Thomas Bogle has worked in the footwear industry for years. He also loves to run. He runs every day in the forest near his home in Colorado. But while training for a race, he couldn't stop thinking about the bits of plastic and rubber that his shoes were shedding on the forest floor.
With every step we take, our shoes leave behind an invisible trail of contaminants(污染物). These contaminants can potentially harm the soil, water and animal health.
Shoes contain different types of plastics. Every year, about 500,000 tons of microplastics seep into the world's oceans. Microplastics are tiny pieces of plastic. They form as larger plastic objects break down. They can harm living things and the environment.
Now, several companies are starting to develop plant-based soles (鞋底). They don't leave plastics behind when they break down. Plant-based soles address some of these issues. They won't shed plastic into the environment. Plus, they generate fewer toxic chemicals. But shoes made with natural materials face some of the same challenges as plastic-based shoes once they're thrown out. Taking the shoes apart is still hard. Recycling shoes will require setting up new systems.
Bogle had an idea to create an entirely plastic-free shoe outsole. He got some help from Gene Kelly. He is a professor of soil science at Colorado State University and a fellow runner. Together, Bogle and Kelly developed a shoe sole. It is made of beeswax, vegetable oils and plant products such as leaves and husks from corn and other crops.
Bogle's company, Solum, partners with farmers across the country. The farmers grow and harvest the plant materials. Then, the materials are transformed into little plant balls and blended with natural rubber to create the sole. Solum's shoes don't shed toxic chemicals. Instead, the soles put nutrients back into the soil as they naturally wear down over time.
These days, Bogle runs, hikes and golfs in shoes with his company's plant-based soles. "Footwear is a very hard product to fix," he said. "It really requires completely shifting how we think about footwear and how we make footwear and the materials we use."