They’re small enough to fit on your fingertip, but in the ocean they can cause outsized damage.
After a string of major spills, an international group of researchers is urging the International Maritime Organization (IMO) to officially recognize plastic pellets – often called “nurdles” – as a marine pollution hazard.
The experts are also calling for tighter rules to prevent spills and improve how they are handled when they occur.
The new scientific commentary, accepted for publication in Cambridge Prisms: Plastics, pulls together years of evidence from scientists who have tracked pellets in the real world and in the lab.
The team’s work spans field sampling, chemical and toxicity testing, studies of wildlife exposure, and investigations of large spill events.
The message is blunt: current shipping rules don’t adequately protect the marine environment from pellet pollution, even though we’ve known for decades that pellets regularly escape into the sea.
Plastic pellets are small, lentil-sized particles, typically 2-5 millimeters across. They’re made from virgin or recycled plastic and shipped globally as raw material for making countless plastic products.
The problem is that pellets are easy to spill. They can be lost during storage, loading, and handling on land.
They can also spill at sea during transport, something that has been documented since the early 1970s.
Once they’re out, they’re extremely difficult to clean up. They spread widely, blend into sand and seaweed, and can keep circulating for years.
That’s why scientists argue pellets shouldn’t be treated like ordinary, low-risk cargo. They’re small, persistent, and prone to leaking into the environment at many points in the supply chain.
One of the clearest harms is physical. Pellets are easily swallowed by animals that mistake them for food, especially seabirds, fish, turtles, and other marine wildlife.
“Today the volumes of plastic pellets entering the marine environment are enough to ‘feed’ millions of young seabirds,” noted Jennifer Lavers from Charles Sturt University, who studies pollutants in seabirds.
“In some areas we are already seeing a nearly 100% rate of plastic ingestion, with pellets being particularly problematic for some species.”
“When birds and other wildlife eat these plastics, it can block their digestive system and lead to a wide range of serious health conditions.”
That “block their digestive system” part is not a minor issue. Ingestion can reduce appetite, prevent proper nutrition, and lead to injury or death.
And because pellets can build up in the environment, exposure isn’t a one-time event. It can become a steady background threat, especially in hotspots where currents and winds concentrate floating debris.
The commentary also emphasizes chemical risks. Pellets aren’t just inert plastic beads drifting around.
They contain additives from manufacturing, and they can absorb toxic substances from seawater and later release them, meaning they can act like tiny transport vehicles for persistent pollutants.
“Plastic pellets are not inert,” said Sinja Rist from DTU Aqua, who works with pelagic pollutants.
“Pellets are persistent, widely dispersed, readily ingested by wildlife, and capable of transporting hazardous chemicals, posing a threat to a wide range of marine organisms.”
This matters because the ocean is not an isolated sink. Chemicals can move through food webs. When smaller organisms ingest pellets, predators can ingest them too, and the contaminants can travel upward through the ecosystem.
The researchers’ point isn’t that every pellet is a chemical bomb, but that the risk is real and predictable enough to justify stronger controls.
Pellet spills have been happening for decades, but the commentary points to one event that jolted global attention in a different way: the 2021 X-Press Pearl disaster off Sri Lanka.
The container ship caught fire, and its cargo of chemicals and plastic pellets spilled into the ocean. The article describes an estimated $6.4 billion in damages, much of it tied to environmental contamination from burned and spilled pellets.
For scientists and communities on the ground, this wasn’t an abstract concern. Beaches, fisheries, and coastal ecosystems were hit quickly and visibly.
“After studying the aftermath of the X-Press Pearl disaster, it is impossible to argue that plastic pellets are harmless cargo,” said Hemantha Withanage, a chairperson at the Center for Environmental Justice in Sri Lanka.
“The impacts in Sri Lanka were immediate, widespread, and long-lasting. Stronger international regulation is essential to prevent this from happening again.”
The takeaway from this example is not only that pellets are harmful, but that a single shipping incident can release huge volumes at once, creating a long-term cleanup and contamination problem that stretches far beyond the initial accident.
Under MARPOL – the International Convention for the Prevention of Pollution from Ships – the intentional release of plastics is banned.
But the study argues that the rules aren’t strong enough when it comes to accidental spills, container losses, and shipping disasters.
In other words, the system is set up to say “don’t dump plastic,” but not set up well enough to stop massive releases when things go wrong.
The researchers note that the European Union has recently adopted rules aimed at preventing pellet losses across the full supply chain.
The IMO, meanwhile, committed in 2021 to address pellet pollution from shipping as part of its wider effort to reduce marine plastic litter.
Since then, multiple proposals have been discussed, including giving environmental hazard ellets a specific UN number, which would formally recognize their potential and trigger requirements around packaging, labeling, and notification.
The experts’ argument is that the science is already strong enough to justify that step – and that treating pellets as hazardous in shipping practice would make prevention and response more serious by default.
The authors’ call is straightforward: recognize the hazard, then regulate accordingly. That means better prevention measures to stop pellets escaping in the first place, plus clearer requirements for what happens when spills occur.
“There are decades of studies highlighting threats from plastic pellets released into the oceans, including threats to marine animals and the food chain,” said lead author Therese Karlsson, a science advisor for IPEN.
“Plastics are made with thousands of chemicals, including many known to cause harm to the environment and our health. It is past time for global regulations to protect the oceans from spills of hazardous plastic pellets.”
What makes this feel urgent is the combination of scale and familiarity. Pellets are everywhere in the plastics economy, and spills have been “normal” for a long time. The scientists behind this commentary are basically saying: normal doesn’t mean acceptable.
If pellets are persistent, widely spread, easy for animals to eat, and linked to serious physical and chemical harm, then the rules should treat them like the hazard they are – not like harmless grains that just happen to float.
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