Screening of the Toxicity of Polystyrene Nano- and Microplastics Alone and in Combination with Benzo(a)pyrene in Brine Shrimp Larvae and Zebrafish Embryos.

Amaia Orbea,Miren P Cajaraville,Marie-Hélène Devier,Karyn Le Menach,Ignacio Martínez-Álvarez,Hélène Budzinski

doi:10.3390/nano12060941

Abstract

The occurrence of nanoplastics (NPs) and microplastics (MPs) in aquatic ecosystems and their capacity to sorb hydrophobic pollutants is nowadays an issue of great concern. This study aimed to assess the potential bioavailability and acute toxicity of polystyrene (PS) NPs (50 and 500 nm) and of MPs (4.5 µm), alone and with sorbed benzo(a)pyrene (B(a)P), in the embryo/larval stages of brine shrimps and zebrafish. Exposure to pristine plastics up to 50.1 mg PS/L did not cause significant impact on brine shrimp survival, while some treatments of plastics-B(a)P and all concentrations of B(a)P (0.1–10 mg/L) resulted acutely toxic. In zebrafish, only the highest concentrations of MPs-B(a)P and B(a)P caused a significant increase of malformation prevalence. Ingestion of NPs was observed by 24–48 h of exposure in the two organisms (from 0.069 to 6.87 mg PS/L). In brine shrimps, NPs were observed over the body surface and within the digestive tract, associated with feces. In zebrafish, NPs were localized in the eyes, yolk sac, and tail at 72 h, showing their capacity to translocate and spread into the embryo. MP ingestion was only demonstrated for brine shrimps. In zebrafish embryos exposed to plastics-B(a)P, B(a)P appeared in the yolk sac of the embryos. The presence of B(a)P was also noticeable in brine shrimps exposed to 500 nm NPs-B(a)P. In conclusion, NPs entered and spread into the zebrafish embryo and PS NPs, and MPs were successful vectors of B(a)P to brine shrimp and zebrafish embryos. Particle size played a significant role in explaining the toxicity of plastics–B(a)P. Our study provides support for the idea that plastics may pose a risk to aquatic organisms when combined with persistent organic pollutants such as B(a)P.

Highlights

Due to their durability and widespread use in populated areas, the presence of nano(NPs) and microplastics (MPs) in aquatic ecosystems is reported worldwide [1]
We aimed to assess the potential acute toxicity and bioavailability of PS NPs and MPs in brine shrimp larvae and zebrafish embryo development and whether these plastic particles can act as carriers of polycyclic aromatic hydrocarbons (PAHs)
LC50 value higher than the highest tested concentration (100 mg/L) [12]. For smaller plastics, such as functionalized PS NPs (40 nm PS-COOH and PS-NH2), toxicity tests were performed in A. franciscana larvae, and no effect was recorded on mortality, even for the highest exposure concentration (100 mg/L) [8]

Summary

Introduction

Due to their durability and widespread use in populated areas, the presence of nano(NPs) and microplastics (MPs) in aquatic ecosystems is reported worldwide [1]. The polymer types mostly present in aquatic ecosystems include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyurethane (PUR), and polyethylene terephthalate (PET). PS has an intermediate density (1.05 g/cm3 ) among the previously mentioned polymers and is close to water density (1–1.03 g/cm depending on salinity). This makes PS MPs behave differently in waters of different salinity and become bioavailable for aquatic organisms, from surface water to bottom waters or sediments [3].

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