The Japanese government has told people not to eat the vegetables, and not to drink the water, because of radiation contamination.  At the same time they say “There is no immediate threat.”

What they mean by that is, that the levels, and types, of radiation contamination is such that you will not notice any bad effects “immediately”.  However, if you continue to eat, drink, or expose yourself to even the lowest levels of contamination, over time you will suffer bad effects.

For example: Iodine-131 is a short life span radioactive isotope. It collects on your thyroid glands (just like iodide), and if it builds up will cause cancer. Even low levels of iodine-131 will build up on your thyroid if you keep eating, drinking, or exposing yourself to the contamination.  This is why the Japanese government is telling people to stop eating the vegetables, and stop drinking the water, even though there is no “immediate” threat.

In other words, it’s still bad, bad, bad!