Surveillance of Seafood for Microplastics

Abstract

Surveillance of seafood for microplastic is in high demand, but there are challenges in the establishment of appropriate methods. Even though there are more than hundred scientific publications presenting numbers about the occurrence of plastics in seafood organisms, currently, these numbers are largely not comparable and afflicted with high uncertainty. They represent rather pioneering work, than surveillance. The research field is developing rapidly, continuously challenging and updating definitions and descriptions on the location, quality and quantity of microplastic. A major reason behind those challenges is of a new type, due to the particular nature of this pollutant, as opposed to other previously analyzed pollutants, which are soluble. When dealing with particle uptake into organisms, we claim that it is pivotal to take into account the size and shape of the particles. Most often, only plastic particles above several hundred µm and only from the gastrointestinal tract were included in field studies, typically leading to observations of on average 0-3 particles per fish. However, for both seafood organisms and human health, plastic particles in edible tissue are of higher concern, than those passing through the gastrointestinal system. According to exposure studies, the size of microlitter particles that are most likely to be transported into tissue and have accumulation potential, is lower than 50 µm. The few publications investigating the smaller size classes and tissues, do detect and report microlitter contamination, and therefore, warrant further investigation. Additionally, appropriate quality control needs to be included, and measurement uncertainties assessed.