Salmon: down on the farm

From the School of Public Health WellnessLetter.com Volume 20, Issue 7 April 2004

It’s important to eat fish because of its heart-healthy omega-3 fats. Salmon has been catching up with tuna, America’s favorite fish, in large part because it is rich in omega-3s. Canned or fresh, salmon is widely available in markets and restaurants—and most salmon in the marketplace is farm-raised, which means it is now plentiful and cheap.

Wild salmon costs two or three times as much, and even if you can afford it, you can’t always find it. Moreover, some wild salmon is endangered. Salmon grew even more popular after the government issued warnings about mercury in large fish such as swordfish, tilefish, and possibly even tuna. But now farmed salmon has turned up on the high-anxiety list, not because of mercury but because of toxins, notably PCBs (polychlorinated biphenyls). PCBs are organic pollutants and are thought to promote health problems, including cancer.

No one knows for certain that they cause cancer in humans, or how much PCBs it would take to cause it, but they do cause cancer in animals. The toxins come from plastics, waste incinerators, leaky transformers, and insecticide residues. Ubiquitous in our environment, they are found in many foods besides fish. The farmed salmon get their doses from their chow, which is a mix of ground-up fish and oil. Wild salmon get some PCBs, too, but they have a more varied diet. The worrisome thing about these potential carcinogens is that fish (and humans) store them in fat, where they can accumulate.

A study by researchers at Indiana University and other centers, recently published in Science, found that salmon from all over the world is contaminated with PCBs and other compounds. They analyzed two metric tons of fish, some farmed, some wild. The farmed fish was far worse, with levels high enough to damage the brains of fetuses and infants, at least according to the standards of the Environmental Protection Agency (EPA), which are tougher than the Food and Drug Administration (FDA) standards.

And this is not the only study to come up with such findings. In spite of this, the FDA and Health Canada were critical of the new study and say it’s still okay to eat farmed salmon. The salmon industry was also critical, saying that the fish in the study were collected three years ago, and that fish chow has since been improved, with further measures underway. And some scientists questioned the findings of the study for other reasons as well.

The American Heart Association and other health authorities are in favor of eating fish. Because of concerns about mercury, we have advised eating no more than 12 ounces of fish per week, on average, chosen from a variety of species.

Thus, if you follow our advice, you don’t eat salmon or any other single species two or three times a week. But letters from readers lead us to think that a lot of people have been eating much more salmon lately.

The lead researcher of the Science study, Dr. Ronald Hites, concluded that nobody should eat more than one 8-ounce serving of farmed salmon per month. That’s not a lot of fish, and it leaves people wondering where the rest of the fish in their diet is supposed to come from. Dr. Hites said that he himself eats farmed salmon twice a month, because he is “an old guy” and older people may have less to worry about when it comes to the potential long term dangers of PCBs.

A fine kettle of fish
Thus, once again, the public is left in the dark. Is it better to cut fish out of your diet entirely and lose the heart benefits, or should you keep eating farmed salmon and risk getting cancer? Which agency is right? Can you believe the signs that have gone up in fish stores and on restaurant menus claiming that their farmed salmon is okay? Has the industry really reformed? Is that “wild salmon” really wild? How old would you have to be to safely eat two servings of farmed salmon a month? Pretty soon you’ll need a diary or maybe a computer to keep track!

Here’s some food for thought:
•  Don’t stop eating fish. Do vary your intake. We suggest cutting back on farmed salmon if you eat it as your main fish. There are plenty of other fish to choose from.
•  Watch for news. The farmed fish industry has made improvements in fish chow and has promised more. It has also been under attack for its impact on drinking water and air pollution, and for the use of additives (such as antibiotics and colorants). Maybe this adverse publicity will motivate it to fix the problems.
•  Buy wild salmon, if you can afford it.
•  Use canned salmon. Almost all of it is wild.
•  Ask your fish seller where the salmon comes from. Fish labeled “Atlantic salmon” or “Icelandic salmon” sound wild, but are usually farmed. By this October a new law will require fish to be labeled as to country of origin, and whether it is wild or farmed.
•  See if you can find farmed salmon from Chile, which exports a lot of fish to the U.S. It is lower in PCBs and other contaminants than other farmed salmon, according to the study.
•  To reduce the PCBs in salmon: before you cook it, remove the skin and the fat under it (not a hard job if you use a very sharp knife—or get the fish seller to do it). Then broil, bake, poach, or grill the fish instead of sautéing it. These methods allow the fat to drain off. Plenty of beneficial omega-3s will remain.