Starch-based plastics, which are derived from treated starch from plants, may not be as safe or environmentally benign as previously assumed. Composed mainly of starch and typically blended with other biobased polymers such as polylactic acid (PLA), starch-based plastics were hailed as a green alternative to conventional plastics and are now widely used in everyday products like food packaging and disposable cutlery. These natural polymers readily degrade in the environment, aided by the action of microbes in the soil, but evidence increasingly suggests that this breakdown process may take longer than originally predicted. For Yongfeng Deng, a geomaterials researcher at Southeast University in China, the most worrying consequence of this incomplete breakdown is the accumulation of biomicroplastics in environmental media and, ultimately, the food chain.
While many studies have examined the health implications of ingesting petroleum-derived microplastics, none have looked at the long-term health effects on a living organism ingesting starch-based microplastics. To help elucidate the safety of these ecoplastics, Deng and his team used a mouse model to simulate long-term exposure to varying doses of starch-based microplastics. (J. Agric. Food Chem. 2025, DOI: 10.1021/acs.jafc.4c10855) They incorporated various concentrations of starch-based microplastics into the animals’ food, scaled to reflect typical human exposure; after 3 months, they euthanized the mice to probe the impacts of no, low, and high consumption of microplastics.
Organ-sample analysis revealed system-wide physiological changes, including reduced ovary size, liver damage and inflammation, and impaired colon function. “Starch-based microplastics exhibit widespread harm, potentially affecting multiple tissues and functions,” Deng says. “Given that humans also face real-life scenarios of chronic exposure to starch-based microplastics, these findings serve as an important warning regarding their potential health impacts.”
Notably, the exposed mice consistently had elevated blood glucose levels and disrupted insulin regulation—both heavily implicated in conditions such as diabetes and fatty liver disease. “The effect that they see is twofold,” says Vahitha Abdul Salam, a microplastics researcher at Queen Mary University of London who was not involved in the study. “With all microparticles there is a physical effect of it being a foreign compound that itself exerts a harm. But with starch we know it converts to glucose, and that is an added aspect of harm.”
But Abdul Salam cautions that the design of Deng’s study means that it’s too early to draw any firm links between the starch-based microplastics and adverse health effects: Differences between the digestive pathways of humans and mice could profoundly affect the metabolism of the starch component of the plastic. And other sources of starch exposure, such as textiles, pharmaceuticals, and adhesives, could also contribute to the overall measured glucose level in the mice.
“This is association by inference,” Abdul Salam adds. “They've given the mice the microplastics in food and then separately looked at what damage it has done. But we don't know whether it's the starch, or the PLA component within those microplastics, or a chemical associated with the microplastics, which causes the harm.”
Abdul Salam says that, despite the work’s limitations, it is an interesting study that begins to address some of the key gaps in our understanding of biomicroplastics. “They've got a good overview of the changes within the organ system, but more studies are needed to make a firm conclusion, especially in humans,” she says.
