The debate over Benchmark’s new lice medicine

How clean is CleanTreat?

Benchmark’s new lice treatment has come under fi re already, but the company is confi dent that it will prove to be safe

Benchmark’s CleanTreat® is set to become one of aquaculture’s big talking points for the year. On one hand, it is being hailed as a game-changer – not just as a poten� ally successful product for the company but also as a powerful weapon in the salmon farmers’ war against sea lice.

On the other, cri� cs fear that if the system is nodded through by regulators, it could prove catastrophic for the marine environment. The European Parliament’s Environment Commi� ee has already passed a mo� on condemning it. So who’s right?

The point at issue is not CleanTreat itself but the sea lice treatment that it uses. CleanTreat itself is a water purifi ca� on system that allows fi sh to be treated with types of medicine – or pes� cide, if you will – that cannot be used in open water.

Benchmark has been trialling the system in conjunc� on with its new sea lice solu� on, BMK08, which it says has been shown to be highly eff ec� ve against lice, without causing any ill eff ects for the fi sh. The treatment was originally marketed as Ectosan and, now, as BMK08. It is based, however, on an established, eff ec� ve and once commonly used insec� cide: imidacloprid.

The trouble is, imidacloprid is one of the substances classed as neonico� noids, which became infamous when campaigners linked widespread use of these pes� cides to a collapse in bee popula� ons.

An� -fi sh farming campaigner Don Staniford, of Sco� sh Salmon Watch, said in a complaint to the European Parliament’s Environment Commi� ee: “Benchmark has patently failed to inform shareholders, investors, the public, the stock exchange and the media that BMK08/Ectosan is in fact the banned neonico� noid imidacloprid.”

Imidacloprid has indeed been banned – but not completely. At one � me it was the most widely used insec� cide in the world. Like other neonico� noids, it is a systemic toxin that acts on the central nervous system of insects and arthropods.

Dave Goulson, a biology professor at Sussex University, talking to the Guardian (27 May 2021) put it this way: “These chemicals are incredibly poisonous – the novichok for insects. It takes a billionth of a gram to harm aqua� c life, so even � ny traces would have major impacts on marine life.”

In April 2018 the European Union resolved to ban outdoor use of the three main neonico� noids, including imidacloprid. They con� nue to be used, quite lawfully, in enclosed greenhouses and also as fl ea and � ck treatments for cats and dogs. As the la� er suggests, neonico� noids are deemed to be quite safe up to a certain dose for vertebrates, including humans and our pets.

A spokesperson for Benchmark told Fish Farmer: “BMK08 has been proven to be safe for salmonids and the medicine will always be administered in a closed contained system; and it will be exclusively used with the award-winning and validated CleanTreat® purifi ca� on system to remove the medicine before release of purifi ed water back into the sea”.

The company’s confi dence that the treatment is safe for salmonids is, it says, based on extensive fi eld trials carried out in Norway.

The spokesperson added: “We have made significant progress towards commercialisa� on of our new sea lice solu� on, BMK08 and CleanTreat®, our fi rst customer agreements for CleanTreat® have been signed and EU ra� fi ca� on of the

Below: Benchmark’s CleanTreat vessel Opposite: CleanTreat processing tanks

Maximum Residue Limit (MRL) opinion was achieved in April. The MRL confi rms the safety of Benchmark’s sea lice solu� on for consumers.

“The commercial launch of BMK08 and CleanTreat® remains subject to the grant of a Marke� ng Authorisa� on from the Norwegian Medicines Agency”.

The MEPs on the Environment Commi� ee are not convinced, however, and they voted at their May mee� ng in favour of a lengthy mo� on that, among other things, stated: “…hazardous chemicals that are applied under veterinary prescrip� on and used to treat infec� ons of sea lice are ul� mately released into the aqua� c environment; their eff ects not only have the poten� al to nega� vely impact sensi� ve non-target organisms, the release of those compounds has been iden� fi ed as a major environmental concern due to the high mobility of imidacloprid in soil and the resul� ng contamina� on of ground and surface water…”

The mo� on argues that the European Commission should withdraw its MRL for imidacloprid in animal products for human consump� on – in other words, they believe there should be no acceptable level for it in the fi sh we eat.

Whether the mo� on is endorsed by the European Parliament will be se� led at one of the Parliament’s plenary sessions this month. Even if the Parliament votes to rescind the MRL, its vote will be advisory and not binding for the Commission. It would place the Commission under poli� cal pressure, however, if the mo� on is upheld.

Further controversy arose when The Ferret, an independent news source in Scotland, reported that emails from Marine Scotland appeared to show that the agency was sympathe� c to promo� ng BMK08 for trials in the UK.

Both the Sco� sh Government and Benchmark have made it clear, however, that there is no plan to trial the new treatment in Scotland, at least in the short term.

The company told Fish Farmer: “We are currently focused on launching our new sea lice solu� on, BMK08, which is used together with CleanTreat, in Norway. At this � me we do not have any scheduled trials for BMK08 in Scotland”.

The company stresses: “BMK08 has been developed to work exclusively in a wellboat which is a closed treatment system, so the medicine is not exposed to the environment. A� er treatment with BMK08, fi sh are removed from the treatment water and rinsed to remove external residues before being returned to their pens. The rinse water and treatment water remains on board the wellboat and is transferred to the CleanTreat vessel via a system of secured pipes. The medicine is then removed by CleanTreat through a series of steps, monitored closely by our on-board laboratory to confi rm the medicine has been removed before returning purifi ed water back to the sea”.

In terms of its passage through the regulatory process, Benchmark says: “The commercial launch of BMK08 and CleanTreat remains subject to the grant of a Marke� ng Authorisa� on from the Norwegian Medicines Agency.

“The MRL (Maximum Residue Limit) for BMK08 (imidacloprid) has been ra� fi ed under European Law and confi rms the safety of Benchmark’s sea lice solu� on for consumers. For an MRL to be granted the Commi� ee for Medicinal Products for Veterinary Use (CVMP) review all toxicology and safety data for the substance.

“Used together with CleanTreat, this medicine and treatment system is a breakthrough development for the salmon industry in eff ec� vely managing sea lice levels and improving fi sh welfare whilst protec� ng the environment.”

There is no doubt that simply releasing imidacloprid into the marine environment in order to kill sea lice would be highly reckless; equally, it is clear that is not what Benchmark is intending to do.

The ques� on for regulators will be twofold, therefore: is the treatment safe for the fi sh (and for consumers); and is CleanTreat eff ec� ve in ensuring that no ac� ve imidacloprid is le� in the residue that enters the sea?

Failing to address this properly could be bad for the environment, but an overly cau� ous approach could also risk losing out on an opportunity to tackle one of the biggest issues for fi sh health. FF

“This medicine and treatment system is a breakthrough development for the salmon industry”