Toxicity of environmental and polystyrene plastic particles on the bivalve Corbicula fluminea: focus on the molecular responses.

Among aquatic organisms, filter feeders are particularly exposed to the ingestion of microplastics (MPs) and nanoplastics (NPs). The present study investigates the effect of environmental microplastics (ENV MPs) and nanoplastics (ENV NPs) generated from macro-sized plastic debris collected in the Garonne River (France), and polystyrene NPs (PS NPs) on the freshwater bivalve Corbicula fluminea. Organisms were exposed to plastic particles at three concentrations: 0.008, 10, and 100 µg L-1 for 21 days. Gene expression measurements were conducted in gills and visceral mass at 7 and 21 days to assess the effects of plastic particles on different functions. Our results revealed: (i) an up-regulation of genes, mainly involved in endocytosis, oxidative stress, immunity, apoptosis, and neurotoxicity, at 7 days of exposure for almost all environmental plastic particles and at 21 days of exposure for PS NPs in the gills, (ii) PS NPs at the three concentrations tested and ENV MPs at 0.008 µg L-1 induced strong down-regulation of genes involved in detoxication, oxidative stress, immunity, apoptosis, and neurotoxicity at 7 days of exposure in the visceral mass whereas ENV MPs at 10 and 100 µg L-1 and all ENV NPs induced less pronounced effects, (iii) overall, PS NPs and ENV MPs 0.008 µg L-1 did not trigger the same effects as ENV MPs 10 and 100 µg L-1 and all ENV NPs, either in the gills or the visceral mass at 7 and 21 days of exposure. This study highlighted the need to use MPs and NPs sampled in the environment for future studies as their properties induce different effects at the molecular level to living organisms.

Role of Ripening in the Deposition of Fragments: The Case of Micro- and Nanoplastics.

Particulate contaminants, such as microplastics (1 µm to 5 mm) and nanoplastics (<1 µm), are disseminated in many terrestrial environments. However, it is still unclear how particles' properties drive their mobility through soils and aquifers due to (i) poor environmental relevance of the model particles that are studied (e.g., spherical and monodisperse) and (ii) the use of packed bed experiments which do not allow a direct observation of deposition dynamics. Using transparent 2D porous media, this study analyzes deposition dynamics of rough polystyrene fragments with irregular shapes and with a size continuum (≈10 nm to 5 µm). Using in situ and ex situ measurements, particle deposition as a function of size was monitored over time under repulsive conditions. In the absence of natural organic matter (NOM), micrometric particles rapidly deposit and promote the physical interception of smaller nanoparticles by creating local porous roughness or obstacles. In the presence of NOM, differences according to particle size were no longer observed, and all fragments were more prone to being re-entrained, thereby limiting the growth of deposits. This work demonstrates the importance of pore surface roughness and porosity of the pore surface for the deposition of colloidal particles, such as microplastics and nanoplastics, under repulsive conditions.

Kinetics of metal and metalloid concentrations in holopelagic Sargassum reaching coastal environments.

Since 2011, the Caribbean Islands have experienced unprecedented stranding of a pelagic brown macroalgae Sargassum inducing damages for coastal ecosystems and economy. This study measures the kinetics of metal trace elements (MTE) in Sargassum reaching different coastal environments. In July 2021, over a period of 25 days, fixed experimental floating cages containing the three Sargassum morphotypes (S. fluitans III and S. natans I and VIII) were placed in three different coastal habitats (coral reef, seagrass, and mangrove) in Guadeloupe (French West Indies). Evolution of biomasses and their total phenolic content of Sargassum reveals that environmental conditions of caging were stressful and end up to the death of algae. Concentrations of 19 metal(loid) trace elements were analyzed and three shapes of kinetics were identified with the MTE that either concentrate, depurate, or remains stable. In the mangrove, evolution of MTE was more rapid than the two other habitats a decrease of the As between 70 and 50 µg g-1 in the mangrove. Sargassum natans I presented a different metal composition than the two other morphotypes, with higher contents of As and Zn. All Sargassum morphotype are rapidly releasing the metal(oid)s arsenic (As) when they arrive in studied coastal habitats. In order to avoid the transfer of As from Sargassum to coastal environments, Sargassum stranding should be avoided and their valorization must take into account their As contents.

