Chemical Uptake Research Articles

Hybrid nanoparticles emulsified vegetable oil as an environmentally friendly and sustainable leather fatliquoring agent

Introducing sustainability by a reduction in chemical input has added value to technology innovations, especially in the leather fatliquoring process. Major concern of sustainable leather fatliquoring process lies in factors like usage of natural oil, avoidance of hazardous substances and reduction in organic load to the environment. Due to their special features, such as their ease of preparation and environmental friendliness, Pickering emulsions and their applications have received significant attention in recent years. The present study reports a novel sustainable leather fatliquoring process by usage of hybrid particles (alumina coated with silica) stabilised Pickering emulsions as fatliquor instead of conventional sulphated oil based fatliquor. Eco fatliquoring agent with a particular choice of vegetable oil stabilised by hybrid alumina functionalised with silica (Al-O-SiO2)/ hybrid nanoparticles through Pickering emulsion was reported. During the post tanning process, the uses of this developed fatliquoring agent causes a reduction in the 30% of fatliquoring agent input and 40% reduction in dye input. The presence of alumina nanoparticles resulted in an immediate improvement of the abrasion resistance, softness, and physical properties of the crust leather. Utilizing hybrid particles (Al-O-Si) as a stabiliser readily improves the uptake of other post tanning chemicals. Thus, the prepared fatliquoring agent suitably softened the leather and significantly improved the mechanical properties, light fastness, and fullness with the reduction in the pollution load. To divulge the sustainability of the fatliquoring process, the sustainability analysis for the developed product was analyzed and presented. As compared to the conventional fatliquoring process the E factor of the experimental process was estimated to be lower (at a value of 0.25) which indicates minimum emissions. Based on cost estimation, leather fatliquoring is economically viable when using the prepared fatliquoring agent.

Contaminant uptake in wastewater irrigated tomatoes

As population growth and climate change add to the problem of water scarcity in many regions, the argument for using treated wastewater for irrigation is becoming increasingly compelling, which makes understanding the risks associated with the uptake of harmful chemicals by crops crucial. In this study, the uptake of 14 chemicals of emerging concern (CECs) and 27 potentially toxic elements (PTEs) was studied in tomatoes grown in soil-less (hydroponically) and soil (lysimeters) media irrigated with potable and treated wastewater using LC-MS/MS and ICP-MS. Bisphenol S, 2,4 bisphenol F, and naproxen were detected in fruits irrigated with spiked potable water and wastewater under both conditions, with BPS having the highest concentration (0.034–0.134 µg kg−1 f. w.). The levels of all three compounds were statistically more significant in tomatoes grown hydroponically (<LOQ - 0.137 µg kg−1 f. w.) than in soil (<LOQ - 0.083 µg kg−1 f. w.). Their elemental composition shows differences between tomatoes grown hydroponically or in soil and tomatoes irrigated with wastewater and potable water. Contaminants at determined levels showed low dietary chronic exposure. When the health-based guidance values for the studied CECs are determined, results from this study will be helpful for risk assessors.

Do organic farming initiatives in Sub-Saharan Africa improve the sustainability of smallholder farmers? Evidence from five case studies in Ghana and Kenya

Organic agriculture (OA) is often regarded as a sustainable agricultural pathway for smallholder farmers in Sub-Saharan Africa, and an increasing number of initiatives promoting OA were initiated over the last decades. However, holistic empirical evidence on the effects of such initiatives on the sustainability of smallholder farmers is still scanty. We analyzed the effects of five initiatives promoting OA on farm-level sustainability. We selected farmers exposed to the initiatives (n = 678) and control farms (n = 957) in five different case studies, two implemented in Ghana and three in Kenya. We used a farm-level multi-criteria assessment tool that evaluates to what extent the environmental, social, economic, and governance sustainability goals formulated in the FAO-SAFA Guidelines are addressed by farmers. We found that the initiatives had limited effects on reducing farmers reliance on chemical inputs use (pesticides and synthetic fertilizers) and uptake of organic or agro-ecological practices. Nevertheless, the results show that the initiatives were able to trigger significant (p-value < 0.05) positive effects mainly for the environmental sustainability goals. In contrast, the goals within the economic, social and good governance sustainability dimensions were rarely affected. Moreover, certified initiatives had more frequently a positive sustainability effect compared to uncertified initiatives.

