EVA actually stands for Ethylene Vinyl Acetate and is a polymer widely used in a number of applications – from biomedical engineering to photovoltaic modules (solar panels). In the case of footwear, these companies are using the expanded rubber of foam version forms of the polymer. The reason EVA is considered more eco-friendly is that it doesn’t use chlorine in its production. This means there is less toxicity released during degradation in a land fill somewhere if you discard your shoes.