A 2-Tier standard method to test the toxicity of microplastics in marine water using Paracentrotus lividus and Acartia clausi larvae

New insights into the impact of leachates from in-field collected plastics on aquatic invertebrates and vertebrates

The impact of leachates from micronized beached plastics of the Mediterranean Sea and Atlantic Ocean on coastal marine ecosystems was investigated by using a multidisciplinary approach. Chemical analysis and ecotoxicological tests on phylogenetically distant species were performed on leachates from the following plastic categories: bottles, pellets, hard plastic (HP) containers, fishing nets (FN) and rapido trawling rubber (RTR). The bacteria Alivibrio fischeri, the nauplii of the crustaceans Amphibalanus amphitrite and Acartia tonsa, the rotifer Brachionus plicatilis, the embryos of the sea urchin Paracentrotus lividus, the ephyrae of the jellyfish Aurelia sp. and the larvae of the medaka Oryzias latipes were exposed to different concentrations of leachates to evaluate lethal and sub-lethal effects. Thirty-one additives were identified in the plastic leachates; benzophenone, benzyl butyl phthalate and ethylparaben were present in all leachates. Ecotoxicity of leachates varied among plastic categories and areas, being RTR, HP and FN more toxic than plastic bottles and pellets to several marine invertebrates. The ecotoxicological results based on 13 endpoints were elaborated within a quantitative weight of evidence (WOE) model, providing a synthetic hazard index for each data typology, before their integrations in an environmental risk index. The WOE assigned a moderate and slight hazard to organisms exposed to leachates of FN and HP collected in the Mediterranean Sea respectively, and a moderate hazard to leachates of HP from the Atlantic Ocean. No hazard was found for pellet, bottles and RTR. These findings suggest that an integrated approach based on WOE on a large set of bioassays is recommended to get a more reliable assessment of the ecotoxicity of beached-plastic leachates. In addition, the additives leached from FN and HP should be further investigated to reduce high concentrations and additive types that could impact marine ecosystem health.

Comparative assessment of the acute toxicity of commercial bio-based polymer leachates on marine plankton

Conventional plastics have become a major environmental concern due to their persistence and accumulation in marine ecosystems. The development of potential degradable polymers (PBP), such as polyhydroxyalkanoates (PHAs) and polylactic acid (PLA), has gained attention as an alternative to mitigate plastic pollution, since they have the potential to biodegrade under certain conditions, and their production is increasing as replacement of conventional polyolefins. This study aimed to assess and compare the toxicity of leachates of pre-compounding PBP (PLA and the PHA, polyhydroxybutyrate-covalerate (PHBv)) and polypropylene (PP) on five marine planktonic species. A battery of standard bioassays using bacteria, microalgae, sea urchin embryos, mussel embryos and copepod nauplii was conducted to assess the toxicity of leachates from those polymers. Additionally, the presence of chemical additives in the leachates was also verified through GC-MS and LC-HRMS analysis. Results showed that PHBv leachates exhibited higher toxicity compared to other polymers, with the microalgae Rhodomonas salina, being the most sensitive species to the tested leachates. On the other hand, PP and PLA generally displayed minimal to no toxicity in the studied species. Estimated species sensitivity distribution curves (SSD) show that PHBv leachates can be 10 times more hazardous to marine plankton than PP or PLA leachates, as demonstrated by the calculated Hazardous Concentration for 5 % of species (HC5). Qualitative chemical analysis supports the toxicological results, with 80 % of compounds being identified in PHBv leachates of which 2,4,6-trichlorophenol is worth mentioning due to the deleterious effects to aquatic biota described in literature. These findings underscore the fact that whereas environmental persistence can be targeted using PBP, the issue of chemical safety remains unsolved by some alternatives, such as PHBv. Gaining a comprehensive understanding of the toxicity profiles of PBP materials through a priori toxicological risk assessment is vital for their responsible application as alternatives to conventional plastics.

Marine degradation and ecotoxicity of conventional, recycled and compostable plastic bags