Solubility of Foreign Molecules in Stratum Corneum Brick and Mortar Structure.

The barrier function of the skin is mainly assured by its outermost layer, stratum corneum (SC). One key aspect in predicting dermal drug delivery and in safety assessment of skin exposure to chemicals is the need to determine the amount of chemical that is taken up into the SC. We here present a strategy that allows for direct measures of the amount of various solid chemicals that can be dissolved in the SC in any environmental relative humidity (RH). A main advantage of the presented method is that it distinguishes between molecules that are dissolved within the SC and molecules that are not dissolved but might be present at, for example, the skin surface. In addition, the method allows for studies of uptake of hydrophobic chemicals without the need to use organic solvents. The strategy relies on the differences in the molecular properties of the added molecules in the dissolved and the excess states, employing detection methods that act as a dynamic filter to spot only one of the fractions, either the dissolved molecules or the excess solid molecules. By measuring the solubility in SC and delipidized SC at the same RHs, the same method can be used to estimate the distribution of the added chemical between the extracellular lipids and corneocytes at different hydration conditions. The solubility in porcine SC is shown to vary with hydration, which has implications for the molecular uptake and transport across the skin. The findings highlight the importance of assessing the chemical uptake at hydration conditions relevant to the specific applications. The methodology presented in this study can also be generalized to study the solubility and partitioning of chemicals in other heterogeneous materials with complex composition and structure.

A Novel High Temperature Fuel Cell Proton Exchange Membrane with Nanoscale Phase Separation Structure Based on Crosslinked Polybenzimidazole with Poly(vinylbenzyl chloride)

A semi-aromatic polybenzimidazole (DPBI) is synthesized via polycondensation of decanedioic acid (DCDA) and 3,3-diaminobenzidine (DAB) in a mixed phosphorus pentoxide/methanesulfonic acid (PPMA) solvent. Ascribing to in-situ macromolecular crosslinker of ploly((vinylbenzyl chloride) (PVBC), a robust crosslinked DPBI membrane (DPBI-xPVBC, x refers to the weight percentage of PVBC in the membrane) can be obtained. Comprehensive properties of the DPBI and DPBI-xPVBC membranes are investigated, including chemical structure, antioxidant stability, mechanical strength, PA uptake and electrochemical performances. Compared with pristine DPBI membrane, the PA doped DPBI-xPVBC membranes exhibit excellent antioxidative stability, high proton conductivity and enhanced mechanical strength. The PA doped DPBI-10PVBC membrane shows a proton conductivity of 49 mS cm-1 at 160 °C without humidification. Particularly, it reveals an enhanced H2/O2 single cell performance with the maximum peak power density of 405 mW cm-2, which is 29% higher than that of pristine DPBI membrane (314 mW cm-2). In addition, the cell is very stable in 50 h, indicating the in-situ crosslinked DPBI with a macromolecular crosslinker of PVBC is an efficient way to improve the overall performance of HT-PEMs for high performance HT-PEMFCs.

Metal–Organic Cage Extended Amorphous Network via Anionic Organic Linkers for Cr2O72– and Iodine Adsorption on Nanopores

The covalent linking of metal–organic cages (MOCs) with a nanoscale cavity is an efficient strategy to construct functional materials with different properties compared with bulk MOCs, but studies based on this topic are still less explored. In addition, toxic chemical and pollutant uptake, especially iodine vapor adsorption on MOC-based materials, still lacks investigation. Herein, an MOC-extended amorphous network (denoted MOC–DASD) via the covalent linking of an aldehyde-functionalized cationic Pd12L24 MOC (with about 3.5 nm in diameter) with an anionic organic linker, 4,4′-diamino-2,2′-stilbenedisulfonic acid (DASD), was constructed and applied to absorb Cr2O72– in water and capture I2 molecules in vapor. The covalent linkage of MOC and DASD via C═N bonds was confirmed by IR, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and ζ-potential tests. In addition, the original NO3– anions can be easily removed from the MOC–DASD due to the introduction of an anionic linker, thus releasing more effective cavities for guest adsorption. Although there is a lack of exchangeable anions, MOC–DASD still exhibits the ability to capture Cr2O72– in water with moderate capacity and high selectivity. In addition, the MOC–DASD showed a significantly enhanced iodine vapor uptake capacity. The iodine uptake capacity of MOC–DASD reached 3.67 g/g, which is 1.8 times higher than that of bulk MOC. A mechanistic study shows that some of the iodine was closely adsorbed by charge transfer. The release of iodine at 120 °C reveals that approximately 74% of the absorbed iodine can be removed, and the MOC can uptake the iodine again with a capacity of 1.5 g/g, showing good reusability.

