Page - 42 - in Freshwater Microplastics - Emerging Environmental Contaminants?

towards an understanding of their potential environmental effects. This applies to general scientific knowledge as well as ongoingwork on developing appropriate test methods that are applicable to the testing of particle pollutants rather than soluble chemicals. Based on experience within the field of engineered nanomaterials, we recom- mend that the following aspects be considered in work with nano- and microplastics: • Development of clear, commondefinitions for plastic particle categorisation • Thoroughparticlecharacterisation inexposurestudies (includingparticle intrin- sic properties, aggregation, agglomeration, sedimentation, dissolution, etc.) • Inclusion of chemical leaching controls (monomers, additives, etc.) • Development and use of reference materials for method validation and comparison • Development of protocols for ecotoxicity testing, sample preparation and ana- lyticalmethods tominimise test artefacts • Studies into the influence of environmental transformation processes (‘aging’) onnano- andmicroplastic behaviour and ecotoxicity • Development of analytical techniques that introduce minimal changes to the plasticparticlesduring samplepreparation,provide informationonseveral phy- sicochemical parameters and canhandle complex, heterogeneous samples. Whilewe shoulddrawon theexistingknowledgeonengineerednanomaterials, it is equally important to understandwhere the similarities begin andwhere they end. In some respects, nano- and microplastics are likely to present different environmental, analytical and methodological problems compared to engineered nanomaterials, and this shouldbeconsidered in theplanningofexperiments and in making informeddecisions regarding endpoints and tests of interest. Finally, it is very important to understand the fundamental effect mechanisms associatedwith nano- andmicroplastics:Which propertiesmake themhazardous? This is thewayforwards towards replacingproblematicplasticmaterialswithsafer alternatives in consumer products and industrial applications. Such considerations are important when discussing strategies for future plastic manufacturing, minimising environmental risks and increasing the potential for plastic reuse and recycling. References 1.AndradyAL(2011)Microplastics inthemarineenvironment.MarPollutBull62:1596–1605. doi:10.1016/j.marpolbul.2011.05.030 2.Koelmans AA, Besseling E, Shim WJ (2015) Nanoplastics in the aquatic environment. Critical review. In: BergmannM, Gutow L, KlagesM (eds) Marine anthropogenic litter. Springer,Cham, pp325–340. doi:10.1007/978-3-319-16510-3_12 3.ArthurC,Baker J,BamfordH(2009)Proceedingsof the international researchworkshopon theoccurrence, effects, and fate ofmicroplasticmarine debris.Group, 530 42 S.Rist andN.B.Hartmann