Toxic potential of organic constituents of submicron particulate matter (PM1) in an urban road site (Barcelona)

The utility of alternative models in particulate matter air pollution toxicology

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Countless unique particulate matter (PM) samples with limited or no toxicity information.

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Alternative in vivo models offer greater throughput than traditional mammalian models.

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Use of zebrafish, fruit flies, and nematodes in PM toxicology lacks systematic review.

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Their utility in PM toxicity and mechanistic research and as screening tools is reviewed.

Exposure to particulate matter (PM) air pollution increases risk of adverse human health effects. As more attention is brought to bear on the problem of PM, traditional mammalian in vivo models struggle to keep up with the risk assessment challenges posed by the countless number of unique PM samples across air sheds with limited or no toxicity information. This review examines the utility of three higher throughput, alternative, in vivo animal models in PM toxicity research: Danio rerio (zebrafish), Caenorhabditis elegans (nematode), and Drosophila melanogaster (fruit fly). These model organisms vary in basic biology, ease of handling, methods of exposure to PM, number and types of available assays, and the degree to which they mirror human biology and responsiveness, among other differences. The use of these models in PM research dates back over a decade, with assessments of the toxicity of various PM sources including traffic-related combustion emissions, wildland fire smoke, and coal fly ash. This article reviews the use of these alternative model organisms in PM toxicity studies, their biology, the various assays developed, endpoints measured, their strengths and limitations, as well as their potential role in PM toxicity assessment and mechanistic research going forward.

The effect of toxic components on metabolomic response of male SD rats exposed to fine particulate matter

PM_2.5 pollution was associated with numerous adverse health effects. However, PM_2.5 induced toxic effects and the relationships with toxic components remain largely unknown. To evaluate the metabolic toxicity of PM_2.5 at environmentally relevant doses, investigate the seasonal variation of PM_2.5 induced toxicity and the relationship with toxic components, a combination of general pathophysiological tests and metabolomics analysis was conducted in this study to explore the response of SD rats to PM_2.5 exposure. The result of general toxicology analysis revealed unconspicuous toxicity of PM_2.5 under environmental dose, but winter PM_2.5 at high dose caused severe histopathological damage to lung. Metabolomic analysis highlighted significant metabolic disorder induced by PM_2.5 even at environmentally relevant doses. Lipid metabolism and GSH metabolism were primarily influenced by PM_2.5 exposure due to the high levels of heavy metals. In addition, high levels of organic compounds such as PAHs, PCBs and PCDD/Fs in winter PM_2.5 bring multiple overlaps on the toxic pathways, resulting in larger pulmonary toxicity and metabolic toxicity in rats than summer.

Chemical composition and in vitro aryl hydrocarbon receptor-mediated activity of atmospheric particulate matter at an urban, agricultural and industrial site in North Africa (Bizerte, Tunisia)

As recognized risk factor to pose a health threat to humans and wildlife globally, atmospheric particulate matter (PM) were collected from a North African coastal city (Bizerte, Tunisia) for one year, and were characterized for their chemical compositions, including mercury (Hg_PM), as well as organic contaminants (polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs)), organic carbon (OC) and organic nitrogen (ON), determined in a previous study. Then, we applied an in vitro reporter gene assay (DR-CALUX) to detect and quantify the dioxin-like activity of PM-associated organic contaminants. Results showed that average Hg_PM concentration over the entire sampling period was found to be 13.4 ± 12 pg m^-3. Seasonal variation in the Hg_PM concentration was observed with lower values in spring and summer and higher values in winter and autumn due to the variation of meteorological conditions together with the emission sources. Principal component analysis suggested that fossil fuel combustion and a nearby cement factory were the dominant anthropogenic Hg_PM sources. Aryl hydrocarbon receptor (AhR)-mediated activities were observed in all organic extracts of atmospheric PM from Bizerte city (388.3-1543.6 fg m^-3), and shows significant positive correlations with all PM-associated organic contaminants. A significant proportion of dioxin-like activity of PM was related to PAHs. The dioxin-like activity followed the same trend as PM-associated organic contaminants, with higher dioxin-like activity in the cold season than in the warm season, indicating the advantage and utility of the use of bioassays in risk assessment of complex environmental samples.