Speed it up: How temperature drives toxicokinetics of organic contaminants in freshwater amphipods.

The acceleration of global climate change draws increasing attention towards interactive effects of temperature and organic contaminants. Many studies reported a higher sensitivity of aquatic invertebrates towards contaminant exposure with increasing or fluctuating temperatures. The hypothesis of this study was that the higher sensitivity of invertebrates is associated with the changes of toxicokinetic processes that determine internal concentrations of contaminants and consequently toxic effects. Therefore, the influence of temperature on toxicokinetic processes and the underlying mechanisms were studied in two key amphipod species (Gammarus pulex and Hyalella azteca). Bioconcentration experiments were carried out at four different temperatures with a mixture of 12 exposure relevant polar organic contaminants. Tissue and medium samples were taken in regular intervals and analysed by online solid-phase extraction liquid chromatography high-resolution tandem mass spectrometry. Subsequently, toxicokinetic rates were modelled and analysed in dependence of the exposure temperature using the Arrhenius equation. An exponential relationship between toxicokinetic rates versus temperature was observed and could be well depicted by applying the Arrhenius equation. Due to a similar Arrhenius temperature of uptake and elimination rates, the bioconcentration factors of the contaminants were generally constant across the temperature range. Furthermore, the Arrhenius temperature of the toxicokinetic rates and respiration was mostly similar. However, in some cases (citalopram, cyprodinil), the bioconcentration factor appeared to be temperature dependent, which could potentially be explained by the influence of temperature on active uptake mechanisms or biotransformation. The observed temperature effects on toxicokinetics may be particularly relevant in non-equilibrated systems, such as exposure peaks in summer as exemplified by the exposure modelling of a field measured pesticide peak where the internal concentrations increased by up to fourfold along the temperature gradient. The results provide novel insights into the mechanisms of chemical uptake, biotransformation and elimination in different climate scenarios and can improve environmental risk assessment.

IFITM proteins assist cellular uptake of diverse linked chemotypes.

The search for cell-permeable drugs has conventionally focused on low-molecular weight (MW), nonpolar, rigid chemical structures. However, emerging therapeutic strategies break traditional drug design rules by employing flexibly linked chemical entities composed of more than one ligand. Using complementary genome-scale chemical-genetic approaches we identified an endogenous chemical uptake pathway involving interferon-induced transmembrane proteins (IFITMs) that modulates the cell permeability of a prototypical biopic inhibitor of MTOR (RapaLink-1, MW: 1784 g/mol). We devised additional linked inhibitors targeting BCR-ABL1 (DasatiLink-1, MW: 1518 g/mol) and EIF4A1 (BisRoc-1, MW: 1466 g/mol), uptake of which was facilitated by IFITMs. We also found that IFITMs moderately assisted some proteolysis-targeting chimeras and examined the physicochemical requirements for involvement of this uptake pathway.

Impregnation Properties of Nigerian-Grown Gmelina arborea Roxb. Wood

The success of any wood treatment process and the measure of protection conferred on treated wood are determined by the uptake and penetration of the treatment chemicals, in addition to the efficacy of the chemicals used for the treatment. Hence, the level of treatability of wood species should be pre-determined prior to the wood treatment to ensure the overall protection of the treated wood. Gmelina arborea wood, due to its low durability, requires impregnation with chemicals for preservation or chemical modification to enhance its durability. However, more details are required to establish the influence of its anatomy on impregnation to recommend appropriate treatment methods. Therefore, gmelina wood samples were treated under pressure to determine the solution uptake and penetration, while anatomical studies were carried out with light microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) measurements. Variations in stem heights, stem diameters, and samples from other tree stands were considered. The outcome of the study showed that the liquid uptake was generally low for gmelina wood among the selected stands (16%–23%) and there was no significant difference in stem diameters; meanwhile, penetration was less than 4 mm in the axial direction, and very low in the lateral (radial and tangential) direction. Vessels of gmelina wood have abundant tyloses, while crystalline structures with needlelike shapes are present in a large proportion of the ray parenchyma cells, and are confirmed with SEM-EDX to be made up of calcium oxalate. The low liquid uptake and penetration in gmelina wood suggest that the impregnation of chemicals into its microstructure is next to impossible. Hence, alternative treatment methods other than those involving impregnation with chemicals should be sought to enhance its durability.

