Good short article here by Manninen, http://www.sportsnutritionsociety.or...45-51-2004.pdf
Not to fond of the millions of years in the intro, but the rest is pretty darn accurate!
Couple years back, but many may have not read it.
There are numerous other ones like this. Not only has protein been shown to be safe, but there are countless health benefits. Not only that, but it clearly is the key macronutrient for growth and optimal body composition (both for lower fat mass and greater lean body mass).