Toxicity assessment of environmental MPs and NPs and polystyrene NPs on the bivalve Corbicula fluminea using a multi-marker approach.

Small plastic particles, microplastics (MPs) and nanoplastics (NPs) represent a major threat in aquatic environments. Freshwater organisms are exposed to MPs and NPs, particularly in industrial and urban areas. The present study aimed to compare the toxicity between polystyrene NPs (PS NPs) and environmental microplastics (ENV MPs) and nanoplastics (ENV NPs) generated from macro-sized debris collected in the Garonne River on the freshwater bivalve C. fluminea. The organisms were exposed to the different plastic particles at three environmentally relevant concentrations: 0.008, 10, and 100 µg L-1 for 21 days. The biological responses of organisms were assessed using a multi-biomarker approach from the sub-individual to the individual level. The results demonstrated that: i) ENV NPs triggered more effects on detoxification processes and immune response, confirming that using manufactured NPs for laboratory exposure can lead to misleading conclusions on the risks posed by plastic particles; ii) effects of ENV MPs were less marked than ENV NPs, emphasizing the importance of testing a size continuum of plastic particles from NPs to MPs; iii) some effects were only observed for the low and/or intermediate concentrations tested, underlining the importance of using environmentally relevant concentrations. In light of these results, laboratory studies should be continued by exposing aquatic species to environmental MPs and NPs. The properties of these particles have to be characterized for a better risk assessment of environmental plastic particles.

Are nanoplastics potentially toxic for plants and rhizobiota? Current knowledge and recommendations.

Soil is now becoming a reservoir of plastics in response to global production, use/disposal patterns and low recovery rates. Their degradation is caused by numerous processes, and this degradation leads to the formation and release of plastic nanoparticles, i.e., nanoplastics. The occurrence of nanoplastics in the soil is expected to both directly and indirectly impact its properties and functioning. Nanoplastics may directly impact the physiology and development of living organisms, especially plants, e.g., by modifying their production yield. Nanoplastics can also indirectly modify the physicochemical properties of the soil and, as a result, favour the release of related contaminants (organic or inorganic) and have an impact on soil biota, and therefore have a negative effect on the functioning of rhizospheres. However all these results have to be taken carefully since performed with polymer nano-bead not representative of the nanoplastics observed in the environment. This review highlight thus the current knowledge on the interactions between plants, rhizosphere and nanoplastics, their consequences on plant physiology and development in order to identify gaps and propose scientific recommendations.

Identification of polystyrene nanoplastics from natural organic matter in complex environmental matrices by pyrolysis-gas chromatography-mass spectrometry.

Due to the flux of plastic debris entering the environment, it becomes urgent to document and monitor their degradation pathways at different scales. At the colloidal scale, the systematic hetero-association of nanoplastics with the natural organic matter complexifies the ability to detect plastic signatures in the particle collected in the various environments. The current techniques used for microplastics could not discriminate the polymers at the nanoscale from the natural macromolecules, as the plastic mass in the aggregate is within the same order. Only a few methods are available concerning nanoplastics identification in complex matrices, with the coupling of pyrolysis with gas chromatography and mass spectrometry (Py-GC-MS) as one of the most promising due to its mass-based detection. However, natural organic matter in environmental samples interferes with similar pyrolysis products. These interferences are even more critical for polystyrene polymers as this plastic presents no dominant pyrolysis markers, such as polypropylene, that could be identified at trace concentrations. Here, we investigate the ability to detect and quantify polystyrene nanoplastics in a rich phase of natural organic matter proposed based on the relative ratio of pyrolyzates. The use of specific degradation products (styrene dimer and styrene trimer) and the toluene/styrene ratio (RT/S) are explored for these two axes. While the size of the polystyrene nanoplastics biased the pyrolyzates of styrene dimer and trimer, the RT/S was correlated with the nanoplastics mass fraction in the presence of natural organic matter. An empirical model is proposed to evaluate the relative quantity of polystyrene nanoplastics in relevant environmental matrices. The model was applied to real contaminated soil by plastic debris and literature data to demonstrate its potential.

