Difference in sensitivity of Daphnia magna to pristine and aged microplastic fibers

Plastic production has increased considerably in recent years, leading to an increase in plastic pollution. High concentrations of microplastics (MPs) are found in aquatic environments, which can have a wide range of effects on organisms. A large proportion of these microplastics are fibers, used mainly in textiles. Once released into the environment, these fibers undergo degradation processes that can alter them and therefore modify their toxicity. This is why it is important to carry out studies comparing the toxicity of new materials versus degraded materials, which are more environmentally representative. The aim of this study was therefore to investigate the toxicity of 3 different plastic fibers (polyamide, polyacrylonitrile and polyester) and two natural fibers (wool and cellulose) as reference materials. All fibers were cryomilled and then sieved (¡ 63µm) before being aged using a UV-C chamber for 20 days. The fibers were then characterized using SEM, FTIR and a Coulter Counter (size distribution). The experiment was carried out on Daphnia magna, a sensitive crustacean species found worldwide and playing a key role in freshwater ecosystems. Acute and chronic toxicity were assessed in accordance with OECD recommendations (202 and 211 respectively). Mortality, reproduction, growth, and oxygen consumption were investigated. This study contributes to improve knowledge of the toxicity of fibers, particularly aged fibers, and is therefore relevant to current environmental problems. Also see: https://micro2024.sciencesconf.org/559198/document