Japanese scientists created a plant-based plastic that completely dissolves in salt water within hours, leaving no microplastics behind.

The core claim is supported by the Japanese research organization RIKEN, which reported in December 2025 that its plant-based material decomposed completely in artificial seawater within two hours and left no microplastics behind. EurekAlert, Phys.org, and Plasticstoday reported the same study and described the material as using cellulose-based or otherwise plant-derived components.

Reuters and The Independent had earlier reported, on June 4, 2025, that a Japanese research team demonstrated a related plastic-like material disappearing in a container of salt water after roughly an hour of stirring. These reports support the general claim that Japanese scientists created a saltwater-dissolvable plastic, but they provide less precise evidence for the specific plant-based formulation and the zero-microplastics result later described by RIKEN.

The important qualification is that “salt water” in the strongest evidence means artificial seawater under laboratory conditions. The findings do not establish that every product made from the material will dissolve within hours in the open ocean, nor do they by themselves demonstrate safety and complete degradation across different temperatures, salinity levels, thicknesses, additives, or disposal environments. “No microplastics” is accurate as reported for the tested material and conditions, but it should not be interpreted as proof that all environmental breakdown products are harmless or that the technology is already commercially established.