New Evidence of Rubber-Derived Quinones in Water, Air, and Soil.

p-Phenylenediamines (PPDs) have been extensively used in the rubber industry and found to be pervasive in various environmental compartments for decades, while their transformation products and associated ecological and human health risks remain largely unknown. Herein, we developed and implemented a mass spectrometry-based platform combined with self-synthesized standards for the investigation of rubber-derived quinones formed from PPD antioxidants. Our results demonstrated that five quinones are ubiquitously present in urban runoff, roadside soils, and air particles. All of the identified sources are closely related to mankind's activities. Among the identified quinones, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone has been recently found to be highly toxic, causing acute mortality of coho salmon in the Pacific Northwest. Ultrahigh-performance liquid chromatography coupled with triple quadrupole mass spectrometry was then applied for quantification of the five quinones and their corresponding PPD antioxidants. The results revealed interesting distinct distribution and concentration patterns of PPD-derived quinones in different environmental matrices. Daily intake rates of these quinones in a compact city of Hong Kong were estimated to be varied from 1.08 ng/(kg·day) for adults to 7.30 ng/(kg·day) for children, which were higher than the exposure levels of their parent compounds. Considering the prevalence of the use of rubber products, the outcome of this study strongly suggests for additional toxicological studies to investigate potential ecological and human health risks of the newly discovered quinones.

Metabolomics Reveal Nanoplastic-Induced Mitochondrial Damage in Human Liver and Lung Cells.

Plastic debris in the global biosphere is an increasing concern, and nanoplastic (NPs) toxicity in humans is far from being understood. Studies have indicated that NPs can affect mitochondria, but the underlying mechanisms remain unclear. The liver and lungs have important metabolic functions and are vulnerable to NP exposure. In this study, we investigated the effects of 80 nm NPs on mitochondrial functions and metabolic pathways in normal human hepatic (L02) cells and lung (BEAS-2B) cells. NP exposure did not induce mass cell death; however, transmission electron microscopy analysis showed that the NPs could enter the cells and cause mitochondrial damage, as evidenced by overproduction of mitochondrial reactive oxygen species, alterations in the mitochondrial membrane potential, and suppression of mitochondrial respiration. These alterations were observed at NP concentrations as low as 0.0125 mg/mL, which might be comparable to the environmental levels. Nontarget metabolomics confirmed that the most significantly impacted processes were mitochondrial-related. The metabolic function of L02 cells was more vulnerable to NP exposure than that of BEAS-2B cells, especially at low NP concentrations. This study identifies NP-induced mitochondrial dysfunction and metabolic toxicity pathways in target human cells, providing insight into the possibility of adverse outcomes in human health.

Determination of Environmental Micro(Nano)Plastics by Matrix-Assisted Laser Desorption/Ionization-Time-of-Flight Mass Spectrometry.

Micro(nano)plastics (MNPs) are widely acknowledged as global environmental threat while determination methods for MNPs are still lacking and becoming a growing concern. This study provides a novel method for MNPs identification/quantification by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Factors affecting the measurement were optimized, including laser energy, matrix (M), analyte (A), cationization agent (C), and MAC volume ratio. Under the optimal conditions, the peaks representative of polystyrene (PS) and polyethylene terephthalate (PET) were identified, and the mass differences were consistent with the molecular weight of the corresponding oligomer. A quantitative correlation was built between normalized signal intensity and ln[polymer concentration] with a correlation coefficient above 0.96 for low-molecular-weight polymers and 0.98 for high-molecular-weight polymers. Furthermore, two types of environmental MNP samples were prepared, including aviation cup particles as fresh plastics and aged MNPs extracted from river sediment. By using MALDI-TOF MS, the PS-related MNPs (in both aviation cup and sediment) consisted of C8H8 and C16H16O oligomers, while the PET-related MNPs (only found in sediment) were identified with repeated units of C10H8O4 and C12H12O4. According to the quantitative correlation curve, the contents of PS and PET MNPs were quantified as 8.56 ± 0.04 and 28.71 ± 0.20 mg·kg-1, respectively, in the collected sediment. This study is the first attempt to propose a quantification method with the employment of MALDI-TOF MS for aged MNPs analysis in environmental samples, which can not only supply an effective method for MNP analysis but also inspire future studies on the in situ distribution and transformation of MNPs in environmental and biological samples.

Microplastics in terrestrial insects, long-horned beetles (Coleoptera: Cerambycidae), from China.

