Aquatic toxicity of chemically defined microplastics can be explained by functional additives.

Area of Science:

• Environmental Science
• Ecotoxicology
• Polymer Science

Background:

• Microplastic pollution is a growing concern in aquatic ecosystems.
• Understanding the ecotoxicological impact of different plastic types and their additives is crucial for environmental risk assessment.

Purpose of the Study:

• To systematically investigate the relationship between the chemical composition of microplastics and their aquatic toxicity.
• To compare the environmental impact of petroleum-based polymers (low-density polyethylene, polyvinyl chloride, polyamide) and a biopolymer (polyhydroxybutyrate) with various additives.

Main Methods:

• Manufacture of microplastics (<250 µm and <20 µm) from PE, PVC, PA, and PHB using conventional and alternative additives.
• Standard ecotoxicity tests using marine organisms: microalgae (Tisochrysis lutea), crustaceans (Acartia clausi), and echinoderms (Paracentrotus lividus).

Main Results:

• Aquatic toxicity of conventional microplastics is attributed to leached chemical additives, not physical ingestion.
• Alternative additives did not consistently reduce toxicity, with lawsone showing promise as a replacement for triclosan.
• The biopolymer PHB exhibited distinct impacts on marine plankton, potentially linked to nanometric particle abundance.

Conclusions:

• Chemical additives are the primary drivers of aquatic toxicity for conventional microplastics.
• Biopolymer PHB may affect marine ecosystems through different mechanisms, possibly related to its particle size distribution.
• Targeted assessment of chemical additives and particle characteristics is essential for evaluating microplastic environmental risks.