Micro- and Nanoplastics in Sediment: Considerations for Risk Assessment
By Jennifer L. Wollenberg, Ph.D., Principal, Sustainability
Kristian Fried, Ph.D., Dr. rer. nat., DABT, ERT, Senior Consultant
Lisa Tolbert, E.I.T., Consultant
Chris Pfeifer, Senior Consultant
Presented at Battelle Sediments, January 29, Tampa, Florida.
Background/Objectives
Micro- and nanoplastics (MNPs) are ubiquitous in the environment and are a contaminant of emerging concern. MNPs are increasingly reported in food, with the highest levels observed in seafood, raising public concern about potential human health impacts. In aquatic systems, MNPs accumulate in sediment, are present in surface water, and can be taken up by benthic invertebrates (e.g., mussels) as well as fish. Furthermore, there is emerging evidence that MNPs can interact with chemical contaminants in the environment (e.g., PFAS, uranium) and can influence chemical fate, transport, and toxicity. As a result, MNPs may be a baseline stressor or possibly a site-specific stressor in some settings and may be appropriate to consider in both ecological and human health risk assessment.
Approach/Activities
Our analysis includes a literature survey to examine the prevalence of MNPs in sediment and seafood, with a focus on identifying potential considerations for investigation and risk assessment at contaminated sediment sites. In particular, we identify areas of uncertainty, and discuss a number of factors that must be considered in the evaluation of MNP risks. Such considerations include the variability and complexity of MNPs, lack of standard sampling and analytical approaches, limited availability of toxicological/hazard assessments, and lack of regulatory criteria against which data can be compared.
Results/Lessons Learned
MNP characteristics vary widely based on source, and the environmental fate and transport and potential toxicological effects of MNPs following uptake by organisms depend upon particle size, shape, and chemical composition. MNPs have also been reported to adsorb and carry unrelated chemicals on their surfaces, thus serving as vectors for other environmental pollutants. These factors complicate the development of typical risk assessment metrics such as no-observed-adverse-effects levels and dose-response relationships. However, the presence of MNPs in sediments does not inherently signify a risk. Instead, it should prompt a careful examination of MNP sources, characteristics, pathways of exposure, and interactions with other environmental factors. By adopting a measured and evidence-based approach, we can better discern the real risks and develop effective strategies to mitigate potential impacts on ecological receptors and human health.