Overview
- Published in PNAS, the analysis drew on 10,412 necropsies across 57 seabird species, all seven sea turtle species, and 31 marine mammals to model species‑ and material‑specific lethal doses.
- For a bird the size of an Atlantic puffin, less than three sugar cubes of ingested plastic corresponds to about a 90% chance of death, while six pea‑sized pieces of rubber reach 90% mortality in seabirds broadly.
- Loggerhead sea turtles face a 90% mortality risk at roughly two baseballs’ worth of plastic, and some marine mammals reach similar risk at about a soccer ball’s volume.
- Risk varies by material: synthetic rubber and hard plastics were most lethal for seabirds, soft and hard plastics for sea turtles, and soft plastics along with discarded fishing gear for marine mammals.
- The estimates reflect acute gastrointestinal trauma only and exclude entanglement and chronic toxicity, leading the authors to warn the thresholds likely underestimate overall harm as they urge bans on high‑risk items and stronger waste controls.