Seite - 277 - in Freshwater Microplastics - Emerging Environmental Contaminants?

2 MitigationWhereThere IsHarm Demonstratedharm towildlife fromplastic is documented fromentanglement and macrodebris ingestion,andingestionofmicroplasticshaveshownnegative impacts on individual organisms, but demonstrating that microplastics cause harm to the whole ecosystems is unclear [58]. In a recentmeta-analysis of available research demonstrating impacts onwildlife frommarine debris, 82%of 296 demonstrated impactswerecausedbyplastic [59]. Interestingly, thevastmajorityof those (89%) were impacts at suborganismal levels from micro- and nanoplastics, including damages to tissues or organ function, with only 11% due to impacts from large debris, suchas entanglement in ropes andnettingordeath from ingestionof larger items. According toRochman et al. [59] there aremany cases of suborganismal level impacts, like the ingestionof20μmmicroplasticparticlesby thecopepodCalanus helgolandicusaffectingsurvival and fecundity [60], toxiceffectson theembryonic development of the sea urchinLytechinus variegatus [61], and reduced feeding in the annelid worm Arenicola marina after ingesting 400 μmparticles [43].What these studies and others have in common is that they are limited to laboratory settings, oftenusingPSmicrospheres only, anduse anarrowscaleof particle size, shape,anddurationofexposure [62].Thiscriticismwasalsopointedout inarecent studyof the freshwatermud snailPotamopyrgus antipodarum,wherebyfive com- mon and environmentally relevant non-buoyant polymers were introduced in a rangeofsizesandhighconcentrations in their food, resulting innoobservedeffects [56], suggesting that more work in real settings with environmentally relevant microplastic particle size, shape, and polymer type is needed to better understand ecological harm. Can we say ecological harm exists without the weight of evidence in the literature to say so?One could argue that the volumeof research published lately, especially the proposal fromRochmanandothers to classify plasticmarine debris as a hazardous substance [63], indicates substantial concern from the scientific community. That classification would meet criteria for mitigation from policymakers in terms of shifting the burden of proof that plastic is safe to the producer [64].While further studies of ecological impacts areneeded, it is reason- able to employ the precautionary principle considering the risk ofwidespread and irreversible harm. Equally,wemustnot forget theharmtosociety fromplasticpollution.Theflow of thematerial from plastic production to waste management and environmental pollution affects societies inways that are often difficult to quantify and are often ignored.Forexample,plasticwastehasbeenshowntoincubatewater-borneinsects andact as avector for dengue fever in thePhilippines [65].The industryofwaste- pickingindevelopingcountries isplaguedwithsubstantialhumanhealthcostsfrom illness and injury from collecting and handling plastics. Open-pit and low-tech Microplastic:WhatAre theSolutions? 277