Plastic debris is collecting in the ocean, but the real threat to marine health is the plastic that can’t be measured.

Scientists have long known that plastic detritus is piling up in the world’s oceans. Until recently, researchers considered this debris to be collecting in large “garbage patches” in five major spots throughout the marine environment, pushed there by the five major gyres whose circulation dominates the flow of ocean currents around the world.
But this synopsis has recently been challenged by a new study which supports a radical reframing of the debate about how to manage plastic pollution.
In a recent article in PLOS ONE, researchers reported more than 5 trillion plastic pieces, with a combined mass of more than 250,000 tons, floating in the ocean. As it turns out, this is a lower-than-expected estimate, amounting to less than 1 percent of the annual global production of plastic. Five trillion, by the way, is a 5 followed by 12 zeroes.
Given that plastic is estimated to last 1,000 years, this finding was surprising to some but not all of the paper’s co-authors. While more research remains to be done on exactly how plastic breaks down in the marine environment, lead author Marcus Eriksen, co-founder of 5 Gyres, an ocean plastics research and advocacy institute, speculates that the problem is not one of missing plastic, but of how we conceive of plastic pollution.
“We really need to look at plastic in the oceans as clouds of microparticles, very similar to the way we look at air pollution,” said Eriksen. Noting that plastics break down under ultraviolet light and then disperse into the water column and the stomachs of marine animals, Eriksen hopes that this study will help to reframe how to manage the problem.
Current methods of studying marine plastic rely on surface sampling only, due to the difficulty of developing long-term deep-sea sampling methods. Study co-author Hank Carson, a marine biologist with the Washington Department of Fish and Wildlife, said that little is known about how plastic breaks down or gets incorporated into marine ecosystems.
“I don’t think anyone’s been able to put a piece of plastic in the middle of the ocean and then retrieve it to see how much it broke down or what happened to it,” said Carson. “People have done it on shorter time scales, near the coast, attached to a buoy, and are starting to learn a few things, but I think it’s a new area of study.”
What we do know suggests that Eriksen’s view of plastic as clouds rather than patches may be a useful shift in thinking about the issue.
Plastic pieces get to the ocean by blowing down rivers and off of shorelines and then migrating into the five subtropical gyres where they quickly fragment. Through a combination of UV sunlight and the constant churning of waves, particles break down into tiny fragments, which then are taken in by foraging fish and filter feeders that eat by straining ocean water to randomly capture food particles and microscopic organisms.
Carson said more research needs to be done on the health and environmental effects of plastics. “We’re still in the era of just trying to see what we’ve done, where it is.”
Still, Eriksen is pushing forward to advocate changes in how we conceptualize and manage plastic production. Emphasizing that most scientists classify plastic as hazardous waste, he rejects postconsumer cleanup efforts as insufficient to recover the miniscule particulate clouds that plastics become.
“Recycling means nothing unless you can recover it,” he notes. “We really shouldn’t be entertaining ideas that going to the ocean to clean up microplastic particles is viable. Much like air pollution, you solve the problem by emissions controls.”
On the research side, more work also needs to be done to further study the biochemical effects of plastic on marine organisms and ecosystems. Eriksen hopes to enlist more citizen scientists in collecting and analyzing ocean water samples.
“Weekly, I get sailors saying, ‘I want to help,’” he says. Eriksen provides these sailors with easy-to-use trawls to collect samples.
On the advocacy side, scientists continue to work with industry and governments to develop benign alternatives to plastic and battle the single-use throw-away mentality of consumer behavior. While plastic manufacturers participate in litter clean-up programs, Carson and Eriksen both argue that the efforts are not enough.
“They’re focusing on the litter aspect and keeping their products out of the ocean, which is certainly admirable,” Carson says, “but what we need is a whole rethink of how everything is packaged and designed in society. Beach cleanups are really cool, but that’s sort of a Band-Aid and we need to be thinking a little bit deeper.”