Norwegian salmon most toxic food
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Norwegian Salmon: Evaluating Toxicity Concerns
Introduction to Norwegian Salmon and Contaminants
Norwegian farmed Atlantic salmon (Salmo salar) has been under scrutiny due to concerns about environmental pollutants such as dioxins, PCBs, heavy metals, and organochlorine pesticides. These contaminants can bioaccumulate in aquatic biota, potentially posing health risks to humans through chronic exposure1.
Trends in Contaminant Levels
Decrease in Contaminant Levels Over Time
A comprehensive study spanning from 1999 to 2011 analyzed over 2300 samples of Norwegian farmed Atlantic salmon. The results indicated a significant decrease in the levels of mercury, arsenic, dioxins, dioxin-like PCBs, and DDT over the study period. However, levels of cadmium, lead, and several organochlorine pesticides were too low to establish trends1. This suggests that efforts to reduce these contaminants in farmed salmon have been somewhat successful.
Comparison with Other Regions
Comparative studies have shown that farmed salmon from Norway, Maine, and eastern Canada generally have higher levels of PCBs and dioxin-like PCBs than wild Alaskan Chinook salmon. Notably, organically farmed Norwegian salmon exhibited the highest concentrations of these contaminants among the regions studied3. This highlights the variability in contaminant levels based on farming practices and geographic location.
Health Risk Assessments
Tolerable Weekly Intake (TWI) and Risk Assessments
The evaluation of contaminant levels in Norwegian farmed salmon has been conducted with reference to established Tolerable Weekly Intakes (TWIs). The levels of dioxins and dioxin-like PCBs in 2011 allowed for the consumption of up to 1.3 kg of salmon per week without exceeding the TWI1. However, some researchers argue that even these levels might exceed the Tolerable Daily Intake (TDI) when considering cumulative exposure2.
Carry-Over of Contaminants from Feed
The carry-over of persistent organic pollutants (POPs) from feed to salmon fillets has been a significant concern. Studies have shown that the retention rates for organochlorine pesticides, brominated flame retardants, and PCBs in salmon fillets range from 31-58%, while dioxins have lower retention rates of 10-34%4. This indicates that feed composition plays a crucial role in the contaminant levels found in farmed salmon.
Regulatory and Safety Measures
Inspection and Monitoring
The United States Food and Drug Administration (FDA) inspects a small fraction of imported seafood, including salmon. In 2017, only 86 samples from 379,000 tons of imported salmon were inspected, highlighting the challenges in ensuring food safety5. Increased inspections and stricter regulations could help mitigate the risks associated with contaminants in farmed salmon.
Impact of Farming Practices
The use of non-pelagic feeds from terrestrial sources in Norwegian salmon farms has led to lower concentrations of persistent organic pollutants and mercury compared to wild-caught Atlantic salmon from the same region. However, this has also resulted in reduced levels of beneficial nutrients like docosahexaenoic acid (DHA) in farmed salmon5. This trade-off between contaminant reduction and nutritional quality is a critical consideration for consumers and regulators alike.
Conclusion
While the levels of certain contaminants in Norwegian farmed salmon have decreased over time, concerns about the presence of dioxins, PCBs, and other pollutants remain. Comparative studies indicate that farmed salmon generally have higher contaminant levels than wild salmon, although efforts to improve feed quality have shown some success. Ongoing monitoring, stricter regulations, and improved farming practices are essential to ensure the safety and quality of Norwegian farmed salmon for consumers.
Sources and full results
Most relevant research papers on this topic
Contaminant levels in Norwegian farmed Atlantic salmon (Salmo salar) in the 13-year period from 1999 to 2011.
Norwegian farmed Atlantic salmon's contaminant levels generally decreased between 1999 and 2011, allowing safe consumption of up to 1.3kg per week, with dioxins and dioxin-like PCBs being the limiting factor.
Observational Study
Rigorous Journal
Highly CitedReply to the comments to our paper "Contaminant levels in Norwegian farmed Atlantic salmon (Salmo salar) in the 13-year period from 1999 to 2011".
Norwegian farmed Atlantic salmon's contaminant levels are well below established Tolerable Weekly Intakes for dioxins and dlPCBs, and the data presented in our paper supports this conclusion.
Rigorous JournalPCBs, PCDD/Fs, and organochlorine pesticides in farmed Atlantic salmon from Maine, eastern Canada, and Norway, and wild salmon from Alaska.
Farmed Atlantic salmon from Maine and eastern Canada have higher PCB concentrations than wild Alaskan Chinook salmon, with organically farmed Norwegian salmon having the highest concentrations, suggesting skin removal does not protect consumers from health risks associated with farmed salmon consumption.
Highly CitedCarry-over of dietary organochlorine pesticides, PCDD/Fs, PCBs, and brominated flame retardants to Atlantic salmon (Salmo salar L.) fillets.
High carry-over of potentially hazardous persistent organic pollutants (POPs) from feed to Atlantic salmon fillets was found, with maximum levels exceeding the EU upper limit for toxaphene in fish food samples in Norway.
Non-RCT
Animal StudySafely meeting global salmon demand
Salmon farming poses significant health risks due to persistent organic pollutants and mercury, and the FDA needs to improve its inspection methods to ensure safe salmon imports.
Salmonella in fish feed; occurrence and implications for fish and human health in Norway
Salmonella serovars occasionally occur in Norwegian fish feed, but the risk of transmission to humans through fish products is minimal, with no evidence of transmission from fish feed to humans.
Observational StudyHighly CitedToxic and essential elements in seafood from Mausund, Norway
Elevated levels of Cd in edible crabs in Mausund, Norway, indicate local geogenic sources are not a major cause of high levels in local biota.
Observational StudyExpert-driven methodology to assess and predict the effects of drivers of change on vulnerabilities in a food supply chain: Aquaculture of Atlantic salmon in Norway as a showcase
The Bayesian Network model accurately predicts the impact of drivers of change on food safety vulnerabilities in the Norwegian salmon aquaculture supply chain, with a sensitivity of 81%.
Comparison of cadmium concentrations in Atlantic salmon (Salmo salar) fry fed different commercial feeds
Cadmium concentrations in commercial feeds for Atlantic salmon fry vary, potentially reducing growth and impairing fish health.
Non-RCTAnimal StudyNatural and anthropogenic radionuclides in Norwegian farmed Atlantic salmon (Salmo salar).
The risk associated with radioactivity in farmed Atlantic salmon is very low, with levels comparable to or lower than those found in other fish species in the North Atlantic Ocean.
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