if you google it you will find that its not a mental disorder....

in some locations its taught to do these things as survival tools to prevent dehydration and starvation

if you read the religious book the bible there are also many references to doing these things.

in some cultures doing this is also a rite of passage at certain ages

according to google its also pretty normal for children to do these things just to see what its like or as a dare or if they have watched any of these horror shows or reality shows like fear factor and others that require the contestants to eat such things.

ultimately we can not tell you what this is in your friends daughter, only your friends daughter and their own treatment providers can tell you that...

my suggestion is ask the daughter why she did that or leave the issue up to the daughter and the parent to solve.