From the sea to the laboratory: Characterization of microplastic as prerequisite for the assessment of ecotoxicological impact

Abstract

This is 1 of 15 invited commentaries in the series "Current Understanding of Risks Posed by Microplastics in the Environment." Each peer-reviewed commentary reflects the views and knowledge of international experts in this field and, collectively, inform our current understanding of microplastics fate and effects in the aquatic environment. ABSTRACTThe presence of microplastic (MP) in the aquatic environment is recognized as a global-scale pollution issue. Secondary MP particles result from an ongoing fragmentation process governed by various biotic and abiotic factors. For a reliable risk assessment of these MP particles, knowledge about interactions with biota is needed. However, extensive testing with standard organisms under reproducible laboratory conditions with well-characterized MP suspensions is not available yet. As MP in the environment represents a mixture of particles differing in properties (e.g., size, color, polymer type, surface characteristics), it is likely that only specific particle fractions pose a threat towards organisms. In order to assign hazardous effects to specific particle properties, these characteristics need to be analyzed. As shown by the testing of particles (e.g., nanoparticles), characteristics other than chemical properties are important for the emergence of toxicity in organisms, and parameters such as surface area or size distribution need consideration. Therefore, the use of "well-defined" particles for ecotoxicological testing (i.e., standard particles) facilitates the establishment of causal links between physical-chemical properties of MP particles and toxic effects in organisms. However, the benefits of well-defined particles under laboratory conditions are offset by the disadvantage of the unknown comparability with MP in the environment. Therefore, weathering effects caused by biological, chemical, physical or mechanical processes have to be considered. To date, the characterization of the progression of MP weathering based on powder and suspension characterization methods is in its infancy. The aim of this commentary is to illustrate the prerequisites for testing MP in the laboratory from 3 perspectives: (i) knowledge of particle properties; (ii) behavior of MP in test setups involving ecotoxicological test organisms; and (iii) accordingly, test conditions that may need adjustment. Only under those prerequisites will reliable hazard assessment of MP be feasible.

Reproductive toxicity of primary and secondary microplastics to three cladocerans during chronic exposure

“…However, most studies assessing the toxicity of microplastics use a single-sized spherical model PMP (Phuong et al, 2016) for exposure experiments, although SMP are reported to have higher abundance in natural environments (Connors et al, 2017;Potthoff et al, 2017). In a recent study, Ogonowski et al (2016) compared the toxicity of PMP and artificially weathered SMP on processes like feeding, growth as well as reproduction, during chronic exposure to D. magna and found that while PMP had limited impacts, exposure to SMP resulted in reduced reproductive output.…”

Acute sensitivity of three Cladoceran species to different types of microplastics in combination with thermal stress

“…Secondary microplastics are formed by the environmental degradation of larger plastic debris (Andrady, 2011), mainly by wave action and abrasion, UV-B radiation and temperature changes (Andrady, 2011;Browne et al, 2007). To date, however, the majority of studies have used primary microplastics to study adverse impacts, although secondary microplastics are more abundant in natural environments (Connors et al, 2017;Phuong et al, 2016;Potthoff et al, 2017). Ogonowski et al (2016) was the first study to compare the toxicity of primary and secondary microplastics on life history parameters such as feeding, growth and reproductive capacity during chronic exposure to D. magna.…”

A Synthesis of Marine Monitoring Methods With the Potential to Enhance the Status Assessment of the Baltic Sea

“…For the detection and identification of dumped warfare relicts, ROTV and Gliders can be deployed, while the concentrations of leaking contaminants in the water can be monitored employing Active Biomonitoring using Blue Mussels or Passive Samplers. Regarding microplastics, the constant fragmentation and the large diversity within types of particles cannot be adequately addressed by a single method (Potthoff et al, 2017). Therefore, novel methods can be combined, e.g., by sampling larger particles using the Manta Trawl and complement these data by Rocket filtration samples and Sediment Corers.…”