Microplastic Particles’ Effects on Aquatic Organisms and Their Role as Transporters of Organic Pollutants

Microplastic (MP) contamination is considered a growing problem in terms of its production and observed impacts on aquatic organisms. In this study, we investigated the adverse effects that could occur from pure polyethylene (PE) MPs and PE contaminated with phenanthrene (Phe) and chlorpyrifos (CPF) in D. magna and podocopid ostracods. The organisms were exposed to different sizes (1–5, 27–32, 45–53, and 212–250 μm) and concentrations of MPs (0, 16, 160, 1600, 16,000 particles/mL) using a static and dynamic model of exposition. The results indicate that both daphnia and ostracods can ingest MPs, and the effect observed in most cases is directly proportional to the concentration of MPs. Exposure to pure MP did not affect the organisms. However, at 21 days, they induced a significant decrease (p < 0.05) in neonatal daphnia compared to the control. MP + CPF negatively affected the crustaceans when concentration, and exposure time were increased and when the size of the MPs was decreased. Neonatal daphnia were the most sensitive compared to juveniles and adults. MP + Phe caused mortality when increasing the concentration of MPs and in D. magna juveniles with increasing size, while in ostracods, mortality increased with decreasing particle size. The effect of the MPs in crustaceans would depend on the concentration, exposure time, size of the organisms, and size of the MPs. It is also shown that the toxicity of PE increases when these particles are associated with a contaminant, which would indicate its role as a transporter of organic contaminants.