i would be very very careful with those dryers, the guy who said it is not a danger is WRONG! one of the number 1 causes of house fires is DRYERS! people turn them on, leave or go to bed, the dryer heats up, the built up lint is very combustable.
a dryer should NEVER be left running, and should be checked on. it is not always enough to just clean out the lint-trap, lint gets by them and can build up in the hose that takes the exhaust outside, when that gets plugged big fire danger! my hubby (who works in the propane industry) insists that the outside hose be taken apart and cleaned out once a month, the lint trap of course every load, and even if i'm just going to run to the corner store and back i have to shut it off before going out the door.