Table 2 Workshop recommendations. ANDROMEDA workshop recommendations summarised per participant group, which were scientists and researchers in Workshop 1 and policy and decision makers in Workshop 2

Limitations of the research and data should be clearly stated to show that the work focuses on cost-effectiveness only, and that the quality of the method is not included in the survey. Additionally, the calculations are not general but pertain to a specific size of microplastics.

There needs to be a clear distinction between assessing methodologies and approaches focused on research and for monitoring when considering cost-effectiveness.

Scientists need to actively engage with policy and decision-makers concerning the definition of what to measure for the purposes of government monitoring programmes, ensuring that the data being collected is put into perspective.

It is important to feed approaches on cost-efficiency into monitoring programmes that are comparable across the EU and what is used at a wider international level, so that an accepted and feasible approach for microplastics monitoring can emerge. Considerations should be given to what is currently being done. It will be necessary to determine the easiest way to examine trends.

Affordability and cost-effectiveness should be considered in the context of gross national income (GNI) and gross domestic product (GDP).

Cost-effectiveness is of great importance in a monitoring framework and developed approaches must be accessible to and feasible for all Member States and contracting parties.

Should incorporate environmental factors, such as seasonal disruption and the organic matter content of samples, to obtain a more detailed picture of costs that occur for different size classes.

Should incorporate other criteria that are important for monitoring and environmental parameters that are mandatory and link to source emissions for microplastics.

Should consider costs based on the findings of inter-collaboration studies between institutes that apply different methodologies and techniques but get comparable results.

Should consider a repetition of a similar survey that includes a wider stakeholder community with focus on policy needs, harmonisation, and what is feasible for all.

Include calculations that use less expensive equipment or protocols and adjust for different batch level sizes.

Should reflect on how to develop approaches that can support the European Commission’s Zero Pollution Ambition and associated environmental monitoring requirements.