Despite studies have proposed that microplastics (MPs) could exert adverse effects on terrestrial ecosystems and biota, the occurrence of MPs in wild terrestrial insects has been rarely investigated. This study examined MPs in 261 long-horned beetle (Coleoptera: Cerambycidae) samples collected from four different Chinese cities. Detection frequency of MPs in long-horned beetles from different cities was 68-88 %. Long-horned beetles from Hangzhou (4.0 items/individual) had the highest mean abundance of MPs, followed by that from Wuhan (2.9 items/individual), Kunming (2.5 items/individual), and Chengdu (2.3 items/individual). The mean size of MPs in long-horned beetles from four Chinese cities was 381-690 µm. Fiber consistently represented the major shape of MPs in long-horned beetles from different Chinese cities, contributing 60, 54, 50, and 49 % of total items of MPs in Kunming, Chengdu, Hangzhou, and Wuhan, respectively. Polypropylene was the major polymer composition of MPs in long-horned beetles from Chengdu (68 % of total items of MPs) and Kunming (40 %). However, polyethylene and polyester were the major types of polymer compositions of MPs in long-horned beetles from Wuhan (39 % of total MP items) and Hangzhou (56 %), respectively. To our knowledge, this is the first study investigating the occurrence of MPs in wild terrestrial insects. These data are important for evaluating the risks of exposure to MPs for long-horned beetles.

Evaluation of nanoplastics toxicity in the soil nematode Caenorhabditis elegans by iTRAQ-based quantitative proteomics.

Plastic pollution is recognized as a major threat to ecosystems in the 21st century. Large plastic objects undergo biotic and abiotic degradation to generate micro- and nano-sized plastic pieces. Despite tremendous efforts to evaluate the adverse effects of microplastics, a comprehensive understanding of the toxicity of nanoplastics remains elusive, especially at the protein level. To this end, we used isobaric-tag-for-relative-and-absolute-quantitation-based quantitative proteomics to investigate the proteome dynamics of the soil nematode Caenorhabditis elegans in response to exposure to 100 nm polystyrene nanoplastics (PS-NPs). After 48 h of exposure to 0.1, 1, or 10 mg/L PS-NPs, 136 out of 1684 proteins were differentially expressed and 108 of these proteins were upregulated. These proteins were related to ribosome biogenesis, translation, proteolysis, kinases, protein processing in the endoplasmic reticulum, and energy metabolism. Remarkably, changes in proteome dynamics in response to exposure to PS-NPs were consistent with the phenotypic defects of C. elegans. Collectively, our findings demonstrate that disruption of proteome homeostasis is a biological consequence of PS-NPs accumulation in C. elegans, which provides insights into the molecular mechanisms underlying the toxicology of nanoplastics.

Microplastics in Seawater, Sediment, and Organisms from Hangzhou Bay.

Microplastics (MPs) are widely present in global oceans, and can pose a threat to marine organisms. This study examined the abundance and characteristics of MPs in seawater, sediment, and organism samples collected from Hangzhou Bay. Abundance of MPs in seawater (n = 26) and sediment (n = 26) were 0.77-9.6 items/m3 and 44-208 items/kg dw, respectively. Size of MPs in sediment (mean 2.5 mm, range 0.21-5.3 mm) was significantly (p < 0.05) larger than that in seawater (1.1 mm, 0.13-4.9 mm). Fiber was consistently the predominant shape of MPs in seawater and sediment. The major polymer composition of MPs was polyethylene (PE; mean 47 %) in seawater, but textile cellulose (60 %) was the main polymer type of MPs in sediment. Average abundance of MPs in marine organisms (n = 388) ranged from 0.064 (zooplankton) to 2.9 (Harpodon nehereus) items/ind, with the mean size of 0.19-1.4 mm. MP abundance in marine organisms was not significantly correlated with their trophic level. Fiber was always the predominant shape of MPs in different marine organisms, contributing mean 67 (fish)-93 % (zooplankton) of total MPs. MPs in crustacean (mean 58 %), shellfish (64 %), and cephalopod (29 %) were dominated by textile cellulose. Whereas, PE (mean 44 %) and polypropylene (43 %) were the major polymer compositions of MPs in fish and zooplankton, respectively. To our knowledge, this is the most comprehensive study investigating the occurrence of MPs in environmental matrixes from Hangzhou Bay, which contributes to the better understanding of environmental behaviors of MPs in estuarine sea environment.

Microplastics in dust from different indoor environments.

Microplastics (MPs) are present in global indoor dust, which is an important source of MPs for humans. However, few researchers have investigated differences in the abundance and characteristics of MPs in dust in different indoor environments. In this study, we found that residential apartments (mean: 1174 MPs/g; n = 47) had the highest abundance of MPs in indoor dust samples, followed by offices (896 MPs/g; n = 50), business hotels (843 MPs/g; n = 53), university dormitories (775 MPs/g; n = 48), and university classrooms (209 MPs/g; n = 44). The predominant shape of MPs was fiber in most indoor dust samples. The main size fraction of the MPs in the indoor dust samples from university classrooms and business hotels was 201-500 µm, and it was 501-1000 µm in those from offices, university dormitories, and residential apartments. The main MP polymer in indoor dust samples from business hotels, university dormitories, and residential apartments was polyester, whereas those from offices and university classrooms were mainly polyethylene and polypropylene. We calculated the estimated daily intake (EDI) of MPs through the inhalation of indoor dust, and found that infants (7.4 MPs/kg bw/day) had a higher mean EDI of MPs than toddlers (1.4 MPs/kg bw/day), children (0.49 MPs/kg bw/day), adults (0.23 MPs/kg bw/day), and university students (0.22 MPs/kg bw/day). To the best of our knowledge, we are the first to report differences in MP occurrence in dust samples from different indoor environments, and our findings provide a more accurate understanding of exposure risks of MPs to humans.

