I found these two paragraphs an interesting summation:
It's a solid start. But once you look down the rabbit hole, in southeastern China (nexus of the global shoe-manufacturing industry), in research labs, and in our own closets, it turns out that a corporate commitment to build a green shoe is the easy part; the devil is in the details. Environmental impacts, carbon footprints, and toxic substances are hard to gauge in a product with 50 components coming from dozens of different places. The supply chain is hard to identify, much less influence.
Take bamboo, for example. END "infuses" its sockliners with the renewable plant. But Oboz does not. "We explored the process of taking raw bamboo and turning it into a textile, but it requires the use of very strong solvents," says Oboz cofounder Josh Fairchilds. There are similar problems with glue. Is it better to use a nontoxic water-based glue that requires more heat (and thus energy), or is it better to use a more hazardous solvent-based glue as long you use the solvents really carefully? In this manner, each brand has to evaluate its priorities: toxins versus climate change; renewable energy versus renewable materials. Almost every change has its consequences.
Even so, it is important to keep trying to find a better solution. Many shoe companies have made improvements including: reducing the amount of materials in the shoes, reducing the amount of waste, increasing recycled content (though still a small percentage), creating a shoe that biodegrades 50 times faster, and creating programs that collect shoes for recycling and reuse.
It is still an uphill battle. Even beyond the energy, chemicals, etc that go into shoes, this slide show follows a pair of shoes from the factory, to store, to runner, to recycling program - for a total of 12,986 miles. And of course there are the events with their energy use and waste, but efforts are being made there as well. Here are their picks for the ten greenest races and tips on how to be a greener runner.
Damn! Those barefoot runners aren't so crazy after all.