Progress in Fishery Sciences (Aug 2024)
Pollution Characteristics and Risk Assessment of Paralytic Shellfish Toxins in Shellfish from Hebei coastal Waters
Abstract
Paralytic shellfish toxins (PSTs) are a class of acute neurotoxins with nearly 60 congeners. Shellfish that filter feed on toxin-producing algae exhibit PST accumulation in tissues, and the consumption of toxic shellfish poses a major threat to human health. China has the largest aquaculture industry in the world, with shellfish production of approximately 15.89 million tons in 2022 and many shellfish consumers. The PST poisoning incidents in China exhibit the characteristics of a wide distribution area, recurring regional risk, diverse toxin sources, and seasonal differences. PST consumption causes acute symptoms of poisoning and even death in many people, with a high lethality rate. This is a serious threat to the health of consumers and detrimental to the social stability of the region. In northern China, Hebei Province has rich fisheries resources, with a mariculture output of approximately 580, 000 tons in 2022. In recent years, PSTs have been detected several times in bivalve shellfish inshore in Hebei Province, especially along the coast of Qinhuangdao. A serious shellfish poisoning episode was reported in Qinhuangdao in 2016, with PST concentrations exceeding the safety limit of 800 μgSTX equivalents/kg (μg STXeq/kg) by a factor of 65. The main algal species responsible for the poisoning was Alexandrium catenella. However, the current investigations of PST pollution in Hebei Province mainly focus on the shellfish species Mytilus galloprovincialis and Argopecten irradians in the sea area of Shanhaiguan, Qinhuangdao, and investigations on other coastal cities of Hebei Province and a wide range of different shellfish species are lacking. Moreover, few risk assessment studies have been conducted.A continuous PST survey was conducted in 2022 on six species of shellfish, namely M. galloprovincialis, Scapharca subcrenata, A. irradians, Scapharca broughtonii, Ruditapes philippinarum, and Crassostrea gigas, collected by netting in Tangshan and Qinhuangdao, and the residual status of PSTs was assessed for acute exposure using liquid chromatography-tandem mass spectrometry. The results showed that PSTs were detected in shellfish samples collected from March to June, with a detection rate of 100%. However, no values exceeded the European Union limit. Among the shellfish samples collected from March to June, those assessed in April had the highest average concentration, followed by those in May, March, and June, which had the lowest average concentration. The main components detected in shellfish samples from March to June were gonyautoxins (GTX) 1–4; the highest concentrations were detected in April. Highly toxic saxitoxin (STX) and decarbamoylneosaxitoxin (dcNEO) were detected from April to June and not in March. Decarbamoylgonyautoxin (dcGTX) 2 was not detected in March or April; however, it was detected in May and June. The sea area near Qinhuangdao was more polluted than that near Tangshan. Among the collected shellfish samples, significant differences were observed in the average concentration of PSTs in shellfish samples of different species, and the concentration ranged from highest to lowest in species as follows: M. galloprovincialis > S. subcrenata > A. irradians > S. broughtonii > R. philippinarum > C. gigas. Large differences were observed between the six shellfish species regarding the accumulation of 11 PST components, among which GTX1–4 and carbamatetoxin (C) 1 and 2 were the most commonly detected components. The highest concentrations of GTX1 and 4 were observed in M. galloprovincialis, the highest concentrations of GTX2 and 3 were observed in S. subcrenata, and the highest concentrations of C1 and 2 were observed in A. irradians. A low detection rate was recorded for highly toxic STX and neosaxitoxin (NEO in samples, except in M. galloprovincialis and S. subcrenata, in which all 11 PSTs were detected. In the other four shellfish species, only certain of the components were detected. Statistical analysis of the highest levels of PSTs in nearshore shellfish in Hebei Province in recent years showed a decreasing trend. Acute exposure assessments using the maximum value of PSTs showed that none of the six shellfish species exceeded the acute reference dose values recommended by the Food and Agriculture Organization of the United Nations/World Health Organization and European Food Safety Authority, suggesting that toxin levels were safe and acceptable. M. galloprovincialis had the highest dietary exposure risk, as a few residues were present, and symptoms of PST poisoning, such as dizziness and nausea, may occur after ingesting large quantities of M. galloprovincialis. Increased attention should be paid to shellfish with high dietary exposure assessment values, such as M. galloprovincialis and S. subcrenata.In this study, we investigated PSTs in shellfish from Hebei coastal waters and observed that PSTs were detected in shellfish samples from March to June, with the highest average concentration in April, followed by May and March, with the lowest average concentration in June. In addition, the main components detected in shellfish samples were GTX1–4. The analysis of different shellfish species showed that M. galloprovincialis had the highest average PST concentration, followed by S. subcrenata, A. irradians, S. broughtonii, R. philippinarum, and C. gigas; GTX1–4 and C1 and 2 were detected in all six shellfish species. Dietary exposure assessment for consumers in Hebei Province showed that the toxin levels were safe and acceptable. However, follow-up surveys and studies are necessary due to the paucity of surveys for different cities and species on the coast of Hebei.
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