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PubMed1989

Kynurenic acid protects against neurotoxicity and lethality of toxic extracts from contaminated Atlantic coast mussels.

1. An aqueous acidic extract from poisonous Atlantic coast mussels was injected i.p. into groups of Swiss-Webster mice at the LD84 value (= 40 ml of extract/kg). Body-scratching, clonic convulsions and death were consistently observed in response to XTRT injection. These results are consistent with the presumed presence of the neuroexcitant amino acid, domoic acid, in the contaminated mussels. 2. Kynurenic acid at 300 and 600 mg/kg i.p. protected powerfully and significantly against extract-induced neurotoxicity. Greatest protection was observed when the antidote was administered between 30 and 90 min after injection of the toxic extract.

Animals↗
PubMed2004

Mercury and lead during breast-feeding.

Hg and Pb are of public health concern due to their toxic effects on vulnerable fetuses, persistence in pregnant and breast-feeding mothers, and widespread occurrence in the environment. To diminish maternal and infant exposure to Hg and Pb, it is necessary to establish guidelines based on an understanding of the environmental occurrence of these metals and the manner in which they reach the developing human organism. In the present review, environmental exposure, acquisition and storage of these metals via maternal-infant interaction are systematically presented. Though Hg and Pb are dispersed throughout the environment, the risk of exposure to infants is primarily influenced by maternal dietary habits, metal speciation and interaction with nutritional status. Hg and Pb possess similar adverse effects on the central nervous system, but they have environmental and metabolic differences that modulate their toxicity and neurobehavioural outcome in infant exposure during fetal development. Hg is mainly found in protein matrices of animal flesh (especially fish and shellfish), whereas Pb is mainly found in osseous structures. The potential of maternal acquisition is higher and lasts longer for Pb than for Hg. Pb stored in bone has a longer half-life than monomethyl-mercury acquired from fish. Both metals appear in breast milk as a fraction of the levels found in maternal blood supplied to the fetus during gestation. Habitual diets consumed by lactating mothers pose no health hazard to breast-fed infants. Instead, cows' milk-based formulas pose a greater risk of infant exposure to neurotoxic substances.

Breast Feeding↗
PubMed2003

[A food poisoning outbreak caused by purple Washington clam contaminated with norovirus (Norwalk-like virus) and hepatitis A virus].

A party of 57 people dined together in a restaurant in Hamamatsu City on December 11, 2001. The next day, 22 of them developed symptoms of acute gastroenteritis, such as diarrhea, vomiting, and fever. Examination of 4 fecal specimens from these patients by ELISA for Norovirus (Norwalk-like virus, NV) detected both genogroup I (GI) and genogroup II (GII) NV in all the 4 specimens. In addition, RT-PCR and real-time PCR methods for NV detected the NV gene. Approximately one month after the outbreak of the food poisoning (acute gastroenteritis) by NV, 4 individuals in the same party developed type A hepatitis. Both RT-PCR and real-time PCR methods for hepatitis A virus (HAV) detected the HAV gene in their fecal specimens. The party of these patients ate purple Washington clam (Saxidomus purpuratus, imported from China) steamed with red pepper. Since this food appeared to have caused the viral infections, the one with the same lot number was subjected to viral examinations, which successfully detected the NV GI, NV GII, and HAV genes. These results led to the conclusion that the clam contaminated with NV and HAV had caused the food poisoning. The DNA sequences of the NV detected in the patients and the clam had 74 to 99% homology, indicating strains of various genotypes. All the strains of HAV that were derived from the patients and the clam were genotype 1A, and these sequences had over 95% homology, but were not completely identical. This outbreak led to the demonstration of imported fishery products as a cause of type A hepatitis, and indicated the need for guiding and enlightening people on the importance of adequate cooking of bivalves.

Animals↗
PubMedDate not supplied

[Clinical comments on poisoning caused by marine animals in the Marquesas].