Plastic bags are currently a major component of marine litter, causing aesthetical nuisance, and undesirable effects on marine fauna that ingest them or are entangled. Plastic litter also rises concern on the ecotoxicological effects due to the potential toxicity of the chemical additives leached in aquatic environments. Conventional plastic bags are made of polyethylene, either from first use or recycled, but regulations restricting single-use plastics and limiting lightweight carrier bags (<50 μm thickness) have fostered the replacement of thin PE bags by compostable materials advertised as safer for the environment. In this study, we assess the degradation of commercially available plastic bags in marine conditions at two scales: aquariums (60 days) and outdoors flow-through mesocosm (120 days). Strength at break point and other tensile strength parameters were used as ecologically relevant endpoints to track mechanical degradation. Ecotoxicity has been assessed along the incubation period using the sensitive Paracentrotus lividus embryo test. Whereas PE bags did not substantially lose their mechanical properties within the 60 d aquarium exposures, compostable bags showed remarkable weight loss and tensile strength decay, some of them fragmenting in the aquarium after 3-4 weeks. Sediment pore water inoculum promoted a more rapid degradation of compostable bags, while nutrient addition pattern did not affect the degradation rate. Longer-term mesocosms exposures supported these findings, as well as pointed out the influence of the microbial processes on the degradation efficiency of compostable/bioplastic bags. Compostable materials, in contrast toPE, showed moderate toxicity on sea-urchin larvae, partially associated to degradation of these materials, but the environmental implications of these findings remain to be assessed. These methods proved to be useful to classify plastic materials, according to their degradability in marine conditions, in a remarkably shorter time than current standard tests and promote new materials safer for the marine fauna.

Weathering increases the acute toxicity of plastic pellets leachates to sea-urchin larvae-a case study with environmental samples

Microplastics, particles under 5 mm, pervade aquatic environments, notably in Tarragona's coastal region (NE Iberian Peninsula), hosting a major plastic production complex. To investigate weathering and yellowness impact on plastic pellets toxicity, sea-urchin embryo tests were conducted with pellets from three locations-near the source and at increasing distances. Strikingly, distant samples showed toxicity to invertebrate early stages, contrasting with innocuous results near the production site. Follow-up experiments highlighted the significance of weathering and yellowing in elevated pellet toxicity, with more weathered and colored pellets exhibiting toxicity. This research underscores the overlooked realm of plastic leachate impact on marine organisms while proposes that prolonged exposure of plastic pellets in the environment may lead to toxicity. Despite shedding light on potential chemical sorption as a toxicity source, further investigations are imperative to comprehend weathering, yellowing, and chemical accumulation in plastic particles.

Do weathered microplastics impact the planktonic community? A mesocosm approach in the Baltic Sea

Microplastics (MPs) are ubiquitous pollutants of increasing concern in aquatic systems. However, little is still known about the impacts of weathered MPs on plankton at the community level after long-term exposure. In this study, we investigated the effects of weathered MPs on the structure and dynamics of a Baltic Sea planktonic community during ca. 5 weeks of exposure using a mesocosm approach (2 m3) mimicking natural conditions. MPs were obtained from micronized commercial materials of polyvinyl chloride, polypropylene, polystyrene, and polyamide (nylon) previously weathered by thermal ageing and sunlight exposure. The planktonic community was exposed to 2 μg L-1 and 2 mg L-1 of MPs corresponding to measured particle concentrations (10-120 μm) of 680 MPs L-1 and 680 MPs mL-1, respectively. The abundance and composition of all size classes and groups of plankton and chlorophyll concentrations were periodically analyzed throughout the experiment. The population dynamics of the studied groups showed some variations between treatments, with negative and positive effects of MPs exhibited depending on the group and exposure time. The abundance of heterotrophic bacteria, pico- and nanophytoplankton, cryptophytes, and ciliates was lower in the treatment with the higher MP concentration than in the control at the last weeks of the exposure. The chlorophyll concentration and the abundances of heterotrophic nanoflagellates, Astromoeba, dinoflagellate, diatom, and metazooplankton were not negatively affected by the exposure to MPs and, in some cases, some groups showed even higher abundances in the MP treatments. Despite these tendencies, statistical analyses indicate that in most cases there were no statistically significant differences between treatments over the exposure period, even at very high exposure concentrations. Our results show that weathered MPs of the studied conventional plastic materials have minimal or negligible impact on planktonic communities after long-term exposure to environmentally relevant concentrations.

Toxicity of tire particle leachates on early life stages of keystone sea urchin species

Particles from tires are a major fraction of microplastic pollution. They contain a wide range of chemical additives that can leach into the water and be harmful to aquatic organisms. In this study, we investigated the acute toxicity of tire particle leachates in early life stages of three keystone echinoderm species (Paracentrotus lividus, Arbacia lixula, Diadema africanum). Embryos were exposed for 72 h to a range of leachate dilutions, prepared using a concentration of 1 g L-1. Larval growth, abnormal development, and mortality were the measured endpoints. Furthermore, we estimated the activity of glutathione S transferase (GST) and the electron transport system (ETS) in P. lividus. Strong concentration-dependent responses were observed in all species, though with differing sensitivity. The median effect concentrations for abnormal development in P. lividus and A. lixula were 0.16 and 0.35 g L-1, respectively. In D. africanum, mortality overshadowed abnormal development and the median lethal concentration was 0.46 g L-1. Larvae of P. lividus were significantly smaller than the control from 0.125 g L-1, while the other two species were affected from 0.5 g L-1. ETS activity did not change but there was a non-significant trend of increasing GST activity with leachate concentration in P. lividus. Seven organic chemicals and eight metals were detected at elevated concentrations in the leachates. While we regard zinc as a strong candidate to explain some of the observed toxicity, it can be expected that tire particle leachates exhibit a cocktail effect and other leached additives may also contribute to their toxicity. Our results emphasize the importance of multi-species studies as they differ in their susceptibility to tire particle pollution. We found negative effects at concentrations close to projections in the environment, which calls for more research and mitigation actions on these pollutants.

