. Surface NNK was positively correlated with surface nicotine and dust NNK. Detectable surface NNK levels were found in homes with indoor smoking bans, indicating the role of NNK as a persistent thirdhand smoke pollutant accumulating on surfaces as well as in dust.

A comparison between field measurements of vapour concentrations of plant protection products and predictions by the BROWSE model

A database of field measurements of air concentrations of pesticide active ingredients has previously been compiled by CropLife Europe with an aim to revise the default air concentration values and assumptions applied in assessing vapour exposure in the risk assessment of bystanders and residents. The BROWSE model, released in 2014, which is a regulatory risk assessment model that includes the exposure of residents and bystanders has a component relating to post-application vapour inhalation. Predictions of concentration deduced from exposures obtained using the BROWSE model were compared with field measurements of 24-h and 7-day average concentrations. The methodology for obtaining concentration estimates from the BROWSE model is described, and the criteria for including field studies in the comparison are given. The field data were adjusted to account for differences between the field experiment and the BROWSE scenario using factors derived from a separate plume dispersion model. This showed that BROWSE provides a satisfactory level of conservatism in determining potential exposures of residents and bystanders to vapour and could be a reliable alternative to replace the current EFSA approach for predicting vapour inhalation exposures for pesticides where no compound-specific data are available.

An assessment of the ECETOC TRA Consumer tool performance as a screening level tool

BACKGROUND

The European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) Targeted Risk Assessment (TRA) Consumer tool was developed to fill in a methodology gap for a high throughput, screening level tool to support industry compliance with the European Union's Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulation.

OBJECTIVE

To evaluate if the TRA Consumer tool has met its design of being a screening level tool (i.e., one which does not under-predict potential exposures).

METHODS

The TRA Consumer tool algorithms and defaults were reviewed and performance benchmarked vs. other consumer models and/or empirical data. Findings from existing reviews of the TRA consumer tool were also considered and addressed.

RESULTS

TRA predictions based on its default inputs exceeded measured exposures when available, typically by orders of magnitude, and were generally greater than or similar to those of other consumer exposure tools. For dermal exposure from articles, there was no evidence that a diffusivity approach would provide more appropriate exposure estimates than those of the TRA. When default values are refined using more specific data, the refined values must be considered holistically to reflect the situation being modeled as some parameters may be correlated.

SIGNIFICANCE

This is the first evaluation of the ECETOC TRA consumer tool in its entirety, considering algorithms, input defaults, and associated predictions for consumer products and articles. The evaluation confirmed its design as a screening level tool.

IMPACT STATEMENT

The ECETOC TRA Consumer tool has been widely applied to generate exposure estimates to support chemical registrations under the EU REACH regulation. This evaluation supports the appropriateness of the TRA as a screening level exposure assessment tool. It also warrants additional measurements of consumer exposure, especially for article use scenarios, to aid the development of consumer exposure tools and chemical risk assessment.

Occupational exposure to per- and polyfluoroalkyl substances: a scope review of the literature from 1980-2021

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) comprise a large group of chemicals that have been integrated into a wide variety of industrial processes and consumer products since the 1950s. Due to their profuse usage and high persistence in human serum, understanding workplace exposures to PFAS is critical.

OBJECTIVE

We aimed to characterize the PFAS exposure profiles of relevant occupational populations, elucidate trends in the PFAS exposure characterization process, and identify major research gaps that remain within the occupational PFAS exposure literature.

METHODS

A systematic search of four literature databases for peer-reviewed articles published between 1980 and 2021 on PFAS exposure in occupational settings was conducted.

RESULTS

Of the 2574 articles identified, 92 met the inclusion criteria. Fluorochemical workers were the target population in most early exposure assessment research; however, studies conducted within the last 10 years have evaluated a wider range of occupational populations and settings. The highest exposures were reported in fluorochemical workers, but, in comparison to reference populations, one or more PFAS were elevated in most workers and in most workplaces that were assessed. PFAS was most frequently assessed in worker serum using a discrete analytical panel of PFAS, with earlier studies restricted to a few long-alkyl chain PFAS while more recent studies have included more expansive panels due to more robust methods.

SIGNIFICANCE

Characterization of occupational exposure to PFAS is limited but expanding. Current analytical methods are not robust enough to fully capture the potential range of PFAS present across different workers and workplaces. While exposures to PFAS for certain occupational groups have been studied in detail, exposure information for other occupational groups with high potential for exposure are limited. This review highlights substantial findings and major research gaps within the occupational literature.

Concentrations of PCDD/Fs and dl-PCBs in ambient air in Hanoi, Vietnam, between 2017 and 2021, and health risk assessments

The concentrations and seasonal and temporal variations in polychlorodibenzo-p-dioxins/polychlorodibenzofurans (PCDD/Fs) and dioxin-like polychlorobiphenyls (dl-PCBs) in ambient air from November 2017 to September 2021 were investigated via passive air samplers containing polyurethane foam (PUF) discs in three residential areas: the Cau Giay (CG) urban, Quang Minh (QM) industrial-suburban, and Ba Vi (BV) rural areas, Hanoi, Vietnam. The average total toxic equivalents (TEQs) of PCDD/Fs and dl-PCBs (∑TEQs), using WHO2005-TEFs, were highest in the QM area (506 fg WHO-TEQ/PUF day) and ranged from 317 to 752 fg WHO-TEQ/PUF day. Compared to that in the QM area, the average ∑TEQs were lower in the CG area, ranging between 372 and 615 fg WHO-TEQ/PUF day with an average value of 482 fg WHO-TEQ/PUF day. The average ∑TEQs were lowest in the BV area, ranging from 121 to 414 fg WHO-TEQ/PUF day with an average of 231 fg WHO-TEQ/PUF day. PCDD/F and dl-PCB air pollution increased during spring and winter. The highest seasonal average ∑TEQs in the CG area was 534 fg WHO-TEQ/PUF day in winter. The highest average ∑TEQs in the QM and BV areas were 653 and 280 fg WHO-TEQ/PUF day in spring, respectively. The average daily dose (ADD) values of PCDD/Fs and dl-PCBs through inhalation for adults in the three areas were minimal (9.9-96.2 fg WHO-TEQ/kg body weight (BW)/day) and below the 10% threshold of the tolerable daily intake (TDI) value recommended by the WHO (100-400 fg WHO-TEQ/kg BW/day). For children, the ADD values (15.1-244 fg WHO-TEQ/kg BW/day) were less than and within 10% of the recommended TDI value.

Urinary Amino-PAHs in relation to diesel engine emissions and urinary mutagenicity

Diesel exhaust has long been of health concern due to established toxicity including carcinogenicity in humans. However, the precise components of diesel engine emissions that drive carcinogenesis are still unclear. Limited work has suggested that nitrated polycyclic aromatic hydrocarbons (NPAHs) such as 1-nitropyrene and 2-nitrofluorene may be more abundant in diesel exhaust. The present study aimed to examine whether urinary amino metabolites of these NPAHs were associated with high levels of diesel engine emissions and urinary mutagenicity in a group of highly exposed workers including both smokers and nonsmokers. Spot urine samples were collected immediately following a standard work shift from each of the 54 diesel engine testers and 55 non-tester controls for the analysis of five amino metabolites of NPAHs, and cotinine (a biomarker of tobacco smoke exposure) using liquid chromatography-mass spectrometry. An overnight urine sample was collected in a subgroup of non-smoking participants for mutagenicity analysis using strain YG1041 in the Salmonella (Ames) mutagenicity assay. Personal exposure to fine particles (PM2.5) and more-diesel-specific constituents (elemental carbon and soot) was assessed for the engine testers by measuring breathing-zone concentrations repeatedly over several full work shifts. Results showed that it was 12.8 times more likely to detect 1-aminopyrene and 2.9 times more likely to detect 2-aminofluorene in the engine testers than in unexposed controls. Urinary concentrations of 1-aminopyrene were significantly higher in engine testers (p < 0.001), and strongly correlated with soot and elemental carbon exposure as well as mutagenicity tested in strain YG1041 with metabolic activation (p < 0.001). Smoking did not affect 1-aminopyrene concentrations and 1-aminopyrene relationships with diesel exposure. In contrast, both engine emissions and smoking affected 2-aminofluorene concentrations. The results confirm that urinary 1-aminopyrene may serve as an exposure biomarker for diesel engine emissions and associated mutagenicity.

