Wow - I wasn't expecting much interest before the show. I'm going to have to step out from time to time for coffee (and I'll have to stop typing during show), but let me see if I can try to help out. And also, don't worry about the "Doctor" part - I really prefer Andy. My great-uncle was Dr Karam - he delivered babies and made people feel better. I usually just put my students and co-workers to sleep, so I'm not sure it really applies to me. Anyhow...
So - David - in all honesty, I wouldn't worry about the health effects on our side of the Pacific. In fact, I was in the area just a few weeks after the accident and I didn't see anything in Japan that really worried me. We can measure radioactivity in such small quantities that, just because we can see it, doesn't mean it's dangerous. In fact, the World Health Organization concluded that there will likely be very few - possibly no - serious health effects even in Japan. So here in North America we really don't have anything to worry about from the radiation from Fukushima. This is not to say that it's not a disaster and that it's nothing to be upset about - but it's NOT going to make us sick. Believe it or not, I picked up more radiation exposure on the flights to and from Japan than in 10 days on the ground!
With respect to Dr. Kaku, he's a smart guy, he knows a lot of physics, and he does a great job of communicating his knowledge to the public. But I hate to say that he's not an expert in radiation safety and I think he's a little too dire in his predictions. In the case of environmental contamination, environmental health effects, and human health effects I'd rather defer to the World Health Organization on this one - I think he's over-estimating the risks quite significantly.