News | Recycled Plastic May Carry Toxic Risks, Zebrafish Study Finds
As the global plastic pollution crisis worsens, recycling is widely viewed as part of the solution. However, a joint study by teams at the University of Gothenburg and in Leipzig, Germany, found that chemicals released from recycled polyethylene plastic may disrupt hormone systems and lipid metabolism in zebrafish larvae, posing potential toxic risks.
Researchers purchased multiple batches of recycled polyethylene pellets from around the world and soaked them in water for 48 hours. Zebrafish larvae were then exposed to the resulting leachate for five days. Expression of several genes involved in fat formation, hormone regulation, and metabolism increased significantly.
“Even after such brief soaking and exposure, we observed clear physiological changes, showing that the effects of chemicals in plastic on living organisms cannot be ignored.”
—Azora König Kardgar, ecotoxicology researcher at the University of Gothenburg and first author
The chemical blind spot in plastic reuse
“We have never truly known every chemical contained in plastic,” said University of Gothenburg professor and principal investigator Bethanie Carney Almroth. “The greatest problem with recycled plastic is that we can never know exactly which chemicals have entered a recycled product or predict how they will interact during recycling and create potential toxicity.”
Previous studies have shown that some plastic additives and contaminants can disrupt the human hormone system, affect fertility and fetal development, and may be associated with certain cancers, obesity, and metabolic disease. This study again warns that complex chemical risks may lie beneath the environmental appeal of plastic recycling.
Pesticide and pharmaceutical residues found in recycled pellets
The team also analyzed the chemicals in the pellet leachate. In addition to common plastic additives such as UV stabilizers and plasticizers, researchers found contaminants not intended for plastic use, including pesticides, pharmaceuticals, and biocides.
“These chemicals were probably left behind during the plastic’s first use and entered new products when the plastic was recycled and reused.”
—Eric Carmona, researcher in exposure science at the Helmholtz Centre for Environmental Research in Leipzig, Germany
The chemical mixtures in leachate varied greatly among recycled pellets from different sources, further highlighting the opacity and complexity of the global plastic recycling system.
Call for the Global Plastics Treaty to address toxic chemicals
With the final round of intergovernmental negotiations on the Global Plastics Treaty scheduled for August 2025 in Geneva, Switzerland, the researchers urged national representatives to confront toxic chemical risks throughout the plastic life cycle.
“We cannot keep avoiding the issue. If we cannot track the chemicals in plastics, we cannot ensure that recycling is safe and sustainable.”
—Professor Bethanie Carney Almroth
She emphasized that genuinely green plastic recycling and reuse will require governments to adopt stricter regulation, including banning or restricting hazardous chemicals in plastics and improving transparency and chemical disclosure throughout the plastic supply chain.
News | Recycled Plastic May Carry Toxic Risks, Zebrafish Study Finds
News | Recycled Plastic May Carry Toxic Risks, Zebrafish Study Finds
As the global plastic pollution crisis worsens, recycling is widely viewed as part of the solution. However, a joint study by teams at the University of Gothenburg and in Leipzig, Germany, found that chemicals released from recycled polyethylene plastic may disrupt hormone systems and lipid metabolism in zebrafish larvae, posing potential toxic risks.
Researchers purchased multiple batches of recycled polyethylene pellets from around the world and soaked them in water for 48 hours. Zebrafish larvae were then exposed to the resulting leachate for five days. Expression of several genes involved in fat formation, hormone regulation, and metabolism increased significantly.
“Even after such brief soaking and exposure, we observed clear physiological changes, showing that the effects of chemicals in plastic on living organisms cannot be ignored.”
—Azora König Kardgar, ecotoxicology researcher at the University of Gothenburg and first author
The chemical blind spot in plastic reuse
“We have never truly known every chemical contained in plastic,” said University of Gothenburg professor and principal investigator Bethanie Carney Almroth. “The greatest problem with recycled plastic is that we can never know exactly which chemicals have entered a recycled product or predict how they will interact during recycling and create potential toxicity.”
Previous studies have shown that some plastic additives and contaminants can disrupt the human hormone system, affect fertility and fetal development, and may be associated with certain cancers, obesity, and metabolic disease. This study again warns that complex chemical risks may lie beneath the environmental appeal of plastic recycling.
Pesticide and pharmaceutical residues found in recycled pellets
The team also analyzed the chemicals in the pellet leachate. In addition to common plastic additives such as UV stabilizers and plasticizers, researchers found contaminants not intended for plastic use, including pesticides, pharmaceuticals, and biocides.
“These chemicals were probably left behind during the plastic’s first use and entered new products when the plastic was recycled and reused.”
—Eric Carmona, researcher in exposure science at the Helmholtz Centre for Environmental Research in Leipzig, Germany
The chemical mixtures in leachate varied greatly among recycled pellets from different sources, further highlighting the opacity and complexity of the global plastic recycling system.
Call for the Global Plastics Treaty to address toxic chemicals
With the final round of intergovernmental negotiations on the Global Plastics Treaty scheduled for August 2025 in Geneva, Switzerland, the researchers urged national representatives to confront toxic chemical risks throughout the plastic life cycle.
“We cannot keep avoiding the issue. If we cannot track the chemicals in plastics, we cannot ensure that recycling is safe and sustainable.”
—Professor Bethanie Carney Almroth
She emphasized that genuinely green plastic recycling and reuse will require governments to adopt stricter regulation, including banning or restricting hazardous chemicals in plastics and improving transparency and chemical disclosure throughout the plastic supply chain.
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