Is Farmed Salmon ‘The Most Toxic Food in the World’?

Is farmed salmon 'the most toxic food in the world'?

Does farmed salmon contain any toxins?

Check out this answer from Consensus:

While farmed Atlantic salmon can contain toxins, ongoing monitoring and improvements in aquaculture practices have contributed to a decrease in the levels of certain contaminants. Both farmed and wild salmon remain good sources of essential fatty acids like EPA and DHA1. Consumers should be aware of the potential risks but also recognize the efforts being made to ensure the safety of farmed salmon for human consumption.


The consumption of farmed Atlantic salmon (Salmo salar) has been increasing globally, raising concerns about the presence of toxins in these fish. Persistent organic pollutants, metals, and other contaminants can accumulate in aquatic biota, potentially posing risks to human health when consumed2. This article examines the levels of various toxins in farmed salmon, comparing them to wild salmon, and discusses the implications for food safety.

Persistent Organic Pollutants and Metals of Toxins in Farmed Salmon

Studies have shown that farmed salmon can contain different levels of contaminants compared to their wild counterparts. For instance, wild Atlantic salmon have been found to have higher levels of dioxins, polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and mercury than farmed salmon1. However, farmed salmon have higher levels of omega-6 fatty acids, which can affect the omega-3 to omega-6 fatty acid ratio, an important factor for human health1.

In Norwegian farmed Atlantic salmon, a decrease in the levels of mercury, arsenic, dioxins, dioxin-like PCBs, and DDT has been observed over a 13-year period, indicating an improvement in the contaminant levels in these fish2. This suggests that efforts to reduce contaminants in farmed salmon are having a positive effect.

Cyanobacterial Toxins in Farmed Fish

Concerns about cyanobacterial toxins in seafood have led to studies on their presence in farmed fish. A study analyzing shrimp and farmed fish sold in Canada, including salmon, found no detectable levels of cyanobacterial toxins, such as microcystins and saxitoxins3. This indicates that, at least for the samples tested, farmed salmon did not contain these specific toxins.

Organochlorine Pesticides in Farmed Salmon

The levels of organochlorine pesticides (OCPs) have been a particular concern in farmed salmon. Research has shown that farmed salmon can have higher flesh residue concentrations of OCPs compared to wild salmon4. However, when adjusted for lipid content, wild salmon may have higher levels of certain OCPs than farmed salmon4. This suggests that the lipid content of the fish can influence the accumulation of these contaminants.

Impact of Feed and Farming Practices in the Fish

The type of feed used in salmon aquaculture can affect the levels of contaminants in the fish. For example, the introduction of vegetable ingredients, such as soybean oil, in fish feed has altered the fatty acid composition of farmed Atlantic salmon, which in turn can affect the metabolism of consumers7. Additionally, salmon farms have been identified as a source of organohalogenated contaminants in wild fish, indicating that farming practices can have broader environmental impacts6.

Regulatory Perspectives and Food Safety

Despite the presence of various contaminants, the levels found in Atlantic salmon are generally below the maximum levels applicable in the European Union1. Moreover, the United States Food and Drug Administration (FDA) inspects imported seafood, including salmon, for banned chemical residues, although the frequency of inspections and testing is relatively low8. The FDA has also approved alternative treatments, such as garlic, for controlling parasites in aquaculture, which may reduce the need for chemical pesticides8.


Is farmed salmon ‘the most toxic food in the world’?

L Neil Frazer has answered Unlikely

An expert from University of Hawaii at Manoa in Earth Sciences, Marine Biology

Farmed salmon isn’t toxic to the people who eat it, but it is certainly “toxic” to the juvenile wild salmon who must pass salmon farms during their out-migration from their natal streams to the ocean . The sea lice and viruses from the salmon farms can be devastating to wild salmon populations.

Nearly all salmon farming is conducted in sea-cages, which protect the farmed salmon from large predators such as seals and porpoises. However, sea-cages do not exclude pathogens and parasites, which pass freely through the mesh of the cage. Being protected from predators, and fed every day, farmed salmon can live for a long time after becoming diseased. During this time they are constantly shedding pathogen into the water, and the elevated levels of pathogen cause wild fish populations to decline. A salmon farm is thus an unintentional pathogen culture facility.

There is yet another sense in which farmed salmon is “toxic”, which is that little oily fish needed to manufacture feed for farmed salmon are an important source of protein in the diets of third world countries. The oil from these fish is needed for salmon feed because salmon are carnivores: even farm salmon cannot thrive without fish oil in their diets. In consequence, the growing of one pound of farm salmon requires the removal of three to five pounds of wild fish from the ocean.


Is farmed salmon ‘the most toxic food in the world’?

Peter D Nichols has answered Extremely Unlikely

An expert from Commonwealth Scientific and Industrial Research Organisation in Analytical Chemistry, Marine Science, Nutrition

CSIRO has performed independent analyses of farmed Tasmanian Atlantic salmon, including with emphasis on the health-benefiting long-chain omega-3 oils. Farmed Tasmanian Atlantic salmon is actually one of the best sources available for Australian consumers of these ‘good oils’. Increasing emphasis also has been placed by the Australian producers on the use of sustainable diets. The diet for this important farmed species now includes use of plant and animal derived ingredients, all produced sustainably and using best practices. Other new CSIRO research has seen further development of land plant sources of the long-chain omega-3 oils, and use of these new sources will allow in the future the content of these ‘good oils’ to increase again.


Is farmed salmon ‘the most toxic food in the world’?

Aleksei Krasnov has answered Extremely Unlikely

An expert from The Norwegian Institute of Aquaculture in Fisheries Sciences

Salmon feeds are made from high quality ingredients that are also used for human consumption. Vaccination success has reduced the use of antibiotics. Farmed salmon is safer than wild fish that can be exposed to environmental pollution.


Is farmed salmon ‘the most toxic food in the world’?

Mo D Salman has answered Unlikely

An expert from Colorado State University in Epidemiology, Veterinary Science

The use of the term “toxic” is wrongly used for an approach to expand on the production of efficient protein to feed the expanded growth of human population. The extensive aquatic farming including farmed salmon, however, has some negative impact on our biological security if this practice is left without consideration to the environment and biological factors that the practice should adjust for.


Is farmed salmon ‘the most toxic food in the world’?

Rafael Franco has answered Extremely Unlikely

An expert from Universitat de Barcelona in Parkinson’s Disease, Alzheimer’s Disease, Antioxidants, Nutrition, Pharmacology, Asthma, Cell Biology, Biochemistry

No. I checked the link: “that is the most toxic food in the world” and info there not scientifically sound.

One may wonder about the approppriate number of fish farms and the best proportion of farms of this versus those of such fish, but farmed salmon cannot be the most toxicc food in the world. Better wild salmon? obvious, as in any other case of “wild versus farmed fish”.

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