Risk assessment of microplastics in the ocean: Modelling approach and first conclusions

Abstract

We performed an environmental risk assessment for microplastics (<5 mm) in the marine environment by estimating the order of magnitude of the past, present and future concentrations based on global plastic production data. In 2100, from 9.6 to 48.8 particles m are predicted to float around in the ocean, which is a 50-fold increase compared to the present-day concentrations. From a meta-analysis with effect data available in literature, we derived a safe concentration of 6650 buoyant particles m below which adverse effects are not likely to occur. Our risk assessment (excluding the potential role of microplastics as chemical vectors) suggests that on average, no direct effects of free-floating microplastics in the marine environment are to be expected up to the year 2100. Yet, even today, the safe concentration can be exceeded in sites that are heavily polluted with buoyant microplastics. In the marine benthic compartment between 32 and 144 particles kg dry sediment are predicted to be present in the beach deposition zone. Despite the scarcity of effect data, we expect adverse ecological effects along the coast as of the second half of the 21st century. From then ambient concentrations will start to outrange the safe concentration of sedimented microplastics (i.e. 540 particles kg sediment). Additional ecotoxicological research in which marine species are chronically exposed to realistic environmental microplastic concentration series are urgently needed to verify our findings.

The occurrence of microplastics in freshwater systems – preliminary results from Krakow (Poland)

“…Both the surface and groundwater that were examined are much less aggressive than the salt marsh used in the experiment. A good argument for using containers is also the fact that in a manta trawl, a mesh with a specific diameter is used, causing the loss of smaller particles in the water (Everaert et al 2018).…”

Toward an ecotoxicological risk assessment of microplastics: Comparison of available hazard and exposure data in freshwaters

“…To the best of our knowledge, only 2 risks assessments of microplastics in water have been published in the peer‐reviewed literature. Everaert et al () analyzed these risks in the marine environment. Based on the procedure outlined by the European Chemicals Agency (), the authors calculated a risk characterization ratio (RCR), dividing a predicted environmental concentration by a predicted‐no‐effect concentration (PNEC).…”

Learned Discourses: Timely Scientific Opinions

“…One type of plastic pollution of notable interest today is microplastics (i.e., plastic pieces less than 5 mm in length). Marine microplastics represent 4.6% of yearly plastic production and are expected to increase 50-fold by the year 2100; furthermore, microplastics can break down into less well-characterized nanoplastics (Everaert et al 2018).…”

“…To date, only 1 in-depth marine microplastics risk assessment does not embrace the holistic framework needed to comprehensively characterize the overall risk to human health (Everaert et al 2018). While an admirable exercise in collating the existing microplastics research, this assessment was conducted using only limited human exposure of ingesting microplastic-containing bivalves (e.g., mussels, clams, oysters).…”