Microplastics in the aquatic and terrestrial environment: sources (with a specific focus on personal care products), fate and effects

Duis and Coors Environ Sci Eur (2016) 28:2 DOI 10.1186/s12302-015-0069-y Open Access REVIEW Microplastics in the aquatic and terrestrial environment: sources (with a specific focus on personal care products), fate and effects Karen Duis* and Anja Coors Abstract Due to the widespread use and durability of synthetic polymers, plastic debris occurs in the environment worldwide. In the present work, information on sources and fate of microplastic particles in the aquatic and terrestrial environ‑ ment, and on their uptake and effects, mainly in aquatic organisms, is reviewed. Microplastics in the environment originate from a variety of sources. Quantitative information on the relevance of these sources is generally lacking, but first estimates indicate that abrasion and fragmentation of larger plastic items and materials containing synthetic polymers are likely to be most relevant. Microplastics are ingested and, mostly, excreted rapidly by numerous aquatic organisms. So far, there is no clear evidence of bioaccumulation or biomagnification. In laboratory studies, the inges‑ tion of large amounts of microplastics mainly led to a lower food uptake and, consequently, reduced energy reserves and effects on other physiological functions. Based on the evaluated data, the lowest microplastic concentrations affecting marine organisms exposed via water are much higher than levels measured in marine water. In lugworms exposed via sediment, effects were observed at microplastic levels that were higher than those in subtidal sediments but in the same range as maximum levels in beach sediments. Hydrophobic contaminants are enriched on microplas‑ tics, but the available experimental results and modelling approaches indicate that the transfer of sorbed pollutants by microplastics is not likely to contribute significantly to bioaccumulation of these pollutants. Prior to being able to comprehensively assess possible environmental risks caused by microplastics a number of knowledge gaps need to be filled. However, in view of the persistence of microplastics in the environment, the high concentrations measured at some environmental sites and the prospective of strongly increasing concentrations, the release of plastics into the environment should be reduced in a broad and global effort regardless of a proof of an environmental risk. Keywords: Plastic debris, Environmental concern, Persistence, Personal care products, Cosmetic products, Microplastic Introduction World production of plastics (i.e. synthetic organic polymers) has strongly expanded during the last decades, from 1.7 million t in 1950 to 299 million t in 2013. While the amount of plastics produced in Europe has been relatively constant in the last 10 years, world plastic production continues to increase [1, 2]. In view of the *Correspondence: k‑ ECT Oekotoxikologie GmbH, Böttgerstr. 2‑14, 65439 Flörsheim/Main, Germany large production volumes and the durability of plastics, it is not surprising that plastics are found in the environment. Initially, scientific and public attention focused on larger plastic debris. However, the occurrence of small plastic particles in the marine environment was already described in the early 1970s [3, 4]. During the last few years, microplastics in the environment have received increasing attention and are now an emerging area of research [5–8]. Most commonly, microplastics have been defined as synthetic organic polymer particles with a size (or, more © 2016 Duis and Coors. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Duis and Coors Environ Sci Eur (2016) 28:2 specifically, largest dimension) <5 mm [6, 8–11]. The majority of definitions do not include a lower size limit. In view of the definition of nanoscale (1–100 nm [12]), the term microplastics is used in this review for solid synthetic organic polymer particles with a size between 100 nm and 5 mm. In studies on the occurrence in the environment, the upper size limit of the sampled plastics is not always indicated. In such cases, the term microplastics is used, if it can be assumed that the sampled plastic items are in the size range mentioned above. In cases where sampling included microplastics, but the upper size limit of the sampled plastics is somewhat above 5 mm (e.g. 10 mm) the term ‘small plastic items’ is employed. Plastic items larger than 5 mm are designated as macroplastics. In the present work, currently available information on sources, fate and occurrence of microplastics in the aquatic and terrestrial environment, on their uptake by aquatic and terrestrial organisms and possible effects on these organisms is critically evaluated. Recently, considerable public attention has focused on microplastics particles from personal care products, which was mainly triggered by reports in news media. Therefore, a specific focus is placed on the contribution of microplastics from personal care products (defined and regulated as cosmetic products in the EU [13]) to the overall pollution of the environment with microplastics. An effort was made to report, as far as possible, numerical concentrations of microplastics for studies on occurrence, uptake and effects. Plastic products may contain a number of additives including plasticisers, stabilisers, flame retardants, pigments and antimicrobials [14–16]. Potential effects of these additives, which have been discussed elsewhere (e.g. [17]), are not addressed in this review. Methods to sample, process and analyse microplastics in the environment A number of methods to sample, isolate, characterise, identify and quantify microplastics have been developed for water and sediment. In the following sections, the most relevant methods are briefly presented. In view of the comprehensive review of Hidalgo-Ruz et al. [11] and available guidance on monitoring of marine litter including microplastics [6], emphasis is placed on recent developments. Sampling While in some cases bulk water samples were taken (e.g. [18]), volume-reduced sampling methods have generally been employed to sample microplastics from water: neuston nets for the sea surface layer, and zooplankton nets for sub-surface water [6, 11, 19, 20]. Mesh width of Page 2 of 25 the sampling nets was most commonly 300–390 µm [11]. The sampling method has a strong influence on the study results, especially concerning the smallest microplastics, which require a sufficiently small mesh width or bulk sampling, depending on their size [21]. Samples from subtidal sediments are taken with sediment sampling equipment, e.g. grab samplers [6, 11, 22]. For coastal sediments, direct sampling of visually ide (...truncated)