Toxicity of Commonly Used Plasticizers to the Freshwater Organisms Tilapia sparrmanii (Fish) and Caridina nilotica (Shrimp): Lethal and Sublethal Effects.

The toxicity of microplastics in aquatic environments is usually due to plasticizers, the chemical additives that keep the plastic polymers together. Thus, the current study reports on the toxicity of three common plasticizers found in freshwater ecosystems and their impacts on two South African freshwater organisms at the organismal and biochemical levels. Tilapia sparrmanii (fish) and Caridina nilotica (shrimp) were exposed to varying concentrations of the test plasticizers, including bisphenol-A (BPA), calcium stearate (CAS), and dibutyl phthalate (DBP). The impacts of these plasticizers on mortality and biomarkers (acetylcholinesterase activity and lipid peroxidation) were investigated using 96-h short-term static nonrenewal and 21-day long-term static renewal exposure methods, respectively. All experiments were conducted in temperature-controlled rooms. Mortality was determined after 96 h, while biochemical effects were measured after 21 days. The results revealed that all three plasticizers significantly affected the mortality of both organisms. Also, acetylcholinesterase activity per unit protein in shrimp decreased significantly at all levels of exposure, while lipid peroxidation increased significantly at all levels of exposure. This study has shown that short-term and long-term exposures to the tested plasticizers could adversely impact populations of the tested organisms at both the organismal and biochemical levels.