Mark Herz: Microplastics are everywhere, and that’s causing concerns about their environmental impact and possible impacts on human health. Scientists knew microplastics were present in great numbers in the ocean, but until now they didn’t know how much was below the surface there. Aron Stubbins is a professor of marine and environmental sciences at Northeastern University, an expert on plastics in the environment and a co-author on a new study that found microplastics drifting throughout the ocean depths. Good morning, Professor Stubbins.

Aron Stubbins: Morning, Mark.

Herz: We’ve all seen these images of large garbage patches or gyres floating on top of the ocean. You were looking below those. Why did you do that and tell us what you found?

Stubbins: Yeah, so as you say, we’ve known about plastics floating on the surface for a while because that’s where we can see them, and back in the 70s, people were surprised to even see them there at the surface. That led to lots of people studying plastics in the surface, trying to figure out how much there was, whether they’re having any detrimental impacts on the ocean. It’s harder to sample [down there]. You can lower a pump to depth and you can pump water through a filter at that depth without having to bring the water all the way to the top. In that case, you can capture the plastics on a filter. Filter thousands of liters potentially and capture all those plastics in there. Or you can bring some water to the surface and then filter it on deck, on the ship. All of this takes time and is much harder than just sampling the surface. So yeah, there’s lots of logistical challenges when we’re doing oceanography and looking throughout the ocean’s depths, which is why the ocean depths remain as poorly explored as say the surface of the moon. Once they did, then they found that there’s these very small plastics that just drift around and are becoming distributed throughout the whole of the ocean, from the sea floor to the very surface.

Herz: So the ocean is so vast and it sounds like you all were surprised by how much microplastics you found below the surface. Is that right? And tell us what the experts such as yourself think are the impacts on the ecosystems of the ocean.

Stubbins: Yeah, it’s surprising that we’re finding these plastics distributed everywhere, and that’s because they have small sizes, so they can move around the ocean in the same way as dust moves around the atmosphere. We were surprised to find this smog of plastics distributed throughout the water column rather than just a collection at the top and a collection of the bottom. And what that means now is that now that we’ve found it, we need to try and figure out: Is it problematic? How quickly is it building up? All these sort of questions we’ve been asking in the surface of the ocean for a while and are starting to learn about. So some ways in which it may cause a problem is we have done some work where we show that when there’s a carbon flux from the atmosphere to life at the surface of the ocean that absorb that carbon dioxide they take it up like trees do around us, but they’re phytoplankton, they’re small single-celled plants, they aggregate and die and that’s called marine snow and that’s a significant flux of carbon from the surface of the ocean to the deep ocean,, which actually captures a decent percentage of the carbon dioxide that we emit to the atmosphere and helps reduce the worst impacts of climate change. What we have found in another study we did was that when there are plastics around and they get incorporated into that snow, then that changes the sinking rate. Which will slow down this pump of carbon dioxide from the atmosphere into the deep ocean.

Herz: Microplastic here on land, microplastics have been found in our food. They penetrated the male reproductive system. There was a study last year found 50% more microplastics in human brains than were found a decade ago. So does a study like yours give us even more reason to worry about their effects on our health.

Stubbins: Yeah, with these sort of studies, when we find plastics in strange places or places we might not think they can get to, it keeps telling us just how pervasive plastic pollution is. So we might think of Antarctica or the Himalayas as some of the most distant, protected ecosystems, but we’ll find plastics being carried there by wind. We might think of the deep ocean as one of the most protected or physically separate ecosystems in the world, separate from human activity, but we’re finding plastics there. We think of the brain and the womb as some of the most protected pieces of the human anatomy. We find plastics there. And so this is telling us plastics can get everywhere, and we really need to understand what detrimental impacts they are having when they get into our brains, into the wombs and are in newborn children, and what impacts they’re having on the natural systems as well. And plastics can carry a suite of passenger molecules that can be toxic to us. In the case of the food chain in the oceans, then we could imagine those accumulating through the food chain. So we might know that we shouldn’t eat too much tuna because of the mercury content. So that similar sort of trend could be happening with plastics where we may find plastics and also these passenger toxins that they carry accumulating through food chains and ending up in our food.

The Himalayas. Your neighbor’s brain. Your friend’s uterus. And dispersed throughout the ocean.

“We find plastics there,” said Aron Stubbins, a professor of marine and environmental sciences at Northeastern University.

Stubbins says recent studies have surprised oceanic researchers. In a study published in Nature last month, he and his co-authors in a decade’s worth of data that there’s a “smog of plastics” in the world’s oceans.

Previously, he says, scientists anticipated that they would only find microplastics floating on top of the water’s surface and sunken to the bottom of the ocean.

“It’s surprising that we’re finding these plastics distributed everywhere,” he said, “and that’s because they have small sizes, so they can move around the ocean in the same way as dust moves around the atmosphere.”

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As new research shows the pervasiveness of microplastics in both the environment and in human bodies, scientists are raising the alarm about their possible health and environmental impacts.

Stubbins points out one common process in the ocean: When phytoplankton die and fall to the ocean floor, they capture atmospheric carbon dioxide and helps reduce the worst impacts of climate change. Alarmingly, separate studies have shown that microplastics may slow down that falling process.

“When we find plastics in strange places or places we might not think they can get to, it keeps telling us just how pervasive plastic pollution is,” Stubbins said.

He says these discoveries further emphasize the need for scientists to understand what these plastics do to the human body.

“We really need to understand what detrimental impacts they are having when they get into our brains, into the wombs and are in newborn children — and what impacts they’re having on the natural systems as well,” Stubbins said.