I agree wholeheartedly about not concealing origin information when food may contain things potentially impactful to their health. The difference is that even drinking straight tritiated water (at the Japanese release concentration) as your only beverage for an entire year is 1/10th the exposure you would get from a single mammogram. There is zero potential for any health impacts from this release of tritiated water. I direct your attention to this well-sourced chart from Randall Munroe to give a good visual on different relative radiation doses. One year of drinking tritiated water at a concentration of 1500 Bq/L (the concentration its being released at, and about 1/10th of the WHO limit) gives a dose of approx. 40 μSv, the same as the cross country flight in the above graphic.