The University of the Philippines Marine Science Institute (UP MSI) reported iodine-129 concentrations in the West Philippine Sea that exceed levels measured elsewhere in the archipelago. Analyzing 119 seawater samples from the WPS, the Philippine Rise, the Sulu Sea and other sites, researchers found the isotope at roughly 1.5‑1.7 times higher than baseline readings.

Collaboration with the Department of Science and Technology‑Philippine Nuclear Research Institute, UP MSI’s Geological Oceanography Laboratory and the University of Tokyo traced the most plausible origin to the Yellow Sea. Chinese studies link that region’s iodine‑129 to historic nuclear weapons tests and European fuel‑reprocessing discharges, suggesting ocean currents may have carried the radionuclide toward Philippine waters.

Researchers stress that current iodine-129 levels pose no immediate health or environmental threat, but they call for expanded monitoring and tighter regulation of transboundary radioactive material. Funding from the DOST‑National Research Council and the DOST‑Philippine Council for Agriculture and Resources Research and Development will support ocean‑modeling studies to confirm transport pathways.