If I had to guess.... I'd say it's not "face melting drop-dead in the street doom" but "slow increase in number of cancer cases" type of situation. It won't be sudden and dramatic. You will see a very slow increase in the number of problems. Maybe more deformed children, more leukimias and cancers, etc. It will happen slowly over many years and because of this people will be able to ignore it basically forever. The government will ignore it and manipulate statistics.

Japans society is very very good at denial and lying to itself.