The Analysis Of Paralytic Shellfish Poison Of Bivalves In Seafood Market And Sub-acute Toxic Evaluation

Objective: Through the investigations of the paralytic shellfish poisoning (PSP) of seven kinds of bivalves from Huangsha seafood market of Guangzhou in a year, and the sub-acute toxic evaluation of PSP in low level on rats, It's expected to gain more information on toxicity of PSP and provide a base for the safe standard and detection systems of PSP.Methods: In the investigations of PSP, the concentration and profiles of PSP toxins in bivalves were determined by mouse bioassay of AOAC and high-performance liquid chromatography (HPLC). The risk assessment of PSP in bivalves was conducted with the standard of FAO and Chinese Administration Organization of Fish Culture and Seaport(80ug STX/100g or 4MU/g mussels). The sub-acute toxicity of PSP was evaluated in rat. PSP was extracted from the seafood in market, and the toxicity of the extract was determined by mouse bioassay. A total of 50 rats were divided into 5 groups: three PSP-treated groups were fed with the extracts in 18.4 ug STX /kg/d (high), 9.2ug STX/ kg/d (middle), 4.6ug STX /kg/d (low), respectively, according to the LDso (184.1 ug STX /kg) of PSP. Two controls were set, one group was fed with no toxic HC1 extracts of bivalves and the other with nature water. The extracts in different toxicity were administrated to rats through gastrotube once a day for 35 days. At the 28th and 29th day of experiment, changes in ability of learning and memory of rats were investigated by step-down test and that in motor activity were observed through exhaustive swimming test from the 31st to the 34th day of experiment. The physiological, biochemical, immunological and pathological changes in rat were observed after 24 h withdrawl term.Results: The level of PSP was lower than the safe standard (4MU/g meat) in all of the 84 samples detected, one of which had the highest toxicity with 1.84 MU/g muscle. There was 9 samples' gland in 2 species that be detected to have PSP in the bivalves. The concentration of PSP in one sample's gland exceeded the threshold of FAO (4MU/g) with 14.52MU/g meat, and the profiles of PSP in the gland were B1 GTX2/3 GTX1/4 and C according to HPLC. No biochemical and pathological changes in tissues occurred for the control and low-dose group (4.6 ug STX/ kg), whereas some changes happened for the middle (9.2 ug STX/ kg) and high groups (18.4 ug STX/ kg). These changes included: (1)an increase in K+ ion and a decrease in Cl- ion in blood; (2)decreses in the numble of non specific-defensive cell and thecontent of MCH and MCHC; (3) abnormity in some of functional indexes of liver, especially in ALT; (D an increase in LDH (functional indexes of heart); ?alteration in some of renal functional indexes in the middle dose; ?higher positive rate of leukocyte and urinary protein; ?pathological changes at various degree in liver, kidney and muscles, such as inflammation, vacuolation and fragmentation of fiber; ?lower motor activity and ability in learning and memory; ?a decrease in activity of Na\ K+-ATPase in rats heart Conclusion:1, The concentration and detection rate of PSP of bivalves in seafood market in Guangzhou were low as a whole, all the seafood polluted with PSP are in the threshold of standard.2, PSP did damage to the function of kidney and ability in learning and memory in rats fed PSP with 9.2 ug STX/ kg /d, as well as led extensive injuries to rat with 18.4 ug STX /kg/d, such as disturbance in electroltyte in blood, a decrease in non specific-defensive ability, decline in oxygen carrying capacity of RBC and abnormity in function of liver, kidney, and heart, etc.3, According to the safe standard and the intake of seafood, it's possible for people to take some PSP corresponded to the rat in middle-dose group through seafood. In the long run, it may be unsafe for people to eat seafood polluted by PSP at this level.In a word, the toxicity of PSP had an accumulative effect and it was unsafe for people to eat frequently bivalve seafood polluted by PSP toxins. As a consequence, it's necessary to further evaluate and perfect safe standard systems of seafood.