I came to a realization after being (not so nicely) corrected by a member of another forum about the actual mechanism by which StarSan sanitizes. It's not the low pH that burns/melts/destroys organisms, apparently. StarSan is classified not as an "acid sanitizer," but as an "acid-anionic" sanitizer. So I Google "acid-anionic sanitizer," and from what I can gather what these do is facilitate some kind of anionic attraction that sort of pulls proteins out of the cell walls via some kind of ionic/anionic molecular charge*. This reaction is facilitated somehow by the low pH of the environment (likely because pH itself, and acidity/alkalinity, is a function of the concentration of certain ions).
Someone said earlier in the thread that it's considered a "weak acid." Well, a pH of 3 is certainly an acid, but it's absolutely not a melt-your-skin-quickly kind of acid. Stomach acid (ever had reflux?) has a pH of 1 to 2, and even that takes a while to erode the esophagus in chronic sufferers. Is vinegar safe? Lemon juice?
pH of 2, more acidic than even a strong StarSan solution [
http://www.epa.gov/acidrain/education/site_students/phscale.html]
*It's hard to find public info, at least, about what goes on here, but this page:
http://edis.ifas.ufl.edu/fs077 describes a similar class of sanitizers (QACs) as such:
"Since QACs are positively charged cations, their mode of action is related to their attraction to negatively charged materials such as bacterial proteins." Followed directly by the description of acid-anionic sanitizers as:
"Like QACs, acid-anionic sanitizers are surface- active sanitizers. These formulations include an inorganic acid plus a surfactant, and are often used for the dual function of acid rinse and sanitization.
Whereas QACs are positively charged, these sanitizers are negatively charged. Their activity is moderately affected by water hardness. Their low use pH, detergency, stability, low odor potential, and non-corrosiveness makes them highly desirable in some applications."
So in terms of acids, StarSan is pretty safe -- it doesn't sanitize by corroding things to death, there's some molecular stuff going on that's specifically harmful to single-cell type organisms, that's only facilitated or enabled by the low pH.
EDIT: I'm talking about a properly-diluted solution. Obviously the concentrate itself is pretty corrosive. I don't know what the pH would be before dilution.