From the IAEA:

“Tritium emits weak beta-particles, i.e., electrons, with an average energy of 5.7 keV (kiloelectron-volts), which can penetrate about 6.0 mm of air but cannot penetrate the body through human skin. It may present a radiation hazard if inhaled or ingested but is only harmful to humans in very large doses.”

If a primary producer like phytoplankton is affected, isn’t it likely to impact impact all species that rely on them as a food source?

How about the real concern regarding the question of chronic exposure? If organisms are consistently taking in tritiated water over extended periods, does that constant exposure increases the chances of tritium being incorporated into critical molecules like DNA or proteins? Do we know the likelihood of that leading to long-term biological effects?

Can’t the tritium in tritiated water be incorporated into organic molecules during metabolic reactions? Have we observed the effects of tritium during biosynthesis, where water is a reactant or byproduct? During photosynthesis in phytoplankton, do we know the extent of tritium from tritiated water being incorporated into glucose or other organic molecules?

When marine organisms ingest or absorb tritiated water from their surroundings, it will circulate through their body just like regular water. Since tritiated water behaves chemically like regular water, it would surely be used in all physiological and biochemical processes within the organism.

Do we know the possibility for tritium to become incorporated into marine sediments, especially if it binds with organic matter? Could this create localised hotspots where tritium concentrations are higher than in the surrounding water? If so, won’t benthic organisms (those that live on the ocean floor) be exposed to these at those higher concentrations?

My biggest concern is the possibility of bioaccumulation in the food chain. Granted this would mostly impact small organisms to start, but they would then be consumed by larger predators, and how long before this leads to increased concentrations in apex predators?

I think it’s incredibly foolish for anyone to release water of this nature, Japan or otherwise.