I am not aware of anything which makes Silver Biotics "the safest" other than perhaps their advertising.  The key is to get a product which 1) has no added ingredients, 2) has ultra small particle sizes and 3) has high true colloidal silver content.  I know of only two products which meet all three criteria:  CureZone sponsor Utopia Silver's Advanced Colloidal Silver and Purest Colloids Mesosilver - both of which have only silver and water, particles sizes to 0.065 nanometer and have true colloidal content of 85% or more (compared to ionic silver solutions which call themselves colloidal silver but have 15% or less true colloidal content).

Insofar as safety and turning yourself blue, most silver solutions - including what you make at home - are safe and you really have to work very hard at making large particle, added ingredient, overly strong silver and consume a very large amount for a long time to turn blue - which is why "blue people" are extremely rare despite millions of people taking colloidal/ionic silver.  Just stay away from the added ingredients and the ultra high PPM products (anything over 20 PPM is really more than needed).