Chronic toxic effects of isoflucypram on reproduction and intestinal energy metabolism in zebrafish (Danio rerio)

The intestine is a vital organ involved in chemical and nutrient uptake and biotransformation. Intestinal dysfunction can impair energy and material supply for reproduction. Isoflucypram, a new succinate dehydrogenase inhibitor fungicide, is highly toxic to aquatic systems. However, the chronic toxic effects of isoflucypram on intestinal differentiation in aquatic organisms remain unknown. In this study, zebrafish (F0, 4-month-old) were exposed to 0, 0.008, or 0.08 μM isoflucypram for 120 days. After 90 days of exposure, F0 generations of adult zebrafish were paired, and the corresponding F1 generation embryos were obtained and observed. After 120 days of exposure, the gut of F0 generation zebrafish was collected, and intestinal histopathology and mitochondrial morphology were analyzed. Exposure to 0.08 μM isoflucypram resulted in significant death, hatching delay, and malformation (blood clot clustering, pericardial edema, and microphthalmia) of F1 embryos and larvae. Exposure to isoflucypram caused irregular and swollen villi in the zebrafish gut, accompanied by alterations in the intestinal mitochondrial ultrastructure. In addition, the differentially expressed genes involved in mitochondrial energy metabolism were significantly enriched. Overall, our data suggest that chronic exposure to isoflucypram is associated with reproductive and intestinal dysfunction in adult zebrafish.

A lipid transfer protein ensures nematode cuticular impermeability

The cuticle of C.elegans is impermeable to chemicals, toxins, and pathogens. However, increased permeability is a desirable phenotype because it facilitates chemical uptake. Surface lipids contribute to the permeability barrier. Here, weidentify the lipid transfer protein GMAP-1 as a critical element setting the permeability of the C.elegans cuticle. A gmap-1 deletion mutant increases cuticular permeability to sodium azide, levamisole, Hoechst, and DiI. Expressing GMAP-1 in the hypodermis or transiently in the adults is sufficient to rescue this gmap-1 permeability phenotype. GMAP-1 protein is secreted from the hypodermis to the aqueous fluid filling the space between collagen fibers of the cuticle. Invitro, GMAP-1 protein binds phosphatidylserine and phosphatidylcholine while invivo, GMAP-1 sets the surface lipid composition and organization. Altogether, our results suggest GMAP-1 secreted by hypodermis shuttles lipids to the surface to form the permeability barrier of C.elegans.

Cationic Ionomer Thin Films for Alkaline Electrochemical Energy Conversion

Ionomers are used as the solid-electrolyte in many electrochemical energy conversion technologies where they offer many functionalities such as ion conduction, electrical insulation, and water transport. These ionomers are found as nanometer-thick electrolyte thin films within the catalyst layers of fuel cells, electrolyzers, and hydrogen-based redox flow batteries where electrochemical reactions take place. The ionomer performance and durability are strongly related to their properties governed by a myriad of parameters such as chemical structure, water uptake, and morphology, all of which are stimulated differently by the external environment. Typically, the ionomer consists of the same ion-conducting polymer used as the electrode separator but exhibit disparate properties from the bulk membrane when nanometer thickness coatings are confined to a hard substrate (as in a catalyst layer), where the behavior is influenced by the ionomer affinity with the air and hard interfaces. Two motifs of ionomers exist, one as an acidic polymer (e.g. Nafion) and the alternative, and less studied, alkaline polymer (e.g. Sustainion).This talk will focus on filling in the gaps between the disparate properties of alkaline ionomers in the thin film motif that have been extensively studied for acidic ionomers. Aspects such as different backbones (e.g. perfluorinated, aliphatic, aromatic) and side chains (e.g. length, functional group) are explored in X-ray scattering, hydration, and transport measurements. Small-angle X-ray scattering is used to probe the morphology of these different polymer thin-films. Quartz crystal microbalance and spectroscopic ellipsometry under different states of humidity are used to probe hydration and free volume. The resulting correlations provide insights on not only how different polymer respond to the confined environment but how chemistry can be tuned to boost performance in alkaline electrochemical energy devices.

