Chemicals in Recycled Plastics Impact Hormone Systems and Fat Metabolism in Fish Larvae
A new study from a group of researchers in Sweden and Germany, including IPEN Science Advisors, have shown that chemicals in mechanically recycled polyethylene, a common type of plasti can leach into water causing impacts in the hormone systems and lipid metabolism of zebrafish larvae. Previous research has shown similar effects to people, including threats to reproductive health and obesity, from exposures to toxic chemicals in plastics.
Some chemicals used as additives in plastics and substances that contaminate plastics are known to be endocrine disrupting, meaning they have the potential to affect the bodies’ natural hormones, with potential impacts on fertility, child development, links to certain cancers, and metabolic disorders including obesity and diabetes.
The plastic pollution crisis has reached global levels, threatening both planetary and human health, and recycling is proposed as one of the solutions to the plastics pollution crisis. However, as plastics contain thousands of chemical additives and other substances that can be toxic, and these are largely unreported, hazardous chemicals can indiscriminately end up in recycled products. Furthermore, scientists have previously shown that recycled plastics contain hundreds of additional toxic chemicals that contaminate the materials.
“We identified common plastics chemicals, including UV-stabilizers and plasticizers, as well as chemicals that are not used as plastics additives, including pesticides, pharmaceuticals and biocides in recycled plastic,” said IPEN Science Advisor Sara Brosché, PhD. “These may have contaminated the plastics during their use, prior to becoming waste, and when the plastics were recycled. This is further evidence of the complicated issue of plastics waste flows, and of toxic chemicals contaminating recycled plastics.”
The plastics were leached for a relatively short time, only 48 hours, after which zebrafish larvae were exposed for 5 days. The experimental results show increases in gene expression relating to lipid metabolism, adipogenesis, and endocrine regulation. “These short leaching times and exposure times are yet another indicator of the risks that chemicals in plastics pose to living organisms. The impacts that we measured show that these exposures have the potential to change the physiology and health of the fish“ explains Azora König Kardgar, lead author.
“This work clearly demonstrates the need to address toxic chemicals in plastics materials and products, across their life cycle”, says Professor Bethanie Carney Almroth, principal investigator on the project. “We cannot safely produce and use recycled plastics if we cannot trace chemicals throughout the production, use, and waste phases.”
Representatives from the nations of the world are preparing to head to Geneva, Switzerland, in August, for what is planned to be the final negotiating meeting for a Global Plastics Treaty at the Intergovernmental Negotiating Committee under the United Nations Environmental Program. The authors of the work stress that negotiators and decision-makers must include provisions to ban or reduce hazardous chemicals in plastics, and to increase transparency and reporting along plastics value chains. Plastics cannot be recycled in a safe and sustainable manner if hazardous chemicals are not addressed.
Therese Karlsson from IPEN emphasizes, “Recycled plastics spread hazardous chemicals globally, so plastic recycling will exacerbate, not resolve, the plastics crisis. We need a Global Plastics Treaty that limits plastic production and ends the health threats from toxic chemicals in plastics, promoting innovation for safer materials for a healthy, toxics-free future.”