Microplastics increase the toxicity of mercury, chlorpyrifos and fluoranthene to mussel and sea urchin embryos

The objective of this study was to determine whether and to what extent microplastics (MPs) enhance the toxicity of pollutants as well as whether pollutant-loaded MPs act as relevant vectors of chemical pollutants. With this aim, the toxicity for mussel and sea urchin embryos of: 1) three dissolved pollutants (Pol): chlorpyrifos (CPF), fluoranthene (FLT) and mercury (Hg); 2) their mixture with Microplastics (MP + Pol); and 3) pollutant-loaded MPs (MPPol), was assessed. Analyses of CPF, FLT and Hg were also performed to evaluate the transfer among dissolved and particulate phases. In general, the 'MP + Pol' treatments were more toxic as 48-h EC50 (μg/L) than the 'Pol' treatments for sea urchin or mussel. The 48-h and 120-h EC50s (μg/L) for sea urchin showed little variation for CPF and MP + CPF, and no clear pattern was found for FLT and MP + FLT. The performed chemical analysis in the MPPol tests indicated that desorption was the main route to explain the observed toxicity of Hg and a relevant route for CPF and FLT. This study contributes to improve the knowledge about the interactions between MPs and chemical pollutants, which is fundamental for a more realistic ecological risk assessment in aquatic ecosystems.

UV Dosage Unveils Toxic Properties of Weathered Commercial Bioplastic Bags

Previous studies indicated that weathered conventional plastics and bioplastics pose ecotoxicological risks. Here, the effects of artificial and natural weathering on the ecotoxicity of three compostable bags and a conventional polyethylene (PE) bag are investigated. With that aim, a 21-day artificial indoor weathering experiment featuring UV light, UV-filtered light, and darkness was run simultaneously to a 120-day outdoor littoral mesocosm exposure featuring natural light, UV-filtered light, and shaded conditions. Acute toxicity of so-weathered plastic specimens was tested in vivo using the sensitive Paracentrotus lividus sea-urchin embryo test. PE was nontoxic from the beginning and did not gain toxicity due to UV weathering. In contrast, for bioplastics, dry artificial UV weathering increased toxicity in comparison to the dark control. Weathering in outdoor mesocosm led to a rapid loss of toxic properties due to leaching in rainwater. With a higher UV dosage, a plastic-type-dependent regain of toxicity was observed, most likely driven by enhanced availability or transformation of functional additives or due to bioplastic degradation products. PE showed moderate UV absorbance, while bioplastics showed high UV absorbance. This study highlights the potential of biodegradable plastics to pose enhanced ecotoxicological risk due to weathering under environmentally relevant conditions.

Lethal effect of leachates from tyre wear particles on marine copepods

With thousands of tons of Tyre Wear Particles (TWP) entering the aquatic environment every year, TWP are considered a major contributor to microplastic pollution. TWP leach organic compounds and metals in water, potentially affecting the marine food web. However, little is known about the toxicity of TWP leachates on marine copepods, a major food web constituent, and a key group to determine the environmental risk of pollution in marine ecosystems. In this study, we determined the lethal effect of TWP leachates on marine copepods after 24, 48, and 72-h of exposure to 0.05-100% leachate solutions prepared using a concentration of 5 g TWP L-1. The calanoids Acartia tonsa, Temora longicornis and Centropages hamatus, the cyclopoid Oithona davisae and the harpacticoid Amonardia normanni were used as experimental species. TWP leachates were toxic to all the studied species, with toxicity increasing as leachate solution and exposure time increased. Median lethal concentration (LC50, 72-h) ranged from 0.22 to 3.43 g L-1 and calanoid copepods were more sensitive to TWP leachates than the cyclopoid O. davisae and the harpacticoid A. normanni. Toxicity of TWP leachates was not related to the copepod body size, which suggests that other traits such as foraging behaviour or adaptation to contaminants could explain the higher tolerance of cyclopoid and harpacticoid to TWP leachates compared to calanoid copepods. Although field data on the concentration of TWP and their chemical additives are still limited, our results suggest that TWP leachates can negatively impact planktonic food webs in coastal areas after road runoff events.