Intoxications due to sea animals in the Marquesas seem to be relatively frequent in this archipelago. Fish consumption under rarely realized favorable conditions does not induce intoxications. Although statistics are hazardous in Polynesia, the phenomena seem to progress from East to West, and to be cyclic, with a regression phase at the end of 1973. Two complementary syndromes have been isolated: -- one is primary, neuro-sensory, and is prevalent in the case of toxic crustaceans, molluscs or echinoderms consumption. Hemorragic signs are sometimes observed in the case of consumption of fish provoking an unusual toxi-infection. The specificity of the toxic species has not been demonstrated. -- the other one is secondary and presents the characteristics of transistory myalgiae and the strange neuropathic picture of "la Contamine" of Ua-Pou.

Crustacea↗
PubMed2005

Vibrio parahaemolyticus, Vibrio vulnificus and microorganisms of fecal origin in mussels (Mytilus galloprovincialis) sold in the Puglia region (Italy).

Mytilus galloprovincialis is one of the most commonly consumed of all bivalve molluscs. The consumption of raw bivalve molluscs has caused outbreaks of food poisoning due to Vibrio parahaemolyticus and Vibrio vulnificus. This paper reports the results of a survey on the presence of V. parahaemolyticus, V. vulnificus fecal coliform bacteria, Escherichia coli and Salmonella spp. in 600 M. galloprovincialis samples collected from retail outlets in the Puglia region. V. parahaemolyticus and V. vulnificus were found in 47 (7.83%) and 17 (2.83%) of the samples, respectively. One sample (0.16%) was contaminated with Salmonella spp. but no relationship was observed between vibrios and fecal coliforms and E. coli. There were no significant differences among vibrios present in bivalve molluscs during the 3-year survey.

Animals↗
PubMed1989

The toxin tetramine from the "edible" whelk Neptunea antiqua.

The chemical nature of extracts of the marine gastropod Neptunea antiqua collected in the North Sea has been investigated. Amino acid analysis and spectroscopical studies (FAB MS, 1H NMR, 13C NMR and IR) on fractions purified by Biogel P-2 and Amberlite IR 120 column chromatography allowed the identification of 19 components. It was established that the water-soluble toxin responsible for poisonings, following ingestion of this snail, is tetramine (the tetramethylammonium ion present as an unknown salt). Contrary to what occurs in other Neptunea species (N. arthritica and N. intersculpta), tetramine was found not only in the salivary gland, but also in the remaining part of the animal, albeit in smaller concentration. In the isolated guinea-pig ileum assay, synergistic effects with other main components present (betaine, homarine) could not be demonstrated. Choline esters, believed to act synergistically in other Neptunea species, were not detected in Neptunea antiqua.

Animals↗
PubMed2005

First report of saxitoxin in Finnish lakes and possible associated effects on human health.

This study is the first report of saxitoxin in cyanobacterial blooms in Finland. Bloom samples (n = 50) were collected from Finnish freshwater sites during summer months of 2002 and 2003. These samples were screened for the presence of paralytic shellfish toxins (PSTs) using the Jellett rapid PSP screening test. Samples testing positive for PSTs (n = 7) were further analyzed with saxiphilin- and voltage-gated sodium channel [(3)H]-STX-binding radioreceptor assays and liquid chromatography using fluorescence and mass spectrometric analysis. The results indicated that saxitoxin (STX) was the only PST analogue in the samples and that it was present in high concentrations, as much as 1 mg L(-1). Microscopic analysis revealed that 95%-100% of the phytoplankton in the positive samples consisted of Anabaena lemmermannii. The trophic status of lakes in which STX-containing blooms were found varied from oligotrophic to hypertrophic. All the lakes had high nitrogen-to-phosphorus ratios. In some instances, samples had been collected from sites where swimmers had reported adverse health effects, and in three such cases, reported adverse health effects were associated with sites from which samples testing positive for STX had been received. Symptoms of fever, eye irritation, abdominal pains, and skin rash were reported in children aged 2-10 years after exposure to the water. These were not the adverse human symptoms typical of STX poisoning; rather, they represented acute effects often reported following recreational exposure to cyanobacterial blooms.

Abdominal Pain↗
PubMed1996

Probabilistic assessment of health risks of methylmercury from burning coal.

