Organic Mercury Concentrations Research Articles

Mercury in the bivalve Anadara ( Senilia) senilis from Ghana and Nigeria

Samples of the bivalve Anadara ( Senilia) senilis collected from a closed lagoon (Sakumo) and two open lagoons in Ghana (Benya and Ningo; n=550), and the Bonny river estuary in Nigeria ( n=620), were analyzed for their total and organic mercury content. Total mercury concentration showed significant spatial differences, with median values of 0.1 μg/g dry wt. in the closed lagoon, 0.2 in the estuary and 0.3 in the open lagoons. Concentration tended to be higher during the dry season in the lagoons, but lower in the estuary. The median relative organic concentration varied between 20 and 60% methyl Hg, depending on location and season. Age effects were detected in the lagoons, total Hg concentration decreasing with length.

Organic Mercury Determination in Fish Samples using an Automatic Mercury Analyser

An analytical method for simple and rapid determination of organic mercury in fish samples is described, including toluene extraction as a separation technique and Hg measurement by the automatic mercury analyser AMA 254. In order to assess the quality control of analytical results the method has been applied to suitable NRCC reference materials (dogfish muscle and liver, lobster hepatopancreas). Good recovery and reproducibility compared with existing procedures have been achieved; routine analyses of organic mercury content in fish samples can be performed easily as the time required for ten determinations is less than three hours.

Increase of organochlorines and mercury levels in common guillemots Uria aalge during winter in the southern North Sea

Beached seabirds, mainly common guillemots Uria aalge, were collected on the Belgian coast during winter from 1990 to 1995. Concentrations of total and organic mercury, and of organochlorines (PCBs and pesticides) were determined in muscle, liver and kidney. They were high compared to summer data (up to one order of magnitude), and increased during winter. This increase is not due to changes of total body weight nor polar lipid content, and thus reflects an actual increase of the seabirds' contamination while wintering in the southern North Sea. The observed annual cycle can be understood by assuming differences in prey contamination: higher during winter in the southern North Sea ecosystem than during summer in the Atlantic water ecosystem.

Percent methylmercury and organic mercury in tissues of marine mammals and fish using different experimental and calculation methods

AbstractMuscle and liver tissues of marine mammals and fish were extracted with methylene chloride–hexane (DCM‐hexane) or toluene and the extracts were analyzed for organic mercury by cold vapor atomic absorption spectroscopy (CVAAS) and for methylmercury by gas liquid chromatography with an electron capture detector (GC‐ECD). Total mercury in tissues was determined by CVAAS. Methylmercury and organic mercury concentrations in muscle agreed with each other and with total mercury for both marine mammals and fish, indicating that on average 100% of the total mercury in this tissue was in the form of methylmercury. Either total mercury or organic mercury determined by CVAAS was found to be a valid measure of the average methylmercury concentration in muscles of marine mammals and fish. In liver, the CVAAS method produced higher mercury values (15% organic mercury) than the GC‐ECD method (6% methylmercury), methylmercury being only 38% of organic mercury. From this, the presence of organic mercury compound(s) other than methylmercury was inferred. The CVAAS method produced a biased estimate of methylmercury in liver; an accurate measure of methylmercury in this tissue was obtained by GC‐ECD, either with DCM‐hexane or with toluene extraction. The DCM‐hexane extract could be directly analyzed by CVAAS for organic mercury while toluene required an additional back‐extraction step for such a determination. In calculating the average percentage of methylmercury and organic mercury in a sample, three different calculation methods were used. Only one of them, linear, robust regression analysis produced acceptable results when the variables (MeHg, organic Hg, total Hg) were significantly correlated. The other two methods overestimated the mean percentage under these conditions.

Total and organic mercury in the starfish Ctenodiscus crispatus and the polychaete Maldanes sarsi from the Barents Sea

Total and organic mercury concentrations were measured in starfish ( n = 116) and in polychaetes ( n = 30) as a part of a broader ecotoxicological study of the Barents Sea. Total mercury concentration in starfish from the open sea was similar in both Arctic (0.2 μg/g dry wt.) and Atlantic (0.2 μg/g dry wt.) water masses but was higher in the samples from the coast of Novaya Zemlya (0.3 μg/g dry wt.). Though there was no difference in total mercury concentration between polychaete and starfish from the coast, there was a difference in speciation: the polychaetes had a higher percentage of methyl mercury (100%) compared to the starfish (3%). Total mercury concentration in these Barents Sea benthic invertebrates (0.25 μg/g dry wt.) was higher than in pelagic fish (0.07 μg/g dry wt.) but similar to demersal fish and particulate matter (0.25 μg/g dry wt.). They were all considered as close to pristine values.

