Called Health Risk
By Jessica Kowal
July 15, 2003
have become increasingly enthusiastic about the health
benefits associated with eating fish, particularly as they
study the effects of omega-3 fatty acids, or fish oils, on the
human body. In the 1970s, these important nutrients were found
to prevent heart disease. Omega-3 fatty acids are now also
believed to decrease the risk of stroke, to improve infant
brain development, and even to ease rheumatoid arthritis,
Crohn's disease, psoriasis and postpartum depression.
Nevertheless, there remains a troubling aspect to the good
health news: contamination of some species of fish with
mercury, PCBs and other chemicals, researchers and government
And some nutritionists say that lax government regulation of
some contaminated fish has confused the public about which
fish are safe to eat, which need to be eaten in moderate
amounts and which could be dangerous.
The result, some scientists charge, is that Americans are now
baffled by changing lists of contaminated species and
advisories about what type and how much fish to eat. And the
worst outcome of a debate about the safety of fish, many
experts worry, is that people may drop fish from their diets
entirely rather than figure out the messy details.
The best example of consumer confusion and slow regulatory
changes, some experts say, is how the U.S. Food and Drug
Administration has addressed the problem of mercury
In September, after years of debate, the Food and Drug
Administration plans to revise its 1970s-era standard for how
much mercury in fish is safe. The United States may lower its
mercury benchmark, possibly to a Canadian and British standard
that is half the level now acceptable to the FDA.
That could affect government advice about popular fish,
including fresh and canned tuna, red snapper and halibut, some
of which have a fairly high mercury content.
"If you're not regularly getting these fish-based fatty
acids in your diet, you're missing out on a health
bonanza," said Joyce Nettleton, the author of three books
about seafood nutrition. "If I want omega-3s, and I don't
want to have to worry about mercury, which ones do I choose?
There are choices out there."
The Health Benefits of Fish
Three decades ago, studies found that Greenland Eskimos had
remarkably little heart disease, stroke, high blood pressure
and arthritis. Scientists subsequently linked these benefits
to omega-3 fatty acids, nutrients that are produced by
microorganisms in bodies of water and passed to fish in the
Of the various omega-3 fatty acids, three are especially
important biologically: DHA (docosahexanoic acid), EPA (eicosapentaenoic
acid) and ALA (alpha-linolenic acid). These are described as
"long-chain" fatty acids because their structure
comprises more carbon atoms strung together in a chain,
according to Margaret Craig-Schmidt, a nutrition and food
science professor at Auburn University in Alabama.
During the past three decades scientists have tied several
vital health benefits to the omega-3 nutrients found in fish.
They prevent heart disease and dramatically reduce the risk of
a second heart attack; significantly decrease the risk of
stroke for men who eat seafood once a month; ease postpartum
depression in women who eat significant amounts of fish, and
improve symptoms of inflammatory diseases such as rheumatoid
arthritis, rhinitis and psoriasis.
"Not a month or two goes by when we don't have another
scientific study about the benefits of long-chain omega-3
fatty acids in our diets," said Charles Santerre,
associate professor of foods and nutrition at Indiana's Purdue
For pregnant women and children, DHA is the most important
omega-3 fatty acid, because it's essential to human brain and
eye development. Pregnant and nursing mothers who regularly
eat fish rich in omega-3s pass more of these nutrients to
their children through the placenta and in breast milk,
Craig-Schmidt said. And as further evidence of DHA's
importance, two companies began selling infant formula that
included DHA and another fatty acid, ARA (arachidonic acid) in
early 2002. These supplemented formulas are sold under the
brand names Enfamil Lipil and Similac Advance, and cost more
than regular infant formula.
But mothers and children can get a fine supply of DHA if they
eat certain fattier cold-water fish -- particularly salmon,
sardines, herring and mackerel.
Among other species of fish, canned tuna packed in water is a
good source of omega-3s, but that same canned tuna,
particularly albacore, can also be contaminated with fairly
high levels of mercury.
Leaner seafoods, such as cod, pollock, shrimp, clams and
oysters, are less fatty and provide less omega-3s, said Jacob
Exler, a nutritionist with the U.S. Dept. of Agriculture's
Nutrient Data Laboratory.
Mercury and Tuna
Mercury occurs naturally in soil and rock but is released into
the atmosphere primarily through volcanic activity, coal
combustion and medical waste.
Eventually, it settles at the bottom of oceans, lakes and
rivers. Bacteria in bodies of water transform this inorganic
mercury into methylmercury, a particularly toxic form, which
works its way through the food web.
