News Coverage
Something Fishy: The Salmon Debate
Published November 4, 2004
Eat salmon, we're urged. It is rich in omega-3 fatty acids, which help our hearts, cholesterol and blood pressure, fights rheumatoid arthritis, and might even ease depression.
Eat salmon only sparingly, we're warned. The fish, especially when farm-raised -- as is 65 percent of the salmon sold in U.S. supermarkets -- contains PCBs and other toxins that may cause cancer.
What's a health-conscious consumer to do? Studies and counterstudies, alarms and assurances, leave the public unsure, anxious.
Salmon's popularity is leaping vigorously upstream. It just passed fish sticks as America's third favorite seafood after tuna and shrimp -- now 22 percent of all retail seafood sales.
Wild salmon, with fewer toxins, is tasty and popular, but often up to $20 a pound and available fresh only in the summer. Farm-raised salmon, under $10 a pound, has exploded 40-fold in production in the past 20 years.
But two recent studies give pause.
A January report in the prestigious, peer-reviewed journal Science by environmental researchers who studied two metric tons of fish from Europe, the United States, Canada and Chile concluded that farm-raised salmon were so high in PCBs, dioxins, toxaphene and dieldrin -- some of which are listed in U.S. studies as suspected carcinogens -- that consumers should limit consumption.
''This study suggests that consumption of farmed salmon may result in exposure to a variety of persistent bioaccumulative contaminants with the potential for an elevation in health risks,'' it said.
The Science study suggested these limits on eating salmon:
* One eight-ounce serving per month of farmed salmon from Chile or Washington State, the source of about 65 percent of South Florida's farmed salmon.
* One-half serving per month of farmed salmon from Scotland, the Faroe Islands, Norway, Maine, East Canada and West Canada, the source of 35 percent of locally sold farmed salmon.
* Up to eight servings per month of wild salmon, which, while not entirely without toxins, is safer.
Current law requires imported fish in supermarkets to be labeled with the country of origin. A new law going into effect in April will require labels also to say if the fish is farm-raised or caught wild.
Second, a 2003 study by the Environmental Working Group, a Washington, D.C., public health research and advocacy group, urged that ''consumers choose wild instead of farmed salmon, and they should eat an eight-ounce serving of farmed salmon no more than once a month.''
Both studies were pooh-poohed by the Food and Drug Administration, which regulates the safety of salmon sold in supermarkets.
''We hardly see PCBs in the diet at all these days,'' said Mike Bolger, the FDA's director of risk assessment. ''We used to find them routinely in fatty foods in the 1970s. But since the use of PCBs was banned in 1978, levels have come down incredibly.''
Bolger rejects limits on salmon consumption.
''We're aware of the Science article's interpretation,'' he says. ''We disagree with it.''
The salmon industry has reacted cautiously.
''We're not happy with any level of contaminants in salmon -- they don't belong there,'' said Alex Trent, spokesman for Salmon of the Americas, which represents salmon farms from the U.S., Canada and Chile. ''But the Harvard School of Public Health said these low levels carry no risk of cancer.''
At Harvard Medical School, George Blackburn, associate professor of surgery and nutrition, says the benefits of omega-3 fatty acids in salmon outweigh any risks from toxins. He says modern science can detect toxins at levels so small that, while they might sound alarming, are too minute to cause problems.
''I recognize why people hesitate,'' he says. ''You have to do a risk/benefit analysis. But people don't get enough omega-3, and salmon is one of the cheapest ways to get it. Even if there are tiny doses of toxins, we don't want that to guide people away from the benefits.''
Blackburn recommends children and women of child-bearing age limit themselves to one salmon meal a week, while adult men and women past child-bearing can eat salmon every day for its benefits.
Another risk/benefit assessment comes from Robert Lawrence, of the Bloomberg School of Public Health at Johns Hopkins University, who studied fish toxins for the National Academy of Science.
''For middle-aged men and women past child-bearing, there's no question that eating fish at least once a week provides enough omega-3 to decrease the danger of sudden cardiac death,'' he said. ''For children or younger women still anticipating having children, it's probably a good idea to restrict fish.''
One area in which the two sides agree is the source of the toxins. Wild salmon eat small crustaceans and fish in the open ocean. Farmed salmon are fed oil-based mash made from small fish caught nearer the shore -- often in waters polluted by industrial waste.
Twenty years ago, farm-raised fish got 100 percent of their food from the fish-based mash. Today it's 40 percent and dropping, being replaced with a soybean mixture, says Trent, of Salmon of the Americas. It's difficult to create an all-vegetable salmon food without reducing the salmon's levels of the valuable omega-3 fatty acids, but he said they are working on it.
Why are the experts so divided on salmon? A major reason is that different government agencies set conflicting standards, says David O. Carpenter, of the Institute for Health and the Environment at the University at Albany in Rensselaer, N.Y., a leader in the Science journal study.
FDA standards permit up to 2 parts per million of PCBs in salmon, while EPA standards applied in the two critical studies would limit it to 0.05 parts per million, he says.
''That's outrageous. A 40-fold difference,'' Carpenter says. ''People get different messages from different sources. It creates distrust of government, of science.''
The EPA and FDA say there are valid reasons for their differences. The FDA standard is for salmon sold commercially in supermarkets, while the EPA standard is for fish caught recreationally, or by such subsistence fishers as Native Americans, an EPA official said, speaking on condition that his name not be used. Subsistence fishers probably eat more of the same fish from the same place than consumers buying salmon casually in supermarkets, he said.
''It's not fair to compare the two methods,'' the EPA official said.
Lawrence, the Johns Hopkins professor, blasts the inconsistencies: ''It's a classic example of failure to coordinate federal agency standards. It leads to trouble.''
Even the salmon industry is pleading with the FDA and EPA to get together. Without coordination, Trent wrote to the FDA, ''recommendations will continue to be proposed in a reactionary mode by people with incomplete knowledge or a vested interest, both of which are a real detriment to public health.''
The two agencies now have begun meetings to seek common ground, an EPA e-mail says in response to a reporter's questions, although no deadline has been set.
Meanwhile, Salmon of the Americas says its latest round of monitoring shows PCB levels in farmed salmon have come down almost as low as those in wild salmon.
''I'd like to see someone other than the salmon industry document that,'' Carpenter said. ''We're not out to hurt the industry. We're out to protect the public.''
So at least until the FDA and EPA complete their review, consumers are left to decide for themselves whether the benefits of salmon's omega-3 fatty acids outweigh any risk from toxins.
''That's where science is right now,'' Lawrence said. ''Almost always there's a risk/benefit trade-off.''
It's true not only with salmon, he says.
''You go biking for your health, you get hit by a car.''