Good News: Contaminants Very Low in Alaska
Fish
By Joyce A. Nettleton, DSc, RD |
With
every report on contaminants in fish, people wonder if it is safe to eat
fish. How can people determine whether mercury, dioxins, pesticide residues,
or other substances are increasing their chance of developing cancer or
something else? These are important questions that don’t have simple answers,
because the chance of developing a health problem from contaminants in foods
depends on many factors. Frequently we don’t have enough solid information
to reasonably estimate health risk. However, recent data from the state
of Alaska are encouraging. Environmental contaminants in Alaska fish are
very low, particularly in salmon, cod, pollock, and other species.
From
2001 to 2002, the state of Alaska, in cooperation with other government
agencies and fishing organizations, collected over 600 samples of Alaska
fish species for detailed chemical analysis. These samples, analyzed with
the most up-to-date methods, provide the most reliable estimates of environmental
contaminants in Alaska fish.
Are All Fish Contaminated?
Fish
accumulate chemicals from the environment because contaminants from pollution
and waste incinerators wash into lakes and rivers, eventually reaching the
ocean. Some degrade slowly and can spread around the world. Heavy metals
such as mercury, pesticide residues, and other compounds move up the food
chain from plankton to small fish and larger fish that eat smaller ones.
For this reason, nearly all fish have traces of contaminants. However, only
a few species and sizes of fish contain relatively large amounts. These
include larger older fish, some carnivorous species that eat other fish,
and fish from polluted waters. Some recreationally caught fish may have
higher contaminant levels than Alaska fish and other commercially available
fish. The good news is that, because the production of many harmful chemicals
has ended, levels of many contaminants in fish have been slowly decreasing.
Which Contaminants Are Risky?
Not
all contaminants pose a serious health risk and most people, including those
who eat fish several times a week, consume only very small amounts. Increased
levels of contaminants have been observed mainly in people who frequently
eat fish known to have higher contaminant levels. To minimize intake of
contaminants without sacrificing the health benefits of seafood, eat mostly
fish known to be low in contaminants. Eating a variety of fish species reduces
the risks from contaminants. The healthiest fish choices are those high
in omega-3 fatty acids and low in contaminants, like Alaska salmon.
Mercury
The contaminant of greatest concern is mercury, found
in fish as methylmercury. Mercury is a risk mainly for pregnant women and
young children. Women of childbearing age who may become pregnant should
also avoid eating fish with high mercury levels. Mercury can potentially
damage the brain during fetal and infant development. For this reason, the
Food and Drug Administration (FDA) advises pregnant and nursing women and
young children to avoid eating shark, swordfish, tilefish, and king mackerel,
which are high in mercury. For all other adults, small amounts of mercury
from seafood have very little risk. High blood mercury levels may be linked
to cardiovascular disease, but so far the data are inconclusive. In contrast,
the cardiovascular benefits of eating seafood are well established. Eating
a variety of fish, especially those known to be low in contaminants, protects
health and minimizes risks.
Mercury
is distributed throughout fish tissues, so removing the skin and draining
the fat have little effect on mercury content. The maximum amount of mercury
in seafood permitted by the FDA is one part/million (1 ppm). According to
recent Alaska Dept. of Environmental Conservation data, all five species
of Alaska salmon have less than one thirtieth of FDA’s permitted level,
averaging 0.027 ppm1.
Alaska
cod and pollock also have low levels, averaging 0.07 ppm, less than one
tenth of FDA’s permitted level. These species are among the lowest in mercury
content in FDA’s database of commercial fish species2.
Organic Contaminants
Organic
contaminants include mainly PCBs, dioxins, and various pesticide residues.
These substances persist in the environment for years, degrading only slowly.
Although manufacture of PCBs and several pesticides ended in the 1970s,
these substances continue to be detected at low levels in many species of
fish and other foods. Dioxins, chemically related to PCBs, enter the environment
from activities such as waste incineration, forest fires, and volcanic eruptions.
Environmental levels of PCBs and dioxins have been decreasing for the past
30 years.
Adverse
health effects from PCBs and dioxins have occurred almost exclusively in
industrial workers and children of mothers exposed to levels 100 to 1000
times above background3,4. Although the Environmental Protection
Agency (EPA) considers PCBs and dioxins probable carcinogens, the
Although
much publicity has been given to differences in the amounts of organic contaminants
in wild and farmed fish from various parts of the world, all reported levels
have been well below safe limits set by the FDA, EPA, and the World Health
Organization. On balance, the health risks for people who do not eat fish
are greater than for those who do.
Certain
pesticide residues can be detected in the environment and at trace levels
in some fatty fish, even though manufacture of 51 of the most harmful pesticides
has been banned in the U.S. Alaska fish were analyzed for over 40 pesticides
and fewer than one quarter of the samples had detectable levels, all less
than one thousandth of FDA’s guidelines for these substances. Thus, risk
from pesticide residues from Alaska fish is essentially negligible.
Minimizing Contaminant Intake
The
best way to ensure the lowest levels of contaminants is to eat fish known
to have low levels, such as Alaska-caught fish. These include salmon, cod,
and pollock. Vary the types of fish and shellfish you eat to further reduce
risk. Cook fish so that the fat drains away, taking with it possible organic
contaminants.
Conclusion:
Recent analyses confirm that popular Alaska fish–salmon, cod, and pollock–present
negligible health risks from mercury and organic contaminants such as PCBs
and dioxins. These fish can safely be consumed any time by people of all
ages. The well recognized health benefits of consuming fish regularly for
heart health, infant development during pregnancy and nursing, immune function,
and other conditions far outweigh potential risks from trace levels of contaminants.
5/05
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