Plastics, recycled plastics, and dangerous chemicals

Okay, so I want to start this post by saying that we need to reduce plastic use overall and that the message in the research I’m going to discuss is not that recycled plastics are the problem. But there are consequences of viewing plastic recycling as the thing that will save us from our plastic addiction.

Kardgar and colleagues (2025) collected recycled plastic pellets from multiple countries. They then soaked the pellets in water for 48 hours before exposing zebra fish larvae to the water for five days. They also tested the water itself. What they found was that the plastics all leached (released) toxic chemicals but the chemicals varied between different samples. The chemicals had impacts on the larvae on both gene expression and endocrine (hormone) regulation.

There are a lot of takeaways from this research. The traceability of chemicals in the original plastics is problematic. There isn’t good information about what chemicals are in different plastics which means that we also can’t know what is going into recycled plastics. This creates an added problem because there could be different chemicals in the sources of recycled plastics which then end up mixing together. The original plastics can also be contaminated with materials like pesticides which can also end up in the recycled plastic.

I think it’s really important here that the problem is the original plastics and the lack of regulation and traceability. There is actually a meeting in August that is intended to finalize a global plastics treaty, but I admit I wonder about how successful the treaty will be and how enforcement will actually happen.