Variations of inhalation risks during different heavy pollution episodes based on 3-year measurement of toxic components in size-segregated particles

Toxic metals (TMs) and polycyclic aromatic hydrocarbons (PAHs) in size-segregated particles during common days (CD) and different heavy pollution (HP) episodes were measured during 2018-2021 in a Chinese megacity. The Multiple Path Particle Dosimetry Model (MPPD) was performed to estimate deposition efficiency, and then inhalation risks in the human pulmonary region during different types of HP were assessed and compared. The higher pulmonary deposition efficiency of PAHs and TMs during all types of HP than those during CD was confirmed. The accumulative incremental lifetime cancer risk (ILCR) of different HP were 2.42 × 10^-5, 1.52 × 10^-5, 1.39 × 10^-5, 1.30 × 10^-5 and 2.94 × 10^-6 for HP4 (combustion sources HP), HP1 (ammonium nitrate HP), HP5 (mixed sources HP), HP3 (resuspended dust HP) and HP2 (ammonium sulfate HP), respectively. The accumulative hazard quotient (HQ) during different HP episodes decreased in the order of HP4 (0.32) > HP3 (0.24) > HP1 (0.22) > HP5 (0.18) > HP2 (0.05). The inhalation risks were dominated by Ni and Cr, what's more, the HQ of Ni and ILCR of Cr during the five HP episodes shared a similar size distribution pattern. However, the characteristic components during different HP episodes and their size distributions of them were distinctive. The size distribution of inhalation risks of the related components (Ni, Cr, BaP, and As) from the combustion process during HP4 peaked at fine mode (0.65-2.1 μm). The size distribution of inhalation risks of the dust-related components (Mn and V) and the components (As and BaP) that are likely to volatilize and re-distribution peaked at coarse mode (2.1-3.3 μm) during HP3. Notably, Mn and Co as catalysts at fine mode could increase the degree of secondary formation and toxicity.

Cooking methods and kitchen ventilation availability, usage, perceived performance and potential in Canadian homes

BACKGROUND

Cooking is a substantial contributor to air pollutant exposures in many residences. Effective use of kitchen ventilation can mitigate exposure; however, information on its availability, usage, and potential to increase its use across the population has been limited.

OBJECTIVE

This study aimed to obtain nationally representative information on cooking methods, kitchen ventilation availability and usage, and the potential for education to increase effective usage.

METHODS

An online survey was sent to a representative sample of Canadian homes to collect data on cooking methods, the presence and use of mechanical kitchen ventilation devices, perceived device performance, and willingness to implement mitigation strategies. Responses were weighted to match key demographic factors and analyzed using non-parametric statistics.

RESULTS

Among the 4500 respondents, 90% had mechanical ventilation devices over the cooktop (66% of which were vented to the outside), and 30% reported regularly using their devices. Devices were used most often for deep-frying, followed by stir-frying, sautéing or pan-frying, indoor grilling, boiling or steaming. Almost half reported rarely or never using their ventilation devices during baking or oven self-cleaning. Only 10% were fully satisfied with their devices. More frequent use was associated with the device being vented to the outdoors, having more than two speed settings, quiet operation if only one speed, covering over half of the cooktop, and higher perceived effectiveness. After being informed of the benefits of kitchen ventilation, 64% indicated they would consider using their devices more often, preferentially using back burners with ventilation, and/or using higher ventilation device settings when needed.

IMPACT

This study provides population-representative data on the most used cooking methods, kitchen ventilation availability and usage, and influencing factors in Canadian homes. Such data are needed for exposure assessments and evaluating the potential to mitigate cooking-related pollutant exposures via more effective use of kitchen ventilation. The data can be reasonably extrapolated to the United States, given the similarities in residential construction practices and cultural norms between the two countries.

Pollution characteristics and human health risks of PM2.5-bound heavy metals: a 3-year observation in Suzhou, China

This study aimed to analyze the temporal trends, pollution levels, and health risks associated with eleven PM_2.5-bound heavy metals (Sb, Al, As, Hg, Cd, Cr, Mn, Ni, Pb, Se and Tl). A total of 504 PM_2.5 samples were collected in Suzhou from January 2019 to December 2021. The pollution levels were estimated based on enrichment factors (EFs) which can be used to calculate the enrichment of heavy metals in PM_2.5 and determine whether the concentrations of PM_2.5-bound heavy metals are influenced by the crustal or anthropogenic sources, and the health risk of PM_2.5-bound heavy metals via inhalation was assessed following US EPA's Risk Assessment Guidance for Superfund (RAGS). The annual average concentration of PM_2.5 was 46.76 μg m^-3, which was higher than the WHO recommended limit of 5 μg m^-3. The average of the sum of eleven PM_2.5-bound heavy metals was 180.61 ng m^-3, dominated by Al, Mn, and Pb. The concentration of PM_2.5 in 2020 was significantly lower than that in 2019 and 2021. The PM_2.5 and PM_2.5-bound heavy metal concentrations in winter and spring were significantly higher than those in autumn and summer. The EF of As, Cr, Cd, Hg, Ni, Pb, Sb, Mn, Se, and Tl was higher than 10, indicating they were mainly from anthropogenic sources. Exposure to a single non-carcinogenic heavy metal via inhalation was unlikely to cause non-carcinogenic effects (HQ < 1), but the integrated non-carcinogenic risks should be taken seriously (HI > 1). The cumulative carcinogenic risks from the carcinogenic elements were exceeding the lower limit (1 × 10^-6) of the acceptable risk range. The carcinogenic risks of As and Cr(VI) contributed 60.98% and 26.77%, respectively, which were regarded as two key carcinogenic risk factors. Overall, the government policies and countermeasures for the PM_2.5 pollution control should be performed not only based on the PM_2.5 concentration but also based on the PM_2.5-bound heavy metals and their health risks for the local residents.

Metal-oxide inhalation induced fever - Immuntoxicological aspects of welding fumes

Metal fume fever is a well-known occupational disease that arises from prolonged exposure to subtoxic levels of zinc oxide-containing fumes or dust. This review article aims to identify and examine the possible immunotoxicological effects of inhaled zinc oxide nanoparticles. The current most widely accepted pathomechanism for the development of the disease involves the formation of reactive oxygen species following the entry of zinc oxide particles into the alveolus resulting the release of pro-inflammatory cytokines by activation of the Nuclear Factor Kappa B transcriptional signal, thus evoking the symptoms. The role of metallothionein in inducing tolerance is believed to be a key factor in mitigating the development of metal fume fever. The other, poorly proven hypothetical route is that zinc-oxide particles bind to an undefined protein in the body as haptens to form an antigen and act as an allergen. After activation of the immune system, primary antibodies and immune complexes are developed and type 1. hypersensitivity reaction occurs, that can cause asthmatic dyspnoea, urticaria and angioedema. The development of tolerance is explained by the formation of secondary antibodies against primary antibodies. Oxidative stress and immunological processes cannot be completely separated from each other, as they can induce each other.

