Mercury Levels in Popular Sushi Varieties
Jillian Capaldo
University of Delaware
Abstract
Using meta-analysis of published studies, four types of seafood
commonly seen in sushi dishes are examined to conclude their safety in
terms of average concentration of methylmercury, a base element in the
environment which does not degrade under normal conditions which can
enter the environment through use of power plants and burning of
waste. The four types in question are tuna, salmon, shrimp and eel. This
meta-study incorporates several sources to calculate these averages,
including information from the FDA website. After pooling together data
from previously published studies, the average mercury concentrations
(in ppm) are calculated for each category. The results show that by far
tuna contains the highest amount of mercury, much more than any of the
other types. Salmon comes in second in terms of potency, although it has
considerably less than tuna. Shrimp has an extremely low average
mercury content, and eel is declared undefined, as there is too much
fluctuation in the data for this type of seafood. We can conclude from
this data that tuna, including the variety eaten commonly in sushi, should
be eaten in moderation, and completely avoided in pregnant women.
Salmon and shrimp can be safely eaten, while eel consumption can vary
in toxicity.
Introduction
• In this study, different sources were looked at to
analyze average concentrations of methylmercury in
different varieties of seafood used in sushi dishes.
• It is important to consider the amount of mercury in
our diets because it can be very toxic at high levels,
which can result in neurological disorders and even
death.
• The results were assessed to determine the relative
safety of consuming the various types.
• It can be noted that mercury is an element which
bioaccumulates, which is explained in Figure 1.
• Figure 2 shows the relative average levels of mercury
in the different varieties of seafood.
• The four types of seafood examined were:
• Tuna
• Salmon
• Eel
• Shrimp
Figure 2.
0.4
0.35
0.3
0.25
Tuna
Salmon
0.2
Shrimp
0.15
0.1
0.05
•
•
http://2.bp.blogspot.com/-HaZVXuJp6mU/T01CHQH9nNI/AAAAAAAAABU/NKDNFtaqwck/s1600/bioaccumulation.jpg
References
0.45
Mercury Level (ppm)
A visual depiction of how mercury bioaccumulates in
the environment; as it moves up the food chain, it
becomes higher in concentration.
• More research and studies need to be done to provide
an adequate estimate for mercury levels in eel
populations. It is undefined as of now due to high
fluctuation and variation in mercury levels previously
recorded.
Results
0
Figure 1.
• From these findings, we can conclude that while the
other types of seafood are fairly safe to consume, one
must be careful when adding a large amount of tuna
into their diet. This primarily concerns pregnant
women, as high mercury content in food has been
shown to have negative effects on the developing
baby13
In
the
general
population,
it
can
be
advised
that
tuna
• should be eaten in strict moderation to avoid going
above levels considered to be toxic to the body.
Depending
on
the
source,
eel
can
be
consumed
safely,
• as can salmon and shrimp which were shown to
contain very low levels of mercury on average.
Pregnant
women
should
however
avoid
eating
any
• sushi with tuna for the duration of their pregnancy,
due to the risk level being too high in this life stage.
http://hayashirestaurant.com/images/banner1.png
Materials & Methods
This experiment was a meta study, performed by
pulling together information from various sources
and compiling the data into a more concentrated
form. The resources included:
• Information on individual seafood species
• General facts on mercury and its dangers
• Regards to wild caught vs. farm raised seafood
• Regulations on sushi consumption
• Online articles and journals, as well as lay
literature, were used in the course of this study
Sources were identified by searching 5 databases
using the search terms ‘mercury levels’, ‘sushi
varieties’, and ‘tuna’, ‘salmon’, ‘shrimp’ and ‘eel’. 14
total references were identified.
Discussion
•
Tuna is the variety of sushi seafood with the highest
average concentration of mercury (0.392ppm).
Salmon and shrimp with an average of 0.022ppm and
0.009ppm mercury, respectively, by comparison are very
low in mercury content.
Levels of mercury in eel was found to be undefined.
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