HIGH TRACES OF iodine 129, an isotope used as an indicator of nuclear activity in seawater, were found at the West Philippine Sea, the University of the Philippines Marine Science Institution (UP-MSI) said.
According to UP-MSI, the nuclear indicator could have come from elsewhere since the Philippines neither operates nuclear power plants, nor does it have the financial capability to buy nuclear weapons.
The UP-MSI suspects the traces of iodine 129 could have been swept to the Philippine waters from the Yellow Sea which is located near Korea and that of the Bohai Gulf off the northern coast of China.
TESTING GROUNDS
Citing historical accounts, both seas are where old nuclear weapons from Europe are tested. It also hosted nuclear fuel reprocessing facilities.
UP-MSI said the concentrations found in the WPS were higher than in any other part of the country, despite the Philippines having no active nuclear power plant or nuclear weapons program, reads part of a report published by the Philippine Star.
The findings are based on an analysis of 119 seawater samples collected from the WPS, the Philippine Rise, the Sulu Sea and other areas across the archipelago.
Researchers found iodine-129 levels in the WPS to be about 1.5 to 1.7 times higher than those recorded in other sampling sites.
POSE NO THREAT
The study was conducted by experts from the Department of Science and Technology-Philippine Nuclear Research Institute, UP-MSI’s Geological Oceanography Laboratory and the University of Tokyo.
The study added that iodine-129 may have reached Philippine waters through ocean circulation systems, particularly the Yellow Sea Coastal Current and the Chinese Coastal Current, though further oceanographic modeling is needed to confirm the transport pathways.
While iodine-129 is radioactive, the researchers said its current levels in the WPS pose no threat to human health or the environment.
RADIOACTIVE WATCH
They also underscored the need to strengthen monitoring and regulation of radioactive materials, especially those that cross national boundaries.
The research was funded by the DOST-National Research Council of the Philippines and the DOST-Philippine Council for Agriculture and Resources Research and Development.
Iodine-129 is a long-lived radioactive isotope, primarily from human nuclear activities, that acts as an environmental tracer for nuclear pollution, water movement and geological processes due to its extreme persistence (millions-year half-life) and mobility, especially in water, making it useful for tracking nuclear releases but also a long-term radiological concern in contaminated areas like groundwater and oceans, often studied via its ratios with stable iodine.
FUNCTIONS, IMPACT
Scientific data showed that iodine 129 acts as environmental tracer since its unique signature from nuclear reprocessing and testing allows scientists to map ocean currents, groundwater flow and dispersal of nuclear contamination over vast distances.
Additionally, iodine 129 is an indicator of nuclear pollution where high levels signal past or present nuclear activities, serving as a marker for radioactive releases from facilities or accidents, as seen in recent West Philippine Sea studies.
While its levels in seawater might not be immediately harmful, its long half-life means it is a persistent contaminant that can accumulate in the thyroid, posing a long-term health risk, especially in contaminated groundwater.
Iodine 129 also participates in natural iodine cycles, influencing atmospheric chemistry and accumulating in marine life, particularly brown algae (kelp). The term used here is biogeochemical cycling.
DREADED SOURCES
Iodine 129 can come from nuclear fuel reprocessing where the isotope is released into the environment; from past atmospheric tests that dispersed it globally; from releases from nuclear accidents at nuclear facilities; and from natural occurrences but in smaller, less significant amounts.
In essence, Iodine-129 is a persistent “radioactive fingerprint” that helps us understand large-scale environmental transport and monitor nuclear contamination, despite being a long-term radiological concern.
It has a long half life of 15.7 million years produced by human activity such as nuclear fuel reprocessing, weapons tests, and reactor accidents. Because of its longevity and mobility in water, it is used by scientists as a tracer to map ocean currents and detect nuclear pollution.
The West Philippine Sea 2026 Trace Detection (2026) was participated by researchers from UP MSI, in collaboration with the DOST-PNRI and the University of Tokyo, detected “unusually high” levels of Iodine-129 in the West Philippine Sea (WPS).
The source of isotope traces was likely from the Yellow Sea and Bohai Sea in China, where the isotope was deposited from decades-old nuclear reprocessing and weapon tests.
RESEARCH PURPOSES
Scientists emphasized that the levels, while elevated, pose no immediate threat to public health, fisheries, or the marine environment.
Iodine 129 is used in studies to determine the age of old groundwater.
Also because it lasts millions of years, it is considered a key factor in selecting sites for high-level radioactive waste disposal, ensuring that waste containers can isolate the material for geological timeframes.