Cave explorers have sought many things, from treasure to mineral veins to mummies. One group of cave explorers, however, went searching for something much less exciting and potentially far more toxic — microplastics.
What happened?
A recent article in Vice reports that an expedition team of scientists led by Elizabeth Hasenmueller, associate director of the Water Access, Technology, Environment, and Resources (WATER) Institute at Saint Louis University, found high levels of plastic pollution in a Missouri cave system that has been closed to the public for 30 years.
Cliff Cave, a system of passageways near Saint Louis, has been closed to the public for safety and conservation reasons since a fatal flash flood in 1993, per a university report. To explore the system, Hasenmueller and her colleagues were given special permits to extract samples of its water and sediments during day trips in May 2019 and April 2022, according to Vice.
They took samples every 82 feet until they reached as far as they could — about 590 feet from the entrance. They discovered anthropogenic (human-sourced) microplastics, tiny plastic particles less than 5 millimeters (about 0.2 inches) long, at every site they sampled.
"We found anthropogenic microparticles in all samples that were mainly fibers (91%) and clear (59%)," the team wrote in its study, published in ScienceDirect. "Quantities in sediment were ~100 times those in water. These findings indicate that sediment sequesters anthropogenic microparticle pollution in the cave. Microplastic concentrations were similar among all sediment samples, but only one water sample at the main entrance contained microplastics."
Why is this cave finding concerning?
The team's discovery suggests that many underground systems like this are likely contaminated by human pollution even in the absence of humans; the pollution poses potential risks to the fragile ecosystems that live in these systems and to human water resources, such as aquifers.
While disturbing, the results aren't surprising as microplastics flood the environment, potentially endangering humans and animals alike. Microplastics have now been found in places as remote as Arctic air and even in human hearts.
What can be done about microplastic pollution?
Microplastics have permeated nearly every area of Earth, and removing them all will likely be impossible. Scientists are working on ways to remove what they can, but we must also do our part.
The best thing we can do is not contribute more to the pollution by reducing our use of plastic. Finding alternatives to plastic bottles, straws, and bags is a great place to start. Proper recycling is also key to eliminating microplastic pollution from our environment and bodies.
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