Microplastic in an ecotoxicological and regulatory context

Anne Nielsen

Student thesis: Master thesis

Abstract

Microplastic (MP), plastic particles with a diameter <5 mm, have in recent years become acknowledged as a potential hazard for marine organisms, and thus as a pollution that potentially needs to be regulated. Determination of MP hazardousness has however proven problematic, which may impede the development of regulation on the issue. Thus, in this master’s thesis, the complexity of handling MP in the context of regulatory ecotoxicology is analysed. To understand whether ecotoxicology under its current paradigms can deal with this unique pollutant, and to evaluate whether MP potentiates hydrophobic organic contaminants, the acute effects of single and combined exposure to polyethylene MP (10-90 µm) and Triclosan (TCS), was tested on the copepod Acartia tonsa following the ISO 14699 guideline with slight modifications. Adult female copepods were exposed to TCS (50; 100; 150; 250; 300 µg L-1) in absence and presence of MP (500 and 5000 beads mL-1), as well as MP alone (0; 500; 1000; 5000; 10,000; 15,000; 20,000; 25,000 beads mL-1). From the MP-only and TCS-only treatments, MP was found non-toxic to A. tonsa and TCS was found toxic with a LC50 of 162 µg L-1. From the coexposure treatment, exposure to TCS and MP (500 and 5000 beads) was found more toxic than exposure to TCS alone. However, exposure to TCS + 500 MP beads mL-1 proved significantly more toxic than exposure to TCS + 5000 MP beads mL-1. Accordingly, it was concluded that the presence of MP potentiates the toxicity of TCS, possibly by inducing physical stress, and that the potentiating effect of MP is dependent on MP concentration, possibly due to MP acting as a sink for TCS, thereby counteracting the potentiation effect. Furthermore, to understand how academia’s results are considered in a regulatory context, European legislation’s frameworks for hazard assessment of MP was identified and analysed. The marine Strategy Framework Directive and REACH were identified as frameworks for a site specific and generic assessment, respectively. From the analysis it was concluded that both frameworks promoted a balancing between science’s evidence of risk and society’s demands, resulting in a disregard of some of the hazards identified by academia. Lastly, through an analysis of identified main stakeholders’ perception and handling of the MP issue, the prospects for European regulation of MP was analysed and discussed. From the analysis it was concluded that the weighting of identified risks and societal benefits, as identified in the framework analyses, implies that academia, in order to effectively affect regulation, must communicate its results very clearly, thereby prompting as broad a spectre of regulatory stakeholders as possible to consider and give weight to the identified risks.    

EducationsEnvironmental Risk, (Bachelor/Graduate Programme) Graduate
LanguageEnglish
Publication date28 Jun 2016
Number of pages173
SupervisorsKristian Syberg

Keywords

  • Microplastic
  • Ecotoxicology
  • European legislation