Determination of mercury and organic mercury contents in Malaysian seafood

The contents of mercury and organic mercury in various types of seafood from various location in Malaysia were determined by neutron activation analysis. Total mercury was determined by instrumental neutron activation analysis (INAA) whilst organic mercury was determined by INAA after chemical separation. Samples were digested in acid media and into the solution was added copper ion and KBr to release organic mercury compound from sulphur component of the tissue. The organic mercury was then extracted into toluene and then treated with cysteine paper to convert the compound into sub-organo-mercury from. The paper was then transferred into polyethylene vials and irradiated in the MINT TRIGA Reactor. Analytical results of organic mercury in Indian mackerel (Rastrelliger kanagurta), Spanish mackerel (Scomberomurus commersoni), shrimp (Peneaus sp.), squid (Loligo sp.) and cockle (Anadara granosa) is in the range of 45%–94% of the total mercury.

Total and inorganic mercury in breast milk in relation to fish consumption and amalgam in lactating women.

Total mercury concentrations (mean +/- standard deviation) in breast milk, blood, and hair samples collected 6 wk after delivery from 30 women who lived in the north of Sweden were 0.6 +/- 0.4 ng/g (3.0 +/- 2.0 nmol/kg), 2.3 +/- 1.0 ng/g (11.5 +/- 5.0 nmol/kg), and 0.28 +/- 0.16 microg/g (1.40 +/- 0.80 micromol/kg), respectively. In milk, an average of 51% of total mercury was in the form of inorganic mercury, whereas in blood an average of only 26% was present in the inorganic form. Total and inorganic mercury levels in blood (r = .55, p = .003; and r = .46, p = .01 6; respectively) and milk (r = .47, p = .01; and r = .45, p = .018; respectively) were correlated with the number of amalgam fillings. The concentrations of total mercury and organic mercury (calculated by subtraction of inorganic mercury from total mercury) in blood (r = .59, p = .0006, and r = .56, p = .001; respectively) and total mercury in hair (r = .52, p = .006) were correlated with the estimated recent exposure to methylmercury via intake of fish. There was no significant between the milk levels of mercury in any chemical form and the estimated methylmercury intake. A significant correlation was found between levels of total mercury in blood and in milk (r = .66, p = .0001), with milk levels being an average of 27% of the blood levels. There was an association between inorganic mercury in blood and milk (r = .96, p < .0001); the average level of inorganic mercury in milk was 55% of the level of inorganic mercury in blood. No significant correlations were found between the levels of any form of mercury in milk and the levels of organic mercury in blood. The results indicated that there was an efficient transfer of inorganic mercury from blood to milk and that, in this population, mercury from amalgam fillings was the main source of mercury in milk. Exposure of the infant to mercury from breast milk was calculated to range up to 0.3 microg/kg x d, of which approximately one-half was inorganic mercury. This exposure, however, corresponds to approximately one-half the tolerable daily intake for adults recommended by the World Health Organization. We concluded that efforts should be made to decrease mercury burden in fertile women.

Total and organic mercury concentrations in offshore crustaceans of the Ligurian Sea and their relations to the trophic levels

Total mercury and organic mercury were measured in five crustaceans representative of an offshore pelagic food web in the Gulf of Genoa, Italy: Meganycthiphanes norvegica, Gennadas elegans, Pasiphaea sivado, Pasiphaea multidentata and Aristeus antennatus. According to their predator-prey relationships, they represent three trophic levels in the Ligurian Sea. The concentrations of total and organic mercury increase with the trophic levels and with the weight of the specimens (except in G. elegans and in females of A. antennatus). However, at higher trophic levels the specimens are also larger. Only in P. sivado, do levels of inorganic mercury increase significantly (P = 0.001) with the size of the specimens. The ratio between organic mercury and total mercury did not increase with the trophic level.

