Mercury
in Fish: The Methyl Mercury Contamination Conundrum
Grilled
tuna, succulent sushi, roasted lobster … there’s
virtually no end to the delicacies you can find in the water.
Disturbing studies, however, have detected high levels of
mercury in fish and shellfish. More specifically, fish and
shellfish worldwide have elevated levels of methyl mercury—a
form of mercury that is linked to several serious health
issues when ingested by animals and humans. This, of course,
begs the question: is any fish safe to eat?
Generally
speaking, the answer is yes, but you have to be careful.
It is practically impossible to find mercury-free fish,
because regardless of the species, you’ll find at
least a small amount of mercury in fish and shellfish. Mercury
exists naturally in the environment, and mercury is also
released into the atmosphere by coal-burning power plants
and other industrial facilities. Eventually, mercury settles
in water and on land where microorganisms turn mercury into
methyl mercury. Once methyl mercury is absorbed by fish
and shellfish, it enters the food supply of both animals
and humans.
As
you eat seafood over time, mercury in fish and shellfish
can accumulate in your body over time and cause mercury
toxicity years down the road. According to the Food
and Drug Administration (FDA), mercury in fish and shellfish
should not exceed 1 part per million, or 1ppm. Cooking does
not remove mercury in fish, so the only way to reduce methyl
mercury consumption is to monitor the amount and types of
fish you eat. Species that are considered high in mercury—close
to or more than 1ppm—include king mackerel, swordfish,
shark, and tilefish.
Other
species tend to have elevated mercury levels, too (up to
0.6 ppm) including grouper, orange roughy, fresh tuna, and
frozen tuna. However, these species are not considered problematic
as long as you watch your consumption and try to limit it
to about three servings a week. If you are concerned about
your fish consumption, there are therapies that can help
you with heavy
metal removal from your body tissues.
It
is important to note that, when monitoring the amount of
mercury in fish you consume, you should listen for news
about mercury in fish because officials may find elevated
levels from time to time. Recently, certain species of very
large tuna sold as fresh steaks and sushi were found to
have methyl mercury levels of more than 1 ppm.
Mercury
in fish can be a true health hazard for fetuses and children
because their nervous systems are still developing and are
very sensitive to methyl mercury. For this reason, babies,
children, and women who are pregnant should be especially
careful about the types and amounts of fish and shellfish
they eat. This warning also applies to women who may one
day become pregnant, because mercury in fish can accumulate
in the body over time.
Fish
and shellfish are full of essential fatty
acids and other nutrients that are an important part
of a nutritious diet. As long as you don’t have other
health issues like allergic reactions, you don’t have
to ban fish and shellfish from your life. Simply be aware
of mercury in fish, pay attention to news reports, and keep
track of the amount you eat.
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