Microplastics in the aquatic environment: Evidence for or against adverse impacts and major knowledge gaps

Abstract

There is increasing scientific and public concern over the presence of microplastics in the natural environment. We present the results of a systematic review of the literature to assess the weight of evidence for microplastics causing environmental harm. We conclude that microplastics do occur in surface water and sediments. Fragments and fibers predominate, with beads making up only a small proportion of the detected microplastic types. Concentrations detected are orders of magnitude lower than those reported to affect endpoints such as biochemistry, feeding, reproduction, growth, tissue inflammation and mortality in organisms. The evidence for microplastics acting as a vector for hydrophobic organic compounds to accumulate in organisms is also weak. The available data therefore suggest that these materials are not causing harm to the environment. There is, however, a mismatch between the particle types, size ranges, and concentrations of microplastics used in laboratory tests and those measured in the environment. Select environmental compartments have also received limited attention. There is an urgent need for studies that address this mismatch by performing high quality and more holistic monitoring studies alongside more environmentally realistic effects studies. Only then will we be able to fully characterize risks of microplastics to the environment to support the introduction of regulatory controls that can make a real positive difference to environmental quality. Environ Toxicol Chem 2018;37:2776–2796. © 2018 SETAC

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

“…However, as recently discussed by Schur et al (2019), caution may be warranted not to overinterpret the potential for translocation based on observations utilizing fluorescence, because 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) attempted to replicate earlier observations, but a general lack of reproducibility of studies that found translocation has been cited as cause for concern (Burns and Boxall, 2018). This is an important cautionary note, in that recent publications (Schur et al 2019; Triebskorn et al 2019) have drawn attention to the inherent challenges that particles face when crossing cellular membranes.…”

“…The literature data on ingestion of microplastic particles to include in the present review was initially based on the reference lists reported in several robust reviews recently published for organisms at all levels of biological organization (Schuyler et al 2014; Deudero and Alomar 2015; Lusher et al 2017; Poeta et al 2017; Burns and Boxall 2018; Foley et al 2018; Fossi et al 2018; Hermsen et al 2018; Battisti et al 2019; Botterell et al 2019; Triebskorn et al 2019; Wang et al 2019). The initial list was further complemented by identification of other studies, using a range of methods.…”

Toward the Development and Application of an Environmental Risk Assessment Framework for Microplastic

“…Problem formulation is a critical component, whereby the development of standard test systems should focus on environmental compartments, organisms, and exposure scenarios that are ecologically relevant (Lenz et al 2016;Koelmans et al 2017a;Burns and Boxall 2018). For instance, although there have been several studies assessing effects in various aquatic species, there is currently less understanding of effects for freshwater-, sediment-, and terrestrial-dwelling organisms (Burns and Boxall 2018). But awareness of the environmental fate and exposure potential of microplastic particles for organisms in freshwater systems and sediment is increasing (Corcoran 2015;Blettler et al 2018;Burns and Boxall 2018;Triebskorn et al 2019).…”

Toward an ecotoxicological risk assessment of microplastics: Comparison of available hazard and exposure data in freshwaters

“…On this global scale, the authors found no immediate risk in marine waters until 2100. Burns and Boxall () published a risk evaluation of microplastics in both freshwaters and marine waters. Their critical review highlighted that organisms are usually exposed in the laboratory to smaller particles and in higher concentrations than those found in the environment.…”