Source apportionment of urban PM1 in Barcelona during SAPUSS using organic and inorganic components

Source apportionment of atmospheric PM1 is important for air quality control, especially in urban areas where high mass concentrations are often observed. Chemical analysis of molecular inorganic and organic tracer compounds and subsequently data analysis with receptor models give insight on the origin of the PM₁ sources. In the present study, four source apportionment approaches were compared with an extended database containing inorganic and organic compounds that were measured during an intensive sampling campaign at urban traffic and urban background sites in Barcelona. Source apportionment of the combined database, containing both inorganic and organic compounds, was compared with more conventional approaches using inorganic and organic databases separately. Traffic emission sources were identified in all models for the two sites. The combined inorganic and organic databases provided higher discrimination capacity of emission sources. It identified aerosols generated by regional recirculation of biomass burning, secondary biogenic organic aerosols, harbor emissions, and specific industrial emissions. In this respect, this approach identified a relevant industrial source situated at NE Barcelona in which a waste incinerator plant, a combined-cycle power plant, and an industrial glass complex are located. Models using both inorganic and organic molecular tracer compounds improve the source apportionment of urban PM.

Toxic effects of a methanolic coal dust extract on fish early life stage

Coal dust is a contaminant that impacts the terrestrial and aquatic environment with a complex mixture of chemicals, including PAHs and metals. This study aims to evaluate the toxic effect of a methanolic coal dust extract on a fish early life stage by analyzing phenotypic alterations, transcriptome changes, and mortality in zebrafish (ZF) embryos. ZF embryos were exposed to methanolic coal dust extract at 1-5000 mg·L-1 and monitored using bright field microscopy 24 and 48 hpf to determine malformations and mortality. In situ hybridization, RNA sequencing, and qRT-PCR were employed to identify transcriptome changes in malformed embryos. Three malformed phenotypes were generated in a dose-dependent manner. In situ hybridization analysis revealed brain, somite, dorsal cord, and heart tube development biomarker alterations. Gene expression profile analysis identified changes in genes related to structural constituent of muscle, calcium ion binding, actin binding, melanin metabolic process, muscle contraction, sarcomere organization, cardiac myofibril assembly, oxidation-reduction process, pore complex, supramolecular fiber, striated muscle thin filament, Z disc, and intermediate filament. This study shows, for the first time, the malformations generated by a mixture of pollutants from a methanolic coal dust extract on a fish early life stage, constituting a potential risk for normal embryonic development of other aquatic vertebrate organisms. Furthermore, we establish that phenotypes and changes in gene expression induced by the extract constitute a target for future studies about mechanical toxicity and their utility as sensitive tools in environmental risk assessments for biota and humans exposed to coal mining activities.

Atmospheric pattern of volatile organochlorine compounds and hexachlorobenzene in the surroundings of a chlor-alkali plant

The outdoor atmospheric distributions of chlorinated volatile organic compounds (VOCs) from locations receiving the emissions of a chlor-alkali plant have been studied. Trichloroethylene and tetrachloroethylene (medians 2.4 μg/m³ and 1.7 μg/m³, respectively) were the most abundant compounds, which was in accordance with the production processes from these installations. The concentrations of trichlorofluoromethane, median 1.6 μg/m³, are rather similar to the average levels described in general in the troposphere and cannot be attributed to this specific source. Several by-products involving dichloroacetylene, carbon tetrachloride, hexachloroethane, hexachlorobutadiene, trans-1H-pentachloro-1,3-butadiene, 2H-pentachloro-1,3-butadiene, cis-1H-pentachloro-1,3-butadiene, tetrachloro- and trichloro-butadienes and hexachlorobenzene were also identified. Some of these compounds, e.g. carbon tetrachloride, chloroform and tetrachloroethane, could also have been manufactured during some periods. The occurrence of these manufactured compounds and by-products in the atmosphere could also reflect, at least in part, volatilization during the extraction of previously discharged chlor-alkali residues developed within the environmental restoration program of the Flix water reservoir. In this respect, the tri-, tetra- and pentachloro-1,3-butadienes could also originate from microbial transformation in the solid deposits accumulated in the water reservoir which were volatilized after extraction. Among all identified VOCs, trichloroethylene showed the highest health risks considering the measured airborne concentrations and the WHO and USEPA recommendations.