Abstract
Microplastics (MP) are perceived as a threat to aquatic ecosystems but bear many similarities to suspended sediments which are often considered less harmful. It is, therefore pertinent to determine if and to what extent MPs are different from other particles occurring in aquatic ecosystems in terms of their adverse effects. We applied meta-regressions to hazard data extracted from the literature and harmonized the data to construct Species Sensitivity Distributions (SSDs) for both types of particles. The results demonstrate that the average toxicity of MPs is approximately one order of magnitude higher than that of suspended solids. However, the estimates were associated with large uncertainties and did not provide very strong evidence. In part, this is due to the general lack of comparable experimental studies and dose-dependent point estimates. We, therefore, argue that a precautionary approach should be used and MP in the 1–1000 µm size range should be considered moderately more hazardous to aquatic organisms capable of ingesting such particles. Organisms inhabiting oligotrophic habitats like coral reefs and alpine lakes, with naturally low levels of non-food particles are likely more vulnerable, and it is reasonable to assume that MP pose a relatively higher risk to aquatic life in such habitats.
Synopsis A meta-analysis indicates that microplastics are one order of magnitude more toxic than suspended sediments/solids, an estimate surrounded by considerable uncertainty.
Competing Interest Statement
Martin Wagner is an unremunerated member of the Scientific Advisory Board of the Food Packaging Forum (FPF). He has received travel funding from FPF to attend its annual board meetings and from Hold Norge Rent (Keep Norway Beautiful) to speak at one of their conferences. Martin Ogonowski has received travel funding to present his research at the chemicals industry′s annual meeting in 2019 organized by IKEM — Innovation and Chemical Industries in Sweden and KTF — The Chemical Technical Industries (Kemisk Tekniska Företagen). All authors have received financial compensation from the Norwegian Scientific Committee for Food and Environment (VKM) for working on this dataset.
Footnotes
Supplementary data table 1 has been uploaded. This data table contains the raw data used in the analyses.
Abbreviations
- pNOEC
- predicted No Effect Concentration
- eNOEC
- estimated No Effect Concentration
- UF
- Uncertainty factor
- MP
- microplastic
- SS
- suspended sediments
- LOEC
- Lowest Observed Effect Concentration
- HONEC
- Highest Observed No Effect Concentration
- PNEC
- Predicted No Effect Concentration
