I am finding that most children's sandals have some sort of antimicrobial treatment. For instance, Keen uses an Aegis technology and Teva uses a Microban technology. They say that the Microban is " environmentally friendly zinc technology". I am pretty partial to the Keens b/c they work well for my son, and I feel that they protect his feet really well. the Aegis website says that it doesn't leach to any other organism it comes into contact with. I read somewhere on here or another parenting forum a few years back by a mother of a child with autism that she would not use any clothing/shoes that had antimicrobials. I can't remember why. Can anyone shed any light on this? It is going to be hard to find shoes w/out the treatments it seems.