Mealworms Can Safely Consume Toxic Additive-Containing Plastic Say Researchers

Brandon, Wu and their colleagues looked at Styrofoam or polystyrene, a common plastic typically used for packaging and insulation, that is costly to recycle because of its low density and bulkiness. It contained a flame retardant called hexabromocyclododecane, or HBCD, that is commonly added to polystyrene. The additive is one of many used to improve plastics’ manufacturing properties or decrease flammability. In 2015 alone, nearly 25 million metric tons of these chemicals were added to plastics, according to various studies. Some, such as HBCD, can have significant health and environmental impacts, ranging from endocrine disruption to neurotoxicity. Because of this, the European Union plans to ban HBCD, and U.S. Environmental Protection Agency is evaluating its risk.

Mealworms in the experiment excreted about half of the polystyrene they consumed as tiny, partially degraded fragments and the other half as carbon dioxide. With it, they excreted the HBCD – about 90 percent within 24 hours of consumption and essentially all of it after 48 hours. Mealworms fed a steady diet of HBCD-laden polystyrene were as healthy as those eating a normal diet. The same was true of shrimp fed a steady diet of the HBCD-ingesting mealworms and their counterparts on a normal diet. The plastic in the mealworms’ guts likely played an important role in concentrating and removing the HBCD.

The researchers acknowledge that mealworm-excreted HBCD still poses a hazard, and that other common plastic additives may have different fates within plastic-degrading mealworms. While hopeful for mealworm-derived solutions to the world’s plastic waste crisis, they caution that lasting answers will only come in the form of biodegradable plastic replacement materials and reduced reliance on single-use products.

“This is a wake-up call,” said Brandon. “It reminds us that we need to think about what we’re adding to our plastics and how we deal with it.”

Co-authors of the study include Craig Criddle, a professor of civil and environmental engineering in Stanford’s School of Engineering, a senior fellow at the Stanford Woods Institute for the Environment, a member of Bio-X and an affiliate of the Precourt Institute for Energy. Other co-authors of the study include Sahar El Abbadi, a civil and environmental engineering graduate student; Uwakmfon Ibekwe, an undergraduate student in civil and environmental engineering at the time of the research and current graduate student at Carnegie Mellon University; and YeoMyoung Cho, a senior research engineer in civil and environmental engineering.

The research was funded by the Stanford Woods Institute for Environment, the National Science Foundation and the Stanford Interdisciplinary Graduate Fellowship.

Contacts and sources:Rob Jordanm Stanford Woods Institute for the Environment
Anja Malawi-Brandon, Stanford School of Engineering
Wei-Min Wu, Stanford School of Engineering