Association of Potential Human Pathogens with Microplastics in Freshwater Systems Loriane Murphy, Kieran Germaine, David N. Dowling, Thomais Kakouli-Duarte, and John Cleary (&) enviroCORE, Department of Science and Health, Institute of Technology Carlow, Kilkenny Road, Carlow, Ireland {loriane.murphy,john.cleary}@itcarlow.ie 1 Introduction Microplastics (MPs) have become the main form of pollution in the world’s oceans (80% of marine litter consists of plastic) because of their slow degradability leading to their accumulation in the environment [1]. MPs have become a global hazardous pollutant [2, 3]. MP particles result from the degradation of large plastic materials in the environment via physical, chemical or biological processes. Potential risks of plastic particles in ecosystems have been reported through both laboratory and field investi- gations [4]. These include potential endocrine disruption in vertebrates and some invertebrate species, physical injuries of gastrointestinal and digestive tracts of animals, and tissue damage [5–7]. Over the past decade, numerous studies have demonstrated that MPs can serve as vectors for the dispersal of toxic substances such as heavy metals, persistent organic pollutants (POPs), and pathogens, increasing their dispersal opportunities in marine and freshwater systems [4, 8, 9]. Concerns have been raised regarding the potential for MPs to represent new substrates for microorganisms, mainly harmful and pathogenic ones [10]. Recently, MPs have been observed in drinking water sources, which has triggered discussions on their possible implications for human health [11]. The aim of this study is to look at potential human pathogens that can be found on the surfaces of MP particles after being released into the freshwater environment. The current study enhances our knowledge of freshwater microbial assemblages on MPs, while focusing on pathogenic bacteria, and assessing the potential risks that their presence in freshwater has for humans. 2 Experiment Design and Set up Polyethylene (PE) particles (0.96 g/cm 3 , 1000 lm diameter) were treated with chicken egg white lysozyme used to burst the bacteria by degrading the polysaccharide chain found in bacterial cell walls. 100% ethanol was then used to sterilise MP particles prior to the experiment. MP particles were then incubated for 14 days in freshly sampled river water taken from the River Barrow, Ireland (52°49′37.9″N 6°56′17.9″W). A total © Springer Nature Switzerland AG 2020 M. Cocca et al. (Eds.): ICMPMS 2019, SPWA, pp. 112–120, 2020. https://doi.org/10.1007/978-3-030-45909-3_19