Researchers from the university's industrial chemistry department analyzed various points along the banks of the Arno and Serchio rivers in Tuscany, both of which flow into the sea on Italy's western coastline.
The results showed a burgeoning environmental hazard: In some areas where samples were taken, between 5 and 10 grams of microplastics were found below the surface of the sand, leading the scientists to estimate that there are potentially thousands of tonnes of such semi-degraded particles across Italy's beaches.
The research team analyzed plastic particles smaller than 2 millimetres, most of which had been washed in from the sea.
Polyolefins, used for food packaging, and polystyrene – a rigid and cheap plastic also used for disposable CD containers or razors – were the main microplastics observed.
"Our research highlights how this form of environmental contamination can be pervasive and almost omnipresent even in areas where tourists come to swim in large numbers," Professor Valter Castelvetro, the study's main author, said in an executive summary issued by the University of Pisa.
"One of the main risks is that microplastics act as collectors of pollutant substances that are also highly toxic such as pesticides and polycyclic aromatic hydrocarbons," added Castelvetro.
Most studies into maritime pollution focus on larger plastic debris, which is usually collected using nets in the open sea. Few studies have focused on microplastics and their impact on beaches, adds the university's report.
The University of Pisa's study concludes that there are between 1,000 and 2,000 tonnes of microplastics on Italy's beaches.
Pollution is not limited to Italy's beaches, however. A 2017 report by Italian environmental institute Legambiente found that 40 per cent of the water along the Italian coastline is polluted.
That report found that 105 samples of water out of a total 260 tested, approximately 40 per cent, "contained polluted results with bacterial charges above legal limits," according to Legambiente's final report.
Legambiente's study – part of a 30-year project to monitor pollution along Italy's coastline – highlighted 38 "critical points." with the regions of Lazio, Campania, Calabria and Sicily populating most of the black list. Thirty per cent of all recorded cases of pollution in 2016 were in Campania or Sicily alone.
In April 2018, the Tremiti Islands – an archipelago off Italy's eastern coast – banned plastic plates, cups, forks and other picnicware, with fines of up to €500 for those who break the law.