Many sustainability-minded consumers likely assume that reusable products have fewer environmental impacts, but just how green are they? A new study uncovers some surprising and counterintuitive results.

These consumers are moving away from single-use plastic products and turning to reusable alternatives. In the kitchen, trendy alternatives include bamboo drinking straws and beeswax sandwich wrap.

To compare the lifetime environmental impacts of common kitchenware products—both single-use plastics and reusables—researchers looked at consumer kitchenware products in four categories: drinking straws, sandwich bags and wraps, coffee cups, and forks.

They calculated the environmental “payback period” for reusables, defined as the number of times a product must be reused before its environmental impacts per use equal those of a comparable single-use plastic product.

They found that some reusable alternatives never manage to reach that break-even point because of the energy and water used each time a reusable item is washed.

For example, reusable bamboo drinking straws and two reusable sandwich storage options—beeswax wrap and silicone bags—never reached the break-even point in any of the three environmental impact categories assessed in the study: energy use, global warming potential, and water consumption.

“Reusable alternatives have quickly become a popular solution for replacing single-use products and helping to combat the ubiquity of disposable plastic,” says Shelie Miller, an environmental engineer at the University of Michigan’s Center for Sustainable Systems, which is based at the School for Environment and Sustainability.

“But don’t always assume that reusable is the best option,” says Miller, senior author of the study in the International Journal of Life Cycle Assessment. “Our study showed that some reusable alternatives never break even because it takes more energy, and generates more greenhouse gas emissions, to wash them than it takes to make the single-use plastic item.”

Read the full article about reusable products by Jim Erickson at Futurity.