Microplastics Are Making Photosynthesis Harder for Plants—and That Could Slash Crop Yields, Study Suggests

Microplastics are everywhere. The tiny plastic particles have been found in the ocean breeze, soil and even our brains. Now, a new study suggests microplastics are hindering plants’ ability to generate energy through photosynthesis, with devastating potential impacts to key crops.

This plastic-induced stress on plants could exacerbate food insecurity for hundreds of millions of people, the researchers say, though others add that more studies would help clarify the extent of this impact. The new assessment was published in the Proceedings of the National Academy of Sciences on March 10.

“Humanity has been striving to increase food production to feed an ever-growing population, [but] these ongoing efforts are now being jeopardized by plastic pollution,” the researchers write, per Damian Carrington of the Guardian. “The findings underscore the urgency [of cutting pollution] to safeguard global food supplies in the face of the growing plastic crisis.”

Microplastics are fragments of plastic measuring less than five millimeters long—some may be the size of a pencil eraser, while others are several times smaller than the width of a human hair. They can form when plastic pollution in the environment breaks down into tiny pieces, or they might be manufactured to be small in the first place.

Previous research suggests microplastics in the soil can be taken up by plants and obstruct their absorption channels for nutrients and water, according to the Guardian. They might release toxic chemicals into the plant or block algae’s access to light.

To measure these impacts on photosynthesis, the researchers analyzed more than 3,000 data points from 157 studies of microplastics and plants, then they used artificial intelligence to model those results on a global scale, per the Washington Post’s Shannon Osaka. Their work revealed that microplastics could reduce plant photosynthesis by as much as 12 percent on average. In turn, the researchers estimate that will cause a 4 to 14 percent yield loss for wheat, rice and corn worldwide.

Marine plants and algae at the bottom of the aquatic food chain are also impacted, potentially leading to a predicted 7 percent loss in fish and seafood, per the Guardian.

“It’s really scary,” says Marcus Eriksen, a marine scientist at the 5 Gyres Institute, a nonprofit focused on reducing plastic pollution, to Joanna Thompson at Scientific American. He was not involved in the study.

Other researchers argue that more work will be needed to add credibility to the team’s predictions. The findings are “speculative,” says Florian Busch, a plant physiologist at the University of Birmingham in England who was not involved with the work, in a statement to the Science Media Center. For instance, he adds, even if a plant grows more slowly due to a reduced ability to photosynthesize, it might still produce the same amount of food in the end.

“The topic is of considerable importance, but the conclusions should be treated with great caution,” adds Richard Lampitt, a research scientist at the National Oceanography Center in the United Kingdom, in a statement. “I have considerable concerns about the quality of the original data used by the model, and this has led to over-speculation about the effects of plastic contamination on primary productivity and food supplies.”

Still, the study is further support for a global treaty on plastic pollution, says Richard Thompson, a marine biologist at the University of Plymouth in England who was not involved in the study, to Scientific American. And not all hope is lost—cutting current environmental microplastic levels by 13 percent could alleviate that photosynthesis loss by around 30 percent, according to the paper. United Nations member states have yet to agree on a treaty, however, after talks stalled in December.

“If we don’t take action now,” adds Thompson, “within the next 70 to 100 years, we’ll see much more wide-scale ecological harm.”

Sara Hashemi | READ MORE

Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.