Recently, the Institute of Marine Research (IMR) made headlines in the national media, warning about environmental toxins in salmon. It was quite alarming to read that a new toxic substance from net impregnation had been found in the fish. The case was picked up by several media outlets and posted on HI's own website. What is not mentioned in this article is that the study was funded by Norway’s largest supplier of copper antifouling, which in turn is supported by Europe’s largest producer of cuprous oxide. In other words, a competitor to the substance in question.
The Institute of Marine Research is tasked with solving some very important societal missions, which form the basis for public administration in Norway, such as contributions to the Aquaculture traffic light system. It is therefore crucial that their integrity and trustworthiness are never in doubt. Their research must be impartial, and an institution like this must be particularly careful that any comments or statements they make in the public sphere are not speculative or sensationalized.
Let me say a bit more about this specific study, which formed the basis for the article about environmental toxins. I am not in a position to comment on the execution of the experiment. Some fish swam in tanks with impregnated nets. After some time, IMR measured small amounts of the active substance in the fish fillet. I have nothing to criticize about the main conclusion of the experiment, which simply confirms what was already demonstrated in 2017: that fish swimming near impregnated nets absorb trace amounts of the active substances. This was risk-assessed by the Norwegian Environment Agency, which concluded: "... a child weighing 15 kg would have to consume 973 kg and an adult 3891 kg of fish per day to exceed the limit. Therefore, no risk to consumers is expected from consuming fish contaminated with Tralopyril."
IMR reports that they measured concentrations of approximately 0.3 nanograms per gram, which is less than half of what the Environment Agency based its assessment on. IMR presents this as alarming news without putting the values in context or discussing whether they pose any risk. The IMR researcher claims that the conditions for approving the active substance are not met. However, the case has already been mapped out through previous research and assessments, which are publicly available and formed the basis for the approval.
In Dagens Næringsliv, a Norwegian news paper, the researcher is further quoted saying that the active substance was approved and sold without establishing limits for what is acceptable. There are likely different limits depending on the regulations being followed, but for those of us working with biocides, there are strict limits to comply with. These include limits on what is acceptable in the environment (PNEC), acceptable exposure levels (AEL), and what is acceptable in fish fillets (ADI). These limits have wide safety margins and are determined by the EU/BPR directive.
Finally, the researcher from IMR speculates whether the active substance could harm the gills of the salmon, damage energy production, or even be lethal to the fish. However, their own experiment showed that the substance had no negative impact on the fish, and there were no statistically significant differences in growth. Previous experiments have shown the same, and we also have hundreds of anecdotal reports from fish farmers who have tried operating both with and without antifouling. Neither gill health nor appetite tends to improve without protection against biofouling; quite the opposite, in fact. That said, at very high doses, Tralopyril can be toxic to fish. This has also been previously mapped through studies establishing safe limits, and the products are designed with large safety margins.
I believe we all want a safer future with well-documented products. Producing healthy seafood is a noble goal, but it's hard to achieve without some use of chemicals. Preventing biofouling on fish farms is very important because it can affect fish welfare, pose a biosecurity risk, and unintentionally spread invasive species. Therefore, we need a toolbox with all the active substances available. The EU's biocide regulations are considered among the strictest in the world. We must be able to trust that these approved substances are safe to use for their intended purpose. We welcome new knowledge, and I encourage the Institute of Marine Research and others to engage in dialogue on this matter.
By Ulrik Ulriksen, CEO in Steen-Hansen AS