Airborne Microplastics Detected in Plant Leaves, Entering Food Chain: Study

A fresh science study has found that plant leaves are directly absorbing microplastics and nanoplastics from the air, and this has raised concern over how the particles are entering the food chain and eventually animals and even human beings. The research, published in the journal Nature, was carried out by scientists from the Nankai University, the University of Massachusetts Amherst, the Chinese Academy of Sciences, Northeastern University, and the Beijing Academy of Agriculture and Forestry Sciences.

Microplastics are fragments of plastic up to 5 millimeters in length, and nanoplastics are smaller again, less than 1,000 nanometers. It was discovered by the study that the particles enter leaves through a variety of surface characteristics including stomata—minute pores on the leaf surface—and the waxy cuticle layer. Inside, the plastics are able to travel through intercellular space and even collect in plant bodies like trichomes, hair-like structures which are able to trap particles and slow their rate towards other regions of the plant.

The study also revealed that microplastics are able to move along the plant's internal nutrient and water transport system to other plant tissues. While there is some natural filtering by structures like trichomes, a lot of the plastic particles remain in the plant. Since leaves are typically consumed by herbivores or humans through leafy greens, there is a clear pathway for plastics to move up the food chain.

Scientists compared plant tissue from greenhouses and field environments. One thing noted was that vegetables produced in the field contained 10 to 100 times more microplastic material than vegetables produced in greenhouses. The difference had been attributed to the density of microplastics in the air. One specific trial in Tianjin, China, demonstrated that the air-exposed lettuce plants from the outside environment absorbed between 7 and 10 nanograms per gram plant dry weight polystyrene nanoplastics. Regions with higher airborne levels of microplastic contamination had significantly higher levels of accumulation in plant tissues compared to regions with cleaner air.

The research found some of the most prevalent types of plastics found in plants, including polyethylene terephthalate (PET) and polystyrene. It further showed that longer plant growth periods and older outer leaves deposited more microplastics than younger or inner leaves. This implies that the duration of exposure to contaminated air and the age of the plant can both have a significant impact on the amount of plastic taken up.

Specifically, the authors emphasized that it is not difficult for such particles to find their way into animals and human beings. Leafy vegetables form an important component of diets of both human beings and animals and thus act as a prevalent link in microplastic transfer from the environment to organisms. While the work supports extensive accumulation of plastic by plants, the research further remarks that the entire health impact remains unknown. More research needs to be conducted in an attempt to discover how such particles react within the human body and whether they are capable of seeping into crucial organs when ingested.

The study adds to increasing evidence of the ubiquity of microplastic contamination and serves to underscore the requirement for further investigation into its long-term impact on the environment and human health. It also puts questions marks over agricultural practice, food safety, and how airborne pollutants need stricter regulation.

Source/Credits:
Himanshu Nitnaware, 11 April 2025
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