GENEVA – There is an island of debris floating in the Pacific Ocean called the Great Plastic Patch; North Sea birds have intestines full of plastic bits; and the ubiquitous plastic shopping bags can be found all over the planet – including in the depths of the oceans. The fact that plastic fills our seas can no longer be overlooked.

Experts agree that only a small part of this trash comes from oil rigs and ships that dump their garbage into the sea. Up to 80% of it comes from sewage, garbage dumps, street litter and other sources on land that flow into the seas, in part via lakes and rivers.

But to what extent are inland waterways polluted? There isn’t a lot of significant data available on this. For Switzerland at least the country’s Federal Office for the Environment (FOEN) aims to change that and has mandated researchers from the Federal Institute of Technology’s Lausanne campus (EPFL) to find out more.

The team’s first results concerning Lake Geneva – also known as Lac Léman – have now been published by the Geneva-based Archives des Sciences journal. Every single one of the samples gathered by the group working under EPFL's Florian Faure on the beaches of the Franco-Swiss lake contain plastic remnants.

“Polystyrene beads were the most common culprits, but hard plastics, plastic membranes, and bits of fishing line were also widespread,” say the researchers.

“Lake water was also shown to contain significant amounts of microplastic contamination – pieces of plastic waste up to 5 millimeters in diameter,” they say.

Environmentally aware country?

The researchers write that in this preliminary study, the amount of debris caught in Lake Geneva using the manta trawl was comparable to measurements made in the Mediterranean Sea. A manta trawl is a floating, thin-meshed net mounted behind a boat to pick up any solid matter in the top layer of the water. However, they warn, the concentration of plastic in various areas differ strongly and the Lake Geneva measurements still have to be verified.

No diving and no swimming - Photo: champmol

Faure believes however that these results are cause for concern: "We were surprised to find such high concentrations of microplastics, especially in an environmentally aware country like Switzerland." According to Faure, given the massive efforts put into protecting the lakeshores over the past decades, both on its French and Swiss shores, “the situation is likely to be representative of fresh water bodies around the world.”

However the researchers say they found no plastic particles in any of the 41 fish they dissected.

Microplastic pollution threatens the animals that inhabit aquatic ecosystems both physically and chemically, Faure says. When inadvertently swallowed by aquatic birds and fish, the tiny bits of plastic can end up stuck in the animals’ intestines, where they obstruct digestive tracts, or cause animals to suffocate by blocking their airways.

“Ingested plastics may also leach toxic additives and other pollutants stuck to their surface into the animals that swallow them, such as bisphenol (BPA) and phthalates, two carcinogenic agents used in transparent plastics, or other hydrophobic water pollutants, such as PCBs (polychlorinated biphenyls)," he says.