Insights by Goldie
Sound Consumer | December 2002
by Goldie Caughlan
Quality Standards Specialist
Q: I'm concerned about the levels of mercury in fish, especially in tuna. I am not pregnant, nor planning to be, but I love fish and certainly I'm still concerned about my health when I choose fish. Is canned tuna better or worse than fresh tuna? I've heard that Albacore is lower in mercury. Is this true? And why would that be? I'd probably switch, but it is somewhat higher priced. And what about mercury in all the other kinds of seafood we have at PCC?
A: It is like swimming in murky waters, looking at the varying reports and perspectives on mercury content of fish! The Food & Drug Administration (FDA) in January, 2001 warned that very large, predator, and older fish — particularly shark, swordfish, king mackerel and tilefish — should be avoided by women who are pregnant, nursing, or of childbearing age.
The advisory was issued primarily because of mounting evidence that mercury has a devastating impact on fetal and infant health. Mercury is from many sources, including waste incineration, coal-fired plants, and other polluting sources.
Fish absorb methyl mercury (the most toxic form) from water as it passes over their gills and as they feed on aquatic organisms. It is generally the larger, older predator fish that are exposed to the highest levels of methyl mercury from the food they eat. The toxin binds to the proteins in fish tissue, including muscle. Cooking does not appreciably reduce the mercury level.
And like the legendary "canary in the coal mine," which indicated that air quality was unsafe for mine workers, the rest of us look at such chilling advisories and wonder, "How does that translate to guide the rest of us in making the most healthful fish choices?"
The FDA sets one part per million (ppm) mercury in fish as the upper limit for safety for human consumption. The advisory was based on tests showing that fresh or frozen tuna has a mean (average) of .32 ppm for mercury, with a range from "none detected" (or ND) to 1.30 ppm.
Canned tuna (all types grouped), tested from ND to .75 ppm, with a mean of .17 ppm. As for albacore, since it is one of the smaller types of tuna, the presumption is it would be in the lower range for contamination by mercury.
Specifically, PCC does not carry any of the four varieties of fish on the FDA's radar (shark, swordfish, king mackerel and tilefish) even though, according to the FDA, any healthy adult or child could safely eat "occasional" and "moderate" servings of those varieties. The FDA's position, however, is not necessarily shared by many environmental science groups nor by health practitioners, including noted medical experts such as Dr. Andrew Weil and others.
All varieties in the fish case at PCC are supplied through EcoFish, working with the independent experts of their Seafood Advisory Board. The board includes scientists with the National Audubon Society's Living Oceans Program, the Monterey Bay Aquarium, the World Wildlife Fund, the Oceans Program of Environmental Defense, and others.
Apart from the direct issue of health, the EcoFish Seafood Advisory Board makes species recommendations using measurable criteria and using a broad range of sustainability issues. Please, pick up a copy of the PCC brochure on environmentally responsible seafood at the fish counter at any PCC.
In April, 2001, the Environmental Working Group and the U.S. Public Interest Research Group issued a joint report, "Brain Food: What women should know about mercury contamination in fish" which included an expanded list of fish recommended to avoid altogether.
The authors said, "The widespread contamination of fish with mercury has given its reputation as 'brain food' a new and disturbing connotation. Mercury is toxic to the developing fetal brain and exposure in the womb can cause learning deficiencies and delay mental development in children."
The EWG/US-PIRG report was the first-ever computer analysis of mercury contamination in fish and the diets of American women. It drew from seven different governmental sources and four separate agencies to create a database on fish contamination containing 53,000 records of mercury test results.
The report lists 13 fish that pregnant women are advised to avoid totally, based on computer modeling which included variations in women's weight, blood volume, diet, metabolism and level of mercury already in their blood.
To date, the FDA has not changed its position nor updated its advisory. The EWG/US-PIRG group continues to criticize FDA's position and charges bluntly that the FDA's own working documents and transcripts of meetings show that the FDA's senior scientist knew that the current advisory is wholly inadequate, especially as it pertains to women and infants.
Particularly offensive to the group is the FDA's refusal to add "tuna" to the "avoid" list because, they say, the FDA left tuna off the list after a flurry of meetings with tuna industry representatives.
EWG does give a big "thumbs up" for many types of wonderful available fish, including several that PCC regularly carries: farm-raised trout and catfish, wild shrimp, fish marketed as "fish sticks," flounder (referred to as "summer flounder"), wild pacific salmon, croaker, mid-Atlantic blue crab, haddock and tilapia.
Although they do not list tuna, the fresh EcoFish tuna at PCC is Albacore — a smaller, younger tuna variety, from Hawaii. We do not carry the Yellowfin (called ahi in Hawaii), the Bluefin, which is large, nor the Bigeye, generally used as "sashimi" (raw) in sushi.
You can read the EWG/US-PIRG report in its entirety on their web site at www.ewg.org/pub/home/reports/brainfood/pr.html.
The latest studies
During the past few months, two disturbing reports emerged. In the first, Finnish researchers found that men with the highest mercury levels in their hair — which correlated to the amount of mercury-laden fish consumed — were statistically more likely to die from heart disease, heart attack and stroke.
This information was presented at an American Heart Association (AHA) meeting in April, 2002. The AHA still recommends consuming up to 12 ounces of fish such as mackerel, lake trout, herring, sardines, albacore tuna, and salmon twice a week, noting that the study is a single study, preliminary, and does not prove that eating fish leads to heart problems.
And a very interesting study was just reported in October, 2002 in the science journal Environmental Health Perspectives, a publication of the National Institute of Environmental Health Sciences.
Researchers looked at upper-income individuals whose diet included large amounts of fish and found "dangerously high levels of mercury" in their blood. The study followed 720 patients in a San Francisco internal medicine practice over a one-year period. Mercury levels in tested blood and hair correlated with their high intake of specific fish, particularly swordfish.
The relatively high incomes of the study participants was said to be related to their more expensive dietary choices in seafood: They reported regular and frequent use of sushi with Yellowfin tuna, (also called ahi), mackerel or salmon, sashimi (raw tuna, usually raw Bigeye), as well as shrimp, prawns, crab, oysters, scallops and other seafood.
Mercury levels in tested women averaged 10 times the levels recommended by the Environmental Protection Agency and the National Academy of Sciences, with similar levels in men.
Most disturbing were the seven children followed in the study, who tested at mercury levels 40 times the recommended safe levels! It was also noted that after the subjects with such high levels withdrew from their high seafood consumption over a period of months, their blood mercury levels dropped back to safe levels.