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NEARLY 200 fish farms are allowed to use a carcinogenic chemical called formaldehyde which is used to embalm corpses, The Ferret can reveal. Documents disclosed under freedom of information law reveal that 184 Scottish fish farms are permitted to use formaldehyde in a solution called formalin, which is used as a disinfectant to guard against parasites and diseases.

Formaldehyde has been famously used by artist Damien Hirst to preserve dead animals such as cows, lambs and sharks.

Formalin, which is legal to use, is a water solution containing formaldehyde, but there are concerns over its safety.

In India last year, for example, there was a scare over preserved fish laced with the chemical, prompting a ban on fish imports in Goa state.

The UK Government classified formaldehyde as a carcinogen in 2016, which means there are restrictions on its use, but it is allowed to be used by the farmed salmon industry.

The campaign group, Scottish Salmon Watch (SSW), which obtained the documents, want formaldehyde banned. Concerns have been expressed over the potential of formalin leaks into lochs, seas and rivers.

The documents were released by the Scottish Environmental Protection Agency (Sepa). They reveal that a company called Mowi, formerly known as Marine Harvest, used 50.7 tonnes of formalin between May 2017 and September 2018 on salmon farms at Loch Shiel, Loch Arkaig, Loch Lochy and Loch Garry.

One document revealed there was an “accidental overdose” of formalin at Mowi’s Glenfinnan salmon farm at Loch Shiel in October 2017. This was “due to human error” leading to the deaths of 1343 fish.

As part of its investigation, SSW filmed vats of formaldehyde labelled “corrosive” and “toxic” this month outside The Scottish Salmon Company’s Russel Burn Hatchery on the shore of Loch Kishorn.

Don Staniford, director of Scottish Salmon Watch, said: “The salmon farming industry uses formaldehyde, via a formalin solution, as a disinfectant to guard against parasites and diseases although there are fish welfare and environmental concerns as well as human health impacts due to its carcinogenicity.

“The use of carcinogenic chemicals such as formaldehyde on salmon farms should be banned immediately. A public register of all chemicals used by salmon farms in Scotland is urgently required. The public surely have a right to know which toxic chemicals – including formaldehyde – are being used at which salmon farms.”

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Certain restrictions apply to the use of formalin because it is deemed a “substance presumed to have carcinogenic potential for humans”.

Guidance from the UK Department for Environment Food and Rural Affairs says: “Fish, poultry, sheep and cattle farmers – as professionals – will be able to continue to use products containing formaldehyde for dis-infection, fumigation and foot bathing purposes.

“Whoever is physically using the product must be competent enough to meet the restrictions and precautions detailed by the labelling. There is no requirement to prove competency before purchase and use.

“However if a health and safety issue arose through its use and be (sic) investigated, and the person using it found not to have been suitably trained and competent, then there could be grounds for prosecution.”

John Aitchison, of Coastal Communities Network, Scotland, said any discharge of toxic chemicals from salmon farms and hatcheries into Scotland’s rivers and seas “is a real cause for concern”.

He added: “That an overdose of formaldehyde/formalin killed 1343 fish shows that this is a potent chemical. It has no place being dumped into rivers or the sea, where it can harm wild animals and where people from coastal communities live or make their living.”

Aquaculture chemicals used to treat farmed fish can also kill or harm crustaceans that many fishermen depend on catching, Aitchison said.

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He added: “Sepa allows fish farms and well boats to discharge of another toxic compound, hydrogen peroxide, without any licence being required. This chemical is used in huge quantities, then dumped straight into the sea, despite research in Norway showing that it can kill commerciallyfished crustacean species days later.”

MOWI spokesman Ian Roberts said: “We can confirm that human error during application of formalin in 2017 resulted in the unfortunate loss of about 1300 juvenile salmon. When realised, we quickly rectified the situation and have since ensured it hasn’t occurred again.

“Formalin is used to protect small salmon in our freshwater farms from water-borne bacteria. Safe use of the product is licensed by Sepa under the Controlled Activities Regulations, following Sepa’s established environmental risk assessment that ensures product application meets environmental quality standards. Formaldehyde biodegrades quickly in water after contact with bacteria and/or sunlight.”

The Scottish Salmon Company was asked for a comment but referred us to the Scottish Salmon Producers’ Organisation which represents Scotland’s farmed salmon industry.

A spokesperson for Scottish Salmon Producers Organisation said: “Formalin is a fully licensed medicine approved by SEPA for use in freshwater to protect fish health. It is a dilute form of formaldehyde, which is a naturally occurring compound. After use it swiftly breaks down and is, therefore, safe to use for both fish and the environment. Fish farmers are fully trained in the correct usage of any medicinal product used to protect fish health and welfare.”

READ MORE: Nine million fish killed by diseases at Scotland’s salmon farms

The Soil Association, which grants organic status to fish farms, said formalin may be used a maximum of twice per year under the direction of a farm’s contracted vet.

The association’s spokesman added: “However, if the production cycle is less than 18 months you may use parasite treatments once per year. This is highly regulated.

‘‘Fish farmers must obtain prior approval from their certification officer for all parasite treatments on each occasion, and must give preference to the use of cleaner fish for biological control of ectoparasites or freshwater, marine water and sodium chloride solutions.

“The use of this treatment must also be within their Sepa license and is at very low concentrations.”

A spokesperson for Sepa said: “Uncontrolled releases of formaldehyde have the potential to cause significant harm to the environment. It is therefore important to ensure that formaldehyde is stored, handled and used appropriately to minimise the risk of any uncontrolled releases.

“The use of formaldehyde is authorised at the Russel Burn hatchery by Sepa and the operators are required to record each individual use of formaldehyde. These records are audited as part of Sepa’s routine compliance inspections.

“We take any allegations of environmental breaches very seriously and as an evidenced based organisation we would always take action to investigate where information comes to light. We would encourage anyone with information of non-compliance to contact Sepa, in confidence, via the pollution hotline 0800 807060.”

Earlier this month The Ferret revealed that the salmon farming industry was pushing behind the scenes for environmental limits on a toxic pesticide to be 100-times weaker than government regulators recommend.

The pesticide’s US manufacturer, Merck, and the Scottish Salmon Producers’ Organisation (SSPO), funded an unpublished study arguing that wildlife in sea lochs could withstand high concentrations of the pesticide.

The industry’s move to relax the limits was condemned as “beyond belief” by community groups, while environmentalists urged fish farmers to protect wildlife by ceasing to use the pesticide.

The industry, however, insisted that it had confidence in its science.

The Ferret is an editorially independent, not-for-profit co-operative run by its journalists and subscribers. You can find it at https://theferret. scot/ and can subscribe for £3 a month here: