So today I came in from outside and found my 2 yr old sucking on my one piece airlock. It was empty. Only thing is... it was full of starsan last time i looked. Worst case is that he swallowed about 25ml or so of properly diluted starsan. I'm not really worried, but I gave hims something to drink to dilute it further. It was probably about 3 weeks old, on the bucket of Guinness clone that I am about to keg/bottle. I've drank diluted starsan before by accident, to no ill, and really am not worried, but you bet your ass, from now on i'll just be using some water.