i've read so much about this that i almost can't buy shoes anymore (well, or anything, really, but that's my problem). there are so many factors, but i think it's often a draw. here's a slate
article:http://www.slate.com/articles/health_an ... ather.html
i'll try to pull together better resources when it isn't midnight, if someone doesn't beat me to it.
eta: moo shoes and novacas use a pvc-free vinyl for their shoes, and that's generally more environmentally friendly. if the company she's writing for uses something similar, that's something to draw attention to.