We seem to be working toward coming full circle. So here's a piece on the salmon that lacks the aggressive POV of the one you posted. This one is from Science 1/9. It's subscription so I don't have a link.
Global Assessment of Organic Contaminants in Farmed Salmon Ronald A. Hites,1* Jeffery A. Foran,2 David O. Carpenter,3 M. Coreen Hamilton,4 Barbara A. Knuth,5 Steven J. Schwager6
The annual global production of farmed salmon has increased by a factor of 40 during the past two decades. Salmon from farms in northern Europe, North America, and Chile are now available widely year-round at relatively low prices. Salmon farms have been criticized for their ecological effects, but the potential human health risks of farmed salmon consumption have not been examined rigorously. Having analyzed over 2 metric tons of farmed and wild salmon from around the world for organochlorine contaminants, we show that concentrations of these contaminants are significantly higher in farmed salmon than in wild. European-raised salmon have significantly greater contaminant loads than those raised in North and South America, indicating the need for further investigation into the sources of contamination. Risk analysis indicates that consumption of farmed Atlantic salmon may pose health risks that detract from the beneficial effects of fish consumption.
1 School of Public and Environmental Affairs, Indiana University, Bloomington, IN 47405, USA. 2 Citizens for a Better Environment, Milwaukee, WI 53202, USA. 3 Institute for Health and the Environment, University at Albany, Rensselaer, NY 12144, USA. 4 AXYS Analytical Services, Post Office Box 2219, 2045 Mills Road, Sidney, British Columbia, Canada V8L 3S8. 5 Department of Natural Resources, Cornell University, Ithaca, NY 14853, USA. 6 Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY 14853, USA.
* To whom correspondence should be addressed. E-mail: HitesR@Indiana.edu
TOXICOLOGY:
Salmon Survey Stokes Debate About Farmed Fish
Erik Stokstad
Salmon's popularity has boomed in the past 2 decades as aquaculture has made salmon available year-round at low cost. The fish is a good source of protein, vitamin D, and heart-friendly fats. But fish farms have boosted less welcome ingredients: The largest survey yet of pollutants in salmon, reported on page 226, has found that farmed fish have higher levels of polychlorinated biphenyls (PCBs) and other organochlorine compounds than do wild-caught salmon. The source, as many researchers suspected, is the feed.
"This is a definitive study," says nutritionist and toxicologist Miriam Jacobs of the University of Surrey, U.K., and Royal Veterinary College, London. "Further action has to be taken to reduce the contaminant levels in feed." The authors argue that consuming more than one meal of farmed salmon per month may hike the risk of cancer. "The punch line is that eating the wrong kind of fish has real dangers," says team member David Carpenter of the State University of New York, Albany, in Rensselaer.
Other experts say the risk is outweighed by the benefits of eating farmed salmon. Avoiding the fish would mean giving up its nutritional benefits, including protection against heart attacks. What's more, they say, the contaminant levels aren't high enough to pose real dangers. "In my view, the study says we should be eating more farmed salmon," says toxicologist Charles Santerre of Purdue University in West Lafayette, Indiana.
While nutritionists debate the study's implications, consumers can use its data to try to select the cleanest fish possible. "I think we can begin to make informed choices about what kind of fish to eat," says toxicologist Linda Birnbaum of the U.S. Environmental Protection Agency (EPA).
The massive study, funded by the Pew Charitable Trusts' Environment program and conducted by six scientists, sampled about 700 salmon from around the world and analyzed them for more than 50 contaminants. The greatest difference between farmed and wild salmon was in organochlorine compounds. For 13 of 14 of these chemicals tested, farmed salmon were more contaminated than wild ones. Farmed salmon in Europe had the highest levels, followed by those from North America, whereas Chilean salmon were the cleanest. The researchers also tested the oil and meal fed to salmon and found a similar pattern. Feeding salmon with fish meal boosts their growth and nutritive value, but it also concentrates contaminants.
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Seeing red. Farmed salmon has more PCBs than wild salmon, but scientists don't agree on how much one should eat.
CREDIT: PAT WELLENBACH/AP
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The team took a closer look at PCBs and two other persistent pesticides called dieldrin and toxaphene, all of which have been correlated with risk of liver and other cancers. The researchers used EPA guidelines to calculate the maximum amount of salmon that can be eaten before boosting cancer risk by at least 1 case in 100,000. For the most contaminated fish--from farms in Scotland and the Faroe Islands--the limit came to 55 grams of salmon (uncooked weight) every month, or a quarter of a serving. One half-serving a month of farmed salmon from Canada or Maine adds no significant risk, they say; and double that is acceptable for fish from Chile or the U.S. state of Washington. Some types of wild salmon from Alaska or British Columbia are safe to eat eight times a month.
Although no U.S. government agency has said how much fish one should eat, the American Heart Association recommends 168 to 336 grams per week. Consumption of the omega-3 fatty acids found in fatty fish reduces the risk of sudden cardiac death after a heart attack. For people with cardiovascular disease, that benefit outweighs any added cancer risk, Carpenter says.
How much salmon people without cardiovascular disease ought to eat is less clear. Advice for pregnant women is the source of the most heated debate. Organochlorines can damage the developing endocrine system, immune system, and brain. The compounds build up in body fat and linger there for decades--where they can be passed to a woman's fetus during pregnancy or excreted in breast milk. "For a woman before menopause, especially for a young girl, [farmed salmon] really is not good to consume," Carpenter says.
Others disagree. "I think it's unconscionable to direct pregnant women away from farmed salmon," says Santerre, who consults for the industry group Salmon of the Americas in Princeton, New Jersey. Omega-3 fatty acids are important for brain development, and they may reduce the risk of preterm births and slightly increase a child's cognitive abilities.
Santerre says that 226 grams of farmed salmon per week is safe for anyone, and he points out that the PCB levels are all below the level determined by the U.S. Food and Drug Administration (FDA) to be safe for sale in supermarkets. That cutoff is 40 times higher than what EPA has determined is safe in recreationally caught fish, in part because FDA considers safety and nutrition whereas EPA looks solely at health risks.
Fish farms are already working on the problem, such as by finding fish meal with low contaminant levels, says Alex Trent of Salmon of the Americas. Researchers are experimenting with ways to substitute fish oil in feed with vegetable oil. One variety of transgenic canola, for example, contains a precursor to the omega-3 fatty acids. |
