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

Abstract

A 2‐tier standardized protocol was designed to test the toxicity of microplastics to planktonic organisms. This approach uses sea urchin (Paracentrotus lividus) and copepod (Acartia clausi) larvae because they are common biological models in marine research, and standard methods for toxicity testing with regulatory applications are available. In Tier I, leachates obtained at a 100 to 1 liquid to solid ratio are tested, and toxic units are calculated using a probit dose–response model to quantify the toxicity of the plastics. In Tier II, which is conducted only if significant toxicity (> 1 toxic unit) is found in Tier I, particles less than 20 μm in size are tested at concentrations between 0.1 and 10 mg L−1, and a toxicity threshold suitable for ranking materials according to their toxicity is obtained from the 10% effect concentration (EC10) values. Results point to chemical additives as being responsible for the toxicity found in certain plastic materials. This process is suitable for both a priori identification of the hazard posed by plastic objects in the aquatic environment, and a posteriori assessment of environmental risk caused by microplastic pollution. The method also provides a quantitative procedure appropriate for ranking plastic materials according to their toxicity to aquatic organisms. Environ Toxicol Chem 2019;38:630–637. © 2018 SETAC

Plastic additives: challenges in ecotox hazard assessment

“…For example, the presence of biocidal additives in MNPs may prevent microorganisms from utilizing other chemical additives as a source of energy and thus preventing degradation, resulting in organisms being exposed to unusually high concentrations of residues than would otherwise be the case (Hansen, Nilsson & Slot Ravnholt Vium, 2014). The assessment of additive toxicity vs MNP toxicity is an emerging research topic with increasing interest but little standardization, presenting a significant barrier to establishing concise conclusions on the potential hazards they present in the environment (Beiras, Tato & López-Ibáñez, 2019;Luo et al, 2019aLuo et al, , 2019bOliviero et al, 2019;Capolupo et al, 2020). This issue is exacerbated by the fact that degradation of plastic through weathering and ageing makes ecotoxicity assessment challenging as the number of potentially leachable chemical additives and polymer degradation products can be likened to a veritable cocktail of chemical toxicants and stressors (Hansen et al, 2013;Fred-Ahmadu et al, 2020).…”

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

“…Endpoints recorded after 48 h were, for sea urchins, length (maximum dimension) in 35 individuals per vial using a Leica DMI 4000B inverted microscope, and for copepods nauplius larvae survival. Further details on the bioassay methods were provided by Tato et al ( 2018 ) and Beiras et al ( 2019 ). All experiments were conducted in isothermal rooms at 20 ± 0.5 °C.…”

“…For chemicals with a S w < 1 mg/L, in addition to the DMSO test, a leachate test was conducted. With that aim, a leachate was obtained using ASW as liquid phase, and serial dilutions were further tested according to the procedures of Tier I in Beiras et al ( 2019 ). The lixiviate was separated from the insoluble chemical by filtering with GF/F (Whatman, Merck, nominal pore 0.7 µm) filters for solid substances and by centrifugation at 2000 rpm for 5 min for liquid substances.…”

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

“…Marine aquatic toxicity of PVA leachates was tested using the Paracentrotus lividus sea-urchin embryo test (SET) according to [41]. The leachates were obtained in artificial seawater [42] at 10 g/L and tested using geometrical serial dilutions (×1, ×1/3, ×1/10.…”