The Oceans Have All Kinds of Plastic
The oceans on Earth have many different kinds of plastic, however, estimating the time it takes for trash in the seawater to disintegrate is challenging. This is because it’s difficult to date the fragments of debris that have an unknown origin. However, for a single Lego part, it can be fairly easy.
Lego pieces have a distinct shape, and since the chemical additives that are used to make the Lego have changed significantly over time, the bricks have clues as to when they were made.
Research on Lego Blocks
Andrew Turner works at the University of Plymouth in England as an environmental scientist. He and his colleagues were able to use an X-ray fluorescence spectrometer to measure the chemical composition of Lego blocks washed up on beaches.
Using the Lego’s chemical fingerprints, the team was able to identify that the particular Lego bricks were manufactured around and during the 1970s. Cadmium was the key chemical indicator as it was used to make bright red and yellow pigments from the 1970s-1980s. It has since been phased out.
The team used the X-ray fluorescence measurements to gauge how worn out the Lego pieces were during their 30 to 40 years at sea by matching them with pristine versions from the 1970s. The condition of the Lego suffered due to exposure to sunlight and abrasive sediment, so there was a big difference.
The weathered Lego versions had 30% to 40% less mass than the Legos in pristine condition. Based on this information, it can be estimated that a single Lego brick can take between 100 and 1,300 years to break down completely in the ocean.