2021 Volume 24 Pages 53-61
Microplastic contamination in the environment is an emerging concern worldwide. In this review, by putting a particular focus on the ecological risk assessment of microplastic particles, we introduced several results of hazard assessments that have focused on the hazardous concentration for 5% of the species (HC5) estimated using species sensitivity distribution. In these previous studies, point estimates (mean/median) for HC5 were derived on the order of 0.01–1 µg/L (based on particle number, 105–106 particles/m3). We then summarized and discussed the relevant issues on the hazard assessments for microplastic particles: (1) identification of effect mechanisms relevant for risk assessment, (2) consideration of the influences of microplastic properties on effect concentrations, (3) identification of a proper concentration unit (i.e., mass-based or particle-based concentration), (4) handling of effect concentrations obtained from experiments that failed to establish concentration-response relationships, (5) consideration of bioavailability of microplastic particles, (6) consideration of environmentally realistic exposure conditions, (7) consideration of naturally occurring particles, (8) consideration of the influences of chemical additives and preservatives on effect concentrations, and (9) application of uncertainty factors to effect concentrations.
