...all over the place

A small, but possible chance of Pu-238 spreading over Florida. I just read that 238 (half-life 87 years) emits mostly alpha, which is said to be easily blocked, even by paper. In FL, many go about half naked, so I'm not sure if this matters. I wonder how thoroughly Kaku considered everything.

Seems his concern was based partially on NASA's (small but not null) history of failures. I don't know, but doubt he was being deliberately unreasonable. Maybe his Japanese (distant) ancestry was a factor? Publicity would be a surprising motive. So would general ignorance.