A toxic chemical that leaked into a canal in Walsall could be removed or neutralised within a week, an expert has claimed.

Sodium cyanide was one of three substances released into the sewer following a waste disposal incident, according to the Environment Agency (EA). at Anochrome Ltd.

Twelve miles of canals in the Black Country and Birmingham were closed on Tuesday, but the EA said on Wednesday the contamination zone was “smaller than expected”.

Dr Jonathan Paul, lecturer in geosciences, said the situation would hopefully be resolved within a week.

Anochrome Ltd, a specialist in surface coatings and sealants, said it “regrettably” released chemicals into the Walsall Waterway in the early hours of Monday morning.

About 100 dead fish were observed floating on the surface of the canal near Reservoir Place.

People were urged to approach a long stretch of the canal network from the centre of the borough to Birmingham and the connected waterways in Wednesbury, Tipton and West Bromwich.

Dr Paul, a lecturer at Royal Holloway, University of London, told BBC Radio WM that there are several strategies available for EA to dilute or remove the toxic substance in the water.

“One of the more cost-effective solutions would be to simply dilute the water and pump in a lot of fresh water from somewhere else to bring the concentration down,” he said.

“You could do other, more active things. You could run it through a filter and try to remove it.

“Or they could add certain chemicals to the water that would remove the cyanide from the water and create a kind of foam on the surface that could be skimmed off and then safely disposed of.”

Sodium cyanide can cause seizures, vomiting and loss of consciousness.

Dr Paul said the EA would likely implement these measures within days.

“Hopefully this situation – touch wood – will be resolved within a week,” he said.

“If there is a bright spot, it is the fact that cyanide naturally decays quite quickly, within a few days.”

The EA believed that three substances had entered the sewer following the incident at Anochrome Limited.

These were sodium cyanide, sodium hydroxide and possibly zinc.

Dr. Paul expressed suspicion that the company was using sodium cyanide to treat the surfaces of metals, describing it as “a very strong solvent like glue.”

He said sodium hydroxide, better known as caustic soda, could potentially make water “very alkaline,” posing a threat to aquatic life, while zinc would make the water “very cloudy.”

Dr Alex Baker, assistant professor of chemistry at the University of Warwick, said the incident would cause problems in the local ecosystem “for quite some time”.

He told the BBC: “If another predator comes and eats the fish, the cyanide enters the food chain.”

“We’ll also see cyanide in the soil, so it’s actually going to cause biological problems in the ecosystem for quite some time – not for humans, but definitely for small animals.”

In the days following the spill, ducks, geese and moorhens have been seen on or near the canal, and a wide variety of birds can be seen diving for fish throughout the Black Country canal network, including kingfishers and cormorants.

Dr Delia Garratt, chief executive of the Birmingham and Black Country Wildlife Trust, said the incident would have a devastating impact on the wildlife that lives along the canal.

“Our canals and waterways are constantly exposed to pollution from toxic substances and plastic waste,” she said.

“While budget cuts to law enforcement and environmental protection over the past decade have left these countries increasingly defenseless.

“Environmental watchdogs must be given the powers and resources necessary to ensure they can monitor and control polluters and punish those who break the law.

“We hope that whoever is responsible for this damaging and dangerous oil spill in Walsall’s canals will face the full force of the law in due course.”

Referring to similar cases of chemical accidents, Dr Baker said: “Romania had a serious problem (with sodium cyanide) in the 2000s that went far beyond what Birmingham is currently experiencing.”

“It took several weeks for it to completely migrate into the sea.”

The oil spill occurred in January 2000when waste containing sodium cyanide entered the Tisza, a tributary of the Danube, after a dam burst in a gold mine in Romania.

The accident killed about 80% of the fish in the river and severely decimated the local bird and animal population.

• The chemical sodium cyanide is a white crystalline solid with a faint almond odor
• It is used in industry for metal cleaning, coating and extraction
• When cyanide salts are swallowed, cyanide is released into the body. Absorption through the skin is also possible.
• Exposure may cause symptoms such as headache, nausea, dizziness, loss of consciousness, seizures and vomiting.
• It can quickly cause death if inhaled or ingested because it impairs the body’s ability to use oxygen.

(Source: British Health Security Agency)

Sodium cyanide is soluble in water and can have serious adverse health effects if humans or pets come into direct contact with it, the council warned.

A spokesman for the authority added that anyone who was exposed to the water and felt unwell should seek medical advice via the NHS emergency number 111 or call 999 in an emergency.

People living in boats on the canal in the affected area have been informed about the oil spill, the Canal and River Trust said.