Nanoplastics can move up the food chain from plants to insects and from insects to fish

A new study shows that lettuce can take up small particles from the soil and transfer them into the food chain. The paper is in a magazine.

Microplastics andnanoplastics are small pieces of plastic that break down into smaller pieces when mishandled. It is possible that small particles can enter organisms.

Our understanding of plastic transfer in food webs is limited despite the growing body of evidence. Despite the fact that agricultural soil is potentially receiving nanoplastics from different sources such as atmospheric deposition, irrigation with wastewater, application of sewage sludge for agricultural purposes, and use of mulching film, little is known about the effect of these particles on the soil environment. Measurement of the amount of nanoplastics in the soil by plants, particularly vegetables and fruit, is a critical step to discover whether or not they can make their way into food webs.

In a new study, researchers at the University of Eastern Finland applied a metallic fingerprint-based technique to a model food chain consisting of three trophic levels. Polystyrene and polyvinylchloride are commonly found in the environment.

The black soldier fly, which is used as a source of proteins in many countries, was fed the lettuce plants after they were exposed to the contaminated soil. The insects were fed to the fish for five days.

Researchers used scanning electron microscopy to analyze the fish and plants. The pictures showed that the plastic was taken up by the roots of the plant. The plastic was transferred to the insects. Even though the insects were allowed to empty their guts for 24 hours, they still had plastic in their mouths and gut. The lower number of PS particles in the insects was similar to the lower number of PS particles in the lettuce. Particles were found in some parts of the fish, but not in the brain.

According to our results, lettuce can take up plastic from the soil and transfer it into the food chain. If these findings are found to be generalizable to other plants and crops and to field settings, the presence of tiny plastic particles in soil could be associated with a potential health risk. Further research into the topic is still needed.

More information: Fazel Abdolahpur Monikh et al, Quantifying the trophic transfer of sub-micron plastics in an assembled food chain, Nano Today (2022). DOI: 10.1016/j.nantod.2022.101611 Journal information: Nano Today