The toxicity of microplastics and their leachates to embryonic development of the sea cucumber Apostichopus japonicus

Microplastic pollution has been widely detected across the global ocean, posing a major threat to a wide variety of marine biota. To date, the deleterious impacts of microplastics have predominantly been linked to their direct exposure, while the potential risks posed by the leachates emanating from microplastics have received comparatively less attention. Here, the toxicity of virgin plasticized polyvinyl chloride (PVC) microspheres and their leachates were evaluated on the embryo-larval development of sea cucumber Apostichopus japonicus using an in-vitro assay. Results showed that a significant toxic effect of both PVC microspheres and their leachates on the embryo development and larval growth of sea cucumbers follows a dose-dependent and time-dependent pattern. Nonetheless, the toxicity of PVC leachates surpasses that of the microspheres themselves. Abnormal developmental phenotypes, such as aberrant gastrulation, misaligned mesenchymal cells, and delayed arm development, were also observed in embryos and larvae treated with PVC. Further chemical analyses of PVC microspheres and leachates revealed the existence of five distinct phthalate esters (PAEs), with DIBP (diisobutyl phthalate) and DBP (dibutyl phthalate) exhibiting higher concentrations in the PVC leachates. This finding suggests that the elevated toxicity of plastic leachate may be attributed to the leaching of phthalate additives from the plastic particles.

Functional Trait-Based Evidence of Microplastic Effects on Aquatic Species

Microplastics represent an ever-increasing threat to aquatic organisms. We merged data from two global scale meta-analyses investigating the effect of microplastics on benthic organisms' and fishes' functional traits. Results were compared, allowing differences related to vertebrate and invertebrate habitat, life stage, trophic level, and experimental design to be explored. Functional traits of aquatic organisms were negatively affected. Metabolism, growth, and reproduction of benthic organisms were impacted, and fish behaviour was significantly affected. Responses differed by trophic level, suggesting negative effects on trophic interactions and energy transfer through the trophic web. The experimental design was found to have the most significant impact on results. As microplastics impact an organism's performance, this causes indirect repercussions further up the ecological hierarchy on the ecosystem's stability and functioning, and its associated goods and services are at risk. Standardized methods to generate salient targets and indicators are urgently needed to better inform policy makers and guide mitigation plans.

A protocol for lixiviation of micronized plastics for aquatic toxicity testing

Plastics contain various types and amounts of additives that can leach into the water column when entering aquatic ecosystems. Some leached plastic additives are hazardous to marine biota at environmentally relevant concentrations. Disparate methodological approaches have been adopted for toxicity testing of plastic leachates, making comparison difficult. Here we propose a protocol to standardize the methodology to obtain leachates from microplastics (MPs) for aquatic toxicity testing. Literature reviewing and toxicity tests using marine model organisms and different types of MPs were conducted to define the main methodological aspects of the protocol. Acute exposure to leachates from the studied plastics caused negative effects on the early life stages of sea urchins and marine bacteria. We provide recommendations of key factors influencing MPs lixiviation, such as MP size (<250 μm), solid-to-liquid ratio (1-10 g/L), mixing conditions (1-60 rpm), and lixiviation time (72 h). The proposed methodology was successful to determine the toxicity of leachates from different micronized plastics on marine biota. Our recommendations balance feasibility and environmental relevance, and their use would help ensure comparability amongst studies for a better assessment of the toxicity of plastic leachates on aquatic biota.

Toxicity of tyre wear particle leachates to marine phytoplankton

Tyre wear particles (TWP) are some of the dominant sources of microplastics in the aquatic environment. Once TWP enter aquatic systems, they can leach certain plastic additives that can be potentially toxic to biota. However, little is known about the impact of TWP lixiviates on marine phytoplankton, the base of marine food webs. This study aims to determine the acute toxic effect of leachates derived from TWP on three phytoplankton species: the cryptophyte Rhodomonas salina, the diatom Thalassiosira weissflogii and the dinoflagellate Heterocapsa steinii, using the median effect concentration (EC₅₀) for specific growth rate as endpoint. Leachates were obtained by incubating 1 g L^-1 of < 250 µm TWP in artificial seawater for 3 days. Each phytoplankton species was exposed to leachates at five different concentrations, and cell concentrations were measured every 24 h over 3 days. Leachates from TWP were toxic to marine phytoplankton. The dinoflagellate H. steinii was the most sensitive species, with 72-h EC₅₀ of 23% leachate concentration, whereas R. salina and T. weissflogii exhibited EC₅₀ values of 64% and 73%, respectively. Our results suggest that TWP leachates have a negative effect on phytoplankton growth, although more field data on the concentration of TWPs and their leachates is needed to fully evaluate the environmental impact of TWP.