Because mercury accumulates in the body, long-lived predators
such as shark or swordfish have exceptionally high
concentrations, as do other large fish, said M. Christopher
Newland, a professor in Auburn University's department of
experimental psychology who studies the impact of mercury on
the nervous system.
The FDA has found relatively high levels of mercury in red
snapper, marlin, orange roughy, saltwater bass, freshwater
trout and bluefish. But the agency has sampled only limited
quantities of these fish, so the typical mercury levels are
not well known.
Small, short-lived fish -- again, fish such as sardines and
herring -- have the least mercury, as do salmon, king crab,
scallops, catfish, oysters and shrimp. The most common
farm-raised fish -- namely salmon, trout and catfish --
typically have less mercury contamination than fish caught
commercially in the wild, according to experts. But it's
important to remember that wild salmon, trout and catfish
caught commercially have very low mercury levels, anyway, so
the difference is not significant from a health perspective.
In a developing fetus, mercury impairs development of the
nervous system and brain. High mercury exposure at any stage
of life including in the womb, may speed aging and affect
motor skills and learning ability in adults, and may increase
the risk of heart disease, Newland said.
The FDA says its advisories about mercury lay out safe,
healthy guidelines for fish consumption. In 2001, the FDA told
consumers to eat no more than 12 ounces (3/4 pound) of a
variety of fish per week, a standard that integrated the
Environmental Protection Agency's stricter mercury limits,
said David Acheson, chief medical officer in the FDA's Office
The FDA also has advised the public not to eat four
mercury-rich fish: swordfish, shark, king mackerel and
But the FDA has taken a less aggressive approach to answering
questions about tuna, the most popular fish in America, and a
cheap source of protein and omega-3 fatty acids. Some tuna
steaks tested by the FDA have mercury levels above the
agency's safety standard. Canned tuna has less mercury, but
FDA samples found a wide range of mercury content, from
undetectable to a level approaching the FDA's unsafe reference
The FDA now advises pregnant women to eat no more than one
6-ounce can of tuna each week -- one fat tuna sandwich, say,
from a deli.
Some health experts say this still poses too great a risk, and
last summer, the FDA's own food advisory committee told the
agency to re-examine the tuna-mercury issue. In April, the
California Medical Association demanded better labeling of
tuna after the Centers for Disease Control and Prevention
found high mercury levels in a surprisingly large number of
In reply to that and many other studies critical of tuna, the
U.S. Tuna Foundation has consistently argued that canned tuna
"poses no health risks" and "offers significant
health benefits to pregnant women."
As the debate plays out, and as the FDA tests more fish,
Nettleton, who has a PhD in nutrition science from the Harvard
School of Public Health, advises pregnant women not to risk
the purchase of a can of tuna, particularly white albacore
tuna, that might be high in mercury.
"Is this the time to play Russian roulette with mercury?
If you're really cautious about this, choose other fish,"
There are some better tuna choices. "Chunk light"
tuna offered by the major tuna brands and small, troll-caught
Pacific albacore tuna and imported Spanish tuna in some
specialty food stores have less mercury than white albacore,
The general public should also be more cautious about mercury
in large fish, according to Dr. Jane Hightower, a San
Francisco internist. After seeing one patient with hair loss
problems, who also ate a lot of fish, Hightower questioned
more than 700 patients about their fish intake and found,
after blood and hair analysis, that about 80 of these patients
had unsafe mercury levels in their bloodstream.
Of this group, 78 percent regularly ate canned tuna, most of
it albacore tuna. Some high-income patients also routinely ate
ahi tuna steaks, tuna sushi and swordfish, and some suffered
from fatigue, muscle aches and hair loss associated with
"Essentially, we are eating too much mercury" in
fish, said Hightower, who published her study in April 2003.
Newland, the mercury expert from Auburn University, believes
the current FDA regulations limiting tuna intake to one can
per week is appropriate and safe. He says federal regulators
could do more for public health if they would ban commercial
sale of the highest-mercury fish, rather than confuse people
about detailed lists.
"You can go into a restaurant and get swordfish. That
just makes no sense to me," Newland said. "Federal
authorities should keep fish that contain a lot of mercury out
of the market."
Artificially Colored Salmon
Salmon has very low mercury levels and few other contaminants
and is one of the best sources of omega-3 fatty acids. This
fish has become increasingly popular in the United States as
fresh, farm-raised salmon, mainly imported from South America
and Norway, has become very cheap and widely available in
But even salmon has surprised consumers lately.
In grocery stores across the country, and in at least some
supermarkets in the metropolitan area, packages of farm-raised
salmon -- also called "Atlantic salmon" -- are
sporting new labels describing it as "color added"
or "color enhanced."
