Interactions of Ingested Polystyrene Microplastics with Heavy Metals (Cadmium or Silver) as Environmental Pollutants: A Comprehensive In Vivo Study Using Drosophila melanogaster

Abstract

Living organisms are now constantly exposed to microplastics and nanoplastics (MNPLs), and besides their toxic potential, they can also act as carriers of various hazardous elements such as heavy metals. Therefore, this study explored possible interactions between polystyrene microplastics (PSMPLs) and two metal pollutants: cadmium chloride (CdCl2) and silver nitrate (AgNO3). To better understand the extent of biological effects caused by different sizes of PSMPLs, we conducted in vivo experiments with five doses (from 0.01 to 10 mM) that contained polystyrene particles measuring 4, 10, and 20 µm in size on Drosophila larvae. Additional experiments were performed by exposing larvae to two individual metals, CdCl2 (0.5 mM) and AgNO3 (0.5 mM), as well as combined exposure to PSMPLs (0.01 and 10 mM) and these metals, in an attempt to gain new insight into health risks of such co-exposure. Using transmission electron microscopy imaging, we managed to visualize the biodistribution of ingested PSMPLs throughout the fly’s body, observing the interactions of such plastics with Drosophila intestinal lumen, cellular uptake by gut enterocytes, the passage of plastic particles through the intestinal barrier to leak into the hemolymph, and cellular uptake by hemocytes. Observations detected size and shape changes in the ingested PSMPLs. Egg-to-adult viability screening revealed no significant toxicity upon exposure to individual doses of tested materials; however, the combined exposure to plastic and metal particles induced aggravated genotoxic effects, including intestinal damage, genetic damage, and intracellular oxidative stress (ROS generation), with smaller sized plastic particles + metals (cadmium and silver) causing greater damage.

Real-time assessment of the impacts of polystyrene and silver nanoparticles on the hatching process and early-stage development of Artemia using a microfluidic platform

“…At the maximum NP concentration (1 mg L −1 ), Artemia mortality for PS and Ag NPs was 28.47 ± 3.41% and 40.66 ± 4.48%, respectively, comparable with the literature. 52,53,58 Ag NPs exhibited higher toxicity, aligning with previous studies 129,130 indicating poorer gut health, increased oxidative stress, and DNA damage caused by Ag compared to PS, which could be due to the release of different Ag ions from Ag NPs, 131,132 especially at higher salinities. 57 Depending on the redox state of the ions, they adsorb on the Artemia cuticle structural component, chitin, via physisorption, causing significant cellular deformation.…”

Ingestion of polystyrene microparticles impairs survival and defecation in larvae of Polistes satan (Hymenoptera: Vespidae)

“…The exposed larvae fully ingested the contaminated prey just as they ingested prey without MPs before and after exposure, and just as control larvae ingested prey without MPs. Other insect larvae, including mealworms (Wu et al 2019), silkworms (Muhammad et al, 2021), and fruit ies (Demir et al 2022), are capable of ingesting MPs and they have been successfully used in experiments with these pollutants.…”

Phytotoxic Effects of Polystyrene and Polymethyl Methacrylate Microplastics on Allium cepa Roots

“…No significant damage of DNA molecules was recorded in the current study with either PS- or PMMA-MPs, suggesting that MP treatments, tested by Comet assay, do not induce genotoxic effects in onion roots. The Comet test, a simple method for measuring DNA strand breaks in eukaryotic cells, has not yet been employed in testing MP genotoxicity in plant cells, although it was successfully applied to test MP toxic effects in fish larvae [ 68 ], earthworms [ 69 ], Drosophila melanogaster [ 70 ], and human colon epithelial cells [ 71 ]. As for the cytological parameters, mitotic index was not affected by any of the MP treatments, which is in agreement with no observed changes in root growth.…”