Multi-endpoint effects of derelict tubular mussel plastic nets on Tigriopus fulvus

Microplastic debris from direct and indirect human activities is considered a major threat to the marine biodiversity mainly due to its abundance, durability, persistence, and ability to accumulate contaminants from the environment. Derelict tubular plastic nets of various colours (blue (BN), yellow (YN), green (GN), pink (PN), and white (WN) net), used to distinguish mussel farming owners, were collected by scuba-dive from the Mar Piccolo of Taranto (Ionian Sea). All nets were made of polypropylene. Investigations looked for potential acute (mortality) and sub-chronic (mortality, larval development and moult release number, and adult percentage after 5-9 days) effects on Tigriopus fulvus nauplii considering both whole plastics (microplastic (MP), 50 mg/L) and leachates (12.5-100%). Acute test determined a median lethal concentration (LC50) only for BN for both MPs (107 mg/L) and leachates (50.1%). The prolonged exposure (5 days) to microplastics did not affect the T. fulvus survival. After 9 days, YN and BN decreased of approximately 100% larval development.

Performance assessment of bubbles barriers for microplastic remediation

We report the results of experiments designed to evaluate the performance of a bubble barrier device for microplastics collection in natural and artificial streams. Bubble barrier is an innovative device based on the principle that pumping air to produce a vertical curtain of small air bubbles along the depth of a waterway creates a sufficient current to direct floating and non-floating particle towards a catchment device. The bubble barrier has been designed and already tested in rivers. Despite its use, there is a lack of information on the fluid mechanical functioning and performance, i.e., its ability to catch the largest number of microplastic particles. The aim of the present study is to test different bubble barriers configurations (length of the bubble generator, alignment with the main current) in different hydraulic conditions. We used a laboratory channel to produce a scaled river flow and we performed velocity measurements, and particle tracking visualization to understand how the bubble curtain could influence the water flow. The catchment performance of the different barriers has been tested using two types of particles, lighter and heavier than water. The results show that the system performance is strongly linked to a combination of the bubble generator configuration and the main properties of the flow. This study is the first attempt to provide scientific data on the bubble barrier and future design strategies depending on its application.

Mesocosm trials reveal the potential toxic risk of degrading bioplastics to marine life

If biodegradable plastics tackle the marine plastic pollution problem sufficiently remains questionable. To gain more insight in degradability, performance, and the impact of degradation on the toxicity, commercial bags made from two biodegradable plastics and one conventional plastic (PE) were exposed for 120 days in a mesocosm featuring benthic, pelagic, and littoral habitat simulations. Degradability was assessed as weight loss, and specimens were tested for toxicity using Paracentrotus lividus sea-urchin larvae after different exposure times. Both biodegradable bags showed degradation within 120 days, with the littoral simulation showing the highest and the pelagic simulation the lowest decay. Disregarding habitat, the home-compostable plastic showed higher marine degradation than the industrial-compostable material. The relevant initial toxicity of both biopolymers was lost within 7 days of exposure, pointing towards easily leachable chemical additives as its cause. Interestingly, littoral exposed specimens gained toxicity after 120 days, suggesting UV- induced modifications that increase biopolymer toxicity.

Acute toxicity of bioplastic leachates to Paracentrotus lividus sea urchin larvae

In an attempt to ensure that bioplastics, progressively replacing petrochemical-derived plastics, do not release any harmful compound to the environment, the study assessed the toxic effects of three innovative bioplastic products: polyhydroxybutyrate resin (PHB), polylactic acid cups (PLA) and a polylactic acid/polyhydroxyalkanoate 3D printing filament (PLA/PHA), together with a synthetic polyvinyl chloride (PVC) toy in Paracentrotus lividus sea urchin larvae. PVC toy was the most toxic material, likely due to the added plasticizers; remarkably, even if PHB is conceived as a nontoxic polymer, it showed a slight toxicity and Gas Chromatography-Mass Spectometry analysis (GC-MS) revealed the presence of a wide range of additives. Conversely, PLA cups and PLA/PHA filament were innocuous for the larvae, a positive outcome for these renewable solutions. Proven that additives are also used in some bioplastic formulations, they should be carefully addressed to ensure that they are as safe as regarded.

Physical and chemical threats posed by micro(nano)plastic to sea urchins

The awareness of the plastic issue is rising in recent years. Our seas and coastal seawaters are investigated with the aim to evaluate the possible fate, behavior and the impact of these novel contaminants upon marine biota. In particular, benthic organisms are exposed to micro(nano)plastics that sink and accumulated on the seabed. Sea urchins can be prone to the plastic impact for all their lifespan with effect that can be extended upon the trophic cascade since their key role as grazer organisms. Moreover, they are largely used in the assessment of contaminant impact both as adult individuals and as early larval stages. This review analyzes the recent literature about the chemical and physical hazards posed by diverse polymers to sea urchins, in relation to their peculiar characteristics and to their size. The search was based on a query of the keyword terms: microplastic _ OR nanoplastic_AND Sea urchins in Web of Science and Google Scholar. The effects provoked by exposure of different sea urchin biological form are highlighted, considering both laboratory exposure and collection in real world. Additional focus has also been given upon the exposure methods utilized in laboratory test and in the existing limitations in the testing procedures. In conclusion, the micro(nano)plastics major impact seemed to be attributable to leaching compounds, however variability and lacking of realisms in the procedures do not allow a full understanding of the hazard posed by micro(nano)plastics for sea urchins. Finally, the work provides insights into the future research strategies to better characterize the actual risk for sea urchins.

