evidence: Throwing out your pleather once you don’t want to wear it anymore can be a problem. "It is synthetic," said Sonali Diddi, an associate professor in the department of design and merchandising at Colorado State University who researches sustainable clothing production and consumption. "It’s never going to biodegrade." [...] And, he noted, traditional leather tanning often uses heavy metals, most notably chromium, and the resulting waste is a health hazard and could pollute waterways if facilities don’t have proper safeguards in place. Groups such as the Leather Working Group and Oeko-Tex offer sustainability certifications for leather. [...] These textiles could be more sustainable than pleather because they’re plant-based and they don’t require tanning like animal leather, Diddi said.