Volatile organic compounds identification and specific stable isotopic analysis (δ13C) in microplastics by purge and trap gas chromatography coupled to mass spectrometry and combustion isotope ratio mass spectrometry (PT-GC-MS-C-IRMS).

Microplastics (MPs) have become one of the major global environmental issues in recent decades due to their ubiquity in the environment. Understanding MPs source origin and reactivity is urgently needed to better constrain their fate and budget. Despite improvements in analytical methods to characterize MPs, new tools are needed to help understand their sources and reactivity in a complex environment. In this work, we developed and applied an original Purge-&-Trap system coupled to a GC-MS-C-IRMS to explore the δ13C compound-specific stable isotope analysis (CSIA) of volatile organic compounds (VOC) embedded in MPs. The method consists of heating and purging MP samples, with VOCs being cryo-trapped on a Tenax sorbent, followed by GC-MS-C-IRMS analysis. The method was developed using a polystyrene plastic material showing that sample mass and heating temperature increased the sensitivity while not influencing VOC δ13C values. This robust, precise, and accurate methodology allows VOC identification and δ13C CSIA in plastic materials in the low nanogram concentration range. Results show that the monomer styrene displays a different δ13C value (- 22.2 ± 0.2‰), compared to the δ13C value of the bulk polymer sample (- 27.8 ± 0.2‰). This difference could be related to the synthesis procedure and/or diffusion processes. The analysis of complementary plastic materials such as polyethylene terephthalate, and polylactic acid displayed unique VOC δ13C patterns, with toluene showing specific δ13C values for polystyrene (- 25.9 ± 0.1‰), polyethylene terephthalate (- 28.4 ± 0.5‰), and polylactic acid (- 38.7 ± 0.5‰). These results illustrate the potential of VOC δ13C CSIA in MP research to fingerprint plastic materials, and to improve our understanding of their source cycle. Further studies in the laboratory are needed to determine the main mechanisms responsible for MPs VOC stable isotopic fractionation.

Continuum from microplastics to nanoplastics: effects of size and source on the estuarine bivalve Scrobicularia plana.

Plastic has been largely detected in estuarine environments and represents major concern towards aquatic living organisms. The present study evaluates the impact of microplastics (MPs) and nanoplastics (NPs) under realistic exposure conditions. Scrobicularia plana individuals were exposed to low concentrations (0.008, 10, and 100 µg L-1) of environmental MPs and NPs as well as to standard PS NPs, as a comparison condition. The aim of this study was to understand the ecotoxicological effects of environmental plastic particles on S. plana gills and digestive glands but also to compare the effects of plastic polymers size in order to highlight if the size could induce different toxicity profiles within this model organism, at different levels of biological organization. Results showed a differential induction of detoxification enzymes (CAT, GST), immunity (AcP), DNA damage processes as well as a differential effect on behavior and condition index of animals depending upon the type of plastic, the size, the concentration tested, and the type of organ. This study underlines the necessity of testing (i) plastics collected from the environment as compared to standard ones and (ii) the effect of size using plastics coming from the same batch of macrosized plastics. This study concludes on the future need directions that plastic-based studies must take in order to be able to generate a large quantity of relevant data that could be used for future regulatory needs on the use of plastic.

The environmental fate of nanoplastics: What we know and what we need to know about aggregation.

