The other issue is small, dense, metallic objects as projectiles in the event of an accident.
``In the US, a one-year-old child travelling in the family car was hit in the head by a mobile phone that cracked his skull, requiring 10 days in intensive care. The greater the speed, the greater the impact. In fact, an object travelling at 80 km/h is four times more potent than one travelling at 40 km/h.''
http://abcnews.go.com/GMA/story?id=128062&page=1
William