This paper describes a probabilistic assessment of neurological risks incurred from consuming fish containing methylmercury (MeHg), focusing on the incremental effects of Hg deposited from local coal combustion. A Monte Carlo model is used to simulate a "worst case" scenario in which a population of 5000 fish eaters in the upper midwestern United States derive the freshwater fish portion of their diet from local waters near a hypothetical large coal-fired power plant. This population is characterized by distributions of body mass, half-life of MeHg, and the ratios of blood to body burden and hair to blood MeHg. Each person's diet consists of varying amounts of tuna fish, freshwater sportfish, and marine fish and shellfish, the MeHg contents of which are characterized by national distribution statistics, as are the consumption rates for marine fish. The consumption rates for freshwater fish are specific to the region. The fish portion size is linked to body mass by a variable correlation. Each meal is assumed to be an independent sample; thus, as metabolic equilibrium is approached, each person's body burden of MeHg tends to approach the value corresponding to the mean MeHg intake for the population. Predictions of MeHg levels in hair by this model compared well with an observed distribution of 1437 women. Two neurological endpoints were examined: adult paresthesia, as related to MeHg body burden, and congenital neurological effects, as associated with average concentrations of MeHg in maternal hair during pregnancy. Two exposure scenarios are considered: a "baseline" in which the source of the mercury in fish is from background atmospheric deposition, and an "impact" scenario, in which local Hg deposition and concentrations in fish are roughly doubled to represent additional deposition from the hypothetical nearby power plant. For both scenarios, the 99th percentile of MeHg body burden was more than an order of magnitude below the lowest level at which increased transient adult paresthesia was experienced in an acute MeHg poisoning incident in Iraq. We thus conclude that neurological risks to adults from MeHg resulting from atmospheric Hg deposition are trivial. Based on three epidemiological studies of congenital neurological risks, we find that fetal effects appear to be more critical and that there is a smaller margin of safety for pregnant consumers of freshwater sportfish. However, the margin of safety is still considerable and may have been diminished by uncertainties in the relationships between maternal hair Hg and the actual fetal exposures.

Adult↗
PubMed2000

Determination of a site-specific reference dose for methylmercury for fish-eating populations.

