it's in our food, in our water, in our teeth. so radiation isn't dangerous in an everyday sense. and there's enormous variation in different parts of the world. >> do you have any numbers just to put that into kind of a context? >> the units are difficult. it's rays and milligrams and all this kind of thing. the numbers are not familiar to people in any way shape or form. if i said to you the radioactivity is only 400 more millisieverts that wouldn't mean anything to you. >> reporting radiation levels are as confusing as they could possibly be. >> has just about 0.7 rem. you have to get up to 50 to 75 rem. >> we hear rem, microrem, millirems, a lot about millisieverts.