To think that Tritium radioactive treated water from Fukushima is safe just because it takes 12 years of Tritium to decay to half of its original amount, or that the concentration of the treated water is only 190 becquerels of Tritium per liter, well below WHO standard of 10,000 becquerels for safe drinking water is rather misleading.
Regardless of the risk factor, there's a significant difference between accidental, less frequent exposure vs constant, daily exposure. When Tritiated Water (HTO) is poured into the ocean, it may or may not become Organically Bound Tritium (OBT) in the body when you eat Tritium exposed raw fishes. Thus the accumulation of this daily exposure will bring should be matter of concern to study.
Furthermore, if it is safe to drink, and 12 years have already passed since the nuclear accident, then Japan should simply desalinate and drink all of the treated water to proof the argument. But Japan won't. Japan wants Koreans, Chinese, Taiwanese, Hongkongers, Macanese, Filiphinos, fishes and marine animals to proof the argument along with them.