Scientists Forge New Metric to Quantify Plastic's Harm to Marine Life

The growing threat of plastic pollution to marine biodiversity is well-documented, yet its impact has been notoriously difficult to quantify in a standardised way. This has limited its inclusion in crucial environmental tools like Life Cycle Assessment, which help us understand the overall sustainability of products and processes.

To solve this, a new study introduces a 'global effect factor' for plastic ingestion. This powerful metric measures the 'potentially affected fraction of species' (PAF), essentially calculating the proportion of species likely to be harmed at a given concentration of plastic debris.

The research team built their model by analysing extensive data on plastic ingestion in stranded and bycaught air-breathing marine vertebrates—including seabirds, sea turtles, and marine mammals—across eight major ocean basins. By establishing dose-response relationships, they derived a robust factor that links plastic density in the water to ecological harm.

This is a critical step forward, enabling the physical effects of plastic ingestion to be integrated into sustainability modelling for the first time, placing it alongside other major environmental stressors.