Seeking for a perfect (non-spherical) microplastic particle - The most comprehensive review on microplastic laboratory research

In recent decades, much attention has been paid to microplastic pollution, and research on microplastics has begun to grow exponentially. However, microplastics research still suffers from the lack of standardized protocols and methods for investigation of microplastics under laboratory conditions. Therefore, in this review, we summarize and critically discuss the results of 715 laboratory studies published on microplastics in the last five years to provide recommendations for future laboratory research. Analysis of the data revealed that the majority of microplastic particles used in laboratory studies are manufactured spheres of polystyrene ranging in size from 1 to 50 µm, that half of the studies did not characterize the particles used, and that a minority of studies used aged particles, investigated leaching of chemicals from microplastics, or used natural particles as a control. There is a large discrepancy between microplastics used in laboratory research and those found in the environment, and many laboratory studies suffer from a lack of environmental relevance and provide incomplete information on the microplastics used. We have summarized and discussed these issues and provided recommendations for future laboratory research on microplastics focusing on (i) microplastic selection, (ii) microplastic characterization, and (iii) test design of laboratory research on microplastics.

Ecotoxicological Evaluation of Sunscreens on Marine Plankton

In recent years, a large number of sunscreens have emerged to protect our skin. Most of them are made up of simple or compound aromatic structures, which can pose a threat to marine ecosystems. In order to understand their effects on the marine environment, different ecotoxicological bioassays were carried out using planktonic organisms from three phyla and two different trophic levels: larvae of the sea urchin Paracentrotus lividus, the copepod Acartia tonsa, and the microalga Tisochrysis lutea. The aim of these tests was to expose these organisms to leachates from eight sunscreen formulations. All of them showed a great variability in toxicity on the different plankton organisms. The highest toxicity level was found for cream number 4 when tested on sea urchin, exhibiting an EC50 = 122.4 mg/L. The toxicity of the UV filter 2-phenyl-5-benzimidazolesulfonic acid, exclusively present in that cream, was evaluated in sea urchin, where an EC10 = 699.6 mg/L was obtained under light exposure. According to our results, all tested creams become nontoxic to plankton upon 30,000-fold dilution in seawater; thus, only local effects are expected. This study highlights the need to understand the toxic effects generated by solar protection products, as well as their ingredients, on marine organisms.

Integrated toxicokinetic/toxicodynamic assessment modeling reveals at-risk scleractinian corals under extensive microplastics impacts

Marine microplastics (MPs)-induced threats to shallow-water scleractinian corals are a growing global concern that needs interdisciplinary studies. However, it remains uncertain to what extent the ecotoxicological effects of MPs can explain the potential health impacts on corals at the species-specific scale. Using recent datasets of multiple MPs-induced impacts on coral species, we developed an integrated ecotoxicological modeling approach to quantify the MPs-corals interaction dynamics. Toxicokinetic (TK)-based corals ingestion, egestion, and adhesion processes posed by MPs were comprehensively evaluated. Based on estimated uptake and egestion rates, we showed that corals were much likely to bioaccumulate marine MPs. We applied toxicodynamic (TD) models to appraise time- and concentration-dependent response patterns across MPs-corals systems. We found that marine MPs are highly toxic to corals with a median benchmark concentration causing 10% compromised coral health of 20-40 mg L^-1 and a mean growth inhibition rate of ~2% d^-1. By providing these key quantitative metrics that may inform scientists to refine existing management strategies to better understand the long-term impact of MPs on coral reef ecosystems. Our TK/TD modeling scheme can help integrating current toxicological findings to encompass a more mechanistic-, ecological-, and process-based understanding of diverse coral ecosystems that are sensitive to MPs stressor varied considerably by species and taxonomic group.

Four plastic additives reduce larval growth and survival in the sea urchin Strongylocentrotus purpuratus

Plastic additives are utilized during the production of plastic to modify the attributes and stability of the polymer. As oceanic plastic waste degrades, these additives can leach, and are harmful to global marine ecosystems. Despite the high abundance of additives leached into the marine environment, little is known about their direct impact on marine zooplankton. Here we test for impacts of four plastic additives, UV-327, Irganox 1010, DEHP, and methylparaben, all commonly used in plastic manufacturing, on purple sea urchin (Strongylocentrotus purpuratus) larval growth and survival in a serial dose response for 4 days. Methylparaben, UV-327, and Irganox 1010 significantly reduced larval body length by about 5% for at least one dose. In contrast, all compounds reduced larval survival by 20-70% with strongest effects at intermediate rather than high doses. Our results highlight that plastic additives should be tested for their effects on marine organisms.

