Ecotoxicological Effects of Chemical Contaminants Adsorbed to Microplastics in the Clam Scrobicularia plana

Although microplastics (MPs) are distributed globally in the marine environment, a great deal of unknowns relating to their ecotoxicological effects on the marine biota remains. Due to their lipophilic nature, microplastics have the potential to adsorb persistent organic pollutants present in contaminated regions, which may increase their detrimental impact once assimilated by organisms. This study investigates the ecotoxicological effects of exposure to low-density polyethylene (LDPE) microplastics (11–13 μm), with and without adsorbed contaminants (benzo[a]pyrene—BaP and perfluorooctane sulfonic acid—PFOS), in the peppery furrow shell clam, Scrobicularia plana. Environmentally relevant concentrations of contaminants (BaP−16.87 ± 0.22 μg g−1 and PFOS−70.22 ± 12.41 μg g−1) were adsorbed to microplastics to evaluate the potential role of plastic particles as a source of chemical contamination once ingested. S. plana were exposed to microplastics, at a concentration of 1 mg L−1, in a water-sediment exposure setup for 14 days. Clams were sampled at the beginning of the experiment (day 0) and after 3, 7, and 14 days. BaP accumulation, in whole clam tissues, was analyzed. A multi-biomarker assessment was conducted in the gills, digestive gland, and haemolymph of clams to clarify the effects of exposure. This included the quantification of antioxidant (superoxide dismutase, catalase, glutathione peroxidase) and biotransformation (glutathione-S-transferases) enzyme activities, oxidative damage (lipid peroxidation levels), genotoxicity (single and double strand DNA breaks), and neurotoxicity (acetylcholinesterase activity). Results suggest a potential mechanical injury of gills caused by ingestion of microplastics that may also affect the analyzed biomarkers. The digestive gland seems less affected by mechanical damage caused by virgin microplastic exposure, with the MPs-adsorbed BaP and PFOS exerting a negative influence over the assessed biomarkers in this tissue.

Sarit O’Donovan, Nélia C. Mestre, Serena Abel, Tainá G. Fonseca, Camilla C. Carteny, Bettie Cormier, Steffen H. Keiter and Maria J. Bebianno, Front. Mar. Sci., 26 April 2018

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Microplastics as Vehicles of Environmental PAHs to Marine Organisms: Combined Chemical and Physical Hazards to the Mediterranean Mussels, Mytilus galloprovincialis

The ubiquitous occurrence of microplastics (MPs) in the marine environment is raising concern for interactions with marine organisms. These particles efficiently adsorb persistent organic pollutants from surrounding environment and, due to the small size, they are easily available for ingestion at all trophic levels. Once ingested, MPs can induce mechanical damage, sub-lethal effects, and various cellular responses, further modulated by possible release of adsorbed chemicals or additives. In this study, ecotoxicological effects of MPs and their interactions with benzo(a)pyrene (BaP), chosen as a model compound for polycyclic aromatic hydrocarbons (PAHs) were investigated in Mediterranean mussels, Mytilus galloprovincialis. Organisms were exposed for 4 weeks to 10 mg/L of low-density polyethylene (LDPE) microparticles (2.34 * 107 particles/L, size range 20–25 μm), both virgin and pre-contaminated with BaP (15 μg/g). Organisms were also exposed for comparison to BaP dosed alone at 150 ng/L, corresponding to the amount adsorbed on microplastics. Tissue localization of microplastics was histologically evaluated; chemical analyses and a wide battery of biomarkers covering molecular, biochemical and cellular levels allowed to evaluate BaP bioaccumulation, alterations of immune system, antioxidant defenses, onset of oxidative stress, peroxisomal proliferation, genotoxicity, and neurotoxicity. Obtained data were elaborated within a quantitative weight of evidence (WOE) model which, using weighted criteria, provided synthetic hazard indices, for both chemical and cellular results, before their integration in a combined index. Microplastics were localized in hemolymph, gills, and especially digestive tissues where a potential transfer of BaP from MPs was also observed. Significant alterations were measured on the immune system, while more limited effects occurred on the oxidative status, neurotoxicity, and genotoxicity, with a different susceptibility of analyzed pathways, depending on tissue, time, and typology of exposure. Molecular analyses confirmed the general lack of significant transcriptional variations of antioxidant and stress genes. The overall results suggest that microplastics induce a slight cellular toxicity under short-term (28 days) exposure conditions. However, modulation of immune responses, along with bioaccumulation of BaP, pose the still unexplored risk that these particles, under conditions of more chronic exposure (months to years) or interacting with other stressors, may provoke long-term, subtle effects on organisms’ health status.

