The magnets used in MRIs are causing an increasing frequency of accidents:

The pictures and stories are the stuff of slapstick: wheelchairs, gurneys and even floor polishers jammed deep inside M.R.I. scanners whose powerful magnets grabbed them from the hands of careless hospital workers.

Hospital monitoring equipment sucked into an M.R.I. scanner.

The police officer whose pistol flew out of his holster and shot a wall as it hit the magnet. The sprinkler repairman whose acetylene tank was yanked inside, breaking its valve and starting a fire that razed the building.

But the bigger picture is anything but funny, medical safety experts say. As the number of magnetic resonance imaging scanners in the country has soared from a handful in 1980 to about 10,000 today, and as magnets have quadrupled in power, careless accidents have become more frequent. Some have caused serious injuries and even death.

(McNeil, "M.R.I. Scanners' Strong Magnets Are Cited in a Rash of Accidents", NY Times, Aug.19)