Uptake, Whole-Body Distribution, and Depuration of Nanoplastics by the Scallop Pecten maximus at Environmentally Realistic Concentrations

Abstract

Previous studies of uptake and effects of nanoplastics by marine organisms have been conducted at what may be unrealistically high concentrations. This is a consequence of the analytical challenges in tracking plastic particles in organisms at environmentally relevant concentrations and highlights the need for new approaches. Here, we present pulse exposures of 14C-radiolabeled nanopolystyrene to a commercially important mollusk, Pecten maximus, at what have been predicted to be environmentally relevant concentrations (<15 μg L–1). Uptake was rapid and was greater for 24 nm than for 250 nm particles. After 6 h, autoradiography showed accumulation of 250 nm nanoplastics in the intestine, while 24 nm particles were dispersed throughout the whole-body, possibly indicating some translocation across epithelial membranes. However, depuration was also relatively rapid for both sizes; 24 nm particles were no longer detectable after 14 days, although some 250 nm particles were still detectable after 48 days. Particle size thus apparently influenced the biokinetics and suggests a need for chronic exposure studies. Modeling extrapolations indicated that it could take 300 days of continued environmental exposure for uptake to reach equilibrium in scallop body tissues although the concentrations would still below 2.7 mg g–1. Comparison with previous work in which scallops were exposed to nonplastic (silver) nanomaterials of similar size (20 nm), suggests that nanoparticle composition may also influence the uptake tissue distributions somewhat.

Toward an Improved Understanding of the Ingestion and Trophic Transfer of Microplastic Particles: Critical Review and Implications for Future Research

“…Nevertheless, several laboratory‐based studies have reported translocation of microplastic particles, mostly nanosized plastic, from the gastrointestinal tract into other tissues (Browne et al 2008; Rosenkranz et al 2009; von Moos et al 2012; Farrell and Nelson 2013; Avio et al 2015; Brennecke et al 2015; Mattsson et al 2017; Skjolding et al 2017; Al‐Sid‐Cheikh et al 2018; Chae et al 2018; Ding et al 2018; Pitt et al 2018; Triebskorn et al 2019), implying that when exposure to microplastic particles of a particular size is elevated, translocation from the gastrointestinal tract to internal organs is possible. In some studies, particles coated with a fluorescence dye were used to visually observe the behavior of particles, such as in an early study by Rosenkranz et al (2009).…”

“…Given the research that has been conducted into the bioaccumulation of ENMs, considerable knowledge may already be accessible, and it is recommended that opportunities to build on currently available information should be optimized (Hüffer et al 2017). For instance, 14 C‐labeled polystyrene nanoplastic has recently been employed to study the uptake and depuration of nanosized particles at environmentally relevant concentrations (Al‐Sid‐Cheikh et al 2018). Al‐Sid‐Cheikh et al (2018) observed relatively rapid depuration of the particles, but proposed further research using 14 C‐labeled particles aimed at better characterizing and quantifying the mechanisms of uptake, absorption, and elimination of particles in chronic exposures, which may help us to better understand the fate of biologically ingested particles.…”

“…This understanding is consistent with results reported in various laboratory‐based studies, which have often found efficient egestion of microplastic particles (Graham and Thompson 2009; Cole et al 2013; Ugolini et al 2013; Chua et al 2014; Kaposi et al 2014; Hu et al 2016; Ogonowski et al 2016; Grigorakis et al 2017; Dawson et al 2018; Ory et al 2018b; Woods et al 2018; Fernandez and Albentosa 2019; Song et al 2019). Efforts directed toward further characterization of gastrointestinal tract residence times would thus help to illuminate an important parameter in developing mass balance models aimed at assessing ingestion and trophic transfer and would further increase our understanding of the potential of the particles to bioaccumulate (Al‐Sid‐Cheikh et al 2018; Diepens and Koelmans 2018). For instance, the rate of uptake across the epithelium tissues of the gastrointestinal tract would need to be considered in relation to the relative concentrations of particles in the gastrointestinal tract and their residence time.…”

“…Caution has been suggested, however, regarding the potential for translocation of microplastic particles based on observations utilizing fluorescence, because the results may be characteristic of a study artifact (i.e., lipid accumulation of the leached fraction of hydrophobic fluorescent dye), as opposed to actual particle translocation (Schur et al 2019). Consequently, quantifying and characterizing the bioaccumulation potential of microplastic particles within the tissues of organisms would benefit from the adoption of a mass balance approach, aimed at assessing adsorption, distribution, metabolism, and excretion (Gobas and Morrison 2000; Al‐Sid‐Cheikh et al 2018; Diepens and Koelmans 2018; Petersen et al 2019).…”

Biofilm formation by marine bacteria is impacted by concentration and surface functionalization of polystyrene nanoparticles in a species‐specific manner

“…The majority of studies that do exist, focus on macroorganisms such as mussels ( Mytilus edulis ) and oysters ( Crassostrea virginica ), which have been shown to take up 100 nm polystyrene beads (Ward and Kach, ). Recently, the commercially important mollusc Pecten maximus was shown to uptake polystyrene nanoparticles at environmental concentrations of less than 0.015 ppm (Al‐Sid‐Cheikh et al ., ).…”