Non-target screening and human risk assessment for adult and child populations of semi-volatile organic compounds in residential indoor dust in Spain

Optimizing solvent extraction methods for activated carbon-based passive samplers in atmospheric volatile organic compound analysis: minimizing analytical interferences from pretreatment solvents and ensuring quantitative reliability

A passive sampler was used to effectively monitor trace volatile organic compound (VOC) concentrations in the atmosphere. VOCs are typically extracted from passive samplers using CS2, which is a volatile and hazardous chemical that can leave residues and damage the mass spectrometry (MS) system during gas chromatography (GC)-MS. This study aims to develop and validate alternative solvent extraction methods using acetone, ethanol, n-hexane, and a solution of 99% acetone and 1% CS2 (ATCS) for VOCs from passive samplers using a standard GC-MS system. ATCS had the highest VOC extraction efficiency with the average value of 42.4 ± 21.4%, followed by acetone at 29.9 ± 17.6%. Ethanol and n-hexane exhibited extraction efficiencies of less than 9%. Despite the ATCS extraction efficiency of less than 50%, it demonstrated excellent analytical reproducibility (relative standard deviation of 1.62 ± 0.64%) and detection limit of 20.5 ± 12.9 ppt, which was significantly lower than 1 ppb. When used to extract and analyze VOCs from ambient air samples, ATCS yielded VOC concentrations of 0.57 ± 0.33 ppb, consistent with urban air levels. The variance in the outdoor VOC concentrations was less than 0.1 ppb, confirming its high reproducibility. Thus, the ATCS solvent extraction method developed in this study enables the accurate quantification of trace VOCs below 1 ppb, reduces MS damage, and mitigates health risks to analysts using GC-MS.

Comprehensive air quality assessment including non-targeted approaches in primary schools from Spain

This work aims to establish a strategy to comprehensively assess the indoor air quality in schools including the analysis of chemical pollutants, bio-aerosols like fungi, bacteria and respiratory viruses and the identification of volatile and semi-volatile organic compounds applying non-targeted approaches. For this, a pilot study was performed in four primary schools from Spain, located in different urban and rural areas during different seasons. Common indoor pollutants, like CO2, NO2, O3, CO, particulate matter (PM10, PM2.5), ultrafine particles (UFP), total volatile organic compounds (TVOCs), and formaldehyde (HCHO), were assessed in terms of maximum recommended levels, daily variations, seasonality, and school location. Additionally, fungi and bacteria were studied indoors and they were always found at adequate levels. The most prevalent fungal genera were Aspergillus, Penicillium, and Cladosporium. Seventeen respiratory viruses were measured in the air of the assessed classrooms and none were detected. Volatile and semivolatile organic compounds were identified indoors and outdoors using non-targeted approaches based on GC-HRMS and UHPLC-HRMS. High-confidence identified compounds were classified according to their chemical and toxicological characteristics, revealing that 44% and 26% of them presented a high toxicological risk in outdoor and indoor environments, respectively. This study provides a new strategy to assess comprehensively the IAQ in schools, and expands the knowledge about contaminants present in these environments, giving rise to future research.

Exploring environmental modifiers of LRRK2-associated Parkinson's disease penetrance: An exposomics and metagenomics pilot study on household dust

Pathogenic variants in the Leucine-rich repeat kinase 2 (LRRK2) gene are a primary monogenic cause of Parkinson's disease (PD). However, the likelihood of developing PD with inherited LRRK2 pathogenic variants differs (a phenomenon known as "reduced penetrance"), with factors including age and geographic region, highlighting a potential role for lifestyle and environmental factors in disease onset. To investigate this, household dust samples from four different groups of individuals were analyzed using metabolomics/exposomics and metagenomics approaches: PD+/LRRK2+ (PD patients with pathogenic LRRK2 variants; n = 11), PD-/LRRK2+ (individuals with pathogenic LRRK2 variants but without PD diagnosis; n = 8), iPD (PD of unknown cause; n = 11), and a matched, healthy control group (n = 11). The dust was complemented with metabolomics and lipidomics of matched serum samples, where available. A total of 1,003 chemicals and 163 metagenomic operational taxonomic units (mOTUs) were identified in the dust samples, of which ninety chemicals and ten mOTUs were statistically significant (ANOVA p-value < 0.05). Reduced levels of 2-benzothiazolesulfonic acid (BThSO3) were found in the PD-/LRRK2+ group compared to the PD+/LRRK2+ . Among the significant chemicals tentatively identified in dust, two are hazardous chemical replacements: Bisphenol S (BPS), and perfluorobutane sulfonic acid (PFBuS). Furthermore, various lipids were found altered in serum including different lysophosphatidylethanolamines (LPEs), and lysophosphatidylcholines (LPCs), some with higher levels in the PD+/LRRK2+ group compared to the control group. A cellular study on isogenic neurons generated from a PD+/LRRK2+ patient demonstrated that BPS negatively impacts mitochondrial function, which is implicated in PD pathogenesis. This pilot study demonstrates how non-target metabolomics/exposomics analysis of indoor dust samples complemented with metagenomics can prioritize relevant chemicals that may be potential modifiers of LRRK2 penetrance.