The presence of nanoplastics in the environment has been proven. There is now an urgent need to determine how nanoplastics behave in the environment and to assess the risks they may pose. Here, we examine nanoplastic homo- and heteroaggregation, with a focus on environmentally relevant nanoplastic particle models. We made a systematic analysis of experimental studies, and ranked the environmental relevance of 377 different solution chemistries, and 163 different nanoplastic particle models. Since polymer latex spheres are not environmentally relevant (due to their monodisperse size, spherical shape, and smooth surface), their aggregation behavior in natural conditions is not transferable to nanoplastics. A few recent studies suggest that nanoplastic particle models that more closely mimic incidentally produced nanoplastics follow different homoaggregation pathways than latex sphere particle models. However, heteroaggregation of environmentally relevant nanoplastic particle models has seldom been studied. Despite this knowledge gap, the current evidence suggests that nanoplastics may be more sensitive to heteroaggregation than previously expected. We therefore provide an updated hypothesis about the likely environmental fate of nanoplastics. Our review demonstrates that it is essential to use environmentally relevant nanoplastic particle models, such as those produced with top-down methods, to avoid biased interpretations of the fate and impact of nanoplastics. Finally, it will be necessary to determine how the heteroaggregation kinetics of nanoplastics impact their settling rate to truly understand nanoplastics' fate and effect in the environment.

Effect of size continuum from nanoplastics to microplastics on marine mussel Mytilus edulis: Comparison in vitro/in vivo exposure scenarios.

For several decades, plastic has been a global threat in terms of pollution. Plastic polymers, when introduce in the aquatic environment, are exposed to fragmentation processes into microplastics (MPs) and nanoplastics (NPs) which could potentially interact with living organisms. The objective of this work was to study the effects of plastic particles representative of those found in the environment, on the marine mussels Mytilus edulis, under two exposure scenarios: in vivo and in vitro. Whole mussels or cultured hemocytes were exposed for 24 h to NPs and MPs generated from macro-sized plastics collected in the field, but also to reference NPs, at concentrations found in the environment: 0.08, 10 µg and 100 µg·L-1. Results showed that immune response was only activated when mussels were exposed in vivo. However, cytotoxicity (hemocyte mortality) and genotoxicity (DNA damage) parameters were induced after both types of exposure, but in a dose-dependent manner after in vitro hemocyte exposure to all tested plastic conditions. These results indicate that in vitro approaches could be considered as potential predictors of in vivo exposures.

Wildland-urban interface fire ashes as a major source of incidental nanomaterials.

Although metal and metalloid concentrations in wildfire ashes have been documented, the nature and concentrations of incidental nanomaterials (INMs) in wildland-urban interface (WUI) fire ashes have received considerably less attention. In this study, the total metal and metalloid concentrations of 57 vegetation, structural, and vehicle ashes and underlying soils collected at the WUI following the 2020 fire season in northern California - North Complex Fire and LNU Lightning Complex Fire - were determined using inductively coupled plasma-time of flight-mass spectrometry after microwave-assisted acid digestion. The concentrations of Ti, Zn, Cu, Ni, Pb, Sn, Sb, Co, Bi, Cr, Ba, As, Rb, and W are generally higher in structural/vehicle-derived ashes than in vegetation-derived ashes and soils. The concentrations of Ca, Sr, Rb, and Ag increased with increased combustion completeness (e.g., black ash < gray ash < white ash), whereas those of C, N, Zn, Pb, and In decreased with increased combustion completeness. The concentration of anthropogenic Ti - determined by mass balance calculations and shifts in Ti/Nb above the natural background ratios - was highest in vehicle ash (median: 30.8 g kg-1, range: 4.5-41.0 g kg-1) followed by structural ash (median: 5.5 g kg-1, range: of 0-77.4 g kg-1). Various types of carbonaceous INM (e.g., amorphous carbon, turbostratic-like carbon, and carbon associated with zinc oxides) and metal-bearing INMs (e.g., Ti, Cu, Fe, Zn, Mn, Pb, and Cr) with sizes between few nanometers to few hundreds of nanometers were evidenced in ashes using transmission electron microscopy, including energy dispersive X-ray spectroscopy. Overall, this study demonstrates the abundance of a variety of metals and metalloids in the form of INMs in WUI fire ashes. This study also highlights the need for further research into the formation, transformation, reactivity, fate, and effects of INMs during and following fires at the WUI.

