After a report was issued by the Environmental Working Group (EWG) in August saying that 10 farm-raised salmon had higher levels of PCBs than allowed by the U.S. Environmental Protection Agency, (not the Food and Drug Administration), Jon Lewis, Maine Department of Marine Resources Aquaculture Environmental Coordinator, says people kept asking him if he was still eating farmed salmon.
“Yes,” he told them. “I’m not going to eat it 1,000 times a year – everything in moderation, my father always used to say – but I’m not going to stop eating it entirely.”
The reason, he says – beyond the fact it’s so good – is that “Many knowledgeable nutritionists say that in salmon you don’t get the hormones and antibiotic loads, pesticides and high cholesterol content that you consume in many other foods, and you do get a protein that is high in omega threes. Salmon has all the benefits and is missing many other contaminants.
“Obviously,” he continues, “PCBs are not something you want to see, but it’s clear there are no pure food products. The Native American who kills a deer is going to be eating some PCBs. It’s no surprise that PCBs were found in the salmon. If fat from either you or me was tested, PCBs would be found in some quantity as well.” Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) both set standards for safe levels of PCBs in fish. The EPA redid its standards in 2000, allowing 20 parts per billion, which is dramatically lower than FDA standards of 2,000 parts per billion.
The FDA developed its standards in 1984, but re-evaluated them for salmon in 2000, and did not find cause to change them then. EPA spokespersons have been quoted as saying their standards were formulated for sport fishing and for subsistence fishermen who regularly eat contaminated fish as their primary source of protein – unlike most Americans, who derive protein from many different sources and generally eat fish, sometimes salmon, once a week or less.
PCBs, polychlorinated bi-phenyls, are mixtures of chlorinated compounds that prior to 1977 were used as coolants and lubricants in transformers, capacitors and other electrical equipment. Their manufacture was stopped because they build up in the environment and are suspected, but not proven, to cause cancer in humans. They have been shown to cause cancer in rats. They have entered the air, water and soil, where they are slow to break down. They concentrate in fatty foods, including whole milk, butter, cream, beef and some types of fish.
PCB content intensifies as it moves up the food chain. The higher the content of PCBs in farmed-fish meal, the higher the PCB count will be in the fish. Small fish from waters that are heavily polluted, such as the Baltic Sea, would produce feed with higher PCB content, as opposed to feed formulated with fish from waters off the coasts of less heavily industrialized countries. According to Sebastian Belle, director of the Maine Aquaculture Association, fish meal in Maine aquaculture feed is made from fish caught in waters off relatively unindustrialized areas in South America.
Belle says Maine fish farmers have been making every effort to reduce any possible sources of PCBs. “They have escape clauses in their feed contracts about PCB levels in feed which allow a farmer to reject a shipment if it tests above a certain level,” he says. He noted that farmed fish from Canadian and U.S. waters showed the lowest levels of PCBs in the EWG study.
Alex Trent, acting director of Salmon of the Americas, a trade group formed in June to represent salmon farms in the U.S., Canada and Chile, says researchers are developing a vegetarian feed for salmon that will still contain the high levels of healthful Omega three fatty acids that make the fish such a valued source of protein.
However, Belle noted, “vegetarian feed is not a silver bullet. If you increase the protein sources in fish feed that come from plant sources, you run the risk of increasing the environmental impact because the digestibility of plant protein is less than that of fish-based meal. It will depend on how the feed is formulated.”
Farmers support these experiments with feed, he says, but it will take time to do the necessary nutritional studies before shifting a farm’s feed. Trent says presently most fish feed is 30 to 40 percent fish meal, 60 to 70 percent vegetable-based with soy and canola oils.
The four wild salmon included in the EWG’s 14-fish experiment showed levels of PCBs below the EPA recommended levels, and therefore, the EWG recommended wild over farm-raised salmon. However, research has shown that wild salmon are not necessarily so pure. Lewis noted that a recent study in Alaska found that red salmon returning to fresh water lakes in Alaska had collected PCBs in the ocean and transferred them to the lake sediment when they died after spawning. As their bodies decomposed, they released the PCBs. “Scientists found that the size of the red salmon run correlated with the amount of PCBs found in the sediment,” he says.
Northern Aquaculture newspaper quotes Bill Waknitz, a research fisheries biologist with the National Marine Fisheries Service in Washington State, citing a paper that showed PCB levels in Copper River Sockeye salmon ranged from 670 to 7,910 parts per billion. The 10 farmed fish sampled in the EWG study showed an average of 27 parts per billion, which is far below the tolerance of 2,000 parts per billion (or 2.0 parts per million) set by the FDA, higher than the 20 parts per billion set by the EPA. The four wild fish in the EWG study showed an average PCB level of 5.3 parts per billion.
Trent pointed out that since most Americans consume considerably more dairy products and beef than salmon, they are more likely to acquire PCBs through the fats in these foods. “Unfortunately, we have to live with the fact that PCBs are so ubiquitous in our environment,” he says. “We have to make judgments about our total environmental intake.”