Overlooked Trace Molecules in Organic Aerosol Revealed by Gas Chromatography-Orbitrap Mass Spectrometry

Molecular characterization of organic aerosol (OA) is crucial for understanding its sources and atmospheric processes. However, the chemical components of OA remain not well constrained. This study used gas chromatography-Orbitrap mass spectrometry (GC-Orbitrap MS) and GC-Quadrupole MS (GC-qMS) to investigate the organic composition in PM2.5 from Xi'an, Northwest China. GC-Orbitrap MS identified 335 organic tracers, including overlooked isomers and low-concentration molecules, approximately 1.6 times more than GC-qMS. The "molecular corridor" assessment shows the superior capability of GC-Orbitrap MS in identifying an expansive range of compounds with higher volatility and oxidation states, such as furanoses/pyranoses, di/hydroxy/ketonic acids, di/poly alcohols, aldehydes/ketones, and amines/amides. Seasonal variations in OA composition reflect diverse sources: increased di/poly alcohols in winter are derived from indoor emissions, furanoses/pyranoses and heterocyclics in spring and summer might be from biogenic emissions and secondary formation, and amides in autumn are probably from biomass burning. Integrating partial least squares discriminant analysis (PLS-DA) and potential source contribution function (PSCF) models, the source similarities and differences are further elucidated, highlighting the role of local emissions and transport from southern cities. This study offers new insights into the OA composition aided by the high mass resolution and sensitivity of GC-Orbitrap MS.

Air quality of health facilities in Spain

The present study examines indoor air pollution in health facilities, focusing on compounds from various sources, such as industrial products, healthcare activities and building materials. It assesses chemical and microbiological concentrations in two public hospitals, two public healthcare centres, and one public health laboratory in Spain. Measurements included indoor air quality, microbiological contaminants, ambient parameters and non-target analysis across ten different locations. Outdoor air quality was also assessed in the surroundings of the hospitals. The results showed that around 350 substances were tentatively identified at a high confidence level, with over 50 % of compounds classified as of high toxicological risk. Three indoor and 26 outdoor compounds were fully confirmed with standards. These confirmed substances were linked to medical, industrial and agricultural activities. Indoor Air Quality (IAQ) results revealed that CO, CO2, formaldehyde (HCHO), O3 and total volatile organic compounds (TVOCs) showed average values above the recommended guideline levels in at least one of the evaluated locations. Moreover, maximum concentrations detected for CO, HCHO, O3 and TVOCs in hospitals surpassed those previously reported in the literature. SARS-CoV-2 was detected in three air environments, corresponding to COVID-19 patient areas. Fungi and bacteria concentrations were acceptable in all assessed locations, identifying different fungi genera, such as Penicillium, Cladosporium, Aspergillus, Alternaria and Botrytis.

Emission of volatile organic compounds during open fire cooking with wood biomass: Traditional three-stone open fire vs. gasifier cooking stove in rural Kenya

Cooking with wood biomass fuels releases hazardous air pollutants, including volatile organic compounds (VOCs), that often disproportionally affect women and children. This study, conducted in Kwale and Siaya counties in Kenya, employed thermal desorption gas chromatography - mass spectrometry to analyse VOC emissions from cooking with a wood biomass three-stone open fire vs. top-lit updraft gasifier stove. In kitchens with adequate ventilation, total VOC levels increased from 35-252 μg∙m-3 before cooking to 2235-5371 μg∙m-3 during open fire cooking, whereas use of a gasifier stove resulted in reduced emissions from cooking by 48-77 % (506-2778 μg∙m-3). However, in kitchens with poor ventilation, there was only a moderate difference in total VOC levels between the two methods of cooking (9034-9378 μg∙m-3 vs. 6727-8201 μg∙m-3 for the three-stone open fire vs. gasifier stove, respectively). Using a non-target screening approach revealed significantly increased levels of VOCs, particularly benzenoids, oxygenated and heterocyclic compounds, when cooking with the traditional open fire, especially in closed kitchens, highlighting the effects of poor ventilation. Key hazardous VOCs included benzene, naphthalene, phenols and furans, suggesting potential health risks from cooking. In kitchens with good ventilation, use of the gasifier stove markedly reduced emissions of these priority toxic VOCs compared to cooking with an open fire. Thus, substituting open fires with gasifier stoves could help to improve household air quality and alleviate health risks. The study revealed that VOCs were present prior to cooking, possibly originating from previously cooked food (buildup) or the outside environment. VOC emissions were also exacerbated by reduced air flow in high humidity during rainfall, suggesting an area for further research. The findings underscore the importance of adopting cleaner cooking technologies and enhancing kitchen ventilation to mitigate the impacts of VOCs in developing countries.