The elemental fingerprint as a potential tool for tracking the fate of real-life model nanoplastics generated from plastic consumer products in environmental systems.

Metals and metalloids are widely used in producing plastic materials as fillers and pigments, which can be used to track the environmental fate of real-life nanoplastics in environmental and biological systems. Therefore, this study investigated the metal and metalloids concentrations and fingerprint in real-life model nanoplastics generated from new plastic products (NPP) and from environmentally aged ocean plastic fragments (NPO) using single particle-inductively coupled plasma-mass spectrometry (SP-ICP-TOF-MS) and transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (TEM-EDX). The new plastic products include polypropylene straws (PPS), polyethylene terephthalate bottles (PETEB), white low-density polyethylene bags (LDPEB), and polystyrene foam shipping material (PSF). All real-life model nanoplastics contained metal and metalloids, including Si, Al, Sr, Ti, Fe, Ba, Cu, Pb, Zn, Cd, and Cr, and were depleted in rare earth elements. Nanoplastics generated from the white LDPEB were rich in Ti-bearing particles, whereas those generated from PSF were rich in Cr, Ti, and Pb. The Ti/Fe in the LDPEB nanoplastics and the Cr/Fe in the PSF nanoplastics were higher than the corresponding ratios in natural soil nanoparticles (NNPs). The Si/Al ratio in the PSF nanoplastics was higher than in the NNPs, possibly due to silica-based fillers. The elemental ratio of Si/Al, Fe/Cr, and Fe/Ni in the nanoplastics derived from ocean plastic fragments was intermediate between the nanoplastics derived from real-life plastic products and NNPs, indicating a combined contribution from pigments and fillers used in plastics and from natural sources. This study provides a method to track real-life nanoplastics in controlled laboratory studies based on nanoplastic elemental fingerprints. It expands the realm of nanoplastics that can be followed based on their metallic signatures to all kinds of nanoplastics. Additionally, this study illustrates the importance of nanoplastics as a source of metals and metal-containing nanoparticles in the environment.

Ecotoxicity of Heteroaggregates of Polystyrene Nanospheres in Chironomidae and Amphibian.

Due to their various properties as polymeric materials, plastics have been produced, used and ultimately discharged into the environment. Although some studies have shown their negative impacts on the marine environment, the effects of plastics on freshwater organisms are still poorly studied, while they could be widely in contact with this pollution. The current work aimed to better elucidate the impact and the toxicity mechanisms of two kinds of commercial functionalized nanoplastics, i.e., carboxylated polystyrene microspheres of, respectively, 350 and 50 nm (PS350 and PS50), and heteroaggregated PS50 with humic acid with an apparent size of 350 nm (PSHA), all used at environmental concentrations (0.1 to 100 µg L-1). For this purpose, two relevant biological and aquatic models-amphibian larvae, Xenopus laevis, and dipters, Chironomus riparius-were used under normalized exposure conditions. The acute, chronic, and genetic toxicity parameters were examined and discussed with regard to the fundamental characterization in media exposures and, especially, the aggregation state of the nanoplastics. The size of PS350 and PSHA remained similar in the Xenopus and Chironomus exposure media. Inversely, PS50 aggregated in both exposition media and finally appeared to be micrometric during the exposition tests. Interestingly, this work highlighted that PS350 has no significant effect on the tested species, while PS50 is the most prone to alter the growth of Xenopus but not of Chironomus. Finally, PSHA induced a significant genotoxicity in Xenopus.

Early molecular responses of mangrove oysters to nanoplastics using a microfluidic device to mimic environmental exposure.