Lucia Pittura, Carlo G. Avio, Maria E. Giuliani, Giuseppe d’Errico, Steffen H. Keiter, Bettie Cormier, Stefania Gorbi and Francesco Regoli, Front. Mar. Sci., 03 April 2018

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EU proposes ban on 90% of microplastic pollutants

European Chemicals Agency draft law aims to cut 400,000 tonnes of plastic pollution

A wide-ranging ban on microplastics covering about 90% of pollutants has been proposed by the EU in an attempt to cut 400,000 tonnes of plastic pollution in 20 years.

Every year, Europe releases a bulk amount of microplastics six times bigger than the “Great Pacific garbage patch” into the environment – the equivalent of 10bn plastic bottles. The phasing out proposed by the European Chemicals Agency (Echa) would remove 36,000 tonnes a year of “intentionally added” microplastic fibres and fragments, starting in 2020. Cosmetics, detergents, paints, polish and coatings would all require design overhauls, as would products in the construction, agriculture and fossil fuels sectors. The draft law targets microplastics that are not necessary but have been added to products by manufacturers for convenience or profit.

The Guardian, 30/01/2019

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Fishing lines and fish hooks as neglected marine litter: first data on chemical composition, densities, and biological entrapment from a Mediterranean beach

We reported first data on the densities and chemical composition of fishing lines and fish hooks deposited on a Mediterranean beach. On a sampling area of 1.5 ha, we removed a total of 185,028 cm of fishing lines (density 12.34 cm/m2) and 33 hooks (density 22 units/ha). Totally, 637.62 g (42.5 mg/m2) of fishing lines were collected. We sampled 120 items entangled belongings to 7 animal taxa (density 6.49 items/100 m of fishing lines). We also observed a not quantifiable number of egagropiles (Posidonia oceanica spheroids), Rhodophyceae (Halymenia sp.) and segments of reeds of Phragmites communis, trapped in the fishing lines. Fourier transform infrared (FTIR) spectroscopy was used in order to identify the chemical composition of the fishing lines: 92% was made of nylon while 8.0% was determined as fluorocarbon based polymers (polyvinylidene fluoride). Because of their subtlety and reduced size, sandy beach cleaning operations should include at least two consecutive removal samplings: indeed, a part of this litter (12.14%) is not removed in the first sampling. The unexpected high density of fishing lines suggests specific management actions aimed to periodically remove this neglected anthropogenic litter.

Corrado Battisti, Silvio Kroha, Elina Kozhuharova, Silvia De Michelis, Giuliano Fanelli, Gianluca Poeta, Loris Pietrelli, Fulvio Cerfolli, Environmental Science and Pollution Research, , Volume 26, Issue 1, pp 1000–1007

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Desorption of Hydrophobic Organic Chemicals from Fragment-Type Microplastics

