Proposed safety limits for a toxic pesticide widely used on salmon farms have been made 23 times weaker after sustained behind-the-scenes pressure from the industry, The Ferret can reveal.
Permitted concentrations of the lice-killing chemical, emamectin, in the sediment of sea lochs have increased from 12 to 272 nanograms per kilogram between 2017 and 2023. The increase followed a series of interventions from salmon farming companies, based on private research.
Campaigners said this was a “shocking” example of how regulators bowed to industry pressure, and warned that marine wildlife would suffer. The process was a “shambles” characterised by “backroom dealing and secrecy”, they said.
Environmental regulators insisted they “remain confident” that the process was “led by scientific evidence”. The salmon farming industry described the approach as “scientifically robust” and said it would protect the marine environment.
The repeated weakening of proposed new safety limits for emamectin has been disclosed in a consultation currently being conducted by the Scottish Government. It is asking for views before 24 July on when the limits should be introduced.
Emamectin, marketed as Slice, is fed to caged salmon in lochs around Scotland to kill lice that can plague them. But it is excreted and dumped into the water where it can harm shrimps, crabs, lobsters and other crustaceans.
The Ferret’s previous revelations about the salmon farming industry’s seven-year campaign to block tougher environmental limits on the pesticide resulted in the affair being dubbed “Slicegate” by campaigners.
After scientific research uncovered dangers to marine wildlife, in 2016 the Scottish Environment Protection Agency (Sepa) proposed a complete ban on emamectin. But this was secretly abandoned after pressure from salmon farming companies and the Scottish Government.
Instead, in October 2017, Sepa set an “interim” limit on the amount of emamectin allowed in sediment of 12 nanograms per kilogram (ng/kg). This only applied to applications to increase existing discharges or for new fish farms.
Sepa asked the UK Technical Advisory Group (UKTAG), which brings together scientists from all the UK’s environmental regulators, to recommend safety limits for the pesticide. The Ferret disclosed in 2019 that UKTAG was lobbied by salmon farming companies and emamectin’s US manufacturer, Merck, to relax its proposed limit, based on an unpublished report.
In November 2019 UKTAG recommended, and Sepa accepted, that the interim limit should be raised from 12 to 23.5 ng/kg. But UKTAG said that evidence from the industry needed to be reviewed before final recommendations could be made.
In July 2022, following further submissions from salmon farming companies, UKTAG recommended the limit again be raised, this time to 131 ng/kg. It agreed with the industry’s suggestion that the proposed safety factor, crucial for calculating the limit, should be reduced from 50 to 10.
‘Industry-owned’ pesticide study
Then in January 2023 the Scottish Government postponed publishing the consultation on the introduction of the new limit after an intervention by Salmon Scotland, which represents salmon farming firms.
According to the government, Salmon Scotland had detected a “possible error” in the derivation of the limit. As a result, UKTAG conducted another reassessment and concluded that the limit should be raised for a third time to 272 ng/kg in March.
According to a UKTAG memo from 24 February released by Sepa, Salmon Scotland’s latest intervention relied on an “original, industry-owned study report”. UKTAG had seen summaries, but hadn’t had access to the full report.
“UKTAG does not routinely request study reports owned by industry, as these are proprietary information and may contain trade secrets or confidential commercial information that the study owners claim exempt them from public disclosure,” the memo said.
Nevertheless, UKTAG “worked with Salmon Scotland” and accepted that there had been an error in its assumptions that meant that the proposed safety limit for the pesticide should be doubled.
Relaxing safety limits for emamectin
|Permitted concentration in sediment for new salmon farms (ng/kg)
While the safety limit was being considered, salmon farmers increasingly turned to emamectin as other pesticides became less effective at killing lice. According to a report in March by the campaign group, WildFish, there was a 26 per cent increase in the pesticide’s use at fish farms in Scotland between 2021 and 2022.
WildFish pointed out that emamectin was “highly toxic” and had been found to have a “persistent and detrimental” impact on marine wildlife. “Weakening the proposed safety limits for this chemical could have profound and long-term ecological impacts,” warned the group’s campaign manager, Dr Matt Palmer.
“The newly proposed 23-fold increase in emamectin environmental safety limits is yet another shocking example of regulators bowing to pressure from industry lobbyists. For this increase to also be based on unpublished data commissioned by the industry itself is the antithesis of a transparent and precautionary approach.”
Pesticide saga ‘sorry tale’
The Coastal Communities Network, which brings together 24 groups in Scotland keen to protect the marine environment, said that no other industry was allowed to dump as much pesticide into the sea as salmon farmers. “The saga of emamectin is a sorry tale,” said the network’s John Aitchison.
“It shows how much the fish farming industry is able to affect the standards that are supposed to protect our seas from its toxic chemicals, and how hard it is to uncover what is happening behind the scenes when these decisions are made.”
The process was a “shambles”, Aitchison argued. “All this backroom dealing and secrecy is as counterproductive as it is ridiculous. Fish farming in Scotland has a big problem with loss of trust.”
He criticised the Scottish Government for consulting on a “heavily watered down” safety limit years after the dangers had been recognised. “Instead it ought to be asking itself whether the process that has recommended that pollution standard and others is fit for purpose,” he told The Ferret.
The Scottish Greens suggested that swimmers and fishers shouldn’t have to worry about pesticides in the water. “The full background and explanation for this latest increase in permitted pesticide levels must be made more transparent,” said the Green MSP for the Highlands and Islands, Ariane Burgess.
“This is so everyone who cares about our coasts can be confident that the safe level was determined by independent scientific evidence, not lobbying from the salmon farming industry.”
Pesticide limit ‘led by scientific evidence’
The Scottish Environment Protection Agency stressed it had clear “aspirations” for safeguarding marine wildlife. “Sepa has been applying interim environmental standards to ensure protection of the environment,” said head of ecology, Peter Pollard.
“We remain confident in the approach undertaken by UKTAG which is led by scientific evidence.” Sepa has accepted UKTAG’s recommendations.
Sepa confirmed it had not seen the industry study which led to the latest relaxation of the safety limits for emamectin. Using “robust study summaries” rather than full reports was “normal practice” by regulators around the world, it said.
Sepa pointed out that the pesticide limit now proposed – 272 ng/kg – was still 5.6 times stricter than the one in force before 2017.
The UK Technical Advisory Group said it was committed to providing accurate guidance. “We conducted an extensive review of published scientific papers to derive recommendations for a new standard for emamectin,” a spokesperson told The Ferret.
“All reports included in the evidence base complied with international standards for experimental design.”
According to UKTAG, the latest change to the safety limit was made after “an industry representative” brought a “small arithmetical error” to its attention. The error was in a conversion factor used to derive the limit.
As evidence, the industry “provided an extract of a methodology from a private research report”, which UKTAG said it agreed with. Other evidence came from “relevant unpublished third-party research” shared with UKTAG “on a voluntary basis by industry”.
The Scottish Government stressed it was committed to protecting Scotland’s wildlife. “The implementation of new environmental standards for emamectin is crucial to this aim,” said a spokesperson.
“We are confident that the UKTAG methodology is scientifically robust, and includes obtaining independent scientific peer reviews of the evidence. As such, Scottish Ministers have accepted their recommendations.”
Dr Iain Berrill, head of technical at the industry body, Salmon Scotland, said: “UKTAG independently sets the environmental quality standard based on European Commission guidance.
“As more data has become available, UKTAG is following a scientifically robust approach to review the environmental quality standard and set evidence-led limits that protect the marine environment.”
Cover image thanks to iStock/richard johnson.