Nothing seems safe from the grips of plastic these days. Not national parks, not oceans, and, according to new findings, not even plants. The study, published in Nature Nanotechnology on Monday, found that plants can absorb the tiniest bits of plastic through their roots. It shows the wide-ranging ways that plastic can impact the natural world.
The group of researchers looked at the ability of plants to absorb plastic in a lab setting. They directly exposed Arabidopsis thaliana—a weed that goes by thale cress—to plastics smaller than 100 nanometers. For context, a sheet of paper is 100,000 nanometers thick, so we’re talking extremely small pieces of plastic. The team of researchers assessed how far the plastic traveled into the plants, as well as its impact on the plant’s biology and genetics.
To study the plant, the scientists grew the thale cress in both dirt soil and an agar-based soil medium that has similar nutrients to the soil, which allowed them to more easily study the roots because separating them can cause damage when they’re in regular soil. In each setting, the plants were exposed to a varying amounts of nanoplastic, including 10, 50, and 100 parts per million as well as a control group with no plastic. They let the plants grow in these levels of soil for 10 days in a growth chamber heated to roughly 72 degrees Fahrenheit (22 degrees Celsius) before taking a look.
“The authors took into account concentrations of microplastics measured [in] soils,” Phoebe Stapleton, an assistant professor of pharmacology and toxicology at Rutgers who has studied nanoplastics but not as part of this study, wrote in an email to Earther. “Therefore, these doses were not for laboratory trials only but represent concentrations that are found within the environment.”
The result show that because these particles are so small, they were able to penetrate the tissue of the roots where they appeared to block the roots from properly absorbing water. The authors also found signs that the nanoplastics were preventing the plants from growing properly and harming the development of seedlings.
To make it all worse, the team believes the plastic was, in fact, altering the genetic makeup: The RNA sequence they witnessed suggests that nanoplastics may be hurting the plant’s ability to resist disease. This part requires further analysis, however, and the team is already working on a separate study to learn more about genetic impacts.
These findings are concerning because we eat plants. While thale cress is edible, the real concern is about what’s happening on farms where fields may be protected with plastic sheeting. Should tiny pieces of plastic fragment from any larger plastic object, they may land right onto the soil used to grow our food. So perhaps a plastic sheet isn’t actually protecting crops after all. Even farms that don’t use plastic coverings could see their crops at-risk of plastic contamination. The recent research looking at national parks has found that plastic can be transported hundreds of miles by wind and rain, backing up similar research on microplastic transport.
“Terrestrial plants form the base of many food chains,” co-author Xian-Zheng Yuan, a professor of environmental science and engineering at Shandong University in Jinan, China, wrote in an email to Earther. “Hence, nanoplastic accumulation in plants might have implications on other trophic levels, which could pose a potential risk to food yield, quality, and safety.”
While some research has examined the consequences of nanoplastics in aquatic plants, this paper is the first to find evidence that nanoplastics also affect terrestrial plants. The team used the thale cress in its investigation because it’s a “popular model organism” when studying plant biology and genetics, Yuan said. It was the first plant to have its genome sequenced and is commonly used in studies like these.
The lab-based approach allowed the team to learn about the direct impacts of nanoplastics on plants, but it’s also not directly applicable to plants and plastics in the wild because the plastic that floats transported in atmosphere and deposited in the soil will not be as “pristine” as what the team used in its analysis. In the outdoors, plastics are broken down by chemicals and weather, altering their physical and chemical composition. Depending on how they change, the impacts could be different on plants outside a lab setting.
The new paper creates a strong foundation for future research in this area. Stapleton speculates this study may suggest that nanoplastic absorption could be happening on a global scale given recent research finding that microplastics travel through atmospheric winds.
The impacts on people are still unknown, but findings from last year show we’re eating a credit card-worth of microplastic on average every week. The concerns for food safety are real. The only way to reduce exposure is for the world to cut down the use of plastic in the first place.