Quantifying ecological risks of aquatic micro- and nanoplastic

Diverse effects of nano- and microplastic (NMP) have been demonstrated in the laboratory. We provide a broad review of current knowledge on occurrence, measurement, modeling approaches, fate, exposure, effects, and effect thresholds as regard to microplastics in the aquatic environment. Using this information, we perform a 'proof of concept' risk assessment for NMP, accounting for the diversity of the material. New data is included showing how bioturbation affects exposure, and exposure is evaluated based on literature data and model analyses. We review exposure and effect data and provide a worst case risk characterization, by comparing HC5 effect thresholds from 'all inclusive' Species Sensitivity Distributions (SSDs) with the highest environmental concentrations reported. HC5 values show wide confidence intervals yet suggest that sensitive aquatic organisms in near-shore surface waters might be at risk.