Environmental risk-management decisions in the U.S. involving potential exposures to methylmercury currently use a reference dose (RfD) developed by the U.S. Environmental Protection Agency (USEPA). This RfD is based on retrospective studies of an acute poisoning incident in Iraq in which grain contaminated with a methylmercury fungicide was inadvertently used in the baking of bread. The exposures, which were relatively high but lasted only a few months, were associated with neurological effects in both adults (primarily paresthesia) and infants (late walking, late talking, etc.). It is generally believed that the developing fetus represents a particularly sensitive subpopulation for the neurological effects of methylmercury. The USEPA derived an RfD of 0.1 microg/kg/day based on benchmark dose (BMD) modeling of the combined neurological endpoints reported for children exposed in utero. This RfD included an uncertainty factor of 10 to consider human pharmacokinetic variability and database limitations (lack of data on multigeneration effects or possible long-term sequelae of perinatal exposure). Alcoa signed an Administrative Order of Consent for the conduct of a remedial investigation/feasibility study (RI/FS) at their Point Comfort Operations and the adjacent Lavaca Bay in Texas to address the effects of historical discharges of mercury-containing wastewater. In cooperation with the Texas Natural Resource Conservation Commission and USEPA Region VI, Alcoa conducted a baseline risk assessment to assess potential risk to human health and the environment. As a part of this assessment. Alcoa pursued the development of a site-specific RfD for methylmercury to specifically address the potential human health effects associated with the ingestion of contaminated finfish and shellfish from Lavaca Bay. Application of the published USEPA RfD to this site is problematic; while the study underlying the RfD represented acute exposure to relatively high concentrations of methylmercury, the exposures of concern for the Point Comfort site are from the chronic consumption of relatively low concentrations of methylmercury in fish. Since the publication of the USEPA RfD, several analyses of chronic exposure to methylmercury in fish-eating populations have been reported. The purpose of the analysis reported here was to evaluate the possibility of deriving an RfD for methylmercury, specifically for the case of fish ingestion, on the basis of these new studies. In order to better support the risk-management decisions associated with developing a remediation approach for the site in question, the analysis was designed to provide information on the distribution of acceptable ingestion rates across a population, which could reasonably be expected to be consistent with the results of the epidemiological studies of other fish-eating populations. Based on a review of the available literature on the effects of methylmercury, a study conducted with a population in the Seychelles Islands was selected as the critical study for this analysis. The exposures to methylmercury in this population result from chronic, multigenerational ingestion of contaminated fish. This prospective study was carefully conducted and analyzed, included a large cohort of mother-infant pairs, and was relatively free of confounding factors. The results of this study are essentially negative, and a no-observed-adverse-effect level (NOAEL) derived from the estimated exposures has recently been used by the Agency for Toxic Substances and Disease Registry (ATSDR) as the basis for a chronic oral minimal risk level (MRL) for methylmercury. In spite of the fact that no statistically significant effects were observed in this study, the data as reported are suitable for dose-response analysis using the BMD method. Evaluation of the BMD method used in this analysis, as well as in the current USEPA RfD, has demonstrated that the resulting 95% lower bound on the 10% benchmark dose (BMDL) represents a conservative estimate of the traditional NOAEL, and that it is superior to the use of "average" or "grouped" exposure estimates when dose-response information is available, as is the case for the Seychelles study. A more recent study in the Faroe Islands, which did report statistically significant associations between methylmercury exposure and neurological effects, could not be used for dose-response modeling due to inadequate reporting of the data and confounding from co-exposure to polychlorinated biphenyls (PCBs). BMD modeling over the wide range of neurological endpoints reported in the Seychelles study yielded a lowest BMDL for methylmercury in maternal hair of 21 ppm. This BMDL was then converted to an expected distribution of daily ingestion rates across a population using Monte Carlo analysis with a physiologically based pharmacokinetic (PBPK) model to evaluate the impact of interindividual variability. The resulting distribution of ingestion rates at the BMDL had a geometric mean of 1.60 microg/kg/day with a geometric standard deviation of 1.33; the 1st, 5th, and 10th percentiles of the distribution were 0.86, 1.04, and 1.15 microg/kg/day. In place of the use of an uncertainty factor of 3 for pharmacokinetic variability, as is done in the current RfD, one of these lower percentiles of the daily ingestion rate distribution provides a scientifically based, conservative basis for taking into consideration the impact of pharmacokinetic variability across the population. On the other hand, it was felt that an uncertainty factor of 3 for database limitations should be used in the current analysis. Although there can be high confidence in the benchmark-estimated NOAEL of 21 ppm in the Seychelles study, some results in the New Zealand and Faroe Islands studies could be construed to suggest the possibility of effects at maternal hair concentrations below 10 ppm. In addition, while concerns regarding the possibility of chronic sequelae are not supported by the available data, neither can they be absolutely ruled out. The use of an uncertainty factor of 3 is equivalent to using a NOAEL of 7 ppm in maternal hair, which provides additional protection against the possibility that effects could occur at lower concentrations in some populations. Based on the analysis described above, the distribution of acceptable daily ingestion rates (RfDs) recommended to serve as the basis for site-specific risk-management decisions at Alcoa's Point Comfort Operations ranges from approximately 0.3 to 1.1 microg/kg/day, with a population median (50th percentile) of 0.5 microg/kg/day. By analogy with USEPA guidelines for the use of percentiles in applications of distributions in exposure assessments, the 10th percentile provides a reasonably conservative measure. On this basis, a site-specific RfD of 0.4 microg/kg/day is recommended.

Adult↗
PubMed2004

Blood mercury levels in young children and childbearing-aged women--United States, 1999-2002.

Exposure to high levels of mercury (Hg) can cause neurologic and kidney disorders. Because methylated Hg (methyl-Hg) in the aquatic environment accumulates in animal tissues up the food chain, persons in the United States can be exposed by eating freshwater fish, seafood, and shellfish. Exposure of childbearing-aged women is of particular concern because of the potential adverse neurologic effects of Hg in fetuses. To determine levels of total blood Hg in childbearing-aged women and in children aged 1-5 years in the United States, CDC's National Health and Nutrition Examination Survey (NHANES) began measuring blood Hg levels in these populations in 1999. This report summarizes NHANES results for 1999-2002 and updates previously published information. The findings confirmed that blood Hg levels in young children and women of childbearing age usually are below levels of concern. However, approximately 6% of childbearing-aged women had levels at or above a reference dose, an estimated level assumed to be without appreciable harm (> or =5.8 microg/L). Women who are pregnant or who intend to become pregnant should follow federal and state advisories on consumption of fish.