Absorption, distribution, metabolism, excretion and toxicity of microplastics in the human body and health implications.

Microplastics (MPs; <5 mm) in the biosphere draws public concern about their potential health impacts. Humans are potentially exposed to MPs via ingestion, inhalation, and dermal contact. Ingestion and inhalation are the two major exposure pathways. An adult may consume approximately 5.1 × 103 items from table salts and up to 4.1 × 104 items via drinking water annually. Meanwhile, MP inhalation intake ranges from 0.9 × 104 to 7.9 × 104 items per year. The intake of MPs would be further distributed in different tissues and organs of humans depending on their sizes. The excretion has been discussed with the possible clearance ways (e.g., urine and feces). The review summarized the absorption, distribution, metabolic toxicity and excretion of MPs together with the attached chemicals. Moreover, the potential implications on humans are also discussed from in vitro and in vivo studies, and connecting the relationship between the physicochemical properties and the potential risks. This review will contribute to a better understanding of MPs as culprits and/or vectors linking to potential human health hazards, which will help outline the promising areas for further revealing the possible toxicity pathways.

Typhoon-induced turbulence redistributed microplastics in coastal areas and reformed plastisphere community.

The increasing microplastic pollution together with the plastisphere-associated ecological threats in coastal areas have aroused global concern. Tropical cyclones have been increased in both frequency and intensity under global warming, causing intense impact on the microplastics distribution and the structure of coastal ecosystems. However, until most currently, the extent to which typhoon impacts the microplastics and plastisphere community remains poorly known. This study analyzed the effects of Typhoon Wipha (Code: 1907) on microplastics abundance and composition in surface water and sediment crossed coastal areas of Shenzhen. Here we found a significant typhoon-induced increase in microplastics abundance in surface water, whereas an opposite trend was observed in sediment. Despite the evident transportation of microplastics from sediment to surface water by agitation, a possible microplastics influx was introduced by typhoon as evidenced by the large attribution of unknown force in source tracking analysis. Furthermore, typhoon had adeptly uniformed the plastisphere community in the sediment along the 190 km costal line overnight. A significant increase of nitrogen fixer, Bradyrhizobiaceae, was observed ubiquitously after typhoon, which might alter the nitrogen cycling and increase eutrophic condition of the coastal ecological system. Together, this study expanded the knowledge about the impact of typhoon-induced influx of the microplastics on coastal biogeochemical cycling. Moreover, the microplastics and the plastisphere compositional pattern revealed here will underpin future studies on adsorption behavior, interfacial processes and ecotoxicity of the coastal microplastic pollution.

Cationic Polystyrene Resolves Nonalcoholic Steatohepatitis, Obesity, and Metabolic Disorders by Promoting Eubiosis of Gut Microbiota and Decreasing Endotoxemia.

A pandemic of metabolic diseases, consisting of type 2 diabetes, nonalcoholic fatty liver disease, and obesity, has imposed critical challenges for societies worldwide, prompting investigation of underlying mechanisms and exploration of low-cost and effective treatment. In this report, we demonstrate that metabolic disorders in mice generated by feeding with a high-fat diet without dietary vitamin D can be prevented by oral administration of polycationic amine resin. Oral administration of cholestyramine, but not the control uncharged polystyrene, was able to sequester negatively charged bacterial endotoxin in the gut, leading to 1) reduced plasma endotoxin levels, 2) resolved systemic inflammation and hepatic steatohepatitis, and 3) improved insulin sensitivity. Gut dysbiosis, characterized as an increase of the phylum Firmicutes and a decrease of Bacteroidetes and Akkermansia muciniphila, was fully corrected by cholestyramine, indicating that the negatively charged components in the gut are critical for the dysbiosis. Furthermore, fecal bacteria transplant, derived from cholestyramine-treated animals, was sufficient to antagonize the metabolic disorders of the recipient mice. These results indicate that the negatively charged components produced by dysbiosis are critical for biogenesis of metabolic disorders and also show a potential application of cationic polystyrene to treat metabolic disorders through promoting gut eubiosis.

Controllable snail-paced light in biological bacteriorhodopsin thin film.

We observe that the group velocity of light is reduced to an extremely low value of 0.091 mm/s in a biological thin film of bacteriorhodopsin at room temperature. By exploiting unique features of a flexible photoisomerization process for coherent population oscillation, the velocity is all-optically controlled over an enormous span, from snail-paced to normal light speed, with no need of modifying the characteristics of the incident pulse. Because of the large quantum yield for the photoreaction in this biochemical system, the ultraslow light is observed even at low light levels of microwatts, indicating high energy efficiency.