Geochemistry, Mineralogy, Volcanology News

Will Cigarette Butts Be Our Environmental Legacy?

People litter them by the trillions—but how long will butts last through the ages?

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A smoker takes one last drag of a cigarette, then flicks the butt to the ground and sends it backward with the scrape of a boot.

“People just flick them as if it’s not any sort of waste,” said Bas Boots, an ecologist at Anglia Ruskin University in the United Kingdom.

Turns out, they create one of the biggest piles of waste humanity makes: Each year, we smoke about 5.6 trillion cigarettes, and between 4 and 5 trillion of that number wind up in the environment as litter.

“That’s a lot,” Boots said.

Cigarette butts contain cellulose acetate, a microplastic. Each butt can contain up to 12,000 cellulose acetate fibers. These fibers, Boots explained, help catch pollutants from cigarette smoke before they can reach a smoker’s lungs. But the butt stops there, it seems, because research is revealing that littered butts, and the microplastics within them, can have harmful environmental effects. According to research published in Ecotoxicology and Environmental Safety, butts in soils can stunt plant growth.

A photograph of a cigarette bisected lengthwise to show the tobacco and filter
Fibers of cellulose acetate, a microplastic, filter nicotine and nicotine residue (tar) from cigarette smoke, as seen in these unsmoked (left) and smoked (right) cigarettes. Credit: Akroti, courtesy Wikimedia, CC BY-SA 2.5

Boots, part of the team that conducted the new research, explained that it did not matter if the butt was from a smoked, unsmoked, or partially smoked cigarette—shoots of plants like white clover were still about 28% shorter than normal when exposed to the refuse. This result signaled to the team that the cellulose acetate in butts, rather than burnt or unburnt tobacco, is likely causing the stunting.

Cigarette butts are one of the most commonly found plastic waste items on the planet. During the Ocean Conservancy’s International Coastal Cleanup Day in 2018, butts were the top piece of trash found by volunteer beach cleaners. And microplastics like the ones found in butts are finding their way into every inch of the environment: In 2014, researchers discovered that microplastics can become frozen in Arctic sea ice. As the planet warms, that ice stands to release its load into the oceans, where plastics are already accumulating on the ocean floors and finding their way into animals’ guts.

“We’re now producing so much plastic, and so much of it is leaking into the environment, that it’s almost become sort of like a component of geology, like you would think of a sand grain, or piece of wood,” said Sarah Gabbott, a paleontologist at the University of Leicester in the United Kingdom.

Our Butting Legacy?

But will butts, their plastics, and their concomitant problems stick around as long as sand grains?

“That’s one of the questions. How long do we have to worry about this stuff, assuming we all stop smoking tomorrow?” asked ecologist Jan Zalasiewicz, who is also at the University of Leicester and chairs a group that seeks to determine whether human activities warrant the addition of a whole new period to the geologic timescale known as the Anthropocene.

Although we cannot travel into the future to find out if cigarettes and their microplastics will stand the test of time, researchers can look to the recent geologic past for insights. For instance, in the sedimentary records of ancient lakes, archaeologists regularly find the remains of things like wood associated with human settlement, which can remain intact for thousands of years. So when imagining whether or not butts will stick around for at least that long, “rather than ‘will we find them or not?’ I think the answer is almost certainly yes,” Zalasiewicz said.

Just how many butts will persist through time, though, depends on the environment in which the littered butts find themselves, explained Gabbott. It helps, she said, to think about butt preservation the same way a paleontologist might think about the fossil preservation potential of recently dead organisms. Butts, she explained, need to escape at least two atmospheric forces to avoid decay: sunlight and water. UV light works to decomposes butts, and water creates an environment in which butt-eating bacteria can thrive.

Following these principles, Gabbott and her students are working to find out what proportion of the butts littered every year might be preserved. But, for now, she said, there are still more mysteries than answers. “I think we’ll find that UV light is the most important thing—to bury it in the dark,” she said. “But, you know, no one really knows.”

—Lucas Joel, Freelance Journalist

Citation: Joel, L. (2019), Will cigarette butts be our environmental legacy?, Eos, 100, https://doi.org/10.1029/2019EO132535. Published on 11 September 2019.
Text © 2019. The authors. CC BY-NC-ND 3.0
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