This study assessed the effects of nanoplastics (NPs) using for the very first time microfluidic devices (chip) mimicking transition waters. Three kinds of NPs were tested: crushed NPs from polystyrene pellets (NP-PS), or from Guadeloupe beaches (NP-G); and latex PS (PSL-COOH). The eluted fractions from the microfluidic device showed a low aggregation of NPs. They remained stable over time in the exposure media, with a stabilization of NPs of small sizes (< 500 nm). These chips were thus used for the toxicological assessment of NPs on swamp oysters, Isognomon alatus. Oysters were exposed for 7 days to the chip elution fraction of either NP-G, NP-PS or PSL-COOH (0.34-333 µg.L-1). Gene transcription analyses showed that the tested NPs triggered responses on genes involved in endocytosis, mitochondrial metabolism disruption, oxidative stress, DNA repair, and detoxification. Highest responses were observed after NP-G exposure at low concentrations (1 µg.L-1), as they are originated from the natural environment and accumulated contaminants, enhancing toxicological effects. As salinity influences aggregation and then the bioavailability of NPs, our results demonstrated the importance of using microfluidic devices for ecotoxicological studies on swamp or estuarine species.

Metals and metalloids concentrations in three genotypes of pelagic Sargassum from the Atlantic Ocean Basin-scale.

Since 2011, the Caribbean Islands have witnessed unprecedented massive stranding of a pelagic brown algal Sargassum spp. inducing damages for coastal ecosystems and economy. By accumulating heavy metals, Sargassum can play a role in contaminant transportation from offshore to the coast. In 2019, three genotypes of Sargassum (S. fluitans III, S. natans I, and VIII) were sampled in seven stations along a 3400 km transect in the Atlantic Ocean. Concentrations of 15 heavy metal(loid)s elements were analyzed by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). Mean metal concentrations were ranked following descending order: As >Fe > Al > Mn > Cd > Zn > Ni > V > Cu > Cr > Hg. The metalloid As was the most abundant contaminant with a maximum value of 115 ppm, previously observed in the Caribbean area (80-150 ppm). At Atlantic Ocean Basin-scale, metallic element concentrations do not present spatial longitudinal gradients. Genotypes S. fluitans III and S. natans (I and VIII), present differents metal(loid)s contamination distinct patterns.

The underestimated toxic effects of nanoplastics coming from marine sources: A demonstration on oysters (Isognomon alatus).

This study aims to assess the potential toxicity of (1) nanoplastics (NPs) issued from the fragmentation of larger plastic particles collected on the Caribbean marine coast (NP-G), and (2) polystyrene NPs (NP-PS), commonly used in the literature, on Caribbean swamp oysters (Isognomon alatus). Oysters were exposed to 7.5 and 15 µg.L-1 of each type of NPs, combined or not with arsenic (As) at 1 mg.L-1 for one week before molecular analyses at gene levels. Overall, the NP-G triggered more significant changes than NP-PS, especially when combined with As. Genes involved in the mitochondrial metabolism were strongly up-regulated in most of the conditions tested (up to 11.6 fold change for the NP-PS exposure at 7.5 µg.L-1 for the 12s). NPs in combination with As or not triggered a response against oxidative stress, with an intense repression of cat and sod1 (0.01 fold-changes for the NP-G condition at 7.5 µg.L-1). Both NP-G and NP-PS combined or not with As led to an up-regulation of apoptotic genes p53 and bax (up to 59.3 fold-changes for bax in the NP-G condition with As). Our study reported very innovative molecular results on oysters exposed to NPs from environmental sources. Our results suggest that the composition, surface charge, size, and the adsorbed contaminants of plastics from the natural environment may have synergic effects with plastic, which are underestimated when using manufactured NPs as NP-PS in ecotoxicological studies.

Correction: Micro- and nanoplastic transfer in freezing saltwater: implications for their fate in polar waters.

Correction for 'Micro- and nanoplastic transfer in freezing saltwater: implications for their fate in polar waters' by Alice Pradel et al., Environ. Sci.: Processes Impacts, 2021, 23, 1759-1770, DOI: 10.1039/D1EM00280E.

Molecular impacts of dietary exposure to nanoplastics combined with arsenic in Canadian oysters (Crassostrea virginica) and bioaccumulation comparison with Caribbean oysters (Isognomon alatus).

