Harmonized protocol for monitoring microplastics in biota. Deliverable 4.3.

Microplastic pollution is presently considered a high concern topic by scientists, policy makers, governmental bodies, non-governmental organizations and the general public. Microplastics are highly widespread in all environmental compartments (e.g. air, water, sediments and biota) and increasing empirical evidence points towards potential negative effects on organisms, both at an individual scale and potentially at population and ecosystem level, as well as effects on human health. To understand the levels and effects of microplastics on biota, it is important to conduct risk assessment evaluations based on realistic microplastic concentration exposure scenarios which are targeted at identifying the effects of microplastics on species and ecosystems. Realistic data on exposures should derive from reliable monitoring data on the uptake and accumulation of microplastics in biota. Presently, there is sufficient empirical data available to underpin arguments to suggest species that could serve as suitable candidates for monitoring microplastics in the environment. Comparison of available data is still limited due to the use of different analytical methods and reporting units, nonetheless researchers have been providing recommendations and frameworks to surpass these limitations. Many methods initially focused on particles <5 mm in size, and as time and knowledge progressed, researchers have been able to identify smaller particles. However, as research diversified and the research community expanded, comparison between emerging datasets was hampered even further and accuracy has been a key issue in recent publications. In all studies available, particles extracted from biota are not always analytically confirmed as artificial and/or synthetic polymers, and contamination controls are sometimes lacking. This is especially critical in the case of fibers, which can easily be introduced during sample collection and processing. In addition, some chemicals used to digest biota can cause relevant damage to plastic polymers. While methods have been widely and continually developed and tested, measurement uncertainties are still often unreported or unassessed. Furthermore, reporting formats have also been diverse, depending on the reporter’s background. Data comparison must consider differences between sampled species such as functional group, feeding preferences, habitat and tissue composition (e.g. chitin, calcifications, cellulose, fat, etc.), which have precluded the developments of a reliable harmonized approach to assess microplastic content. In order to understand microplastic uptake and transfer in food webs there is a definite need of ecosystem expertise when selecting species for analysis. This deliverable is a direct contribution to this topic and has been produced under the scope of the JPI-Oceans projects BASEMAN and EPHEMARE, two international and interdisciplinary collaborative research projects aimed at providing solutions to extract and analyze the levels of microplastics in biota. Teams from both projects have worked together to deliver protocols for selecting and analyzing appropriate biota to monitor microplastics in the environment. The provided proposed protocol intends to harmonize laboratory procedures, with recommendations on how to select, extract and monitor microplastics in biota from aquatic environments.