If you throw a polyester sweatshirt in the washing machine, it doesn’t emerge as quite its former self. All that agitation breaks loose plastic microfibers, which your machine flushes to a wastewater treatment facility. Any particles that aren’t filtered out get pumped to sea. Like other forms of microplastic—broken-down bottles and bags, paint chips, and pellets known as nurdles—microfiber pollution in the oceans has mirrored the exponential growth of plastic production: Humanity now makes a trillion pounds of the stuff a year. According to the World Economic Forum, production could triple from 2016 levels by the year 2050.
A new analysis provides the most wide-ranging quantification yet of exactly how much of this stuff is tainting the ocean’s surface. An international team of researchers calculates that between 82 and 358 trillion plastic particles—a collective 2.4 to 10.8 billion pounds—are floating across the world … and that’s only in the top foot of seawater.
That’s also only counting the bits down to a third of a millimeter long, even though microplastics can get much, much smaller, and they grow much more numerous as they do so. (Microplastics are defined as particles smaller than 5 millimeters long.) Scientists are now able to detect nanoplastics in the environment, which are measured on the scale of millionths of a meter, small enough to penetrate cells—though it remains difficult and expensive to tally them. If this new study had considered the smallest of plastics, the numbers of oceanic particles would no longer be in the trillions. “We’re talking about quintillions, probably, that’s out there, if not more,” says Scott Coffin, a research scientist at the California State Water Resources Control Board and a coauthor of the study, which was published today in the journal PLoS ONE.
“That’s the elephant in the room,” agrees Marcus Eriksen, cofounder of the 5 Gyres Institute and the study’s lead author. “If we’re going to talk about the number of particles out there, we’re not even looking at the nanoscale particles. And that really dovetails into all the research on human health impacts.” Scientists have only just begun to study these effects, but they are already finding that the smallest microplastics readily move through the body, showing up in our blood, guts, lungs, placentas, and even infants’ first feces.
Eriksen and Coffin did their quantification by gathering reams of previous data on plastic samples from across the world’s oceans. They combined this with data they collected during their own ocean expeditions. All told, the researchers used nearly 12,000 samples of plastic particle concentrations, stretching between the years 1979 and 2019. That allowed them to calculate not only how much may be out there, but how those concentrations have changed over time.
They found that between 1990 and 2005, particle counts fluctuated. That may have been due to the effectiveness of international agreements, like 1988 regulations limiting plastic pollution from ships. “That’s the first time that we’ve ever had any sort of evidence that those international treaties in plastic pollution have actually been effective,” says Coffin.