Shellfish aquaculture has become an increasingly important factor in Bulgarian economy in the recent years. Marine biotoxins, produced by some phytoplankton species, may accumulate in mussels and present an important challenge in commercialization of shellfish. The aim of this study was to determine the occurrence and variability of hydrophilic toxinsparalytic shellfish poisoning (PSP) and amnesic shellfish poisoning (ASP) as well as lipophilic toxinsincluding diarrheic shellfish poisoning (DSP), pectenotoxins (PTXs) and yessotoxins (YTXs) in plankton, wild and farmed mussel samples from the Southern Black Sea coast, an important shellfish farming area in spring 2017. PSP toxins were determined by HPLC with postchromatographic oxidation and fluorescence detection and domoic acid and lipophilic toxins by liquid chromatograph coupled to tandem mass spectrometry. DA and pectenotoxin-2 were detected in plankton, wild and farmed mussel samples. Yessotoxins were detected only in cultivated mussels and no PSP toxins were detected. The occurrence of phycotoxins differed over both space and time. Toxin profile includes prevalent domoic acid, scarce presence of pectenotoxin-2 and yessotoxins in the samples.
Mussels accumulate marine biotoxins (phycotoxins) produced by certain phytoplankton species. In EU are set limits for toxin concentration (e.g. domoic acid, okadaic acid, yessotoxins etc.) beyond that mussels are safe for consumption. Marine biotoxins tend to accumulate in the digestive gland (hepatopancreas) of the mussel. Consequently, this tissue is preferred for toxin concentration determination. Normally the whole shellfish is consumed and therefore the occurrence data for phycotoxins need to be expressed in terms of whole shellfish meat. A theoretical factor of 5 is used to convert the value to whole shellfish meat. The aim of this study was to determine an empirical factor in order to convert phycotoxin concentrations from hepatopancreas to whole shellfish meat of main marine aquaculture in Bulgaria- mussels Mytilus galloprovincialis. Wild and cultivated mussels were collected from the north Black Sea coast of Bulgaria in 2017. In total 13 mussel samples were studied whereas in each sample subsamples of hepatopancreas only and whole mussel meat are prepared. Phycotoxins were extracted for all types of phycotoxins by means of liquid-liquid extraction and their concentration was determined via LC/MS. Yessotoxins appeared in most of the samples and therefore seemed most suitable for empirical conversion factor determination. It is calculated as ratio between determined concentration in hepatopancreas and whole shellfish meat. Mean defined value was 5.36. Determination and application of empirical conversion factor is important when establishing very low concentration for chronic exposure assessment. It will be advantageous when taking into account interspecies differences and to avoid phycotoxin omission if preparing whole shellfish sample.
INTRODUCTION: Marine biotoxins can be accumulated in shellfish and in turn can lead to severe illness or chronical consequences in human shellfish consumers. AIM: The aim of this study was to assess the levels of hydrophilic marine biotoxins in both farmed and wild mussels from the Bulgarian coast sampled in 2017 and to estimate the exposure (acute and chronic) of Bulgarian consumers to detected toxins if investigated mussels were consumed. To the group of hydrophilic marine toxins belong amnesic toxins (domoic acid, isodomoic acid) and paralytic toxins (neosaxitoxin, gonyautoxins and their decarbamoyl and N-sulfocambamoyl analogs). MATERIALS AND METHODS: The hydrophilic toxin-domoic acid (DA) was determined by liquid chromatography tandem mass spectrometry (LC-MS/MS). Paralytic toxins (saxitoxin (STX), neosaxitoxin (NEO), gonyautoxin-1 (GTX1), gonyautoxin-2 (GTX2), gonyautoxin-3 (GTX3), gonyautoxin-4 (GTX4), gonyautoxin-5 (B1), decarbamoyl gonyautoxin-2 (dcGTX2), decarbamoyl gonyautoxin-3 (dcGTX3), decarbamoyl saxitoxin (dcSTX), N-sulfocarbamoyl gonyautoxin-1 (C1), N-sulfocarbamoyl gonyautoxin-2 (C2)) were investigated via high performance liquid chromatography with fluorescence detection (HPLC-FD). RESULTS: Among all hydrophilic toxins investigated DA and GTX2 were detected in the studied samples. Mean domoic acid in whole mussel meat was estimated to be 0.139 mg/kg mm which is below the regulatory limit of 20 mg/kg mm. Mean GTX2 level in whole mussel meat was calculated to be 0.151 μg saxitoxin dihydrochloride equivalent (STX.2HCl eq)/kg which is far beneath the legislative limit of 800 μg STX.2HCl eq/kg mm. Estimation of acute exposure for both detected toxins-DA and GTX2, and of chronic exposure to domoic acid showed similar results among male and female, as well as among wild and cultivated mussel consumers. CONCLUSION: This study showed an overall low contamination level of wild and farmed mussels with hydrophilic marine biotoxins compared to the regulatory limits. This leads to the conclusion that there is low acute and chronic exposure via consumption of contaminated mussels.
