cab drivers, people who are on the move all day long. so they're essentially leaving that source next to their head the whole time. it's tough to say at a low dose what that's going to do. but it's the duration. and in this case years of doing that, that is potentially the problem. >> incredibly eye-opening for me at least. sanjay, thanks. >> thanks, anderson. coming up, an update to the number of people missing and dead in the aftermath of the devastating tornado in joplin, missouri. we have the very latest next. also ahead, people flock to florida's beaches for the memorial day weekend and find they have some unwelcome company. we'll tell you about the great stinging jellyfish invasion of 2011 coming up. [ male announcer] breathe, socket. just breathe. we know it's intimidating. instant torque. top speed of 100 miles an hour. that's one serious machine. but you can do this. any socket can. the volt only needs about a buck fifty worth of charge a day, and for longer trips, it can use gas. so get psyched.