Particle size distribution in the evaluation of the inhalation toxicity of cosmetic spray products

While applying cosmetic sprays (pump sprays and propellant-based sprays) intended for use on the skin or hair, consumers may unintentionally inhale sprayed droplets/particles. Thus, it is essential to analyze the size distribution of sprayed droplets/particles because those less than 10 μm are considered to be respirable and may present a high systemic and local exposure risk. In this study, we investigated the droplet/particle size distribution of 78 cosmetic sprays by laser diffraction. Our results showed that the level of respirable droplets/particles released by pump sprays averaged 0.5% of all particles measured (0.00%-2.23%) and that released by propellant-based sprays averaged 15.25% (0.15%-32.27%). Dry shampoos (powder) released the highest percentage of respirable droplets/particles (16.66%-32.27%). A default value of 25% of respirable droplets/particles can also be suggested for dry shampoos. Droplet/particle size distribution was influenced by the spray dispensing system (pump or propellant-based), the product type (hairspray, sunscreen, etc.) and the galenic form (powder, oil, emulsion, etc.). However, it should be noted that more confidence is placed in the pump spray data due to the larger sample size. This study provides data on droplet/particle size, which may be used in a modelling approach to predict inhalation exposure. Therefore, it must be known and used, together with assessments of intrinsic and local toxicities to determine the margin of safety of the product by inhalation route, and to assess the risk of cosmetic sprays.

Toxicokinetics of silver element following inhalation of silver nitrate in rats

Silver (Ag) and its compounds are priority contaminants, for which toxicological effects are well documented, but their toxicokinetics are not fully documented for a proper risk assessment. While the toxicokinetics of insoluble Ag nanoparticles (Ag NPs) was recently documented, there is a lack of data on the kinetic behavior of the soluble form, such as one of the mostly used silver nitrate (AgNO₃) form. This study aimed to better document the toxicokinetics of Ag element following inhalation of soluble AgNO₃ for comparison with a previous study on the kinetics of inhaled Ag NPs using a similar experimental design. We exposed male Sprague-Dawley rats to AgNO₃ during 6 continuous hours (typical of a daily worker exposure) to determine the kinetic time courses of Ag element in blood, tissues, and excreta over a 14-day period post-exposure. Only a small fraction of Ag was found in lungs following the onset of the 6-h inhalation of AgNO₃ (on average (± SD) 0.3 ± 0.1% at the end of the 6-h inhalation). Blood profiles of Ag element showed peak levels right after the end of the 6-h inhalation period and levels decreased rapidly thereafter. Toxicokinetic parameter values calculated from the average blood-concentration profiles showed a mean residence time (MRT) of 135 h and mean half-life (t_1/2) of 94 h, with AUC of 2.5 mg/L × h and AUMC of 338 mg/L × h². In terms of percent of inhaled dose, highest levels of Ag in extrapulmonary organs were found in liver, which represented on average (± SD) 1.6 ± 0.6% of calculated inhaled dose followed by the kidney with 0.1 ± 0.08%. Peak levels in the GI tract (including contents) were found at the end of the 6-h inhalation and represented 20 ± 15.6% of the inhaled dose. The dominant excretion route of Ag was through feces. The time course of Ag element in the GI tract and feces following AgNO₃ inhalation is also compatible with an intestinal reabsorption of Ag. When compared to results of Ag NPs of a prior study with the same design, this study showed differences in the kinetics of soluble AgNO₃ compared to insoluble Ag NPs, with higher levels in blood, GI tract, and extrapulmonary tissues but lower levels in lungs following AgNO₃ exposure.

Exposure to polycyclic aromatic hydrocarbons assessed by biomonitoring of firefighters during fire operations in Germany

BACKGROUND

Firefighters are exposed to a variety of hazardous substances including carcinogens such as polycyclic aromatic hydrocarbons (PAH) during firefighting. In order to minimize the uptake of such substances into the body, firefighters wear personal protective equipment. Only few data exist from real-life firefighting missions and under common although highly variable exposure scenarios such as fighting fires in residential buildings, outdoor, and vehicle fires. The aim of this study is to assess the levels of 1-Hydroxypyrene (1-OHP) as marker for incorporated PAH during firefighting operations in Germany using biomonitoring methods.

METHODS

We analyzed urine samples for 1-OHP from 77 firefighters who reported firefighting operations (with and without creatinine adjustment). Urine samples were collected before (baseline) and, where applicable, after firefighting operations at three time points subsequent (2-4, 6-8, and 12 h).

RESULTS

Compared to the baseline measurements, mean 1-OHP concentrations after firefighting missions were doubled (0.14 vs. 0.31 μg/L urine, 0.13 μg/g vs. 0.27 μg/g creatinine) and this increase was observed 2-4 h after firefighting. Firefighting in residential buildings (N = 54) and of outdoor and vehicle fires (N = 17) occurred most frequently, whereas blazes, vegetation fires, and fires in underground facilities (N = 6) were rarely encountered. For residential building fires, a 3-fold increase in mean 1-OPH concentrations was observed, whereas no increase could be observed for outdoor and vehicle fires. The highest increase was observed for firefighters with interior attack missions (0.11 μg/L vs. 0.48 μg/L 1-OHP) despite the use of self-contained breathing apparatus (SCBA). During the suppression of outdoor or vehicle fires using SCBA, again, no increase was observed. Although PAH are taken up during certain firefighting missions, the 1-OHP levels almost entirely remained (in 64 of the 77 reported missions) within the normal range of the German general population, i.e., below the reference levels (95th percentiles) of smokers (0.73 μg/g creatinine) and non-smokers (0.30 μg/g creatine).

CONCLUSION

Under study conditions, properly applied protective clothing and wearing of SCBA led to a significant reduction of PAH exposure levels. But there are individual situations in which PAH are increasingly incorporated since the incorporation depends on several factors and can be extremely variable. In contrast to many workplaces with high occupational exposure levels, firefighters are not exposed to PAH on a daily basis. Nevertheless, the possibility of an individual increased cancer risk for a particular firefighter cannot completely be ruled out.

Efficacy of Do-It-Yourself air filtration units in reducing exposure to simulated respiratory aerosols

Many respiratory diseases, including COVID-19, can be spread by aerosols expelled by infected people when they cough, talk, sing, or exhale. Exposure to these aerosols indoors can be reduced by portable air filtration units (air cleaners). Homemade or Do-It-Yourself (DIY) air filtration units are a popular alternative to commercially produced devices, but performance data is limited. Our study used a speaker-audience model to examine the efficacy of two popular types of DIY air filtration units, the Corsi-Rosenthal cube and a modified Ford air filtration unit, in reducing exposure to simulated respiratory aerosols within a mock classroom. Experiments were conducted using four breathing simulators at different locations in the room, one acting as the respiratory aerosol source and three as recipients. Optical particle spectrometers monitored simulated respiratory aerosol particles (0.3-3 μm) as they dispersed throughout the room. Using two DIY cubes (in the front and back of the room) increased the air change rate as much as 12.4 over room ventilation, depending on filter thickness and fan airflow. Using multiple linear regression, each unit increase of air change reduced exposure by 10%. Increasing the number of filters, filter thickness, and fan airflow significantly enhanced the air change rate, which resulted in exposure reductions of up to 73%. Our results show DIY air filtration units can be an effective means of reducing aerosol exposure. However, they also show performance of DIY units can vary considerably depending upon their design, construction, and positioning, and users should be mindful of these limitations.

Investigation on the effectiveness of ventilation dilution on mitigating COVID-19 patients' secondary airway damage due to exposure to disinfectants

Chlorine-containing disinfectants are widely used in hospitals to prevent hospital-acquired severe acute respiratory syndrome coronavirus 2 infection. Meanwhile, ventilation is a simple but effective means to maintain clean air. It is essential to explore the exposure level and health effects of coronavirus disease 2019 patients' inhalation exposure to by-products of chloride-containing disinfectants under frequent surface disinfection and understand the role of ventilation in mitigating subsequent airway damage. We determined ventilation dilution performance and indoor air quality of two intensive care unit wards of the largest temporary hospital constructed in China, Leishenshan Hospital. The chloride inhalation exposure levels, and health risks indicated by interleukin-6 and D-dimer test results of 32 patients were analysed. The mean ± standard deviation values of the outdoor air change rate in the two intensive care unit wards were 8.8 ± 1.5 h^-1 (Intensive care unit 1) and 4.1 ± 1.4 h^-1 (Intensive care unit 2). The median carbon dioxide and fine particulate matter concentrations were 480 ppm and 19 μg/m³ for intensive care unit 1, and 567 ppm and 21 μg/m³ for intensive care unit 2, all of which were around the average levels of those in permanent hospitals (579 ppm and 21 μg/m³). Of these patients, the median (lower quartile, upper quartile) chloride exposure time and calculated dose were 26.66 (2.89, 57.21) h and 0.357 (0.008, 1.317) mg, respectively. A statistically significant positive correlation was observed between interleukin-6 and D-dimer concentrations. To conclude, ventilation helped maintain ward air cleanliness and health risks were not observed.

