Image by Nikolett Emmert from Pixabay
By Jo Nova
Remember how biodegradable plastic was going to make the world a healthier place? It would save us all from the horrible plastic landfill that lasts 1000 years, and it would protect the dolphins. Well, let’s just hope the dolphins don’t eat the bags.
Despite the rush to put biodegradable bags in every shopping centre, no one had bothered to study whether it had an effect on our health, and we still don’t know, but we can say that the mice on that compost heap with these biodegradable bags will be more likely to have diabetes, smaller ovaries, and liver damage. Degradable plastic affected their gut flora. The authors say: “Prolonged exposure to environmentally relevant doses of Starch-based microplastics can have widespread health effects.”
How many native mice will die that could have been saved, and do the Greens care?
This study came out in April:
Mouse study suggests that starch-based microplastics may harm health
Victoria Atkinson, c&en
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
Notably, the exposed mice consistently had elevated blood glucose levels and disrupted insulin regulation—both heavily implicated in conditions such as diabetes.
Organ-sample analysis revealed system-wide physiological changes, including reduced ovary size, liver damage
and inflammation, and impaired colon function. “Starch-based microplastics [SMPs] 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.”
In lab tests normal plastic bags didn’t harm the cells.
Biodegradable bags are TOXIC – and may be linked to liver and ovary damage, scientists warn
By Xantha Leatham, Daily Mail,
‘Biodegradable starch-based plastics may not be as safe and health-promoting as originally assumed,’ said Professor Yongfeng Deng, one of the study’s authors.
In a previous study the researchers compared the compostable bags to normal plastic bags after they had been left out in the sun and composted. But when they put them next to fish cells, “A ‘high level of toxicity’ was produced by the biodegradable bags, harming the fish cells,”
Cinta Porte, lead author of the study, published in the Journal of Hazardous Materials, said: ‘We were surprised that cells exposed to conventional plastic bags showed no trace of toxicity.
I don’t put these bags into my own compost. The Council can have them.
REFERENCE
Liu et al (2025) Long-Term Exposure to Environmentally Realistic Doses of Starch-Based Microplastics Suggests Widespread Health Effects. J Agric Food Chem, 2025 Apr 23;73(16):9867-9878. doi: 10.1021/acs.jafc.4c10855. Epub 2025 Apr 9.