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The occurrence and distribution of alkylphenols (APs, i.e., 4-tert-octylphenol (4-t-OP) and 4-nonlyphenol isomers (4-NP)) in oysters (Crassostrea gigas), snails (Thais clavigera), coastal water and coastal sediments of the western coast of southern Taiwan are investigated. Alkylphenols were present in all matrices of interest: in water, ranging from 61 to 370 ng/l, in sediments, ranging from 27 to 190 ng/g, and in biota samples (i.e., oyster and snail), ranging from 20 to 5190 ng/g. Statistical analysis indicated that the probability distribution of most determined concentrations in oyster and snail samples was log-normal distribution. The bioaccumulation of APs resulted in a seasonal variation with respect to their compositions and concentrations in oyster and snail samples. For oysters, concentrations of APs in winter exceeded those in summer. In contrast, those in snails in summer exceeded those in winter. Estimated biomagnification factors of APs from snails to oysters ranged from 1.4 to 4.3 in summer, and 0.5 to 0.8 in winter on the dry weight basis. The results suggested that seasonally mediated physiological changes, such as dilution caused by growth, biotransformation and metabolism, may affect the bioaccumulation of APs in according to season and organism.

The toxins in the new gastropods Oliva miniacea, O. mustelina and O. nirasei implicated in a food paralytic poisoning incident in South Taiwan in February 2002 were studied. It was found that the three species of gastropods contained moderate amounts of toxin in edible portion only, and the highest toxicity score was 18 MU/g for O. miniacea, 10 MU/g for O. mustelina, and 27 MU/g for O. nirasei. The toxin was partially purified from the toxic specimens of each species by ultrafiltration using a YM-1 membrane, followed by chromatography on Bio-Gel P-2 column. Analyses by HPLC, GC-MS and LC-MS showed that the toxin from O. miniacea, O. nirasei and O. mustelina contained TTX, and related compounds 4-epi TTX and anhydro-TTX. The paralytic shellfish poisons were not found.

The toxin in the gastropods (snails) Zeuxis sufflatus and Niotha clathrata implicated in a food poisoning incident in northern Taiwan in April 2001 was studied. The symptoms exhibited by four victims were general paresthesia, paralysis of the phalanges and the extremities, paralysis, coma, vomiting, and aphasia. The remaining gastropods were assayed for toxicity in the form of tetrodotoxin (TTX). The ranges of specimen toxicity were 345 to 1,640 mouse units (MU) for Z sufflatus and 190 to 643 MU for N. clathrata. The toxicities of the digestive gland and for other parts of the gastropod were 1,120 +/- 477 MU and 497 +/- 238 MU, respectively, for Z sufflatus and 683 +/- 113 MU and 289 +/- 169 MU, respectively, for N. clathrata. The toxin from the methanolic extract of the gastropods was partially purified by ultrafiltration and Bio-Gel P-2 column chromatography. Cellulose acetate membrane electrophoresis, thin-layer chromatography, high-performance liquid chromatography, and gas chromatography-mass spectrometry analyses demonstrated that the toxin consisted of TTX. It was concluded that the causative agent of the food poisoning in question was TTX.