Long Term Exposure to Virgin and Recycled LDPE Microplastics Induced Minor Effects in the Freshwater and Terrestrial Crustaceans Daphnia magna and Porcellio scaber.

Vambola Kisand,Damjana Drobne,Andraž Dolar,Jelizaveta Titova,Heiki Vija,Meeri Visnapuu,Margit Heinlaan,Luka Škrlep,Anita Jemec Kokalj

doi:10.3390/polym13050771

Abstract

The effects of microplastics (MP) are extensively studied, yet hazard data from long-term exposure studies are scarce. Moreover, for sustainable circular use in the future, knowledge on the biological impact of recycled plastics is essential. The aim of this study was to provide long-term toxicity data of virgin vs recycled (mechanical recycling) low density polyethylene (LDPE) for two commonly used ecotoxicity models, the freshwater crustacean Daphnia magna and the terrestrial crustacean Porcellio scaber. LDPE MP was tested as fragments of 39.8 ± 8.82 µm (virgin) and 205 ± 144 µm (recycled) at chronic exposure levels of 1–100 mg LDPE/L (D. magna) and 0.2–15 g LDPE/kg soil (P. scaber). Mortality, reproduction, body length, total lipid content, feeding and immune response were evaluated. With the exception of very low inconsistent offspring mortality at 10 mg/L and 100 mg/L of recycled LDPE, no MP exposure-related adverse effects were recorded for D. magna. For P. scaber, increased feeding on non-contaminated leaves was observed for virgin LDPE at 5 g/kg and 15 g/kg. In addition, both LDPE induced a slight immune response at 5 g/kg and 15 g/kg with more parameters altered for virgin LDPE. Our results indicated different sublethal responses upon exposure to recycled compared to virgin LDPE MP.

Highlights

The exponentially increasing use of plastics in all areas of human activity has resulted in greater amounts of plastic waste that is often mismanaged and has been considered a persistent pollutant [1] and a hazardous waste [2], reflecting the severity and extent of the plastic pollution problem
In the Fourier transform infrared spectroscopy (FTIR)-attenuated total reflection (ATR) analysis, absorption bands identified in the FTIR spectra of both polymeric samples were all characteristic of low-density polyethylene (LDPE) [52] (Figure S4)
In the ATR-FTIR spectrogram (Figure S4), 2400 cm−1 and 670 cm−1 peaks in the recycled low density polyethylene (LDPE) spectra originate from CO2

Summary

Introduction

The exponentially increasing use of plastics in all areas of human activity has resulted in greater amounts of plastic waste that is often mismanaged and has been considered a persistent pollutant [1] and a hazardous waste [2], reflecting the severity and extent of the plastic pollution problem. In Europe, low density polyethylene (LDPE) is the second most used plastic polymer after polypropylene (PP) and while it dominates the packaging/film industry yet it is less recycled compared to PP and high-density polyethylene (HDPE) packaging [5]. Intensive use of polyethylene (PE) is reflected in the MP contamination [6], where it is among the dominant polymer types found in drinking water [7], fresh water [8,9] marine [10,11,12] and terrestrial environments [13,14] and outdoor air [15,16]. Recycled plastics contain a multitude of (un)intentionally added chemical additives/contaminants (e.g. pesticide residues, pigments, flame retardants) [18,19] identification of which alone is challenging [20] and establishing polymer-based toxicological signature more so [21]

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