Methyl mercury is found in fish everywhere, some types more
than others. The usual amount of mercury found is at levels of
anywhere between 0.01ppm to 0.5ppm, although in larger fish, such
as swordfish or shark, and even some larger tuna, the levels can
be elevated to regions of 1.0ppm, which is the FDA’s limit
for human consumption For “commercially important species,”
the most mercury that was found was less than 0.3ppm. To prevent
fish that contains more than 1.0ppm of methyl mercury from being
sold on the market, the FDA works with state regulators to monitor
all commercial fish that are bought and sold locally, as well
as monitoring imported fish by not allowing fish that exceed the
FDA level of 1.0ppm into the states.
The danger of eating fish with mercury mostly affects women who
are pregnant, and young children. The methyl mercury causes damage
to the nervous system. Methyl mercury accumulates in fish such
as Shark, Swordfish, King mackerel, marlin and Tilefish. Because
these are larger fish, they tend to prey on other fish, and will
contain all of the methyl mercury from every fish eaten. By consuming
less of these, there is less chance of damage to the unborn child,
or infant. The FDA goes on to report that fish in moderation (once
per week) will not affect a person to the point of poisoning.
Even so, in a 2001 consumer advisory report provided by the FDA
and the EPA that women who are pregnant, of nursing age, and young
children should limit their intake of fish, avoiding larger fish,
and also avoid fish that are caught by family or friends from
fresh water sources.
In recent studies done (August 29, 2003), it has been determined
that mercury in fish is not as toxic as proposed. It was found
that the type of mercury that is in fish that are consumed is
not the most toxic type of mercury, and is far less harmful that
methyl mercury chloride causes. In a study done in Seychelles
Islands in Africa, it was found that there was no hard evidence
that children born to mothers who consumed a lot of fish suffered
from neurological problems when they were older. It was also found
that fish do not contain methyl mercury chloride, but contain
methyl mercury cysteine, or something that is similar by using
an X-ray spectroscopy to obtain the spectra of the mercury in
the fish. Although it was noted that the dangers of methyl mercury
cysteine are not known, the zebra fish larva could hold up to
twenty times more of the substance compared to that of methyl
mercury chloride.
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