From "crisis to recovery": A complete insight into the mechanisms of chlorine injury in the lung

Chlorine (Cl₂) gas is a toxic industrial chemical (TIC) that poses a hazard to human health following accidental and/or intentional (e.g. terrorist) release. By using a murine model of sub-lethal Cl₂ exposure we have examined the airway hyper responsiveness, cellular infiltrates, transcriptomic and proteomic responses of the lung. In the "crisis" phase at 2 h and 6 h there is a significant decreases in leukocytes within bronchoalveolar lavage fluid accompanied by an upregulation within the proteome of immune pathways ultimately resulting in neutrophil influx at 24 h. A flip towards "repair" in the transcriptome and proteome occurs at 24 h, neutrophil influx and an associated drop in the lung function persisting until 14 d post-exposure and subsequent "recovery" after 28 days. Collectively, this research provides new insights into the mechanisms of damage, early global responses and processes of repair induced in the lung following the inhalation of Cl₂.

Health risk assessment of inhalation exposure to dry fogging of hydrogen peroxide in a dental clinic during the COVID-19 pandemic

After the outbreak of COVID-19, many dental clinics use dry fogging of hydrogen peroxide (H₂O₂) to disinfect the air and surfaces. Inhalation of highly concentrated solutions of H₂O₂ may cause severe respiratory problems. This study aimed to estimate the health risk assessments of inhalation exposure to dry fogging of H₂O₂ in a dental clinic. This cross-sectional, descriptive-analytical study was performed to determine the inhalation exposure and health risk of 9 dental clinic staff with H₂O₂ in six rooms. Occupational exposure to H₂O₂ was assessed using the OSHA VI-6 method and a personal pump with the flow rate of 500 mL/min connected to the midget fritted-glass impinger containing 15 mL of TiOSO₄ collecting solution. The health effects of H₂O₂ exposure were assessed using a respiratory symptoms questionnaire. The health risk assessment of inhaled exposure to H₂O₂ was also performed using the method provided by the Singapore occupational health department. The mean respiratory exposure of clinic staff to H₂O₂ was ranged from 1.3 to 2.83 ppm for six rooms which was above the limits recommended by international organizations. Dyspnea (44.4%), cough (33.3%), and nasal burning (22.2%) were the most prevalent health problems. The results also showed a medium risk for endodontics and surgery, and lower risk for periodontics, restorative care, orthodontics, and prosthetics. The results of this study indicate that when using an automated hydrogen peroxide-vapor fogger, calculating the spraying time based on room volume and using the rooms after 30 min of fogging is very important and can greatly reduce the risk ranking.

Bridge the gap: correlate face mask leakage and facial features with 3D morphable face models

BACKGROUND

Face masks have been proven to be effective in protecting the public against airborne transmitted diseases when fitted appropriately. However, for homemade cloth masks and surgical masks, the fit is often poor, allowing viruses to escape through the gap.

OBJECTIVE

This work aims to identify the correlation between the mask leakage, mask configurations, and individual's facial features.

METHODS

A novel locally morphing 3D face model, and a minimum-energy-based mask deployment model are used to systematically examine the mask fit for a large cohort of exemplars.

RESULTS

The results show that the mask size and tuck-in ratio, along with selective facial features, especially nose height and chin length, are key factors determining the leakage location and extent. A polynomial regression model is presented for mask fitness based on localized facial features.

SIGNIFICANCE

This study is a complete pipeline to test various masks on a wide range of faces with controlled modification of distinct regions of the face, which is difficult to achieve with human subjects, and provide knowledge on how the masks should be designed in the future.

IMPACT STATEMENT

The face mask "fit" affects the mask's efficacy in preventing airborne transmission. To date, research on the face mask fit has been conducted mainly using experiments on limited subjects. The limited sample size in experimental studies makes it hard to reach a statistical correlation between mask fit and facial features in a population. Here, we employ a novel framework that utilizes a morphable face model and mask's deployment simulation to test mask fit for many facial characteristics and mask designs. The proposed technique is an important step toward enabling personalized mask selection with maximum efficacy for society members.

Characterizing the external exposome using passive samplers-comparative assessment of chemical exposures using different wearable form factors

BACKGROUND

Organic contaminants are released into the air from building materials/furnishings, personal care, and household products. Wearable passive samplers have emerged as tools to characterize personal chemical exposures. The optimal placement of these samplers on an individual to best capture airborne exposures has yet to be evaluated.

OBJECTIVE

To compare personal exposure to airborne contaminants detected using wearable passive air samplers placed at different positions on the body.

METHODS

Participants (n = 32) simultaneously wore four passive Fresh Air samplers, on their head, chest, wrist, and foot for 24 hours. Exposure to 56 airborne organic contaminants was evaluated using thermal desorption gas chromatography high resolution mass spectrometry with a targeted data analysis approach.

RESULTS

Distinct exposure patterns were detected by samplers positioned on different parts of the body. Chest and wrist samplers were the most similar with correlations identified for 20% of chemical exposures (Spearman's Rho > 0.8, p < 0.05). In contrast, the greatest differences were found for head and foot samplers with the weakest correlations across evaluated exposures (8% compounds, Spearman's Rho > 0.8, p < 0.05).

SIGNIFICANCE

The placement of wearable passive air samplers influences the exposures captured and should be considered in future exposure and epidemiological studies.

IMPACT STATEMENT

Traditional approaches for assessing personal exposure to airborne contaminants with active samplers presents challenges due to their cost, size, and weight. Wearable passive samplers have recently emerged as a non-invasive, lower cost tool for measuring environmental exposures. While these samplers can be worn on different parts of the body, their position can influence the type of exposure that is captured. This study comprehensively evaluates the exposure to airborne chemical contaminants measured at different passive sampler positions worn on the head, chest, wrist, and foot. Findings provide guidance on sampler placement based on chemicals and emission sources of interest.

Inhaled tire-wear microplastic particles induced pulmonary fibrotic injury via epithelial cytoskeleton rearrangement

Tire wear microplastic particles (TWMPs) are emerging microplastic pollutants that have gained increasing attention lately. However, the health effect of inhaled airborne TWMPs has never been explored before and may already be included in particulate matter morbidity and mortality. Here, we endeavored to address the preliminary study of TWMP inhalation-induced pulmonary toxic effects and its epigenetic mechanisms in C57BL/6 mice. As a result, restricted ventilatory dysfunction and fibrotic pathological changes were observed in TWMP-treaded mice. Further research found that attenuation of miR-1a-3p plays an important role in TWMP-induced lung injury. Results from in vitro study confirmed that cytoskeleton regulatory gene twinfilin-1 was one of the target genes of miR-1a-3p, and involved in cytoskeleton rearrangement caused by TWMP exposure. Mechanistically, miR-1a-3p inhibited the F-actin formation by targeting cytoskeletal regulatory proteins twinfilin-1, leading to TWMP-induced pulmonary fibrotic injury. While we are in the very early stages of explaining the role of epigenetics in TWMP-induced lung injury, the potential for the use of epigenetic marks as biomarkers is high and discoveries made in this field will likely bring us closer to better understanding this crucial mechanism.

