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Bad Bug Book
Foodborne Pathogenic Microorganisms and Natural Toxins
Tetrodotoxin
1. Toxin
Tetrodotoxin (TTX) and related
compounds (e.g. 4,9-anhydroTTX,
4-epiTTX, 11-deoxyTTX,
tetrodonic acid)
Poisoning from consumption of
members of the family
tetraodontidae (pufferfish) – i.e.,
pufferfish poisoning – is one of the
most dangerous intoxications from
marine species. There are
approximately 185 species of
pufferfish worldwide, and they
occur in both freshwater and
marine environments. Several of
these species are consumed
throughout the world, particularly
in the Indo-Pacific region, such as
Japan, where pufferfish hold great
cultural significance. In several
species, the gonads (mainly ovary),
liver, intestines, and skin can
contain levels of tetrodotoxin
sufficient to produce rapid death.
In a few species, the flesh naturally
contains enough toxin to be lethal,
if consumed.
Among the numerous pufferfish
species, total toxicity, as well as
toxin distribution among different
organs within individual fish, can
vary greatly. However, toxin
presence and distribution does
appear to be fairly consistent
within a given species. As an
example, the table at the end of
this chapter provides the popular
and scientific names for 22 species
of pufferfish consumed in Japan,
including which parts are
For Consumers: A Snapshot
In some parts of the world, especially Japan, pufferfis h (also
called “fugu” or “blowfish”) are thought of as a delicacy – even
though they contain a poison that’s deadly to humans, if the
fish aren’t prepared by a highly trained expert. In some types of
pufferfish, some organs, like the liver and skin, contain the
poison, which is called tetrodotoxin. If the chef or trained
cutter doesn’t cut the fish in exactly the right way, the poison
may get into the meat of the fish, and the person who eats it
may become ill or even die without immediate med ical
treatment. In mild cases of pufferfish poisoning, the person
who eats it may get numbness and tingling in the lips, arms,
and legs, and may feel light‐headed. In severe cases, death is
from suffocation – often awake until the end – because of
paralyzed breathing muscles. There are many types (species) of
pufferfish, and in most of them, only the organs, not the meat,
naturally contain the poison. Other typ es don’t contain any of
the poison at all, like the puffer from the mid‐Atlantic waters of
the U.S., called “northern puffer.” This type of pufferfish used
to be sold as “sea squab,” but today res
taurants sell it under
other names, such as “sugar toad.” On the other hand, a few
types of pufferfish naturally have large amounts of the poison
in their meat (not just the organs), and it’s never safe to eat
them, no matter who prepares them. After a fish has been
cleaned and processed (for example, turned into fillets or fish
cakes), it can be hard to tell what kind it is. Because of this, the
FDA allows only one type of puffer (Takifugu rubripes, also
called torafugu or tiger puffer) to be imported from Japan.
Only certain parts are allo wed, and it has to be prepared by
trained fish cutters before it’s imported. It’s sold only to
restaurants belonging to a specific association. Because of
these strict safety limitations, the availability of this pufferfish
often is limited, and it’s often expensive. Several times, the FDA
has stopped illegally imported shipments of pufferfish. In some
cases, unsafe importers have tried to get puffers into the
country labeled as different fish. Puffer – the dangerous kind –
falsely labeled as monkfish was imported from China in 2007
and sickened people who had eaten bok go jim (blowfish
casserole) or bok jiri (blowfish stew) in restaurants. “Bok” is a
Korean word for “puffer.” In Illinois, home‐made puffer soup
made from bok, from a local ethnic market, caused illness. The
message to take away from all this is that if you choose to eat
pufferfish, eat only those from sources known to be safe. (Also
see the box called “DNA Barcoding” at the end of the
Gempylotoxin chapter of this book.)