Nanoplastic impacts on the foliar uptake, metabolism and phytotoxicity of phthalate esters in corn (Zea mays L.) plants.

Nanoplastic pollution in terrestrial plants is of increasing concern for its negative effects on living organisms. However, the impacts of nanoplastics on chemical processes and plant physiology of phthalate esters (PAEs) remain unclear. The present work offers insight into the foliar uptake, metabolism and phytotoxicity of two typical PAEs, namely, di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), in corn (Zea mays L.) seedlings and the effects of amino-functionalized polystyrene nanoplastics (PSNPs-NH2). The presence of PSNPs-NH2 increased DBP and DEHP accumulation in the leaves by 1.36 and 1.32 times, respectively. PSNPs-NH2 also promoted the leaf-to-root translocation of DBP and DEHP, with the translocation factor increasing by approximately 1.05- and 1.16-fold, respectively. Furthermore, the addition of PSNPs-NH2 significantly enhanced the transformation of PAEs to their primary metabolites, mono-butyl phthalate and mono(2-ethylhexyl) phthalate in corn leaves and roots. The co-presence of PSNPs-NH2 and PAEs showed stronger impairment of photosystem II efficiency via the downregulation of transporter D1 protein, thus exhibiting a greater inhibitory effect on plant growth. Our findings reveal that nanoplastics promote the foliar uptake and transformation of PAE chemicals in crops and exacerbate their toxicity to crop plants, thereby threatening agricultural safety and human health.

Fatty acid ecological tracers highlight the role of diet in perfluoroalkyl acid contaminant exposure in eggs of an omnivorous bird

Herring gulls (Larus argentatus) are generalist feeders; contaminant levels in their eggs reflect chemical exposure and uptake due to foraging in both aquatic and terrestrial environments. Hence, contaminant levels in their eggs provide insights into sources and relative importance of aquatic versus terrestrial pathways of chemical transfer. Here, perfluoroalkyl acids (PFAAs) known to be bioaccumulative were measured in individual herring gull eggs from one site on Lake Superior, Ontario, Canada. Thirteen perfluorinated carboxylates (PFCA, C4-C18) and four perfluorinated sulfonates (PFSA, C4-C10) were measured. Total PFCA and total PFSA concentrations varied 4- and 5-fold, respectively, among eggs. To understand these differences, stable carbon and nitrogen isotopes and fatty acid dietary tracers were measured in the same eggs. Stable isotopes were not useful in explaining inter-egg differences in PFAA concentrations. However, a variety of omega 3 (n-3) and omega 6 (n-6) fatty acid measures were correlated with C9-C13 PFCAs as well as the PFSAs: perfluoro-1-hexanesulfonic acid (PFHxS) and perfluoro-1-octanesulfonic acid (PFOS). In general, n-3 fatty acids were positively correlated with egg PFAA concentrations while only the n-6 fatty acids exhibited negative relationships with egg PFAA levels. Proportions of n-3 and n-6 fatty acids in eggs would be expected to increase and decrease, respectively, with increased aquatic food in the gull diet. Results indicate that increased use of aquatic food led to heightened PFAA exposure in these generalist consumers sampled in a relatively remote area. They also highlight the utility of employing a variety of dietary markers for understanding contaminant exposure and accumulation.

NaCl salinity enhances tetracycline bioavailability to Escherichia coli on agar surfaces.

Soil salinity is a worldwide problem and is damaging soil functions. Meanwhile, increasing amounts of anthropogenic antibiotics are discharged to agricultural soils. Little is known about how soil salinity (e.g., NaCl) could influence the bioavailability of antibiotics to bacteria. In this study, a tetracycline-responsive Escherichia coli bioreporter grew on the surfaces of agar microcosms at the same tetracycline concentration (200μg/L), but various NaCl concentrations (0.5-19.2g/L) with estimated osmotic potential of -0.18 to -1.80MPa, and agar content (0.3%-5%) with estimated intrinsic permeability of 38 to 32,928nm2. These agar microcosms mimicked very fine textured soils with a range of NaCl salinity. Increasing agar content lowered the intrinsic permeability hence decreasing tetracycline bioavailability to E. coli, due likely to the reduced mass transfer of tetracycline via water flow. Intriguingly, tetracycline bioavailability increased with increasing NaCl concentration which caused the increase in osmotic stress. This is contradictory to the notion that osmotic stress reduces bacterial chemical uptake. Further analysis of E. coli membrane integrity demonstrated that the enhanced tetracycline bioavailability to bacteria could result from the compromised cell membranes and enhanced membrane permeability at higher NaCl salinity. Overall, this study suggests that high soil salinity (NaCl) may enhance the selection pressure exerted by antibiotics on bacteria.