Human health risk assessment of PM2.5-bound heavy metal of anthropogenic sources in the Khon Kaen Province of Northeast Thailand

The study aimed to assess the human health risk of PM_2.5-bound heavy metals from anthropogenic sources in Khon Kaen Province, Thailand between December 2020 and February 2021. According to the findings, the geometric mean concentration of PM_2.5 in the university area, residential area, industrial zone, and the agricultural zone was 32.78 μg/m³, 50.25 μg/m³, 44.48 μg/m³, and 29.53 μg/m³, respectively. The results showed that the estimated human health risk assessment, in terms of non-carcinogenic risks among children and adults in an urban area (residential and university), industrial zone, and the agricultural area, was of hazard index (HI) value of >1.0 indicating a greater chance of chronic effects occurring. This study showed that exposure to PM_2.5-bound heavy metal may increase the likelihood that lasting effects will result in a very high carcinogenic risk (CR) in children in residential areas, and an industrial zone with total carcinogenic risk (TCR) values of 0.23×101, and 0.12×101, respectively while resulting in a high TCR of 3.34×10−2 and 4.11×10−2 within the university areas and agricultural zone, respectively. In addition, health risk assessments among adults demonstrate high TCR values of 4.40×10−1 (residential area), 2.28×10−1 (industrial zone), and 7.70×10−3 (agricultural zone), thus indicating a potential health risk to adults living in these areas while the university area was very low effects on carcinogenic risk (CR≤10−8) for adults. Therefore, lowering the risk of exposure to PM_2.5 via the respiratory tract, for example, wearing a mask outside is a very effective self-defense strategy for people within and around the study site. This data study strongly supports the implementation of the air pollutant emission source reduction measures control and health surveillance.

Comparison of the Toxic Effects of Pristine and Photocatalytically Used TiO2 Nanoparticles in Mice

TiO₂ nanoparticles used in the photocatalytic degradation of pollutants in water treatment processes undergo physiochemical changes; therefore, their toxicological effects may be potentially different from those of the pristine nanoparticles. This study compared the toxic effects of exposure to pristine and photocatalytically used TiO₂ nanoparticles in mice. To obtain used TiO₂, the nanoparticles were used for photocatalytic degradation of a model pollutant under UV irradiation several times. Two groups of mice were exposed to pristine (PT group) and photocatalytically used TiO₂ (UT group) at three different concentrations (5-20 mg/m³) using whole-body exposure chambers (2 h/day, 5 days/weeks, 4 weeks). Exposure to both pristine and used TiO₂ increased the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphate (ALP), lactate dehydrogenase (LDH), C-reactive protein (CRP), and creatine kinase (CK-MB) significantly. Both exposed groups showed higher levels of WBC, lymphocytes, platelets, hematocrits, hemoglobin, and mean corpuscular volume (MCV) and lower levels of RBC and mean corpuscular hemoglobin concentration (MCHC) in a concentration-dependent manner. In all analyses, there were small non-significant differences between the PT and UT groups. More pathological changes were observed in the lung, kidney, and brain of the UT group, while the PT group showed more pathological effects in the liver and heart. The histological observations indicated that damage was mostly in the form of vascular endothelial injury. These two types of TiO₂ may activate different pathways to promote adverse effects. Further studies are required to evaluate and distinguish the mechanisms through which pristine and used TiO₂ induce toxicity.

Blood absorption toxicokinetics of glycol ethers after inhalation: A human controlled study

Glycol ethers are organic solvents present in countless products for professional and domestic use. The main toxicological concerns are hematotoxicity, respiratory and reproductive toxicity. The general population can be exposed when using products containing one or several glycol ethers that evaporate or if sprayed, generate aerosols that can be inhaled. The rate at which glycol ethers enters blood following inhalation exposure are unknown in humans, and chemical risk assessors only rely on animal and in vitro toxicity studies. Propylene glycol monomethyl ether (PGME) and propylene glycol monobutyl ether (PGBE) are two examples of glycol ethers used worldwide. Our study aimed to provide human toxicokinetic data after inhalation exposure of low PGME and PGBE concentrations tested alone or in mixture. Healthy participants (n = 28) were exposed to 35 ppm (131 mg/m³) of PGME and 15 ppm (i.e., 83 mg/m³) of PGBE for 2 or 6 h. Blood was regularly collected during the exposure sessions. PGME and PGBE were immediately bioavailable in blood during exposure, and the mean absorption rates were up to 13 μg/L/min and 2.45 μg/L/min, respectively. Maximum mean blood concentration (Cmax) was 2.91 mg/L and 0.41 mg/L for PGME and PGBE. The cumulative internal doses over time (area under the curve, AUC) were 11 mg∗h/L and 1.81 mg∗h/L for PGME and PGBE. PGME and PGBE total blood uptake could possibly be higher in physically active individuals, such as workers. We recommend that glycol ethers present on the market undergo toxicological testing with the internal doses we found in our toxicokinetic study.

Acute and chronic health risk assessment for inhalation and ingestion exposure in acrylic acid leak accidents

We established a hypothetical acrylic acid leak accident scenario, conducted a health risk assessment of local residents, and compared an actual accident case to the hypothetical scenario. The exposed subjects were divided into four age groups, and a noncarcinogenic health risk assessment was conducted for inhalation and soil ingestion. In the hypothetical scenario, 40 tons of acrylic acid was leaked in Ulsan for 1 h from midnight on January 1, 2017. In the actual accident case, 3 L of acrylic acid was leaked in Hwaseong, Gyeonggi Province, for 1 h from 11:00 am on March 5, 2020. The environmental concentration of acrylic acid was calculated using the dynamic multimedia environmental model. Noncarcinogenic assessment of the hypothetical scenario showed the hazard quotient exceeded 1 across all age groups, suggesting that a health risk is likely to occur due to inhalation exposure to acrylic acid resulting from a chemical accident. In addition, Hazard_acute exceeded 1 until 2 h after the accident under the hypothetical scenario, indicating the likelihood of a health risk. Thus, we propose a methodology that can assess changing concentrations in a hazardous chemical leak from a chemical accident based on the time, place, the chemical's behaviors in different environmental media, and the health risk posed by the exposure of the chemical to local residents in the area affected by the accident.

Analyzing pesticides and metal(loid)s in imported tobacco to Saudi Arabia and risk assessment of inhalation exposure to certain metals

Exposure to toxic chemicals through smoked tobacco is a significant global public health issue due to their genotoxic and carcinogenic properties. The study aims to (1) measure Arsenic (As), Cadmium (Cd), Cobalt (Co), Chromium (Cr), Mercury (Hg), Nickle (Ni), lead (Pb), and 407 pesticides in tobacco commercialized in Saudi Arabia; and (2) evaluate human health risks associated with smoking tobacco. Thus, we analyzed 60 tobacco samples per brand from eight of the most popular tobacco brands in the Saudi market. The analyzed tobacco contained significant concentrations of toxic metal (loid)s and banned pesticides. Twenty-three out of 407 pesticide residues were found, with an average concentration of 0.004-1.155 µg/g. Average concentrations of As, Cd, Co, Cr, Hg, Ni, and Pb for all brands were 0.16, 0.57, 0.75, 1.36, 1.94, 0.01, and 0.37 µg/g, respectively. The risk assessment indicated that high cancer risks are associated with exposure to As, Cd, Cr, and Ni, while lower risks are associated with Pb. Additionally, the potential cancer risk estimated for Cr was higher than other toxic elements. The cumulative cancer risks (95%) under three different cases for all brands were greater than the permissible limits (=10-4). The chances of getting cancer through inhalation of particulate As, Cd, Cr, Ni, and Pb was 4 in 10 000 cases in the best case scenario (1 cigarette per day). Therefore, metal content in cigarette tobacco should be reduced to improve public health.HIGHLIGHTSAll tested brands contained banned pesticide residues except for brand C.Tobacco samples contained significant concentrations of toxic metal(loid)s.A high risk of developing cancer is associated with exposure to As, Cd, Cr, and Ni, while a lower risk is associated with exposure to Pb.

Maternal exposure to polycyclic aromatic hydrocarbons in South Texas, evaluation of silicone wristbands as personal passive samplers

BACKGROUND

Prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with adverse health effects in children. Valid exposure assessment methods with accurate spatial and temporal resolution across pregnancy is a critical need for advancing environmental health studies.

