Countless tiny plastic pellets are washing up on the shores of northern Spain and local authorities have declared an environmental emergency after a shipping container fell off a transport vessel last month.

The regional governments of Galicia, which has borne the brunt of the pollution, and neighbouring Asturias asked Spain’s national government to help, and on Monday prosecutors opened an investigation.

Prosecutors fear the pellets could have toxic properties and said there are indications they had also been found on French shores.

“These little balls of plastic are an environmental problem because fish confuse them with fish eggs and eat them and they enter the food chain … and end up on our dinner tables,” Cristobal Lopez, spokesman for the Spanish environmental group Ecologistas en Accion, told the Associated Press.

Spain Plastic Pollution
A volunteer holds plastic pellets collected from a beach in Nigran, Pontevedra, Spain (Lalo R Villar/AP)

The spill was first reported to authorities on December 13 when hundreds of thousands of tiny white balls began washing up on Spain’s Atlantic shoreline.

Spain’s government representative for the Galicia region said the container ship Toconao, sailing under a Liberian flag, lost six containers off the coast of Portugal, 50 miles west of Viana do Castelo.

One of the six containers contained 1,000 sacks of pellets, each holding 55lb of the tiny plastic balls used in the fabrication of plastic products, the government representative said.

Greenpeace and other environmental groups calculate the total amount of pellets to be in the millions. They say the pellets represent a danger for marine and human life because they can break down into even smaller microplastics that can be consumed by fish that are later caught by fishermen.

“The contamination of the oceans and ecosystems with plastics is one of the biggest problems faced by humanity,” said Spain’s minister for the environment, Teresa Ribera. “So the spilling of such an important quantity of plastics requires close oversight and to determine if the transport company and shipping company exercised the proper precautions.”

Maersk, the shipping company contracted to transport the containers, told the AP that the containers were lost on December 8 in the deep sea during the voyage from Spain’s southern port of Algeciras to Rotterdam, Netherlands.

Spain Plastic Pollution
Spanish prosecutors have opened an investigation into countless tiny plastic pellets washing up on the country’s northwest coastline (Lalo R Villar/AP)

It said the Toconao is a charter vessel, not one of the Danish company’s fleet, and it works on the company’s route between northern Europe and the Mediterranean.

“None of the six containers contained dangerous goods. One of them was loaded with bags with little plastic pellets for the production of food-grade packaging like water bottles,” Maersk said. “The vessel owners have appointed multiple clean-up specialists to support removing the pellets.”

Maersk said it is investigating the cause of the lost containers to “take necessary steps to minimise the risk of similar incidents occurring in the future”.

Volunteers and workers are cleaning up the beaches and coasts of the area, which depends on a large fish and shellfish industry. Galicia’s marine coastline was devastated by an oil spill from the Prestige tanker in 2002.

The European Commission proposed measures last October to help prevent the mishandling and spillage of plastic pellets. The measures must be debated by the 27 EU member states and the European Parliament, and would enter into force 18 months after any agreement is reached.

Jordi Oliva, co-founder of Good Karma Projects, a Spanish NGO dedicated to fighting microplastics in the sea, said this is the largest single spill of pellets his group has seen in Spanish waters. He said he hoped this incident could help push the EU and national authorities to act.