Actualy mental retardation is PC. The only reason why it sounds worse is becasue people use it in a dirogatory way. For example using it as an insult.
Mental retardation and mentally challenged are both PC.
Wow. You did a [b]SUPER[/b] job writing this article! I've never heard of Pica, but it makes sense. I saw an episode of [b]Ripley's Believe It or Not[/b] and some guy ate nails for breakfast.