Assessment of Toxicity and Biodegradability of Poly(vinyl alcohol)-Based Materials in Marine Water

Due to the continuous rise in conventional plastic production and the deficient management of plastic waste, industry is developing alternative plastic products made of biodegradable or biobased polymers. The challenge nowadays is to create a new product that combines the advantages of conventional plastics with environmentally friendly properties. This study focuses on the assessment of the potential impact that polyvinyl alcohol (PVA)-based polymers may have once they are released into the marine environment, in terms of biodegradation in seawater (assessed by the percentage of the Theoretical Oxygen Demand, or % ThOD, of each compound) and aquatic toxicity, according to the standard toxicity test using Paracentrotus lividus larvae. We have tested three different materials: two glycerol-containing PVA based ones, and another made from pure PVA. Biodegradation of PVA under marine conditions without an acclimated inoculum seems to be negligible, and it slightly improves when the polymer is combined with glycerol, with a 5.3 and 8.4% ThOD achieved after a period of 28 days. Toxicity of pure PVA was also negligible (<1 toxic units, TU), but slightly increases when the material included glycerol (2.2 and 2.3 TU). These results may contribute to a better assessment of the behavior of PVA-based polymers in marine environments. Given the low biodegradation rates obtained for the tested compounds, PVA polymers still require further study in order to develop materials that are truly degradable in real marine scenarios.

Towards standard methods for the classification of aquatic toxicity for biologically active household chemicals (BAHC) present in plastics, pharmaceuticals, and cosmetic products

A standard method to test the aquatic toxicity of biologically active household chemicals (BAHC), including those with very low water solubility, is proposed. The method uses the common marine models Paracentrotus lividus embryos and Acartia clausi larvae, in order to advance towards derivation of water quality criteria for these emerging pollutants that currently lack environmental standards. Depending on the water solubility and octanol-water partition coefficient (K_ow) of the substance, the protocol consists of testing the toxicity of the substances by serial dilutions of water stocks, dimethyl-sulfoxide stocks, or 100 mg/L lixiviates in seawater. When this method is applied to eleven model BAHC, the pharmaceutical fluoxetine, the antioxidant butylated hydroxytoluene, and the UV filters broadly present in cosmetics octocrylene and 4-methylbenzylidene camphor, are classified as very toxic to aquatic life, since their EC₅₀ values are < 1 mg/L. In general, both biological models, P. lividus and A. clausi, yield the same classification of the substances tested, but variations in the classification of aquatic toxicity depending on methodological aspects are discussed. The use of A. clausi nauplii provides more protecting value to the toxicity parameters obtained by using this protocol.

Glutathione S-Transferases in Marine Copepods

The glutathione S-transferase (GST) is a complex family of phase II detoxification enzymes, known for their ability to catalyze the conjugation of the reduced form of glutathione (GSH) to a wide variety of endogenous and exogenous electrophilic compounds for detoxification purposes. In marine environments, copepods are constantly exposed to multiple exogenous stressors, thus their capability of detoxification is key for survival. Full identification of the GST family in copepods has been limited only to few species. As for insects, the GST family includes a wide range of genes that, based on their cellular localization, can be divided in three classes: cytosolic, microsomal, and mitochondrial. The role of GSTs might have class-specific features, thus understanding the nature of the GST family has become crucial. This paper covers information of the GST activity in marine copepods based on studies investigating gene expression, protein content, and enzymatic activity. Using published literature and mining new publicly available transcriptomes, we characterized the multiplicity of the GST family in copepods from different orders and families, highlighting the possible role of these genes as biomarker for ocean health status monitoring.

Microplastics and plankton: Knowledge from laboratory and field studies to distinguish contamination from pollution

Due to their ubiquitous presence, size and characteristics as ability to adsorb pollutants, microplastics are hypothesized as causing a major impact on smaller organisms, such as plankton. Despite this, there is a need to determine whether these impacts just relate to the environmental presence of the materials or their effects on biological processes. Therefore, we aimed to 1) review current research on plankton and microplastics; 2) compare field and laboratory experimental findings, and 3) identify knowledge gaps. The systematic review showed that 70% of the 147 relevant scientific publications were from laboratory studies and microplastics interactions with plankton were recorded in 88 taxa. Field study publications were relatively scarce and the characteristics of microplastics collected in the field were very different from those used in laboratory experiments thereby limiting the comparison between studies. Our systematic review highlighted knowledge gaps in: 1) the number of field studies; 2) the non-comparability between laboratory and field conditions, and 3) the low diversity of plankton species studied. Furthermore, this review indicated that while there are many studies on contamination by microplastics, the effects of this contamination (i.e., pollution per se) have been less well-studied, especially in the field at population, community, and ecosystem levels.

