LEGO bricks can survive 1,300 years in the sea

The ocean around the UK is strewn with LEGO.

Some of them were flushed there; one UK insurance company estimates that children flushed some 2.5 million LEGO pieces down the loo between 2006 and 2016. Other bricks arrived there in 1997 when a wave slammed a cargo ship and dumped 62 containers – one containing nearly 4.8 million pieces of LEGO – overboard. Some bricks still wash onto the shore, but most sink to the bottom, and there they will remain for a thousand years or more.

In a recent study, researchers compared 50 castaway LEGO bricks trawled from the coastlines of southwest England with 50 matching bricks that never left their boxes. Using X-rays and other analytic tools to measure how much of the marine bricks had weathered away, the team determined that a single LEGO brick can survive in the ocean for anywhere from 100 to 1,300 years before totally degrading.

Because most LEGO bricks are stamped with serial numbers, it was relatively easy for the researchers to date the sea-weathered bricks and then compare them with identical unweathered bricks obtained from local collections. Many of the underwater LEGO dated to the 1970s and 1980s, the researchers said, and had suffered noticeable decay.

“The pieces we tested had smoothed and discoloured, with some of the structures having fractured and fragmented, suggesting that as well as pieces remaining intact, they might also break down into microplastics,” said lead study author Andrew Turner.

Some pieces had lost up to 40 per cent of their original mass while at sea; others lost only three per cent. Ultimately, the researchers said, the type and thickness of the plastic used in a given brick determined how quickly it decayed, but it’s likely that the average LEGO could remain intact in the sea for hundreds of years.

According to the researchers, these findings reinforce the message that people should be more thoughtful about how they dispose of used household items. Please don’t chuck your toys into the toilet or the sea.