Anthropogenic pollution of marine ecosystems is one of the main sources of polycyclic aromatic hydrocarbons (PAHs). Marine bivalves are often used as bioindicators of environmental pollution due to their wide distribution and capability of xenobiotic bioaccumulation. The aim of the present study was to assess the presence of PAHs in soft tissues of wedge clams Donax trunculus (Linnaeus, 1758), collected from sublittoral sandy habitats at different locations off the Bulgarian Black Sea coast. Wedge clams from the different locations showed variations in the content of accumulated PAHs’ compounds. The concentrations of PAHs were measured by gas chromatography system with mass spectrometry detection. The total PAHs content (sum of 13 PAHs’ compounds) measured was in the range from 5.59 to 50.50 ng/g wet weight and was comparable with other European studies. The compounds phenanthrene and fluorene were most abundant in all analyzed samples. The results showed that low molecular weight (LMW) PAHs (2 and 3 aromatic rings) were predominant, accounting for 91% of the total PAHs levels, while high molecular weight (HMW) PAHs (4–5- and 6- rings) presence was 8.9% on average. The ratio LMW/HMWPAHs was higher than one, suggesting predominant pollution of petrogenic origin. The concentrations of benzo (a)pyrene did not exceed the limit set in EC Regulation although it was detected in 20% of the analyzed samples. In conclusion, maximum overall PAHs content was found in clams from Arkutino, while minimum PAHs content was present in samples from Elenite. The Sum PAH4 (sum of four polycyclic aromatic hydrocarbons: benzo[a]pyrene, chrisene, benzo[a]anthracene, and benzo[b]fluoranthene) in the wedge clams for all localities studied was below legislation limits. Data from the present research can be used for assessing pollution levels in the marine environment and also risk of human exposure to PAHs using D. trunculus as bioindicator species.
Polychlorinated biphenyls (PCBs) can still be a problem for the aquatic environment. Fish species are a suitable indicator for the environmental pollution monitoring because they concentrate pollutants in their tissues directly from water. Concentrations of PCBs were measured in marine fish, collected from Bulgarian Black Sea coast in order to monitor the dynamics of these pollutants in 2007, 2010 and 2015. The fish species: goby (Neogobius melanostomus), sprat (Sprattus sprattus sulinus), horse mackerel (Trachurus Mediterraneus ponticus) and grey mullet (Mugil cephalus) were chosen because of their characteristic feeding behavior. The PCBs were determined by gas chromatography system with mass spectrometry detection. The Total PCBs ranged from 93.8 to 513.3 ng/g lipid weight (in grey mullet and goby, respectively). Levels of PCBs in goby and grey mullet decreased in 2010 and 2015. In order to assess the safety of fish as food were calculated TEQ. They are determined by the results of dioxin - like (dl) PCBs. TEQs were calculated from 0.01 to 0.04 pg TEQ/g ww and did not exceed the EC limit of 3 pg TEQ/g ww. The levels of PCBs in fish from Bulgarian Black Sea were comparable to those found in neighboring seas.
Détermination théorique de l'exposition aux toxines des mollusques dans des groupes différents de la population en BulgarieIntroduction. L'intoxication par des mollusques peut être causée de l'ingestion des mollusques contaminés par des bactéries, virus, métaux lourds, pesticides, biotoxines marines, etc. L'objectif de l'étude était de déterminer l'exposition théorique des hommes aux toxines des mollusques et des crustacés par les consommateurs bulgares. L'incidence des cas enregistrés d'intoxications dues à l'ingestion de biotoxines marines -«L'effet toxique: autres intoxications aux poissons et crustacés (T61.2)» a été étudiée. Matériaux et méthodes. L'exposition aiguë (AE), chronique (CE) et le quotient de risque (HQ) sont calculés à la base des niveaux déterminés expérimentalement de toxines des mollusques dans les moules ABSTRACT Introduction. Shellfish poisoning could be caused by ingestion of shellfish contaminated by bacteria, viruses, heavy metals, pesticides, marine biotoxins etc. The objective of the study was to determine the theoretical human exposure to shellfish toxins of Bulgarian consumers. The incidence of registered cases of intoxications due to marine biotoxins ingestion -"Toxic effect: Other fish and shellfish poisoning (T61.2)" in regional hospitals was investigated. Materials and methods. Acute exposure (AE), chronic exposure (CE) and hazard quotient (HQ) are calculated based on experimentally-determined levels of shellfish toxins in mussels harvested from North Bulgarian coast in the period 2012 -2018. We performed a retrospective analysis of the frequency of the diagnosis T61.2, based on medical documentation for the period 1.05.2012 -7.12.2018 in hospitals in Varna and Dobrich, Bulgaria. Results. Shellfish toxins that most often occur in mussels are domoic acid (DA), yessotoxin (YTX) and pectenotoxin-2 (PTX2). The calculated maximum
The presence of phytoplankton responsible for the production of marine biotoxins (phycotoxins) is well recognized globally. Phycotoxins accumulate in filter feeding bivalves and through the food chain find their way to humans. In certain quantities they can cause severe illness. According to the symptoms they cause marine biotoxins are classified as paralytic (e.g. saxitoxin), amnesic (e.g. domoic acid), which are hydrophilic and diarrheic (e.g. okadaic acid) toxins etc. which have lipophilic nature. The aim of this study was to assess the presence of lipophilic toxins in both cultivated and wild mussel (Mytilus galloprovincialis) samples, harvested in summer 2017 from the south coast of the Black Sea, Bulgaria. Determination was performed by liquid chromatography coupled to tandem mass spectrometry. Despite of the recent evidence for the presence of a variety of potentially toxigenic producers in the investigated area, only yessotoxins were found in the studied samples. Mean levels of YTX in cultivated mussels were determined as 5832.86 pg YTX/g hepatopancreas (hp) and as 920.42 pg YTX/g hp in wild mussels. In both cases, YTX levels did not exceed the legislative limit of 3.75 mg/kg shellfish meat. These results indicated that the risk through consumption of studied shellfish is low.
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