Artificially colored pink salmon? It's true. If not for two
additives in their fish food, all farm-raised salmon would be
About 80 percent of fresh and frozen salmon sold in the U.S.
is farmed, and whether it is served as a salmon fillet, a
salmon steak, lox or sushi, all of it is colored. The reason
is that pink salmon sells; according to consumer studies,
people associate richly colored salmon with freshness and
The color issue became a national topic of conversation after
an environmental law firm in Seattle filed suit April 23 in
state Superior Court to force three national supermarket
chains to label the color additives in the farmed salmon, as
longtime FDA rules require.
The three grocery chains cited in the lawsuit, Safeway,
Albertsons and Kroger Co., do not have stores in New York. But
New York City and Long Island stores have begun to change the
labels on their farmed salmon in line with the FDA rules.
Wild salmon get their pink-orange-red color by eating shrimp
and krill, which feed on algae that produce the colorants,
called carotenoids. (Canned salmon is entirely wild salmon).
For the farmed fish, which eat pellets of ground-up fish,
wheat and other nutrients, the two color additives,
canthaxanthin and astaxanthin, mimic the algae's coloring
In the wild, salmon color can vary from ivory white to deep
red-orange. For farmed fish, color depends in part on water
temperature and diet, but fish farmers can, to some extent,
control the hue by altering the amounts of additives in the
Canthaxanthin has raised health concerns in Europe because
high doses cause retinal damage. Earlier this year, European
Union regulators told fish farmers to cut canthaxanthin levels
to one-third of what is currently allowed by the FDA.
Industry experts say no one could or would eat enough salmon
to cause eye damage. They add that problems with canthaxanthin,
which is also fed to farmed trout and broiler chickens in the
United States, were found mainly in people who consumed the
additive in large quantities to give themselves a fake tan. No
health risks have been identified in the second additive,
astaxanthin, which is approved for use only in fish food.
Stewart Anderson, a global marketing manager for F. Hoffmann
La-Roche, the Swiss corporation that dominates the market for
these additives, says they are "safe for human
consumption" if regulations are followed. The FDA is
studying the European decision to see if the United States
should change its policy, a senior official in the FDA's
Office of Food Safety said.
Even if the public accepts the idea of artificially colored
salmon, some environmental groups and wild salmon fishermen,
mainly in the Pacific Northwest, argue that consumers should
refuse farmed fish for environmental reasons.
Comparing fish farms to pig farms, they say fish farms spread
disease-causing waste, and farmed fish genetically weaken wild
Fish farmers say their industry has improved its environmental
record in 20 years in business, and they credit farmed salmon
with creating a rapidly growing market for a healthful,
Contaminants in Sport Fish
Grabbing a fishing pole and catching your supper in a lake or
river might sound pleasant. The reality is far different: In
dozens of metropolitan area lakes and rivers, fish are
contaminated with PCBs, mercury, cadmium, dioxin, DDT and
other toxic chemicals.
These contaminants, byproducts of industry or pesticide
residue that settle at the bottom of lakes, rivers and
reservoirs, can seriously harm infant development, authorities
The 2003-2004 state advisory about sport fish points to
problems in largemouth and smallmouth bass, walleye, perch,
brown bullhead, American eel, carp, American shad, and some
trout in 80 of the state's bodies of water.
For example, the New York State Health Department advises that
people eat no more than a half-pound per week of bluefish and
American eels caught in Long Island Sound, Block Island Sound,
Peconic and Gardiners bays, the lower bay of New York Harbor,
Jamaica Bay and other Long Island South Shore waters because
of PCB contamination.
And it can take six years to clear a high dose of PCBs from a
woman's body, so a woman could eat a contaminated fish today,
become pregnant next year, nurse her baby nine months later
and pass along a higher dose of PCB to her baby than when she
ate the fish, said Santerre, the Purdue University professor.
That means that women of childbearing age and children under
age 15, in particular, should not eat fish caught by anglers
in contaminated waters, according to the New York State Health
Department and experts on toxic substances in fish.
Adults other than women and children shouldn't eat more than
one meal per week of fish caught in any body of freshwater
anywhere in the state or at the mouth of the Hudson River, and
some contaminated fish shouldn't be eaten more than once a
month, state health officials say.
If you want to go out and catch fish, fine, Santerre said.
Check local health advisories, catch a fish and release it.
"Then go to the grocery store and get some good, healthy
fish," Santerre said.
Jessica Kowal is a freelance writer.
© 2003, Newsday,