Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Farmed salmon more toxic than wild salmon, study finds

09.01.2004


Eating salmon may pose health risks



A study of more than two metric tons of North American, South American and European salmon has shown that PCBs and other environmental toxins are present at higher levels in farm-raised salmon than in their wild counterparts.

Researchers at Indiana University and five other research centers say increased toxin levels in farm-raised salmon may pose health risks to people who eat the economically important fish. Their study, which appears in this week’s (Jan. 9) Science, is the most comprehensive analysis to date of salmon toxin concentrations.


"We think it’s important for people who eat salmon to know that farmed salmon have higher levels of toxins than wild salmon from the open ocean," said IU School of Public and Environmental Affairs Distinguished Professor Ronald Hites, who led the study.

The researchers applied U.S. Environmental Protection Agency fish consumption advisory methods to determine consumption recommendations. Farmed salmon purchased for the study from supermarkets in Frankfurt, Edinburgh, Paris, London, Oslo, Boston, San Francisco, and Toronto triggered consumption recommendations of one-half to one meal of salmon per month. (A meal is defined as 8 oz. of uncooked meat.) Farmed salmon from supermarkets in Los Angeles, Washington, D.C., Seattle, Chicago, New York and Vancouver triggered a recommendation of no more than two salmon meals per month. Farmed salmon from Denver and New Orleans supermarkets both triggered a consumption recommendation of two meals of salmon per month. With very few exceptions, farmed salmon samples tested significantly exceeded the containment levels of wild salmon, which could be consumed at levels as high as eight meals per month.

The production of farmed salmon has increased 40-fold over the last two decades, thanks in large part to the world’s salmon farms. Over half the salmon sold globally are raised in Northern Europe, Chile and North America.

While the health benefits of eating salmon have been established by numerous studies, concerns about the fish’s tendency to accumulate toxins have gone largely unaddressed. As fish eaters themselves, salmon occupy fairly high positions in their food chains. As a general rule, carnivorous animals tend to have higher concentrations of toxins in their bodies than herbivores.

To test this ecological principle, Hites and his colleagues measured organochlorine toxin levels in about 700 farmed and wild salmon. Farm-raised Atlantic salmon were purchased from retailers in London (U.K.), Frankfurt (Germany), Edinburgh (Scotland), Oslo (Norway), Paris (France), Toronto, Vancouver, Boston, Chicago, Denver, Los Angeles, New Orleans, New York, San Francisco, Seattle and Washington, D.C., and from wholesalers in North America, Chile and Europe.

For comparison, the researchers collected samples of five wild Pacific salmon species -- Chinook, Coho, chum, pink and sockeye -- from three different regions in North America. The researchers did not study farmed Pacific salmon or wild Atlantic salmon because fish from the two groups are difficult to obtain.

The researchers analyzed the concentrations of 14 organochlorine toxins in salmon from each collection site, using gas chromatographic high-resolution spectrometry. The toxins they studied were polychlorinated biphenyls (PCBs), dioxins, toxaphene, dieldrin, hexachlorobenzene (HCB), lindane, heptachlor epoxide, cis-nonachlor, trans-nonachlor, gamma-chlordane, alpha-chlordane, Mirex, endrin and total DDT. Many of these toxins, including PCBs, dioxins and toxaphene, are each "reasonably anticipated to be a human carcinogen," according to a recent report by the U.S. Department of Health and Human Services.

When samples from all over the world were grouped, the researchers found farm-raised Atlantic salmon had significantly higher levels of 13 toxins when compared with wild Pacific salmon. Breaking it down by region, the researchers found levels of all 14 toxins were significantly elevated in both European and North American farm-raised salmon when compared with wild Pacific salmon. Levels of only 6 toxins were significantly elevated in South American farm-raised salmon. Levels of two toxins (HCB and lindane) were actually significantly lower in farm-raised South American salmon than in wild salmon species.

Only PCBs, dioxins, dieldrin and toxaphene were used to calculate consumption safety guidelines, because the researchers deemed these four toxins to most strongly impact human health.

The researchers also found toxin levels in European farm-raised salmon were significantly higher than in North American or South American farm-raised salmon. Levels of PCBs, dioxins, toxaphene and dieldrin were highest in farmed salmon from Scotland and the Faroe Islands (Denmark) and lowest in farmed salmon from Chile and Washington state, though Hites pointed out that even these comparatively uncontaminated South American salmon had high levels of other toxins.

Hites and his colleagues also measured toxin levels in "salmon chow," a mixture of ground-up fish and oil fed to farm-raised salmon. They found a strong correlation between the toxicities of chow and salmon, suggesting toxins are passed into the salmon from their feed.

Jeffrey Foran (University of Michigan), David Carpenter (University at Albany), M. Coreen Hamilton (AXYS Analytical Services Ltd.), Barbara Knuth and Steven Schwager (Cornell University), and Amy Matthews Amos (Turnstone Consulting, in West Virginia) also contributed to the study. It was funded by a grant to the University at Albany from the Pew Charitable Trusts’ Environmental Division.


To speak with Hites, contact David Bricker at 812-856-9035 or brickerd@indiana.edu.

David Bricker | EurekAlert!
Further information:
http://newsinfo.iu.edu/

More articles from Ecology, The Environment and Conservation:

nachricht Listening in: Acoustic monitoring devices detect illegal hunting and logging
14.12.2017 | Gesellschaft für Ökologie e.V.

nachricht How fires are changing the tundra’s face
12.12.2017 | Gesellschaft für Ökologie e.V.

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>