Long-term exposure to nanoplastics reduces life-time in Daphnia magna

Egle Kelpsiene,Lars-Anders Hansson,Tommy Cedervall,Mikael T Ekvall,Oscar Torstensson

doi:10.1038/s41598-020-63028-1

Abstract

Plastics are widely used in todays society leading to an accelerating amount of plastic waste entering natural ecosystems. Over time these waste products degrade to micro- and, eventually, nanoplastic particles. Therefore, the break-down of plastics may become a critical threat to aquatic ecosystems and several short term studies have demonstrated acute toxicity of nanoplastics on aquatic organisms. However, our knowledge about effects of chronic or life-time exposure on freshwater invertebrates remains elusive. Here, we demonstrate results from life-time exposure (103 days) of a common freshwater invertebrate, Daphnia magna, exposed to sub-lethal concentrations of polystyrene nanoparticles. 53 nm positively charged aminated polystyrene particles were lethal at concentration of 0.32 mg/L which is two magnitudes lower than previously used concentrations in short-term (24 h) tests. At this concentration the life-time of individuals was shortened almost three times. Negatively charged carboxylated 26 and 62 nm polystyrene particles, previously demonstrated to be non-toxic at 25 and 50 mg/L concentrations in short-term tests, were toxic to D. magna at all concentrations used in our long-term study. Although total reproductive output was not significantly affected at increasing concentrations of polystyrene nanoparticles, there was a decreasing trend in the number of offspring over their life-time. Hence, in order to understand how the potential future environmental problem of nanoplastic particles may affect biota, long-term or life-time studies resembling environmental concentrations should be performed in order to provide information for predictions of future scenarios in natural aquatic environments.

Highlights

Plastic materials are of remarkable benefit for modern society due to their low price, easy manufacturing and practical function in a multitude of daily used products[1]
Many studies addressing microplastic pollution have focused on marine environments[17,18], recent reports have shown that microplastics can be found in freshwater ecosystems[19,20]
It has been observed that ingestion of nanoplastic particles may disturb fish feeding behavior and alter their metabolism[23,24,25], as well as induce oxidative stress and tissue damage[26,27]

Summary

Introduction

Plastic materials are of remarkable benefit for modern society due to their low price, easy manufacturing and practical function in a multitude of daily used products[1]. Pollution by micro- and nanoplastics constitutes a potential threat to aquatic ecosystems[11,12] Due to their small size, plastic particles might be ingested by organisms at the lower end of the food chain and can be thansferred by feeding to top consumers[13,14]. Several studies have shown that plastic particles of various sizes can be ingested by aquatic organisms causing tissue damage[15] or even death[16]. Previous studies have shown that D. magna can ingest nano- and microplastic particles ranging in size from nm to 5μm[28,30] and that D. magna show reduced reproduction after days of exposure to 70 nm polystyrene particles[33].

Objectives

Methods

Results