Sammendrag
On one side, recent finding on plastic toxicity from particles to chemical leachates pose a risk for environments, freshwater ecosystems, and raise concerns towards Human Health. Thus, European community have undertaken preventive measures with implementation of the EU Single-Use Plastic Directive, and the Packaging and Packaging Waste Regulation which aim to reduce plastic waste and abolish the use of single use plastic by 2030. Consequently, new plastic alternatives have emerged such as recycled plastic materials. However, such plastic might accumulate more chemicals and additives over their life cycle and so far, toxicity of such recycled materials, of their leachates and degradation products in the environment is still unknown. On the other hand, behavioral ecotoxicology is emerging as a new tool to assess water contamination and ecosystems health. Freshwater Cladocera Daphnia magna is one of the most used model organisms in ecotoxicology. However, due to a lack of standardization, only a few studies have yet included sublethal endpoints despite behaviors being more sensitive to chemicals exposure than reproduction and survival. Additionally, recent studies suggested the existence of a link between behavioral impairments and oxidative stress under microplastic exposure, but no correct evidence was found yet. Thus, in study, behavioral alterations were investigated in parallel with oxidative stress via the development of standardized behavioral swimming tests and of protocols for quantifying oxidative stress measurements methods.
This study also assessed the toxicity of methanolic plastic extracts of pristine, recycled and commercial recycled printed plastic bags called “Shop” on daphnia, before and after
UV-degradation. The study focused on sublethal endpoints and oxidative stress. Thus, after 21-days chronic toxicity test, horizontal, vertical and phototactic swimming were monitored in combination with reactive oxygen species (ROS) and lipid peroxidation (LPO) measurements. Significant disturbances of swimming behaviors were observed for high extract concentration of shop non-degraded, low and medium extract concentration of recycled degraded and all concentrations of shop degraded. Loss of phototaxis was noticed for shop degraded extracts. However, no evidence of oxidative stress was found due to a lack of sensitivity of ROS and LPO methods. Additionally, no clear link between behaviors and oxidative stress has been established observed. Some tendencies might suggest a “cocktail” effects and antagonistic interactions between chemicals released by
non-degraded and degraded extracts, which could lead to muscular, visual or neuronal toxicity. Further studies on plastic chemicals interactions would be necessary to understand the mechanisms of toxicity of recycled materials such as bottom-up experiments screening for pollutants linked to “cocktail” effect and behavioral impairments.
