Exposure protocol for ecotoxicity testing of microplastics and nanoplastics

Area of Science:

• Environmental Science
• Ecotoxicology
• Materials Science

Background:

• Micro- and nanoplastics (MNPs) pose increasing environmental concerns, yet standardized ecotoxicity testing protocols are lacking.
• Current methods often use simplified spherical particles and chemical-based protocols, failing to account for the variable nature and dynamic behavior of MNPs in exposure systems.
• MNPs do not dissolve and exhibit complex behaviors influenced by their properties and environmental conditions (e.g., pH, ionic strength).

Purpose of the Study:

• To develop and describe a harmonized exposure protocol for micro- and nanoplastics (MNPs) ecotoxicity testing.
• To create a protocol that accounts for realistic MNP properties (shape, size, composition) and their dynamic behavior in exposure media.
• To adapt existing ecotoxicity guidelines for chemical testing to specifically address MNPs in soil and aquatic environments.

Main Methods:

• Procedure 1: Top-down production of realistic MNPs and comprehensive particle characterization (e.g., using thermal extraction desorption-gas chromatography/mass spectrometry).
• Procedure 2: Development of exposure systems for short- and long-term soil organism toxicity tests, modifying existing chemical ecotoxicity guidelines.
• Procedure 3: Development of exposure systems for short- and long-term aquatic organism toxicity tests, adapting chemical ecotoxicity guidelines for MNPs.

Main Results:

• A novel, adaptable protocol for MNP ecotoxicity testing has been established, considering particle-specific properties and dynamic behaviors.
• The protocol includes methods for producing representative MNPs and characterizing them, alongside modified testing procedures for soil and aquatic organisms.
• Successful application examples include testing MNP toxicity in marine rotifers, freshwater mussels, daphnia, and earthworms.

Conclusions:

• The developed protocol provides a standardized approach for MNP ecotoxicity testing, enhancing the reliability of environmental risk assessments.
• This method addresses the limitations of current protocols by incorporating realistic MNP characteristics and behaviors.
• The protocol is versatile, applicable to various organisms and exposure durations (24 hours to 2 months), and suitable for researchers, risk assessors, and industry professionals.