[Tetrodotoxin Intoxications in Nagasaki, Japan: Symptoms of Patients, Tetrodotoxin Levels in Leftover Food and Clinical Urine and Serum Samples].

Incidents of food poisoning associated with tetrodotoxin (TTX) contamination occur every year throughout Japan. Here, we determined TTX levels in leftover foods and serum and urine samples from eight food poisoning incidents associated with TTX contamination in Nagasaki, Japan, from 2011 to 2017.Seven food samples associated with four of these food poisoning incidents were classified as weakly toxic (four samples), moderate-to-strongly toxic (two samples), and strongly toxic (one sample).In comparison with previous reports, TTX was detected at harmful levels in the urine samples, but the grade of poisoning symptoms varied.The patients' time to maximum serum TTX levels (Tmax) was estimated to be 12-24 h after ingestion of TTX-containing foods. Additionally, serum TTX levels of 19.5 ng/mL or higher within 24 h after ingestion indicated Grade 3 poisoning associated with respiratory abnormalities.These conditions were considered indicators of severe symptoms, while TTX levels of 1-3 ng/mL relate to the onset and disappearance of symptoms. A negative correlation was found between the logarithm of serum TTX concentration and the time after ingestion for two patients, indicating that the TTX serum levels decreased logarithmically. Furthermore, the TTX serum half-lives (T1/2) were 17.5 and 23.7 h.The results of this study enhance our understanding of TTX food safety and contribute to TTX risk assessment.

[Tetrodotoxin (TTX) Monitoring of Biological Specimens and Toxin Profile in a Food Poisoning Case Caused by the Scavenging Gastropod Nassarius (Alectrion) glans "Kinshibai"].

In November 2015, a patient presented with symptoms of toxicity after eating whole boiled samples of the scavenging gastropod Nassarius (Alectrion) glans "Kinshibai" in Nagasaki. This food poisoning case was the third recorded in Japan. The case was investigated by evaluation of the toxin profile of the gastropod, and monitoring of tetrodotoxin (TTX) levels in serum and urine sampled from the affected individual. One gastropod contained a harmful dose of TTX (2.5 mg/ individual in food residue sample 2). In biological samples, maximum TTX concentrations were 42.8 ng/mL in serum on the day after onset of symptoms. TTX urinary excretion was calculated to be 2.4 mg. From the measured TTX concentrations, it was estimated that a lethal dose had been ingested in this case. Moreover, it was found by LC-QqQ-MS/MS analysis and mouse bioassay that the toxicity of "Kinshibai" was not solely due to TTX. The remaining toxicity was thought to be due to 11-oxoTTX. As in previous poisoning cases, it was concluded that ingestion of this gastropod poses a high risk of food poisoning.