Eden Hataley

Both the potent liver toxins microcystins (MC) and microplastics (MPs) are emerging environmental contaminants now recognized as being widely distributed across the globe. MCs are a diverse group of monocyclic heptapeptide hepatotoxins produced by several genera of freshwater cyanobacteria. MPs are defined as small particles of plastic less than 5 mm in diameter made from a variety of organic synthetic polymers. They may differ in product and polymer type, size, morphology, colour, and chemical additives. MPs are often categorized by primary and secondary sources. They may emerge from plastics intentionally manufactured to have a size less than 5 mm found in textiles, medicines, and personal care products and fragmentation and/or degradation of larger plastic objects, primarily from uncontrolled waste or litter. MPs may impact ecosystems by adhering to and/or being ingested by organisms, which may cause harmful physical effects. Additionally, MPs may be a source of hazardous chemicals via their additive ingredients and/or sorption of environmental contaminants. Recent studies have demonstrated the ability of MPs to act as a medium to concentrate hydrophobic (non-polar) organic contaminants in marine environments, driven by their characteristic surface hydrophobicity. This research has not been extended to MCs, which are relatively hydrophilic (polar) molecules implying that their affinity for MPs is negligible. However, many MC variants contain rare hydrophobic amino acid residues. Inherent in this lies the question: can MPs act as a medium to concentrate waterborne MC? If so, how does this alter the fate of MCs in freshwater ecosystems, and the toxic effects of MCs to freshwater organisms?