How much sand is too much sand?

I love the afternoons when the temperature is not over 85 and the kids and I can play outside. Not necessarily because I am the outdoorsy type, but because my nuerosis (about having everything clean) doesn't seem to rear its ugly head when I have everyone outside. I watched Annaliese happliy using her water gun to single handidly water every blade of grass in our yard, singing "Swing, Swing Night'n Dale", no not a song about a swinger named Dale, a little variation of Cinderella's "Sing Sweet nightingale". I also watched my son, who was holding on to the sand and water table with a death grip, knuckles turning white out of pure fear that he would let go, eating sand. He was having difficulty getting the sand in his mouth with one hand, but by letting go and using both hands, he could have actually learned to stand and eventually walk, and be forced to give up his prime spot on my hip, where he looks down at his sister and with a smurk that says "thats right, those most loved and revered are carried" . I figured one hand full wouldnt hurt him, and since I was comfortably lodged into my chair with iced tea, I didnt want to make any rash decisions that would result in me to having to get up. I did eventually get up, when he learned the shovel can get more into his mouth than his hand alone, and diverted his attention to the grass, but gave up on outside time completly when he found the roly poly.