Seite - 224 - in Freshwater Microplastics - Emerging Environmental Contaminants?

Keywords Global risk, Problem structuring, Risk assessment, Social ecology, Uncertainty 1 TheSocial-EcologicalRiskPerspective:Addressing GlobalRisks A common risk definition is that “the term ‘risk’ denotes the likelihood that an undesirable stateof reality (adverse effects)mayoccur asa result ofnatural events or human activities” [1]. A classical risk analysis calculates the possibility of an adverse event and thepotential damage, for instance, an assessment of ecotoxicity of hazardous substances based on dose-response relationships. For “global risks,” also termed systemic risks, classical risk analysis is not so easily applicable, since thecharacteristicsof“global risks”comprisecomplexcause-effect linkages,which are not fully known, resulting in a high degree of uncertainty and ambiguity in assessing therisk.For this reason,consent to riskmanagementstrategies isdifficult to obtain [2, 3]. Whoorwhatcanbe“at risk”?Insocial-ecological riskresearch, risks tohumans andbiophysical entities (e.g., biocoenoses, ecosystems)areconsidered.Thecauses ofrisksmostlylie inhumanactivities,sincemanynatural resourcesandbiophysical processes are influenced by societies [4]. In social-ecological risk research, it has becomeclear thatassessmentof the riskalone isnot sufficient formanagementand policydecisions[5]. It isalsoimportant toconsider theriskperceptionandconcerns ofdifferent interestgroups[6]. In thecaseofcomplexriskswhichareaccompanied byuncertainty, it is important to define thedegree of tolerability and acceptability inorder tofindmanagement strategies acceptable to all interest groups [7].There- fore, a prerequisite for risk management and related policy-making is not only scientificevidencebut alsoanagreementof thedifferent interest groupsonhowto understand, interpret, andvalue the evidence. Hereafter, we will outline the characteristics of global risks from a social- ecologicalperspectiveandpresentfourargumentsframingmicroplasticsasaglobal risk. (a) Global risks arenotproducedbyanextremeevent or adisaster but are created in modern societies as a side effect of an “everyday mode” of system’s operation [8, 9] and regulationof the supply system[4]. Fromthis understand- ing, we derive our first thesis, arguing that the risks of microplastics are produced as an unintended side effect of everyday operations in modern societies. (b) Global risks are complex; thus, no clear evidence of a cause-effect linkage exists or can be proven, due to “intervening variables,” “long delay periods between cause and effect,” or “positive and negative feedback loops” [10]. These and the state of “not knowing” [8] contribute to a high degree of uncertainty regarding effects, especially in terms of scope and time. Thus,we 224 J.KrammandC.V€olker