Microplastics provide an important medium for hydrophobic organic chemicals (HOCs), and the desorption of HOCs from microplastics is an important process for the dynamics of HOCs associated with microplastics. Although desorption kinetics has been studied for microplastics with ideal geometries, most of the microplastics isolated from the environment are irregular fragment-type microplastics. This study investigated the desorption of six model HOCs from polyethylene (PE) and polypropylene (PP) fragments to artificial seawater and compared the results with those predicted assuming ideal geometries (e.g., sphere and infinitely flat sheet) of microplastics. The experimental desorption was explained well by the model predictions with the characteristic radius for a sphere and the thickness for a plate estimated from visual imaging. The mass fraction remaining at the later stage of desorption was higher than the model simulation assuming a single characteristic length, likely due to the heterogeneity of the particle size distribution. Although there are inevitable uncertainties, it would be useful to assign a single length dimension in desorption modeling for even fragment-type microplastics, especially for the estimation of desorption half-life.

Hwang Lee, Da-Eun Byun, Ju Min Kim, Jung-Hwan Kwon, Ocean Science Journal, , Volume 53, Issue 4, pp 631–639

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Methods for sampling and detection of microplastics in water and sediment: A critical review

Microplastics are widespread contaminants, virtually present in all environmental compartments. However, knowledge on sources, fate and environmental concentration over time and space still is limited due to the laborious and varied analytical procedures currently used. In this work we critically review the methods currently used for sampling and detection of microplastics, identifying flaws in study design and suggesting promising alternatives. This work provides insights on bulk sample collection, separation, digestion, identification and quantification, and mitigation of cross-contamination. The sampling of microplastics will improve in representativeness and reproducibility through the determination of bulk sample volume, filter’s pore size, density separation and digestion solutions, but also through use of novel methods, such as the enhancement of visual identification by staining dyes, and the generalized use of chemical characterization.

J. Correia Prata, J. P. da Costa, A. C. Duarte and al., TrAC Trends in Analytical Chemistry, Volume 110, January 2019, Pages 150-159

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Targeted quantification and untargeted screening of alkylphenols, bisphenol A and phthalates in aquatic matrices using ultra-high-performance liquid chromatography coupled to hybrid Q-Orbitrap mass spectrometry

Plasticizers and other plastics additives have been extensively used as ingredients of plastics and are as a result thereof easily released in the aquatic environment, due to different physical diffusion processes. In this context, a dedicated method was developed for the simultaneous quantification of 27 known and a virtually unlimited number of unknown alkylphenols, Bisphenol A and phthalates in 2 aquatic matrices, i.e. sea- and freshwater. To this extent, a novel instrumental HESI-UHPLC-HRMS (heated electro-spray ionization ultra-high performance liquid chromatographic high resolution mass spectrometric) method was devised for the simultaneous analysis of 7 phenols (i.e. 6 alkylphenols and Bisphenol A) and 20 phthalates within 10 min. Thereafter, a solid-phase extraction protocol was statistically (95% confidence interval, p > 0.05) optimized based on experimental designs. The method was proven fit-for-purpose through a successful validation at environmentally relevant nanomolar concentrations. Analytical precautions were taken for minimizing false-positive results to suppress in-house contamination. The method demonstrated an excellent analytical performance across all known plasticizers and plastics additives for sea- and freshwater, revealing good linearity (R2 > 0.99, n = 39), stable recoveries (98.5–105.8%), satisfactory repeatability (RSD < 8%, n = 54) and reproducibility (RSD < 10%, n = 36). Subsequently, a novel analytical strategy was devised for the tentative identification of unknown plasticizers and plastics additives using specific in-house determined fragments incorporated in a Python code. The applicability of the analytical platform was demonstrated by measuring 24 seawater samples. Interestingly, 16 out of 27 known plasticizers, plastics additives and primary metabolites could be quantified while the untargeted analysis uncovered 1042 compounds, whereof 5% (n = 46) could be assigned a plasticizer-plastics additive chemical identity, providing evidence for the severe plastic contamination status of our marine environment.

S. Huysman, L. Van Meulebroek, O. Janssens and al., Analytica Chimica Acta, Volume 1049, 21 February 2019, Pages 141-151

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