OBJECTIVE

The objective of this study was to quantify maternal PAH exposure in pregnant women residing in McAllen, Texas where the prematurity rate and childhood asthma prevalence rates are high. A secondary objective was to compare PAH levels in silicone wristbands deployed as passive samplers with concentrations measured using standardized active air-sampling techniques.

METHODS

Participants carried a backpack that contained air-sampling equipment (i.e., filter and XAD sorbent) and a silicone wristband (i.e., passive sampler) for three nonconsecutive 24-h periods. Filters, XAD tubes, and wristbands were analyzed for PAHs.

RESULTS

The median level of exposure for the sum of 16 PAHs measured via active sampling over 24 h was 5.54 ng/m³ (filters) and 43.82 ng/m³ (XADs). The median level measured in wristbands (WB) was 586.82 ng/band. Concentrations of the PAH compounds varied across sampling matrix type. Phenanthrene and fluorene were consistently measured for all participants and in all matrix types. Eight additional volatile PAHs were measured in XADs and WBs; the median level of exposure for the sum of these eight PAHs was 342.98 ng/m³ (XADs) and 632.27 ng/band. The silicone wristbands (WB) and XAD sorbents bound 1-methynaphthalyne, 2-methylnaphthalene, biphenyl following similar patterns of detection.

SIGNIFICANCE

Since prior studies indicate linkages between PAH exposure and adverse health outcomes in children at the PAH levels detected in our study, further investigation on the associated health effects is needed. Data reflect the ability of silicone wristbands to bind smaller molecular weight, semivolatile PAHs similar to XAD resin. Application of wristbands as passive samplers may be useful in studies evaluating semivolatile PAHs.

Exposure to concentrated ambient PM2.5 (CAPM) induces intestinal disturbance via inflammation and alternation of gut microbiome

Air pollution causes a great disease burden worldwide. Recent evidences suggested that PM_2.5 contributes to intestinal disease. The objective of present study was to investigate the influence of ambient PM_2.5 on intestinal tissue and microbiome via whole-body inhalation exposure. The results showed that high levels and prolonged periods exposure to concentrated ambient PM_2.5 (CAPM) could destroy the mucous layer of the colon, and significantly alter the mRNA expression of tight junction (Occludin and ZO-1) and inflammation-related (IL-6, IL-10 and IL-1β) genes in the colon, comparing with exposure to the filtered air (FA). The composition of intestinal microbiome at the phylum and genus levels also varied along with the exposure time and PM_2.5 levels. At the phylum level, Bacteroidetes was greatly decreased, while Proteobacteria was increased after exposure to CAPM, comparing with exposure to FA. At the genus level, Clostridium XlVa, Akkermansia and Acetatifactor, were significantly elevated exposure to CAPM, comparing with exposure to FA. Our results also indicated that high levels and prolonged periods exposure to CAPM altered metabolic functional pathways. The correlation analysis showed that the intestinal inflammation was related to the alteration of gut microbiome induced by CAPM exposure, which may be a potential mechanism that elucidates PM_2.5-induced intestinal diseases. These results extend our knowledge on the toxicology and health effects of ambient PM_2.5.

Short-term associations between barbecue fumes and respiratory health in young adults

BACKGROUND

Epidemiological studies have associated biomass combustion with (respiratory) morbidity and mortality, primarily in indoor settings. Barbecuing results in high outdoor air pollution exposures, but the health effects are unknown.

OBJECTIVE

The objective was to investigate short-term changes in respiratory health in healthy adults, associated with exposure to barbecue fumes.

METHODS

16 healthy, adult volunteers were exposed to barbecue smoke in outdoor air in rest during 1.5 h, using a repeated-measures design. Major air pollutants were monitored on-site, including particulate matter <2.5 μm (PM_2.5), particle number concentrations (PNC) and black- and brown carbon. At the same place and time-of-day, subjects participated in a control session, during which they were not exposed to barbecue smoke. Before and immediately after all sessions lung function was measured. Before, immediately after, 4- and 18 h post-sessions nasal expression levels of interleukin (IL)-8, IL6 and Tumor Necrosis Factor alpha (TNFα) were determined in nasal swabs, using quantitative polymerase chain reaction. Associations between major air pollutants, lung function and inflammatory markers were assessed using mixed linear regression models.

RESULTS

High PM_2.5 levels and PNCs were observed during barbecue sessions, with averages ranging from 553 to 1062 μg/m³ and 109,000-463,000 pt/cm³, respectively. Average black- and brown carbon levels ranged between 4.1-13.0 and 5.0-16.2 μg/m³. A 1000 μg/m³ increase in PM_2.5 was associated with 2.37 (0.97, 4.67) and 2.21 (0.98, 5.00) times higher expression of IL8, immediately- and 18 h after exposure. No associations were found between air pollutants and lung function, or the expression of IL6 or TNFα.

DISCUSSION

Short-term exposure to air pollutants emitted from barbecuing was associated with a mild respiratory response in healthy young adults, including prolonged increase in nasal IL8 without a change in lung function and other measured inflammatory markers. The results might indicate prolonged respiratory inflammation, due to short-term exposure to barbecue fumes.

Clinical Features and Outcomes of Acute Chlorine Gas Inhalation; a Brief Report

Introduction

On March 6^th,2020, chlorine gas leak was reported at Engro Polymer & Chemicals Plant in Karachi City, Pakistan. This study aimed to evaluate the clinical features and outcomes of patients who presented to emergency department (ED) following this event.

Methods

This retrospective cross-sectional study, evaluated the clinical features and outcomes (length of hospital stay, complications, and mechanical ventilation requirement) of patients presenting to ED of Aga Khan University Hospital, Karachi, Pakistan, with history of chlorine gas exposure at the Engro Plant from 6^th March to 14^th March 2020.

Results

38 patients with mean age of 33.1 ± 8.1 years presented to ED with history of chlorine gas exposure (100% male). 4 (10.5%) cases had comorbid diseases. Most common presenting symptom was dyspnea, observed in 33 (86.8%) cases, followed by cough, seen in 27 (71.1%) subjects. 13.2% (5/38) patients had infiltration on chest x-ray and 33 (86.8 %) required hospitalization. 6 (15.8%) patients had repeat presentation requiring hospitalization or ED visit. 18 (47.4%) were managed with high flow oxygen therapy, 9 (23.7%) required non-invasive ventilation and one patient was intubated due to development of pneumo-mediastinum. Mean length of stay was 1.55 ± 1.58 days and no patients died. Presence of tachycardia was the only finding significantly associated with need for oxygen (p = 0.033) and non-invasive ventilation (p = 0.012).

Conclusion

The majority of patients presenting with acute chlorine gas exposure showed good clinical outcomes and rapid recovery, however, a high index of suspicion and vigilance should be maintained for complications such as pneumomediastinum and acute respiratory distress syndrome in these patients.

Uniqueness of inspiratory airflow patterns in a realistic rat nasal cavity

In this study, we present a detailed flow analysis using an anatomically accurate rat nasal cavity model, in which the anatomy and physiology of the nasal airway was thoroughly examined. Special efforts were given to the swirling flow structures in the nasal vestibule (anterior section of the nose, lined by squamous epithelium), fractional flow patterns in the olfactory (posterior superior section of the rat nose, lined by olfactory epithelium), and a designated method to precisely quantify flow apportionment in the olfactory region was developed. Results revealed distinct inspiratory flow patterns in the anterior vestibule region, where the accelerated airflow undergoes two sharp turns as traveling through the tortuous airway, making a route in a shape of 8. Besides this, exceptionally large flow apportionment was observed at the interface of the olfactory recess, which can be as much as 15 times greater than that in the human nose. The thorough understanding of the airflow dynamics in the rat nasal cavity is necessary to avoid potential misinterpretation of rat-derived inhalation toxicity results. Research findings are expected to play a fundamental role in developing unbiased rat to human interspecies data extrapolation schemes.

