News Coverage
New Study Finds High Levels of PCBs in Farmed Salmon Purchased in US Grocery Stores
Published July 29, 2003
A study by the Environmental Working Group has found that farmed Atlantic Salmon purchased in US grocery stores contain enough cancer-causing toxins to raise health concerns.
In fact, if wild fish contained polychlorinated biphenyls (PCBs) in the same concentrations, the EPA would restrict consumption to no 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.
The working group purchased farmed Atlantic Salmon at grocery stories in Portland, Oregon, San Francisco, California and Washington D.C.
Seven of the ten 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 &endash; including the US, 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 US?
"Studying salmon also made sense because it is the third most popular type of fish consumed 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 US consumers, according to the group's findings. On average the farmed salmon tested contained 16 times the PCBs found in wild salmon, four times as much as in beef and 3.4 times as much PCBs as found in other seafood.
"The levels of these test track 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 US 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.
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. Second, because farmed salmon are raised to contain 50 percent more fat than wild salmon, more PCBs end up accumulating in each fish.
"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."
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 in food 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.
"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 this week: "Any time we have a standard that goes back to the 70's and 80's, it's time to review it."
In fact the EPA's limits on contamination are 500 times more protective than the FDA's. Moreover, 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 touted health benefits of eating fish -- salmon is now the third most popular seafood in the United States, after tuna and shrimp.
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 according to Thayer.
"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 response 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 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 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 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. The Federal Government also needs to regulate fish farming in the United States to protect wild stocks, which are threatened by salmon farm pollution, disease and escapes.