WASHINGTON, D.C. - A study by the Environmental Working Group has found that farmed Atlantic salmon purchased in U.S. grocery stores contains enough cancer-causing toxins to raise health concerns.
In fact, if wild fish contained polychlorinated biphenyls (PCBs) in the same concentrations, the EPA would advise consumption ofno more than one meal a month.
However, because these are farmed fish - "bought, not caught" - there are no such restrictions or health warnings. Indeed, Americans have been encouraged to eat more salmon because of the health benefits to their diet, and critics of the study say the benefits of eating salmon still outweigh the risks of chemical contamination.
The working group purchased farmed Atlantic Salmon at grocery stores in Portland, San Francisco and Washington, D.C. Seven of the 10 fish purchased in all three locations were contaminated with PCBs at levels that raise health concerns according to independent laboratory tests commissioned by the Environmental Working Group.
The high PCB levels were fairly consistent even though the samples came from supermarkets in three cities. The salmon themselves came from five different countries of origin - including the U.S., Canada, Chile, Iceland and UK - and ten different farming companies.
"We've been following fish issues from the point of mercury contamination for some time and salmon are a better choice in terms of mercury," said Kristina Thayer, senior scientist for the Environmental Working Group. "But then this study came out last fall that showed farmed salmon had other contaminates, including PCBs. That prompted us to ask the question about potential concerns with American purchased fish."
That Canadian Study, conducted by researcher Michael Easton, compared wild Pacific salmon and farmed salmon and concluded that farmed salmon contained significantly higher levels of dangerous chemicals.
"The results were very, very clear," Easton told the BBC last year.
"Farmed fish and the feed they were fed appeared to have a much higher level of contamination with respect to PCBs, organo-chlorine pesticides and polybrominated diphenyl ethers than did wild fish - in fact it was extremely noticeable the difference."
Thayer said the Environmental Working Group wanted to know - is there a risk from farmed salmon purchased at the local grocery store in the U.S.?
"Studying salmon also made sense because it is the third most popular type of fish consumed [in the U.S.] and consumption is increasing," Thayer explained. "Our findings indicated that it may be the single biggest PCB contributor among food sources."
The surprising results mean that farmed-raised salmon now on grocery shelves are the most PCB-contaminated protein source available to U.S. consumers, if the group's findings are borne out by more comprehensive testing. On average, the farmed salmon tested contained 16 times the PCBs found in wild Alaskan salmon, four times as much as in beef and 3.4 times as much PCBs as found in other seafood.
"The levels of these tests track with previous studies of farmed salmon contamination by scientists from Canada, Ireland and the U.K.," according to the report. "In total, these studies support the conclusion that American consumers nationwide are exposed to elevated PCB levels by eating farmed salmon."
PCBs are cancer causing chemicals that also affect the reproductive system, nervous system, immune system and endocrine system. Released into the environment as industrial waste, this class of chemicals was banned in the U.S. in 1976 and is in the process of being banned internationally as part of the "dirty dozen" Persistent Organic Pollutants (POPs).
However, these chemicals tend to persist over time in soil and water and bioaccumulate in the food web.
Peer reviewed studies have shown in Canada and the UK that farmed salmon accumulate PCBs from the fishmeal they are fed. The fishmeal is made up of ground-up smaller fish. The aquaculture industry also supplements its feed with fish oils to increase the level of omega-3 fatty acids - which are considered healthy from a nutritional standpoint.
Unfortunately, PBCs tend to concentrate in oils and fats. This has two negative effects on farmed salmon. First the fats and oils from the feed bioaccumulate PCBs in farmed salmon.
"The small fish ground up for fishmeal are larger than what salmon may eat in the wild," the groups' Press Secretary Jon Corsiglia said. "Salmon naturally eat krill and other small species, if you go up a trophic level, up the food chain, you get a higher accumulation of the contaminates."
Second, because farmed salmon are raised to contain 50 percent more fat than wild salmon, more PCBs end up accumulating in each fish. The concentrations found by the Environmental Working Group are high enough that if these fish were caught, rather than purchased in a grocery store, the EPA would warn against their consumption.
