Challenges in the use of bio-microplastic for sub-chronic bioassays: manufacturing, characterization and biochemical effects over a South American aquatic native species

BERTRAND, LIDWINA; YACELGA, NAOMI; GONZÁLEZ, M. FLORENCIA; RIMONDINO, GUIDO N.; AMÉ, M. VALERIA

París

Conferencia; UNESCO-IWRA Online Conference ?Emerging Pollutants: Protecting Water Quality for the Health of People and the Environment?; 2023

UNESCO

(a)Purpose or objectives and status of study or research hypothesis Evaluate effects of bio-microplastics (BioMPs) and a widely used herbicide over the crustacean Palaemon argentinus. a-Establish a protocol to manufacture and characterize BioMPs.b-Evaluate effects of environmentally relevant concentrations over organism exposed to BioMPs alone and combined with an herbicide.(b) Key issue(s) or problem(s) addressed Biodegradable polymers are seen as a potential “green” solution to the environmental pollution generated by fossil-based plastic. Nevertheless, there is growing concern regarding the potential for environmental occurrence and their impacts remains unclear, especially in presence of other organic pollutants. In the last few years, the number of studies evaluating toxicity of BioMPs over organisms increased. However, observed effects are widely variable and more information is required to understand toxicity mechanisms.(c)Methodology or approach used Adults of P. argentinus were exposed for 7 days to the following experimental treatment: control (Ctrol), 7.5 µgL-1 metolachlor (MET), 5 mgL-1BioMPs and 7.5 µgL-1metolachlor + 5 mgL-1BioMPs (MET+BioMPs). Media was fully aerated to secure dissolved O2 and to keep the MPs in suspension. Microplastics of polylactic acid (PLA) were obtained from 3D printing fiber. Milling and filtering methodologies to manufacture and select BioMPs were adjusted with the aim to obtain a size fraction adequate for the used organisms. The polymer was confirmed by FTIR and particles were characterized under a microscope. Images were analyzed with Fiji Software. Equivalences between the number of particles and the mass of Bio-MPs were obtained. Finally, enzymatic biomarkers were measured in exposed organisms: Catalase (CAT), Cholinesterase (AChE and BChE) and Glutathione-S-Transferase (GST). (d) Results and conclusions derived from the projectPLA was ground with a stainless-steel grinder and sieved using a sieve-array. Sonication and solution of Tween 80 were used to reduce particles aggregation. Particles minor and major axis ranged from 60 to 195 µm and from 90 to 315 µm, respectively. The average area was 0.017±0.007mm2. One milligram of BioMPs was equivalent to 1633±100 particles. Significant effects were observed in analyzed biomarkers: MET inhibited CAT activity compared to Ctrol; MPs inhibited AChE activity compared to Ctrol and MET+MPs; while MET+MPs induced the GST activity respect to all other treatments. No significant difference in activity of BChE has been observed. Our preliminary results show biochemical changes in P. argentinus indicative of oxidative stress, neurotoxicity and detoxification defenses affected by MET and modified by the co-exposure to BioMPs. Further analysis will be necessary to a better understanding of toxicity mechanisms. (e) Policy implications of the project relevant to the selected conference theme, theory and/or practiceThis project expects to contribute to the understanding the risk of BioMPs exposure, alone or in combination with organic pollutants, in species from aquatic environments.