Despite the urge need to address the possible impact of plastic debris, up to now, little is known about the translocation of nanoplastics through the trophic web. Plus, due to their surface reactivity, nanoplastics could sorb and thus increase metals bioavailability to aquatic filter-feeding organisms (e.g., bivalves). In this study, we investigated the dietary exposure route on the oyster Crassostrea virginica through microalgae themselves exposed to three nanoplastic dispersions (PSL, PSC and NPG) at reportedly environmental concentrations combined or not with arsenic. Interactive effects of nanoplastics on arsenic bioaccumulation were studied, along with the expression of key genes in gills and visceral mass. The investigated gene functions were endocytosis (cltc), oxidative stress (gapdh, sod3, cat), mitochondrial metabolism (12S), cell cycle regulation (gadd45, p53), apoptosis (bax, bcl-2), detoxification (cyp1a, mdr, mt), and energy storage (vit). Results showcased that nanoplastic treatments combined with arsenic triggered synergetic effects on gene expressions. Relative mRNA level of 12S significantly increased at 10 and 100 µg L-1 for NPG combined with arsenic and for PSC combined with arsenic. Relative mRNA level of bax increased for PSL combined with arsenic and for PSC combined with arsenic at 10 and 100 µg L-1 respectively. We also observed that relative arsenic bioaccumulation was significantly higher in Crassostrea virginica gills compared to Isognomon alatus'. These results are the first comparative molecular effects of nanoplastics alone and combined with arsenic investigated in farmed C. virginica oysters. Together with I. alatus results we thus shed light on species different sensitivity.

Nanoplastics Identification in Complex Environmental Matrices: Strategies for Polystyrene and Polypropylene.

Identification of nanoplastics in complex environmental matrices remains a challenge. Despite the increase in nanoplastics studies, there is a lack of studies dedicated to nanoplastics detection, partially explained by their carbon-based structure, their wide variety of composition, and their low environmental concentrations compared to the natural organic matter. Here, pyrolysis coupled to a GCMS instrumental setup provided a relevant analytical response for polypropylene and polystyrene nanoplastic suspensions. Specific pyrolysis markers and their indicative fragment ions were selected and validated. Possible interferences with environmental matrices were explored by spiking nanoplastics in various organic matter suspensions (i.e., algae, soil natural organic matter, and soil humic acid) and analyzing an environmental suspension of nanoplastics. While a rapid polypropylene nanoplastics identification was validated, polystyrene nanoplastics require preliminary treatment. The strategies presented herein open new possibilities for the detection/identification of nanoplastics in environmental matrices such as soil, dust, and biota.

Molecular Impacts of Dietary Exposure to Nanoplastics Combined or Not with Arsenic in the Caribbean Mangrove Oysters (Isognomon alatus).

Nanoplastics (NPs) are anthropogenic contaminants that raise concern, as they cross biological barriers. Metals' adsorption on NPs' surface also carries ecotoxicological risks to aquatic organisms. This study focuses on the impacts of three distinct NPs on the Caribbean oyster Isognomon alatus through dietary exposure. As such, marine microalgae Tisochrysis lutea were exposed to environmentally weathered mixed NPs from Guadeloupe (NPG), crushed pristine polystyrene nanoparticles (PSC), and carboxylated polystyrene nanoparticles of latex (PSL). Oysters were fed with NP-T. lutea at 10 and 100 µg L-1, concentrations considered environmentally relevant, combined or not with 1 mg L-1 pentoxide arsenic (As) in water. We investigated key gene expression in I. alatus' gills and visceral mass. NP treatments revealed significant induction of cat and sod1 in gills and gapdh and sod1 in visceral mass. As treatment significantly induced sod1 expression in gills, but once combined with any of the NPs at both concentrations, basal mRNA levels were observed. Similarly, PSL treatment at 100 µg L-1 that significantly induced cat expression in gills or sod1 in visceral mass showed repressed mRNA levels when combined with As (reduction of 2222% and 34%, respectively, compared to the control). This study suggested a protective effect of the interaction between NPs and As, possibly by decreasing both contaminants' surface reactivity.