After years of analysis and research, the weight of the plastic island floating in the waters of the Pacific Ocean, between the south-east of Japan and the north-west of Hawaii, has finally been calculated: it amounts to 21,290 tonnes, a quantity of rubbish that can only be matched by 132 Boeing 747s or 120 blue whales.

Plastic island: the equivalent of 132 Boeings

The calculation of the enormous mass of waste making up the Pacific Trash Vortex — the name given to it by scientists — was carried out by the SEA Education Association, based in Massachusetts. The research, which has so far involved 1,700 students, was published in the journal Environmental Science and Technology.

Plastic waste presents a twofold problem: not only does it put fish and other marine animals at risk, as they may inadvertently ingest it, but it also pollutes the water. Plastic, in fact, has the characteristic of absorbing toxic chemicals and releasing them into the sea. Not to mention the damage that can be suffered by vessels passing through the area.

Shipping is responsible for only a small share of the "blame": plastic from ships' containers accounts for just around 20 per cent of the total. The majority of marine litter comes from land, from the drains of our cities and from rivers that run alongside landfill sites.

How large is the Pacific Trash Vortex according to Noaa

The United States agency for oceans and atmosphere has attempted to give scientific confirmation to the Pacific Trash Vortex, and on its official website writes: "There are many locations with floating rubbish, and by this we mean that waste accumulates to varying degrees in numerous parts of the Pacific and the rest of the sea.

Over the past 50 years, human beings have contaminated the ocean with various substances, radically altering it and causing damage to its flora and fauna. This study is only a first step towards understanding the effect of this pollution.

How much does plastic in the sea weigh

The new estimates, which according to other scientists — such as ecologists from the Spanish University of Cádiz — would be excessive because they rely too heavily on the visual mapping of waste, indicate the presence of approximately 5,250 billion pieces of plastic debris, with a combined weight of around 269,000 tonnes. Almost 75 per cent of that weight would be accounted for by large objects, such as buoys, buckets and other fishing equipment.