Adolescent↗
PubMed1982

Pathology of Minamata disease. With special reference to its pathogenesis.

On the basis of pathological studies of the Minamata disease induced by consumption of large amounts of fish and shellfish contaminated with methylmercury, the neuropathological and metal-histochemical changes in the human body were discussed. Methylmercuric compounds accumulated in the seafoods were absorbed by the human body following oral intake, and distributed widely and accumulated in various organs and tissues. The distribution of the pathological lesions could thus include the nervous system, particularly the brain with a characteristics preference. There were apparently two major mechanisms of destruction of the brain cortex. One was the neurotoxic effect of methylmercury on the neurons which was stronger than its cytotoxic effect on the epithelial and parenchymatous cells in general, and the other was a hypoxemic or anoxemic effect on the brain in its intracranial anatomical situation following disturbance of the blood circulation, resulting in edema of the perivascular space, particularly in the water-shed regions of the brain cortex. Such a vascular mechanism probably exerted a greater influence in acute and subacute severe cases, whereas the neurotoxic effect was functionally more active in chronic onset cases.

Atrophy↗
PubMed1998

The present mercury contents of scalp hair and clinical symptoms in inhabitants of the Minamata area.

A total of 191 fishermen and their family (32-82 years) living in some mercury-polluted areas along the Shiranui Sea volunteered for the present study. They made a living by fishery and had formerly eaten the methyl mercury-contaminated fish and shellfish caught there. The questionnaire on subjective symptoms, fish eating habits, and past living history was conducted on the subjects. In addition, they were clinically examined in detail by several neurologists and scalp hair was collected. With six exceptions, all the 185 subjects showed a normal total mercury level in hair (<10 ppm). The ratio of methyl mercury to total mercury was 79-94% on the average for each group examined, suggesting indirect contamination (perhaps through the food chain). Despite their low mercury level in scalp hair, however, the subjects showed various neurological symptoms, particularly, sensory disturbance (such as the glove and stocking type), at a very high rate. Thus, it seems fair to state that, in addition to officially recognized Minamata disease patients, there still exist many people with atypical, slight Minamata disease on the coast of the Shiranui Sea. The current hair mercury level is not necessarily useful as a criterion for diagnosing chronic Minamata disease because of the long lapse of time.

Adult↗
PubMed1999

Esters of okadaic acid and dinophysistoxin-2 in Portuguese bivalves related to human poisonings.

Liquid chromatography (HPLC) was used to search for esters of DSP toxins in Portuguese bivalves. Hexane-soluble derivatives of okadaic acid (OA) and dinophysistoxin-2 (DTX-2) were found. Presumably they are acyl derivatives, globally known as 'dinophysistoxin-3' (DTX-3). In certain instances DTX-3 content surpassed 50% of the total amount of DSP toxins. A human diarrhetic poisoning (DSP) incident with Donax clams (Donax trunculus) harvested at Fuzeta (Algarve coast) was confirmed where the apolar (DTX-3 type) and other esters remaining in the polar aqueous methanol layer were implicated. The percentage of acyl esters of OA was always higher than those of DTX-2. An enzymic mechanism for the conversion of OA and DTX-2 seems to be implicated in some kind of detoxification process because the percentage of esters increases with the toxin amount ingested by the bivalve and there is some degree of selectivity as DTX-2 seems more difficult to acylate. These findings pose a problem for the current assay methods used to detect DSP because mainly they are able to detect the parent toxins but not their esters. The current bioassay method [Le Baut, C., Bardin, B., Bardouil, M., Bohec, M., Masselin, P., Truquet, P., 1990. Etude de la decontamination de moules toxiques. Rapport IFREMER DERO-90-02 MR. 21 pp.] used in Portugal includes a hexane washing step that prevents interference from free fatty acids. However, it cannot detect the presence of acyl derivatives because they are highly soluble in hexane.

