Environmentalists fear the impact of this plastic pollution on globally important seabirds and marine life and are calling for new laws to stop it at source.
Nurdles are the raw materials for the plastics industry and are used to make a wide range of everyday products.
They are transported around Scotland by the lorryload and shipped in their billions to and from other countries.
But the lentil-sized pellets are easily spilled during handling, and if not cleaned up can end up down drains, in rivers and eventually at sea.
A team of volunteers spent eight hours picking up nurdles at Kinneil nature reserve in Bo’ness last month, scooping them up with dustpans, tweezers and sieves.
But their efforts made almost no impression, with multicoloured beads still making up a major proportion of the sediment afterwards.
“We usually ask volunteers to simply estimate how many pellets they see on the beach, but this becomes difficult when there are such large quantities,” said Madeleine Berg, project officer at environmental charity Fidra, which spearheaded the operation with Marine Conservation Society Scotland.
“Although we collected nurdles all day, we barely scratched the surface. From these estimates there must be many millions on this small stretch of beach alone.”
The UK processes around three million tonnes of plastics a year, almost all in nurdle form.
Fidra estimates up to 53 billion of these lentil-sized balls are lost each year around the UK, and once in the marine environment they can be mistaken for food by animals such as fish and seabirds.
Studies show creatures that have ingested plastic often become malnourished and can even starve to death.
The pellets also pick up and concentrate toxic chemicals from pollution in seawater, which poses a further threat to animals that eat them or feed nearby.
The Forth, which is a major hub for industry, is a known hotspot for nurdles – surveys over the years at Limekilns in Fife have found anywhere between 200,000 to over two million – but the problem is widespread.
Nationwide research carried out earlier this year found nurdles on nearly three-quarters of beaches across the UK, from Shetland to the Scilly Isles.
Nurdles are part of a much bigger problem, with estimates suggesting more than 12 million tonnes of plastic waste ends up in oceans around the world each year.
“Removing all pellets from beaches is a near-impossible task,” according to Sarah Archer, manager of Fidra’s pellet-loss project.
“Instead we focus on stopping these pellets escaping in the first place.”
She says simple best practice measures can mean spills are prevented and cleaned up properly. However, there are currently no checks in place to make sure such measures are applied effectively.
“We want to ensure the positive changes made by parts of the industry are now applied right across the supply chain,” Archer added.
“The plastics supply chain is complex, but legislation would make sure all companies handling plastic pellets do so responsibly, and that this source of micro-plastic pollution is eliminated.”
Some companies based around the Forth have already signed up to a voluntary initiative called Operation Clean Sweep, an international programme designed to prevent plastic waste entering the marine environment.
These include the petrochemicals giant Ineos, which manufactures plastic nurdles at its Grangemouth complex.
A spokesman for Ineos said: “Our commitment to the highest standards of health, safety and environment underpins all of the work we do at Grangemouth.
“In addition to Operation Clean Sweep, we’ve committed to our own Zero Pellet Loss strategy. This ensures we take measures to minimise the risks associated with any pellets finding their way into the local environment from manufacture through to packaging at the site and prior to transportation to the end user.
“We have made investments at Grangemouth in equipment, training and awareness for our employees and mitigation measures to deal quickly and effectively should any spill occur.
“Within the complex supply chain, from manufacturer to converter and to end user, we work closely with our immediate supply chain partners in raising their awareness of Operation Clean Sweep and the tenets of the programme.”
Another company to sign up is local haulage and warehousing firm John Mitchell, which transports large quantities of pellets around the country.
Managing director Iain Mitchell said: “Operation Clean Sweep is vital to implement in a business that is handling any sort of product that could potentially spill.
“The cost of implementation is low -– almost nil – with the biggest investment being in a brush and shovel, along with disposal bags. But the cost of ignoring the issue is huge.
“For me, bluntly, it’s a no-brainer. Sweep up and dispose of spillages responsibly. Or better still, stop the spillage in the first place.”
Local MSP Angus MacDonald, who has helped in beach-cleans at Bo’ness, is backing the calls for new laws.
He said: “I’m pleased that industry representatives in my Falkirk East constituency have acknowledged the issue. However, it is clear that legislation must be seriously considered to ensure the handling of plastic pellets at all stages is properly monitored and controlled.”