North Sea tanker collision: What is sodium cyanide and is it hazardous to humans and the environment?
11 March 2025, 12:34 | Updated: 14 March 2025, 08:38
A collision in the North Sea involving two ships off the Yorkshire coast saw crews battle to contain a monumental fire, with initial reports suggesting the cargo included jet fuel and possibly sodium cyanide.
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One of the vessels - the 183m-long tanker named the US-flagged Stena Immaculate - was carrying around 220,000 barrels of Jet A-1 aviation fuel in separate tanks, some of which was discharged into the North Sea.
The second vessel, a cargo ship named the Solong, was en route to the dutch port of Rotterdam. In the aftermath of the crash there were fears it was carrying a combination of alcohol and 15 containers of sodium cyanide.
However the Solong's owner, Ernst Russ, has confirmed the ship was not carrying the hazardous substance and reports have been "misinterpreted".
"There are four empty containers that have previously contained the hazardous chemical, and these containers will continue to be monitored," the company said in a statement on Tuesday.
As crews fought to battle the flames into Tuesday morning, the latest images appear to show only the US tanker afloat on the ocean.
It's led many to speculate on the short and long-term environmental impact of the crash, given it appears the Solong, as well as its cargo, now lie at the bottom of the ocean.
The images have also led many to question whether or not the cargo poses a risk to humans and wildlife along the Yorkshire the coast.
What is Sodium Cyanide?
Sodium cyanide is a compound with the chemical formula NaCN - widely described as a highly toxic chemical.
A solid substance, sodium cyanide generally appears as a fine white powder or as small crystals or granules that dissolve in water.
Known to be an exceptionally toxic , the compound produces hydrogen cyanide gas when it comes into contact with water.
Experts suggest that the combination can pose grave risks to both human and aquatic life in high concentrations.
What are the risks posed by sodium cyanide?
Experts have now warned that, as with any spill, the impact has the potential to severely affect marine life, seabirds, and living organisms which make up the fragile ecosystems around the Humber Estuary.
Paul Johnston, principal scientist at Greenpeace Research Labs said on Tuesday: "This chemical has even been deliberately used in the past to poison fish. It can swiftly kill marine life and severely disrupt local ecosystems if it leaks."
Dr Jonathan Paul, from the earth sciences department at Royal Holloway, University of London, said that if sodium cyanide leaks into the ocean, there is always a "potential immediate risk to humans and wildlife".
He said if sodium cyanide is involved, it is "likely to be localised to the spill and removed from the water within 12-15 days" as it volatilises to cyanide gas in the atmosphere.
"There is a potential immediate risk to humans and wildlife from this toxic gas, which depends on the volume released - i.e. whether the containers had been pierced or breached," he said.
But he added that cyanide spills are more hazardous in enclosed water courses, while most wildlife will likely have already vacated the area due to the reverberations from the crash and explosions.
"The jet fuel is likely to be longer lived and would require immediate action first to extinguish the fire (obviously using water does not help), then to remove it from the surface of the water," he said.
"Kerosene fuels are 'light', unlike 'heavy' crude oil, so we're unlikely to be dealing with thick deposits washed up onshore and coating nesting birds. The risk is that the fuel might bioaccumulate, i.e. pass up the food chain."
How long could the cleanup take?
Responding to reports that the cargo ship was carrying sodium cyanide, Dr Seyedvahid Vakili, a maritime expert at the University of Southampton, said: "The time required to contain and clean up sodium cyanide spills depends on factors such as the extent of the spill, weather conditions, and the effectiveness of the response measures.
"Given the chemical's high toxicity, specialised hazardous material teams are needed for cleanup operations. While minor spills might be addressed within days, larger incidents can take weeks or longer to fully remediate.
“Perhaps we can link this accident to the Sanchi disaster (2018, East China Sea) due to the similarities in the nature of the cargo. In the Sanchi case, although the vessels were underway, the tanker carried 136,000 tonnes of condensate oil, which burned for over a week, releasing toxic fumes and causing severe ecological damage.
"The incident led to the leakage of condensate—an ultra-light, highly flammable substance —which mostly evaporated after the fire but also contributed to subsequent explosions and environmental contamination.”