Chemistry Techniques, Analytical↗
PubMed2000

[Norwalk virus-like food poisoning after eating oysters].

BACKGROUND: The aim of this study was to conduct a clinical-epidemiological and microbiological investigation into an outbreak of food-borne disease due to the consumption of oysters. PATIENTS AND METHODS: A historic cohort study was conducted into the consumption of 15 food items and clinical symptoms. The influence of each foodstuff was assessed by Mantel-Haenzel stratified relative risk (RRM-H) at 95% confidence intervals, and was confirmed by dose-response analysis with a chi 2 test tendency. We investigated sample stools from 5 patients and 2 food-handlers. RESULTS: The overall attack rate was 38.0% (19/50). The median period of incubation was 39.0 h (maxim 62 and minimum 3 h). The symptoms were: fever 17.6% (3/17), diarrhoea 57.9% (11/19), vomits 84.2% (16/19), nausea 89.5% (17/19) and abdominal pain 89.5% (17/19). In stratified analysis, the Mantel-Haenzel method revealed a statistically risk for oysters (RRM-H = 3.3; IC 95%: 1.1-8.7), while the RRM-H value for sea snails was not significant (RRM-H = 2.8; IC 95%: 0.9-41.1). For oyster consumption, the dose-response test was statistically significant (p = 0.005). Examination by electron microscopy revealed small round structured viruses compatible with Norwalk-like virus. The oyster contamination was reported to the public health authority. CONCLUSIONS: This research highlights the usefulness of dose-response analysis in presenting epidemiological evidence, reveals the potential role of oyster consumption in food-borne disease such us Norwalk-like virus and show the need for monitoring production centres and oyster beds in order to prevent further cases of contamination.

Adult↗
PubMed1994

[Health conditions among fishermen living in the Minamata disease prevalent area].

More than thirty years have elapsed since the major outbreak of Minamata disease. The purpose of this study is to examine the current health conditions among fishermen living along the coastal area of Yatsushiro Sea which received high exposure to methylmercury contamination. From 1988 to 1990 an interview survey was conducted on a random sample of 215 fishermen in two adjoining areas classified as contaminated: Minamata City of Kumamoto Prefecture and Izumi City of Kagoshima Prefecture. Completed responses were collected from 181 (129 males and 52 females). Health conditions were measured by four indicators: activities of daily living, presence of chronic diseases, subjective symptoms, and depressive symptoms. The associations between each health indicator and estimated intake levels of fish and/or shellfish during the heavy contamination period were examined. Residents in areas designated as contaminated can be categorized into three groups: 1) persons who are officially recognized as patients with Minamata disease, 2) persons applying for recognition as having Minamata disease but who have not been officially recognized, and 3) persons who have not applied for official recognition. In the analysis this recognition-related status was used as one of the controlling factors. Findings may be summarized as follows: 1. In both areas, a significant relationship was observed between subjective symptoms and estimated fish intake levels after controlling for sex and age. Judging from subjective symptoms, it appeared that the health level of recognized patients was lowest among the three recognition-related groups; and the health level of non-recognized persons was lower than that of the non-applicants. 2. Among Minamata City fishermen, the significant effect of fish intake levels on subjective symptoms disappeared after controlling for sex, age and recognition-related status. On the other hand, among Izumi City fishermen, a significant relationship between subjective symptoms and fish intake levels still remained by the same analysis. 3. The mental health level of the non-recognized as well as of recognized patients was comparatively lower than that of the non-applicant. However, within the limits of this study, the association between mental health and fish intake levels was not clear.

Adult↗
PubMed2006

[Study on pollutant pathway of norovirus contamination in oysters].