Concentration and mobility of trace elements (Li, Ba, Sr, Ag, Hg, B) and macronutrients (Ca, Mg, K) in soil-orchid system on different bedrock types.

The mobility of chemical elements in the soil-orchid system has been poorly studied. The aim of this study is to evaluate the uptake and mobility of several trace (Li, Ba, Sr, Ag, Hg, and B) and macronutrients (Ca, Mg, and K) in the orchid Anacamptis morio (L.) R.M.Bateman, Pridgeon & M.W.Chase from soils in western Serbia. The sampling sites are characterized by three different bedrock types-cherts, limestones, and serpentines, which are the source of the significant chemical differences in the elemental status of the soil and plant tissues. The four-step Community Bureau of Reference sequential extraction procedure was used to determine the distribution of fractions and predict their potential phytoavailability. The orchid and soil samples were analyzed for total elemental content analysis using ICP-OES. The greatest potential for plant availability was determined for Ba and Sr, representing about 80% of the total soil content. More than 40% of Li in the soils was found to be potentially phytoavailable. Significant correlations were found between the total content of Li, B, and Sr in soils. Between 38 and 60% of Li content and more than 80% of Ba and Sr content were determined to be potentially phytoavailable by sequential analysis. The highest bioconcentration factor (> 1) was determined in the case of B and Sr for all orchid organs, while translocation factor for Li was highest in tubers and leaves. The studied elements were mainly stored in tubers and roots, indicating the exclusion strategy of A. morio as a metal tolerance mechanism. The data obtained showed significant differences in metal content in soils and plants originating from sites with different parent materials, suggesting that bedrock type and associated soil properties are important factors that determine chemical element mobility and uptake.

Effects of Reinforcement Type on the Structure and Properties of Perfluorosulphonic Acid Membranes for Polymer Electrolyte Membrane Fuel Cells

Fuel cell membrane durability remains one of the key challenges limiting the wide scale adoption of fuel cell technology. Membrane degradation in polymer electrolyte membrane (PEM) fuel cells limits the operational lifetime of the fuel cell and prevents the industrial targets from being met. A common approach to increasing the lifetime of membranes includes the addition of a reinforcement layer to increase the mechanical durability of the membrane while not adversely affecting the performance [1,2]. Although reinforced membranes are widely used in industry, there is a literature gap considering membrane structure and properties in relation to durability. This work contributes to characterizing the effects of reinforcement type on the membrane properties. In this study a selection of perfluorosulphonic acid (PFSA) ionomer membranes with expanded polytetrafluoroethylene (ePTFE) reinforcements were tested, these include two novel DMR100 membranes with different reinforcements and Nafion XL compared to a conventional, non-reinforced Nafion NRE-211 for reference. All of these membranes contain common PFSA ionomer and differ primarily in the type of reinforcement layer and membrane thickness. The study addresses comparison between the membrane chemical composition, water uptake, crystallinity, and mechanical strength. Methods of ex situ characterization include solid state nuclear magnetic resonance (SS_NMR), small angle X-ray scattering (SAXS), wide angle X-ray scattering (WAXS), Fourier transform infrared spectroscopy (FTIR), and dynamic mechanical analysis (DMA). Membrane chemical structure and properties are measured by SS-NMR and FTIR, whereas the water uptake, domain spacing, and crystallinity are assessed by SAXS/WAXS study of hydrated and dry membranes [3-5]. Tensile mechanical properties are measured under room temperature (23°C, 50% RH) and fuel cell conditions (80°C, 90% RH) by DMA [6]. Overall, this paper contributes both qualitative and quantitative understanding of the key structural properties of membranes with different reinforcement resulting in novel knowledge about membranes that can be leveraged for improved fuel cell durability.

