According to the study, conducted by researchers from McGill University and the Quebec government, microplastics commonly found in personal care scrubs were widely distributed across the bottom of the river in a total of ten test locations.
The samples were taken in locations covering a 320km section of the river stretching from Lake St. Francis to Quebec City, and were all found to contain the microbeads, which owing to their small size can easily pass through sewage treatment plants.
Painstaking research process
The microbeads were sieved from the river sediment, then painstakingly sorted and counted by the research team using a microscope.
"We found them in nearly every grab sample taken. The perfect multi-coloured spheres stood out from natural sediment, even though they were the size of sand grains," said the lead author of the study, Rowshyra Castañeda, a former McGill MSc student.
Indeed, some of the counts amongst the ten locations registered over 1,000 microbeads per liter of sediment, which the researchers say matches levels registered in some of the world’s most polluted waterways.
'Surprising' that beads remain in the river sediment
According to McGill professor Anthony Ricciardi, who supervised the study, the most surprising aspect of the findings was the fact that the count was so high in the river, as scientists had previously thought the small size of the particle meant they were generally flushed through rivers, to the sea.
“At present, we cannot predict the consequences of the accumulation of these non-biodegradable particles in freshwater ecosystems" said Ricciardi, whose lab is investigating whether the microbeads are being consumed by fish in the river.
Thus far legislators in neighboring United States have been proactive by adopting legislation that has banned the use of plastic microbeads in cosmetics in the states of Illinois, New York, Ohio and California.
The research team believes that the study findings may point the way towards legislative reform to outlaw microbeads in Canada.