Apparently the chemical reaction gets worse as time goes by whether or not you wear the shoes. She said that it didn't even hurt at first, just made red marks on her feet which is why she continued to wear the shoes. I hope Wal-mart takes this seriously and looks into what is going on. I would worry about this showing up in those clogs that they make for children.
Here you can see the full extent of the burns. WARNING - graphic pics
http://www.consumerist.com/photogallery/kerry.s-feet/
Here is her website
http://www.lamanaphotography.com/walmart.htm