Inhalation exposure to 2-ethyl-1-hexanol causes hepatomegaly and transient lipid accumulation without induction of peroxisome proliferator-activated receptor alpha in mice

2-Ethyl-1-hexanol (2EH) is a volatile organic compound known to cause sick building syndrome. However, 2EH-induced hepatotoxicity has been mainly evaluated in experiments orally administering 2EH as a metabolite of di(2-ethylhexyl) phthalate. To evaluate the hepatotoxicity risk of 2EH as an indoor air pollutant, we exposed 10-wk-old male ICR mice to 2EH by inhalation for 8 h/d, 5 d/wk for 3 months (0, 20, 60, or 150 ppm) or 6 months (0, 0.5, 10, or 100 ppm). In both experiments, relative liver weights significantly increased in the highest exposure groups. The 3-month exposure increased histopathological lipid droplets in the liver in a dose-dependent manner, hepatic triglyceride at all exposure levels, hepatic phospholipid at 150 ppm, and microsomal triglyceride transfer protein at 60 and 150 ppm; however, these changes were not observed following the 6-month of exposure. Following the 3-month exposure, alanine transaminase and peroxisomal bifunctional proteins, known markers of liver injury and peroxisome proliferation, respectively, remained unaltered. Therefore, in the present study, the inhalation concentration range of 2EH induced a toxic hypertrophic change, revealing a limited role of peroxisome proliferator-activated receptor alpha (PPARα). The liver weights may have presumably increased via a mechanism independent of PPARα activation.

Kinetic time courses of inhaled silver nanoparticles in rats

Silver nanoparticles (Ag NPs) are priority substances closely monitored by health and safety agencies. Despite their extensive use, some aspects of their toxicokinetics remain to be documented, in particular following inhalation, the predominant route of exposure in the workplace. A same experimental protocol and exposure conditions were reproduced two times (experiments E1 and E2) to document the kinetic time courses of inhaled Ag NPs. Rats were exposed nose-only to 20 nm Ag NPs during 6 h at a target concentration of 15 mg/m³ (E1: 218,341 ± 85,512 particles/cm³; E2, 154,099 ± 5728 particles/cm³). The generated aerosol showed a uniform size distribution of nanoparticle agglomerates with a geometric mean diameter ± SD of 79.1 ± 1.88 nm in E1 and 92.47 ± 2.19 nm in E2. The time courses of elemental silver in the lungs, blood, tissues and excreta were determined over 14 days following the onset of inhalation. Excretion profiles revealed that feces were the dominant excretion route and represented on average (± SD) 5.1 ± 3.4% (E1) and 3.3 ± 2.5% (E2) of the total inhaled exposure dose. The pulmonary kinetic profile was similar in E1 and E2; the highest percentages of the inhaled dose were observed between the end of the 6-h inhalation up to 6-h following the end of exposure, and reached 1.9 ± 1.2% in E1 and 2.5 ± 1.6% in E2. Ag elements found in the GIT followed the trend observed in lungs, with a peak observed at the end of the 6-h inhalation exposure and representing 6.4 ± 4.9% of inhaled dose, confirming a certain ingestion of Ag NPs from the upper respiratory tract. Analysis of the temporal profile of Ag elements in the liver showed two distinct patterns: (i) progressive increase in values with peak at the end of the 6-h inhalation period followed by a progressive decrease; (ii) second increase in values starting at 72 h post-exposure with maximum levels at 168-h followed by a progressive decrease. The temporal profiles of Ag elements in lymphatic nodes, olfactory bulbs, kidneys and spleen also followed a pattern similar to that of the liver. However, concentrations in blood and extrapulmonary organs were much lower than lung concentrations. Overall, results show that only a small percentage of the inhaled dose reached the lungs-most of the dose likely remained in the upper respiratory tract. The kinetic time courses in the gastrointestinal tract and liver showed that part of the inhaled Ag NPs was ingested; lung, blood and extrapulmonary organ profiles also suggest that a small fraction of inhaled Ag NPs progressively reached the systemic circulation by a direct translocation from the respiratory tract.

Size distribution and inhalation exposure of airborne particle-bound polybrominated diphenyl ethers, new brominated flame retardants, organophosphate esters, and chlorinated paraffins at urban open consumption place

At present, the global urban population has exceeded half of the total population and is still on the rise. Urban air pollution has attracted much attention, but most of the research focuses on typical pollution sources and indoor environment. This study reports the occurrence characteristics of particle-bound polybrominated diphenyl ethers (PBDEs), new brominated flame retardants (NBFRs), organophosphate esters (OPEs), short-chain chlorinated paraffins (SCCPs), and medium-chain chlorinated paraffins (MCCPs) at urban open consumption place. Among those pollutants detected in this study, the level of CPs was generally higher than other urban outdoor environments, and even higher than few indoor environments, such as house in Guangzhou (China) and Stockholm (Sweden). The size distributions of PBDEs and NBFRs exhibited bimodal peaks and that of SCCPs presented a unimodal peak, whereas no obvious trend was observed for OPEs or MCCPs. Additionally, the results of calculating the deposition fluxes of target pollutants in various regions based on the size distribution confirmed that total deposition was dominated by deposition in the head airways and alveolar region, and inhalation exposure in the current environment poses no significant health risk. Both discrepancy of the spatial distribution and principal component analysis indicated that sources of these organic pollutants may be related to the type of stores. Various construction and decoration materials might have been responsible for the high concentrations of OPEs and CPs, and thus, these materials require further analysis.

Environmental Surveillance and Transmission Risk Assessments for SARS-CoV-2 in a Fitness Center

Fitness centers are considered high risk for SARS-CoV-2 transmission due to their high human occupancy and the type of activity taking place in them, especially when individuals pre-symptomatic or asymptomatic for COVID-19 exercise in the facilities. In this study, air (N=21) and surface (N=8) samples were collected at a fitness center through five sampling events from August to November 2020 after the reopening restrictions were lifted in Florida. The total attendance was ~2500 patrons during our air and environmental sampling work. Air samples were collected using stationary and personal bioaerosol samplers. Moistened flocked nylon swabs were used to collect samples from high-touch surfaces. We did not detect SARS-CoV-2 by rRT-PCR analyses in any air or surface sample. A simplified infection risk model based on the Wells-Riley equation predicts that the probability of infection in this fitness center was 1.77% following its ventilation system upgrades based on CDC guidelines, and that risk was further reduced to 0.89% when patrons used face masks. Our model also predicts that a combination of high ventilation, minimal air recirculation, air filtration, and UV sterilization of recirculated air reduced the infection risk up to 94% compared to poorly ventilated facilities. Amongst these measures, high ventilation with outdoor air is most critical in reducing the airborne transmission of SARS-CoV-2. For buildings that cannot avoid air recirculation due to energy costs, the use of high filtration and/or air disinfection devices are alternatives to reducing the probability of acquiring SARS-CoV-2 through inhalation exposure. In contrast to the perceived ranking of high risk, the infection risk in fitness centers that follow CDC reopening guidance, including implementation of engineering and administrative controls, and use of personal protective equipment, can be low, and these facilities can offer a relatively safe venue for patrons to exercise.

Potential consumer exposure to respirable particles and TiO2 due to the use of eyebrow powders

BACKGROUND

Cosmetic powders contain numerous components, including titanium dioxide (TiO₂), which is classified as possibly carcinogenic to humans (Group 2B). However, little is known about potential inhalation exposures to particles that are released during cosmetic powder applications.

METHODS

We realistically simulated the application of five different eyebrow powders using a mannequin and then determined concentrations of total suspended particles (TSP), PM₁₀, and PM₄ fractions of particles that would be inhaled during powder application. We determined the size and shape of particles in the original powders and released particles, as well as their TiO₂ concentrations and Ti content of individual particles.

RESULTS

The application of eyebrow powders resulted in the release and inhalation of airborne particles at concentrations ranging from 21.2 to 277.3 µg/m³, depending on the particle fraction and the powder. The concentrations of TiO₂ in PM₄ and PM₁₀ samples reached 2.7 µg/m³ and 9.3 µg/m³, respectively. The concentration of TiO₂ in airborne particle fractions was proportional to the presence of TiO₂ in the bulk powder.