Yet the EPA doesn't regulate the health of food purchased in a grocery store, the Food and Drug Administration does. While the EPA tightened its allowable dioxin levels for recreationally caught fish in 1999, the FDA hasn't updated its thresholds since 1984 and therefore is out of sync with two decades of peer reviewed science showing negative PCB health effects, according to Thayer.
"It was pretty striking to us that the FDA has not updated its guidelines since 1984," Thayer said. "So much has changed since 1984 in terms of the science on PCBs. There is a lot more data on lower dose effects."
Responding to the study FDA toxicologist Terry Troxell told the New York Times last week: "Any time we have a standard that goes back to the 70's and 80's, it's time to review it." In the meantime, Troxell added that the new report did not constitute reason to stop eating salmon.
"Standards are always subject to revision based on what the science tells us and new risk assessments tell us," Troxell, told the Washington Post. He added, "Based on everything we know about PCB in salmon, the FDA maintains its current advice to consumers to not alter their consumption of salmon or other fish, which is highly nutritious."
The EPA's limits on contamination are 500 times more protective than the FDA's. When the FDA rule was written, salmon was still a rare dish in American households.
However, thanks to the boom in salmon aquaculture - and the health benefits of eating fish - salmon is now the third most popular seafood in the U.S., after tuna and shrimp. Fresh salmon has become a regular part of the American diet year-round.
The Environmental Working Group wants the FDA to conduct its own independent laboratory testing of farmed salmon for PCBs. This testing will allow FDA to update its regulations. If the FDA's test confirm these findings, the agency should issue warnings on farmed salmon similar to the EPA, Thayer said.
"This study wasn't trying to be the definitive study," Thayer said. "It was more to raise the issue to see how much of a concern it was. The answer is potentially it is a very big concern. We're asking FDA to do that definitive study and to bring purchased fish in line with caught fish."
Corsiglia added that an earlier study by the Environmental Working Group - which found traces of a rocket fuel chemical in lettuce - has prompted an FDA investigation. The group hopes the FDA will be similarly responsive to this report.
The group also wants to see salmon farmers monitor the PCB concentrations in the feed or refine feed sources to produce fish with lower concentrations of pollution. The PCB level in fishmeal varies from location to location, with some areas having higher levels of PCBs than others.
The market may demand a switch to cleaner feed sources. One grocery store - Wild Oats - has announced that it will begin featuring farmed salmon with PCB concentrations lower than the strict EPA standard. Their Irish supplier - Clare Island Sea Farms - has developed an organic farming operation that claims to be environmentally friendly. Another store - Whole Foods - is reportedly looking to do the same. On the west coast, natural food stores are already featuring wild Pacific Salmon which contain far lower levels contamination. Wild salmon also contain less fat and have more nutrients - including beneficial Omega-3 fatty acids - than farmed fish and cause fewer environmental problems.
Finally, the Environmental Working Group suggests that Congress do more to protect salmon habitat in Alaska, where wild caught salmon have PCB concentration levels ten times lower than the farmed fish. It's worth noting that the wild salmon used for comparison purposes were from Alaska. Alaskan salmon is widely available in stores.
That's not to say that wild salmon in some other areas of the Northwest also contain high levels of PCBs. Puget Sound Chinook for example - when tested by the state - contained higher concentrations of PCBs than the farmed samples, according to a report in the Seattle Times. Orcas in Puget Sound and Georgia Strait have been found to have extremely high concentrations of PCBs. A key part of the resident Orcas' diet is wild salmon.
Currently state officials say there is no dietary restriction on Puget Sound salmon because there is not enough data, the Times reported. However, state officials have suggested limiting consumption of other types of fish from rivers and lakes in 13 areas of Washington.
Editor's note: Tidepool is the online news magazine of Ecotrust, a Portland-based natural resources group. Ed Hunt worked for several years as a reporter for the Chinook Observer before helping found Tidepool.