Plastic additives: challenges in ecotox hazard assessment

The risk of plastic debris, and specifically micro(nano)plastic particles, to ecosystems remains to be fully characterized. One particular issue that warrants further characterization is the hazards associated with chemical additives within micro(nano)plastic as they are not chemically bound within the polymers and can be persistent and biologically active. Most plastics contain additives and are therefore potential vectors for the introduction of these chemicals into the environment as they leach from plastic, a process that can be accelerated through degradation and weathering processes. There are knowledge gaps on the ecotoxicological effects of plastic additives and how they are released from parent plastic materials as they progressively fragment from the meso to micro and nano scale. This review summarizes the current state of knowledge of the ecotoxicity of plastic additives and identifies research needs to characterize the hazard they present to exposed biota. The potential ecological risk of chemical additives is of international concern so key differences in governance between the European Union and New Zealand to appropriately characterize their risk are highlighted.

Aquatic toxicity of chemically defined microplastics can be explained by functional additives

A novel, systematic approach to relate plastic toxicity with chemical composition is undertaken. Using industrial methods, three petroleum-based polymers, low-density polyethylene (PE), polyvinyl chloride (PVC), and polyamide (PA), and the biopolymer polyhydroxybutyrate (PHB) were manufactured in different formularies including conventional and alternative additives, and microplastics of two sizes (<250 and <20 µm) were obtained with the aim to relate their composition with environmental impact in aquatic environments. Internationally accepted standard tests of regulatory use with marine organisms representative of microalgae (Tisochrysis lutea population growth), crustaceans (Acartia clausi larval survival), and echinoderms (Paracentrotus lividus sea-urchin embryo test) support the following conclusions. Aquatic toxicity of microplastics made from conventional oil-based polymers is due to leaching of chemical additives, and not to ingestion of microplastics. Use of alternative formulations based on natural rather than synthetic chemical additives did not consistently reduce aquatic toxicity except for the replacement of triclosan by the alternative biocide lawsone. In contrast, the biopolymer tested, PHB, seemed to impact marine plankton through different mechanisms associated to the higher abundance of plastic particles within the nanometric range found in this resin and absent in other materials.

Chemicals sorbed to environmental microplastics are toxic to early life stages of aquatic organisms

Microplastics are ubiquitous in aquatic ecosystems, but little information is currently available on the dangers and risks to living organisms. In order to assess the ecotoxicity of environmental microplastics (MPs), samples were collected from the beaches of two islands in the Guadeloupe archipelago, Petit-Bourg (PB) located on the main island of Guadeloupe and Marie-Galante (MG) on the second island of the archipelago. These samples have a similar polymer composition with mainly polyethylene (PE) and polypropylene (PP). However, these two samples are very dissimilar with regard to their contamination profile and their toxicity. MPs from MG contain more lead, cadmium and organochlorine compounds while those from PB have higher levels of copper, zinc and hydrocarbons. The leachates of these two samples of MPs induced sublethal effects on the growth of sea urchins and on the pulsation frequency of jellyfish ephyrae but not on the development of zebrafish embryos. The toxic effects are much more marked for samples from the PB site than those from the MG site. This work demonstrates that MPs can contain high levels of potentially bioavailable toxic substances that may represent a significant ecotoxicological risk, particularly for the early life stages of aquatic animals.

Assessment of the relative sensitivity of the copepods Acartia tonsa and Acartia clausi exposed to sediment-derived elutriates from the Bagnoli-Coroglio industrial area

The sensitivity of the copepods Acartia tonsa, commonly used in standardized tests for environmental risk assessment and A. clausi, the dominant autochthonous congener species in the Mediterranean Sea, was assessed using sediment-derived elutriates from the industrial area of Bagnoli-Coroglio and nickel chloride as referent toxicant. Acute A. clausi naupliar immobilization test showed EC₅₀ for elutriates E25, E56 and E84 of 23.3%, 80.5% and >100%, respectively, compared to 59.5%, 66.6% and >100% in A. tonsa. In the 7 day sublethal test, a reduction in A. clausi egg production rates was observed in all elutriates, but only in E56 for A. tonsa. Elutriate 56, which contained the highest amount of polycyclic aromatic hydrocarbons, also induced 70% mortality in A. clausi females. Although A. clausi was more sensitive than A. tonsa, the two species had convergent responses to the three elutriates, thus opening the venue for a potential use of A. clausi in standardized ecotoxicity tests.