Microplastics in the Gulf of Mexico: A Bird’s Eye View

Microplastic debris is a persistent, ubiquitous global pollutant in oceans, estuaries, and freshwater systems. Some of the highest reported concentrations of microplastics, globally, are in the Gulf of Mexico (GoM), which is home to the majority of plastic manufacturers in the United States. A comprehensive understanding of the risk microplastics pose to wildlife is critical to the development of scientifically sound mitigation and policy initiatives. In this review, we synthesize existing knowledge of microplastic debris in the Gulf of Mexico and its effects on birds and make recommendations for further research. The current state of knowledge suggests that microplastics are widespread in the marine environment, come from known sources, and have the potential to be a major ecotoxicological concern for wild birds, especially in areas of high concentration such as the GoM. However, data for GoM birds are currently lacking regarding typical microplastic ingestion rates uptake of chemicals associated with plastics by avian tissues; and physiological, behavioral, and fitness consequences of microplastic ingestion. Filling these knowledge gaps is essential to understand the hazard microplastics pose to wild birds, and to the creation of effective policy actions and widespread mitigation measures to curb this emerging threat to wildlife.

Citizens’ Perception and Concerns on Chemical Exposures and Human Biomonitoring—Results from a Harmonized Qualitative Study in Seven European Countries

Exposure to different chemicals is an inevitable part of our everyday lives. Within HBM4EU, focus group discussions were conducted to gather data on citizens’ perceptions of chemical exposure and human biomonitoring. These discussions were hosted in Cyprus, Denmark, Hungary, Israel, Latvia, the Netherlands, and North Macedonia following a protocol developed in the first round of discussions. Results indicate the very high concern of European citizens regarding food safety and the environment. Focus group participants were well aware of potential uptake of chemicals through food consumption (e.g., preservatives, flavor enhancers, coloring agents, pesticides, fertilizers, metals), drinking water, or from polluted air and water. One of the positive aspects identified here, is the high interest of citizens in awareness and education on personal measures to control exposure. The promotion of personal behavioral changes requires active involvement of society (e.g., commuting habits, energy choices, waste disposal, dietary habits). Activities should focus on raising awareness of the general public, implementation of policy measures, and mainstreaming of related topics into the education system. Raising awareness of the general public may promote engagement of citizens, which in turn may empower them to put pressure on politicians to take effective actions. There is also a need for further research which might focus on the impact of country-specific situations and of the COVID-19 pandemic on the exposure of citizens to chemicals.

Influence of microplastics on the bioconcentration of organic contaminants in fish: Is the “Trojan horse” effect a matter of concern?

Microplastics (MPs) have been shown to act as sorbent phases and thus carriers of organic chemicals in the aquatic environment. Therefore, concerns exist that MP ingestion increases the uptake and accumulation of organic chemicals by aquatic organisms. However, it is unclear if this pathway is relevant compared to other exposure pathways. Here we compared the bioconcentration capacity of two hydrophobic organic chemicals (i.e., chlorpyrifos and hexachlorobenzene) in a freshwater fish (Danio rerio) when exposed to chemicals through water only and in combination with contaminated polyethylene MPs. Additionally, a suite of biomarker analyses (acetylcholine esterase, glutathione S-transferase, alkaline phosphatase, catalase) was carried out to test whether MPs can enhance the toxic stress caused by chemicals. Two 14-day semi-static experiments (one for each chemical) were carried out with adult fish. Each experiment consisted of (1) a control treatment (no chemicals, no MPs); (2) a treatment in which fish were exposed to chlorpyrifos or hexachlorobenzene only through water; (3) a treatment in which fish were exposed to the chemicals through water and contaminated polyethylene MPs (100 mg MP/L). Two additional treatments were included for the biomarker analysis. These contained MPs at two different concentrations (5 and 100 mg MP/L) but no chemicals. The presence of contaminated MPs in contaminated water did not enhance but rather decreased the bioconcentration of both chemicals in fish compared to the treatment that contained contaminated water in absence of MPs. This was more pronounced for hexachlorobenzene, which is more hydrophobic than chlorpyrifos. Enzyme activity levels in fish were only significantly altered in the presence of MPs for alkaline phosphatase. This study indicates that MP presence in freshwater ecosystems is not expected to increase the risks associated with chemical bioconcentration in aquatic organisms and that other exposure pathways (i.e., uptake via respiration, skin permeability) may be of higher importance.