CONCLUSION

The application of eyebrow powders results in user exposures to respirable PM₄ and PM₁₀ particles, including those containing TiO₂. This information should be of interest to stakeholders concerned about inhalation exposure to TiO₂.

A suitable silicosis mouse model was constructed by repeated inhalation of silica dust via nose

Silicosis as the serious occupational disease is highly necessary to construct a suitable mouse model for disclosing mechanism of occurrence and development in this disease. Here, the volume-effect relationship and volume-based survival curves in mice who inhaled silica suspension intranasally were analyzed. Notable, the optimal volume 80 μl repeated-inhalation by nose to silica suspension in the inbred mouse C57BL/6 J with the highest susceptibility to silicosis led to a great entrance into the lung and a high survival rate after instillation. After repeated-exposure to 20 mg/mL, 80 μl silica for 16 days and then fed without silica exposure until 31 days, weight of mice showed a trend of first decrease and then recover. Moreover, the degree of pulmonary inflammation and fibrosis in mice were analyzed by pathological and immunohistochemistry staining. Transforming growth factor-beta (TGF-β), smooth muscle alpha-actin (α-SMA) and collagen type-I (collagen I, Col-I) were significantly increased in the silica-exposed mouse lung at post-exposure day 16 compared with the controls. Sirius red stain and Micro-CT analysis showed that lung fibrosis formed at post-exposure day 31. This study highlights the critical importance of perfusion volume and repeated nasal drops in inducing inflammatory response and pulmonary fibrosis in silicosis.

Airborne microplastics in indoor and outdoor environments of a coastal city in Eastern China

Microplastics (MPs) in marine and terrestrial environments have been intensively studied, but the dynamics of airborne MPs remains limited. Existing studies on atmospheric MPs are mostly derived from collection of atmospheric deposition, whereas direct measurements of airborne MPs are scarce. However, the abundance of airborne MPs is more relevant for evaluating human inhalation exposure risk. Herein, airborne MPs in indoor and outdoor environments from urban and rural areas of a coastal city in eastern China were investigated. MP concentrations (mean±SD) in indoor air (1583 ± 1180 n/m³) were an order of magnitude higher than outdoor air (189 ± 85 n/m³), and airborne MP concentrations in urban areas (224 ± 70 n/m³) were higher than rural areas (101 ± 47 n/m³). MPs smaller than 100 µm dominated airborne MPs, and the predominant shape of airborne MPs was fragments, as opposed to fibers. The larger MP size fractions contained a higher proportion of fibers, whereas the smaller size fractions were nearly exclusively composed of fragments. The health risk caused by ubiquitous airborne MPs should not be discounted as the maximum annual outdoor exposure of airborne MPs can reach 1 million/year, while indoor exposure may be even higher due to higher indoor airborne MP concentrations.

Evaluation of fireground exposures using urinary PAH metabolites

BACKGROUND

Firefighters have increased cancer incidence and mortality rates compared to the general population, and are exposed to multiple products of combustion including known and suspected carcinogens.

OBJECTIVE

The study objective was to quantify fire response exposures by role and self-reported exposure risks.

METHODS

Urinary hydroxylated metabolites of polycyclic aromatic hydrocarbons (PAH-OHs) were measured at baseline and 2-4 h after structural fires and post-fire surveys were collected.

RESULTS

Baseline urine samples were collected from 242 firefighters. Of these, 141 responded to at least one of 15 structural fires and provided a post-fire urine. Compared with baseline measurements, the mean fold change of post-fire urinary PAH-OHs increased similarly across roles, including captains (2.05 (95% CI 1.59-2.65)), engineers (2.10 (95% CI 1.47-3.05)), firefighters (2.83 (95% CI 2.14-3.71)), and paramedics (1.84 (95% CI 1.33-2.60)). Interior responses, smoke odor on skin, and lack of recent laundering or changing of hoods were significantly associated with increased post-fire urinary PAH-OHs.

SIGNIFICANCE

Ambient smoke from the fire represents an exposure hazard for all individuals on the fireground; engineers and paramedics in particular may not be aware of the extent of their exposure. Post-fire surveys identified specific risks associated with increased exposure.

Inhalation bioaccessibility, health risk assessment, and source appointment of ambient PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) in Caofeidian, China

The inhalation bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) is significant for accurately assessing the health risks posed by PM_2.5-bound PAHs. In this study, 96 PM_2.5 samples from Caofeidian, China, were investigated for PM_2.5-bound PAH source appointment and bioaccessibility assessment during four seasons. PAH₁₈ potential sources were identified by positive matrix factorization. The inhalation bioaccessibility of PAH₁₈ was investigated by simulated epithelial lung fluid extraction. The incremental lifetime cancer risk (ILCR) model was subsequently used to evaluate the carcinogenic risk posed by PM_2.5-bound PAHs in children, teenagers, and adults. Four potential sources of PM_2.5-bound PAH₁₈ were identified: industry emissions (44%), petroleum volatilization (30%), vehicle emissions (15%), and coal combustion (11%). The average inhalation bioaccessibility of PAHs ranged from 17.8% (dibenzo [a,h] anthracene) to 67.9% (fluorene). The ILCR values for children and teenagers were lower than the acceptable levels (10^-6) in the four seasons considering inhalation bioaccessibility. However, the ILCR value of adults was higher than the threshold in winter (1.26 × 10^-6). Source identification suggested that reducing industrial pollution was the primary measure for controlling PM_2.5-bound PAHs in Caofeidian. Additionally, the inhalation bioaccessibility of PM_2.5-bound PAHs was evaluated to precisely estimate the health risks caused by PAHs.

Calibration of silicone for passive sampling of semivolatile organic contaminants in indoor air

Semivolatile organic compounds (SVOCs) are mostly man-made chemicals that distribute between the gas and solid phase in the environment. Many of them could pose harm to people and therefore it is important to know their concentrations in the indoor environment to evaluate the related risks. Inhalation exposure can be assessed using passive sampling. In this study, we employed silicone elastomer as a passive sampler for monitoring gaseous polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) in indoor air. We performed a sampler calibration study in which samplers consisting of 0.5 mm thick silicone sheets with a total surface area of 300 cm² were exposed to indoor air in a university lecture theatre for up to 56 days. Uptake kinetics of SVOCs was studied by collecting 2 samplers every week. The results were used to develop a model based on mass transfer theory that can be used to estimate the air sampling rate R_S as a function of compound's molecular volume. We examined release kinetics of performance reference compounds that covered a broad range of silicone-air partition coefficient (log K_SA 5.95-9.49) and investigated a hypothesis of isotropic exchange kinetics, i.e. equality of rate constants for uptake and release, of SVOCs. PCBs and OCPs concentration in air calculated from contaminant amounts accumulated in passive samplers were in good agreement with those determined by active sampling running simultaneously during the entire study. The use of performance reference compounds is suitable for in situ passive sampler calibration.

Inhalational Constrictive Bronchiolitis: The Evolution of our Understanding of this Disease

The case definition of inhalational constrictive bronchiolitis (CB) has changed over the generations. We identify changes in the description of this illness over time associated with different exposures and present the natural history of CB in a case attributed to military burn pit exposure. The initial descriptions of this disease began with nitric acid spills and silage exposures. In these events, there was an acute exposure, typically a short-term resolution of the adverse respiratory events, and then a progression, leading to disability or a respiratory death. The life-saving role of corticosteroid therapy in this situation was recognized. War gas exposures of World War I and then Saddam Hussein's use of sulfur mustard gas in the Iran-Iraq War followed. More recently the findings associated with diacetyl exposure in commercial popcorn workers remained consistent with previously described presentations, but then the clinical presentation in troops returning from deployment to Southwest Asia was very different, yet with the same histologic findings. We recognize unreconciled disparities in the clinical, physiologic, and imaging presentation in those with inhalational bronchiolitis and acknowledge this as perhaps one of the difficult diagnoses in respiratory medicine.