The key to understanding the good, bad, and eco-ugly of both options—and therefore making the best decision as a consumer—explains Northwestern University’s Eric Masanet, PhD, is to consider the impact of each part of the product’s life cycle from cradle to grave. “The science shows that moving from plastic to paper is not necessarily ‘greener,'” he says. Instead, it may simply shift the environmental impact from decreasing litter to increasing resource use and greenhouse gas emissions.