http://www.sma.org.sg/smj/4502/4502a2.pdf
(Medical journal - singapore)
"Since puffer fish poisoning has no specific treatment(9),
people should be made aware of the potential risk
of eating puffer fish. During its preparation, the liver,
gonads, intestines and
skin which contain the
highest level of Tetrodotoxin should be removed."
http://www.fda.gov/food/foodsafety/...thogensnaturaltoxins/badbugbook/ucm070842.htm
(FDA - Government body? I'm english sorry so not familiar with it!)
"The gonads, liver, intestines, and
skin of pufferfish can contain levels of
tetrodotoxin[SUP]2[/SUP] sufficient to produce rapid and violent death."
http://www.isrn.com/journals/toxicology/2011/276939/
(ISRN Toxicology)
"Marine pufferfish generally contain a large amount of tetrodotoxin (TTX) in their
skin and viscera, and have caused many incidences of food poisoning, especially in Japan."
http://www.terrapub.co.jp/onlineproceedings/fs/nu/pdf/nu2010227.pdf
(Nagasaki Uni - same article puffykid linked)
"Recent studies have revealed that the liver of pufferfish has a specific TTXuptake
mechanism, and TTX introduced into the pufferfish body is first
absorbed in the liver and then transferred to the
skin through the circulatory
system."
"The toxic parts are different depending on species, which can be categorized as (1) muscle, testis and skin that are non-toxic (less than 10 MU/g) and edible; T. rubripes, T. xanthopterus, shirosabafugu Logocephalus wheeleri, etc., (2)
skin is toxic, but muscle and testis are edible; T. snyderi, T. porphyreus, T. vermicularis, etc., (3) testis is also toxic, and only muscle is edible; T. niphobles, T. poecilonotus, T. pardalis, etc"
"Small pufferfish inhabiting brackish water (Mahmud et al., 1999a, b) or
freshwater (Kungsuwan et al., 1997; Sato et al., 1997; Ngy et al., 2008b) in Southeast
Asia are also toxic.
Toxicity of the skin is usually higher than that of the viscera in
these pufferfish. The toxin of brackish water species was identified as TTX (Mahmud
et al., 1999a, b),"
Better?
That last article is well worth a read. Really fascinating. Bottom line seems to be yes, it can occur in the skin, but whether it does or not varies depending on a load of variables. (Read the article for that to make more sense! It's stuff like species, location etc) I've never been able to find a definite answer as to whether or not the skin "leeches" ttx into the water in any way, so personally I always err on the side of caution and wear gloves for maintenance etc with my fugu anyway.
I'd hazard a guess that a fish has literally got to take a chunk out of a puff to get poisoned from the skin, and even so the puff would have to be fairly recently wild caught (ttx depletes over time in captive fish - not sure how long it takes) and also be one of the species that has ttx in the skin to start with.
My conclusion would be don't lick pufferfish just in case!!