Screening Disinfection Byproducts in Arid-Coastal Wastewater: A Workflow Using GC×GC-TOFMS, Passive Sampling, and NMF Deconvolution Algorithm

Disinfection during tertiary municipal wastewater treatment is a necessary step to control the spread of pathogens; unfortunately, it also gives rise to numerous disinfection byproducts (DBPs), only a few of which are regulated because of the analytical challenges associated with the vast number of potential DBPs. This study utilized polydimethylsiloxane (PDMS) passive samplers, comprehensive two-dimensional gas chromatography (GC×GC) coupled with time-of-flight mass spectrometry (TOFMS), and non-negative matrix factorization (NMF) spectral deconvolution for suspect screening of DBPs in treated wastewater. PDMS samplers were deployed upstream and downstream of the chlorination unit in a municipal wastewater treatment plant located in Abu Dhabi, and their extracts were analyzed using GC×GC-TOFMS. A workflow incorporating a multi-tiered, eight-filter screening process was developed, which successfully enabled the reliable isolation of 22 candidate DBPs from thousands of peaks. The NMF spectral deconvolution improved the match factor score of unknown mass spectra to the reference mass spectra available in the NIST library by 17% and facilitated the identification of seven additional DBPs. The close match of the first-dimension retention index data and the GC×GC elution patterns of DBPs, both predicted using the Abraham solvation model, with their respective experimental counterparts-with the measured data available in the NIST WebBook and the GC×GC elution patterns being those observed for the candidate peaks-significantly enhanced the accuracy of peak assignment. Isotopic pattern analysis revealed a close correspondence for 11 DBPs with clearly visible isotopologues in reference spectra, thereby further strengthening the confidence in the peak assignment of these DBPs. Brominated analogues were prevalent among the detected DBPs, possibly due to seawater intrusion. The fate, behavior, persistence, and toxicity of tentatively identified DBPs were assessed using EPI Suite™ and the CompTox Chemicals Dashboard. This revealed their significant toxicity to aquatic organisms, including developmental, mutagenic, and endocrine-disrupting effects in certain DBPs. Some DBPs also showed activity in various CompTox bioassays, implicating them in adverse molecular pathways. Additionally, 11 DBPs demonstrated high environmental persistence and resistance to biodegradation. This combined approach offers a powerful tool for future research and environmental monitoring, enabling accurate identification and assessment of DBPs and their potential risks.

Organic toxicants and emerging contaminants in hospital interiors before and during the SARS-CoV2 pandemic: alkanes and PAHs

Indoor pollution and deposition dust (DD), in particular, are acquiring concern, due to long exposure time and importance of intake by humans through contact and ingestion. Hospitals look a special category of sites, owing to peculiar contaminants affecting them and to presence of people prone to adverse effects induced by toxicants. Four in-field campaigns aimed at understanding the chemical composition of DD were performed in five Italian hospitals. Measurements were performed before (autumn 2019), during (spring 2021), and after (winter 2022) the peak of SARS-CoV2 and when restrictions caused by pandemic were revoked (winter 2023). Parallel measurements were made outdoors (2022), as well as in a university and a dwelling. Targeted contaminants were n-alkanes and polycyclic aromatic hydrocarbons (PAHs), while iso- and anteiso-alkanes were analyzed to assess the impact of tobacco smoking. Total n-alkanes ranged from 3.9 ± 2.3 to 20.5 ± 4.2 mg/g, with higher percentages of short chain homologs in 2019. PAHs ranged from 0.24 ± 0.22 to 0.83 ± 0.50 mg/g, with light congeners (≤ 228 a.m.u.) always exceeding the heavy ones (≥ 252 a.m.u.). According to carbon preference indexes, alkanes originated overall from anthropogenic sources. Microorganisms resulted to affect a hospital, and tobacco smoke accounted for ~ 4-20‰ of DD mass. As for PAH sources, the diagnostic concentration ratios suggested the concourse of biological matter burning and vehicle emission. Benzo[a]pyrene equivalent carcinogenic and mutagenic potencies of depositions at hospitals ranged ~ 9-39 μg/g and ~ 15-76 μg/g, respectively, which seems of concern for health. DD composition in hospitals was different from that outside the premises, as well as that found at university and at dwelling.