WHY DONT RUNNING SHOES BIODEGRADE?
Every manmade object — all the things in our homes and workplace — has an invisible back story, a litany of sorry impacts over the course of the journey from manufacture to use to disposal. Take running shoes. Despite the bells and whistles meant to make one brand of running shoe appeal more than another, at base they all reduce to three parts. The shoe’s upper consists of nylon with decorative bits of plastics or synthetic leather. The “rubber” sole for most shoes is a petroleum-based synthetic, as is the spongy midsole, composed of ethylene vinyl acetate. Like any petrochemical widget, manufacturing the soles produces unfortunate byproducts, among them benzene, toluene, ethyl benzene, and xylene. In environmental health circles these are known as the “Big Four” toxics, being variously carcinogens, central nervous system disrupters, and respiratory irritants, among other biological irritants. Those bouncy air pockets in some shoe soles contain an ozone-depleting gas. The decorative bi
