Nurdles are the raw material for almost every plastic product on Earth, from the keys on a keyboard to the juice jug in a refrigerator. They are sometimes known as pre-production plastic pellets, referencing the fact that they are a raw material, or “plastic resin pellets.” As these alternate names imply, they are tiny pellets of plastic that can be melted down and formed into new shapes.
It is estimated that over 250 billion pounds (113 billion kilograms) of nurdles are manufactured and shipped globally every year. They are typically shipped via tanker truck, with each tanker being loaded to the brim with the pellets. The advantage of using tankers is that they can easily be loaded onto container ships, making them easy to move across the ocean and to drop onto trains and shipping trucks for transit inland.
To use nurdles, manufacturers feed the plastic pellets into hoppers which melt them down, allowing the manufacturer to make plastic products. They can be melted and injected into molds, extruded by machines, or pressed in specialized presses which are designed to make specific products, among other things. Nurdles come in a variety of types, allowing manufacturers to make a range of products, and they can be clear or colored, allowing producers to color their own plastics or utilize pre-mixed colors for their products.
Studies on marine pollution suggest that nurdles may be one of the leading constituents of marine debris. They are manufactured in such high volume annually that it is almost inevitable to find some being spilled at every step of the way. As they spill, they work their way into waterways, eventually reaching the ocean, where they can wreak havoc. The pellets can carry harmful chemicals which hurt marine organisms, they can choke small animals, and they appear to be able to act as sponges to concentrate pollutants released into the marine environment.
The amount of nurdles currently bobbing in the world's oceans is impossible to estimate, but beach clean-up groups and researchers routinely collect them by the bucket from beaches and areas like the Great Pacific Garbage Patch, suggesting that they may be an endemic problem. Because plastics take thousands of years to break down, nurdles could potentially endure in the natural environment for generations, leading many people to encourage tighter control of the pellets in an attempt to ensure that less of them make their way out into the world.