Noroviruses (NVs) cause human gastroenteritis through person-to-person transmission and via contaminated foods. In food poisoning, a major suspected cause is the consumption of raw oysters. We detected NVs from environmental water and oysters around a closed gulf where oysters are cultivated. We collected oyster and water samples once or twice a month for 30 months from October 2001 to March 2004. We then studied monthly changes in virus occurrence and in genetic relationships among 208 NVs isolated from water and oyster samples and from the feces of children suffering from acute gastroenteritis during the same period in the same region. In the analysis of untreated water flowing into farm sewage, NVs were detected year round. In other water samples -processed sewage, river water, and seawater-, oysters, and children's feces, NVs were detected mainly in winter. A comparison of NV nucleotide sequences showed genetic diversity, but some strains predominated in certain winter seasons. These predominant strains were detected across sample materials. In 2002/03, an identical strain was detected in sewage, river water, seawater, oysters, and feces. We also found that NV genetic types changed at the beginning of the season, in November or December, in both 2001/02 and 2002/03. This study showed a clear relationship between NVs detected in children's feces and those in environmental water and oysters. These results support the idea that NVs are transmitted from the feces of infected persons to oysters by the flow of water through farm sewage, rivers, and the sea, finally accumulating in the mid-gut gland of oysters.

Animals↗
PubMed2005

Mercury exposure: medical and public health issues.

Mercury exposure is widespread in the United States with methylmercury as the predominant chemical species and fish and shellfish as the source. Use of more advanced diagnostic techniques and application of population-based risk assessment methodologies have assisted in addressing the impact of mercury exposure on the United States population. Biomonitoring, particularly through analyses of blood mercury, provides both population-based data and exposure information that can be informative for physicians. Data from the National Health and Nutrition Examination Survey (NHANES) beginning in 1999 provide population-based exposure estimates for United States overall. Methylmercury exposures among women of childbearing age are of particular concern because of methylmercury's developmental neurotoxicity. Exposures of concern among women are estimated to occur in between approximately 6% to 8% of the 16-to-49-year-old age group based on data from NHANES; and in approximately 15% of this age and sex group if physiological factors such as the degree of transplacental transport of methylmercury are taken into consideration. Subgroups with high fish consumption (e.g., many island and coastal populations, some persons of Asian ethnicity, some individuals following "healthy" diets) can have methylmercury exposures substantially higher than those reported among the NHANES examinees. These subpopulations are not likely to be aware of their blood mercury concentrations or the possible health outcomes associated with such high blood mercury levels. The American Medical Association has adopted policies that express concerns about methylmercury exposure, and advise patient education. Non-neurological risks for adults associated with methylmercury, including the potential for adverse cardiac outcomes, have not yet been incorporated into risk assessments.

Adult↗
PubMed2000

A rapid hemolysis assay for the detection of sodium channel-specific marine toxins.

Current methods of detection for fish and shellfish biotoxins in monitoring and research purposes are either labor intensive, expensive, require specialized techniques or all of the above. This paper reports on the development of a fairly sensitive, rapid, and inexpensive assay which detects the presence of compounds that affect the sodium channel. It is based on the principles of the mouse neuroblastoma tissue culture assay for sodium channel specific-biotoxins using red blood cells (RBCs) from the red tilapia (Sarotherodon mossambicus). This assay has the potential to complement the use of live animal bioassay testing for marine toxins. Veratridine, a sodium channel activator and ouabain, an inhibitor of Na(+)/K(+) ATPase, both react with the tilapia RBCs by affecting the permeability of the cell's membrane. Saxitoxin (STX), its analogs, and tetrodotoxin (TTX) can inhibit the action of veratridine and ouabain leaving the cell morphologically normal. By sequencing the addition of veratridine and ouabain, with either the extracted samples, saxitoxin, tetrodotoxin, or ciguatoxin (CTX-a sodium channel activator) to the RBCs a sodium channel antagonist or activator can be detected. Results using pure concentrations of a sodium channel-specific toxin could be detected to inhibit hemolysis at a concentration of 0.3 microg/ml STX, 3.5 microg/ml for neo-STX, 3.0 microg/ml for GTX, and 5.0 microgl for TTX in the presence of ouabain and veratridine. CTX was detected at a concentration of 50 microg/ml. The RBCs from the red tilapia was used due to the fish's ability to osmoregulate its internal environment to survive in both fresh and saltwater. In addition, with growing opposition to live animal testing, this assay has been designed as a non-lethal means of testing for sodium channel affecting marine toxins. No test animals are sacrificed and blood may be drawn from the same fish for continued sample testing.

Animals↗