Evaluating the genotoxicity, carcinogenic potential, and disease-promoting effects of polystyrene nanoparticles using Drosophila melanogaster models of human disease

The world's oceans are thought to contain more than 170 trillion plastic particles. Unknown amounts are present in both atmosphere and mainland. Thus, plastic pollution is a global emergency. Plastic degradation forms micro- and nanofragments that are ingested by living beings and bioaccumulated in fatty tissues that reduces survival, is genotoxic and causes metabolic alterations. We use Drosophila melanogaster as model organism to assess if 100 nm polystyrene nanoparticles (PSNPs) induce DNA damage, increase cancer risk and potentially worsen disease progression. Ingested fluorescent PSNPs are absorbed into intestinal cells and accumulated in fat bodies of wild-type flies. Compared with controls PSNPs-fed flies weighed considerably less and showed increased developmental time, and compromised starvation resistance and heat shock recovery. Feeding PSNPs to DNAlig4 mutants, known to be susceptible to dietary stressors, decreased climbing performance. Together, these findings imply that PSNPs influence fly development and metabolism. A qPCR analysis of the intestines of PSNP-fed wild type larvae revealed higher expression of cell damage response genes. Increased DNA damage was detected with the comet assay. Reinforcing the hypothesis of the PSNPs carcinogenic potential, PSNPs-fed warts mutants, known to spontaneously develop melanotic tumors even in heterozygous individuals, developed more aberrant masses than untreated ones. We are currently testing the potential effects of PSNPs on disease progression using a fly/Drosophila model of Polycystic Kidney Disease.