Our plastics are loaded with rare-earth materials, and scientists don’t know why

Praseodymium. Dysprosium. Neodymium. These are the extremely precious, rare-earth materials that are inside every iPhone and similar electronics. To acquire them is not just costly, but has led to incredible levels of environmental destruction.

Yet scientists have just discovered that rare-earth materials can actually be found in everyday consumer plastics—including water bottles, children’s toys, yogurt containers, and cosmetic cases. Our disposable plastics are filled with very small amounts of the earth’s most finite treasures.

“The irony is they’re extremely valuable,” says Andrew Turner, an associate professor in environmental sciences at the University of Plymouth, who led the study. “They’re critical elements for modern technology. And yet we’re finding that they’re becoming contaminants.”

Scientists have understood for some time that our plastics can include unexpected materials. Recycled black plastics, in particular, are commonly infused with dangerous levels of bromine or even lead. That’s because TVs and other plastic-using electronic devices add materials such as bromine as a flame retardant, and that plastic can end up recycled into microwave dinner trays.

But this new research, published in Science of the Total Environment, is actually quite different from earlier studies. The first breakthrough was that scientists discovered the presence of rare-earth materials in plastic at all. And in fact, the ratio of rare-earth materials in plastic is almost equal to their distribution in the earth’s crust.

“I think it’s fascinating. . . . Plastic is acquiring an almost geological signal in it,” says Turner. “We’re contaminating everything we use.”

Second, this study examined virgin plastics—plastics that were derived from pure petroleum rather than other recycled goods. That means we can’t trace the presence of rare-earth materials back to recycled electronics or other man-made pollutants. They come from an unknown source.

What does this research mean?

As for what this finding means in a practical sense, “It’s one of those pieces of research that leads to more questions than answers,” Turner admits.

First off, we should recognize that this is not a new phenomenon. Turner’s team notes that rare-earth materials can be found in plastic ocean waste, which means that this contamination may have been happening for decades. Plastics are a modern wonder material that arose out of World War II, and much of the core science behind plastic production remained unchanged over the course of the 20th century. “If I were to make a calculated guess, yes, [rare earth materials] have probably been in plastics all along without us knowing about it,” says Turner.

Is he concerned that these rare-earth materials are toxic? Not particularly, at least not in the current concentrations researchers have observed (rare-earth materials can be harmful at higher concentrations, as in the mining industry). Does he believe the plastics could be recycled, with the rare-earth materials extracted to be used in electronics? No again.

“It wouldn’t be worthwhile recovering [rare earth materials]. The levels are quite small,” says Turner. “It’s not worth melting down a lot of plastic rather than going to a prospective [mining] site.”

What he does believe is important, however, is in the bigger picture. Examining our production processes could reveal an untapped source of rare-earth materials, which might mitigate some of our need for mining. But even if it doesn’t, Turner insists that we should understand plastic production well enough to be able to pinpoint exactly where these unexpected materials come from.

“When we talk about contamination of plastic, even though it’s a small amount, it’s significant because it’s coming from somewhere,” says Turner. “We’ve lost control of what we’re producing.”