Sampling and analysis of mercury species in effluent gases derived from waste incineration

Mercury and its compounds are highly toxic. Therefore, the determination of mercury species present in flue gases from combustion sources is extremely important. Mercury is initially emitted from the combustion chamber as mercury vapour. However, as the combustion products cool the mercury vapour can react with a variety of other flue gas components to form a range of inorganic and possibly organic mercury species. The diversity of mercury compounds which could form means that a sampling and analysis procedure is needed which can determine the elemental, inorganic and organic mercury content of the flue gases. This would allow appropriate clean-up procedures to be employed and, if necessary, the modification of the process to eliminate the formation of particularly toxic mercury species. In this work a sampling train has been developed using model mercury compounds to efficiently trap elemental, inorganic and organic mercury from a hot gaseous environment. Chemical analysis of the sampling mediums was carried out by HPLC-UV to speciate between inorganic and organic mercury.

Variations of Mercury and Selenium Concentrations in Adamussium Colbecki and Pagothenia Bernacchii from Terra Nova Bay (ANTARCTICA) During a Five Years Period

Abstract Pagoihenia bernacchi and Adamussium colbecki specimens have been collected in Terra Nova Bay, Ross Sea, Antarctica, from 1987 to 1992. Total and organic mercury and selenium concentrations were measured in the muscular tissue of P. bernacchii and in the soft parts of A. colbecki. Sampling, samples preparation, and analysis were the same for all the specimens, and the temporal variation in concentrations are discussed. Large variations for total and organic mercury contents are found in A. colbecki, while P. bernacchii shows significant interannual differences in selenium concentration. However, none of these differences reflect a consistent temporal trend. Medians obtained during the five years in 109 specimens of P. bernacchii are: 0.60 μg/g dry weight for total mercury, 78% for the percentage of organic mercury, and 3.0 μg/g dry weight for selenium. Values found in 117 specimens of A. colbecki are: 0.17 μg/g dry weight for total mercury, 28% for the percentage of organic mercury, and 9.1 μg/g d...

Maternal and fetal toxicity of methylmercuric chloride administered to pregnant Fischer 344 rats.

Various doses of methylmercuric chloride (MMC) were administered orally to pregnant Fischer 344 rats on d 7 of gestation. On d 20 of gestation the dams were laparotomized under ether anesthesia, and the fetuses were removed. Maternal body weights were decreased for 2 d and 6 d in rats given 10 and 20 mg/kg MMC, and were continuously decreased for those given 30 mg/kg MMC. Maternal weight gain of each group was decreased to 86.2%, 78.9%, and 61.9% of control group on d 20 of gestation. The reduction of litter weight was greatly enhanced with increasing MMC doses, presumably due to postimplantation loss, which was already increased at high treatment levels. The LD50 of MMC for fetuses was determined to be 16.5 mg/kg. Mercury content in maternal organs was highest in kidney, followed by blood, spleen, liver, and brain, while in fetal organs it was highest in liver. Fetal liver and brain contained more mercury than maternal liver and brain. However, fetal kidney retained less mercury than maternal kidney. Fetal ossification center was not completely formed in sternebrae, particularly in fifth and second bones, pelvic bones, and pectoral phalanges of fetuses in rats treated with 30 mg/kg MMC. The ossified lengths of skeletal bone stained with alizarin red S were developed least in fifth sternebrae, metacarpals in the pectoral girdle, and ischium in the pelvic girdle, and were severely retarded in development as position of the ribs goes from the sixth bone (center) to the first and 13th bone (each edge). These results indicate that MMC is embryotoxic in Fischer 344 rats.

Mercury and cadmium uptake from seawater and from food by the Norway lobster Nephrops norvegicus

AbstractNorway lobsters, Nephrops norvegicus, were fed on a mercury‐ and cadmium‐rich diet for up to 50 d or were exposed to sublethal concentrations of organic mercury, inorganic mercury, or cadmium in seawater for 30 d. Cadmium taken up from seawater accumulated mainly in the hepatopancreas and gill, while it accumulated mainly in the hepatopancreas after feeding. Both organic and inorganic mercury taken up from seawater accumulated mainly in the gill, while highest concentrations were found in the hepatopancreas after the feeding experiment. Accumulation of organic mercury was higher than that of inorganic mercury. Although all treatments resulted in the accumulation of mercury and cadmium from seawater and food, tissue distribution of metals differed significantly among treatments. Distributions of organic and inorganic mercury also varied among tissues after uptake from seawater, with organic mercury being more evenly distributed among tissues than inorganic mercury, the latter being found predominantly in the gill.

In vivo XRF analysis of mercury: the relation between concentrations in the kidney and the urine

The objective of this study was to determine the concentrations of mercury in organs of occupationally exposed workers using in vivo X-ray fluorescence analysis. Twenty mercury exposed workers and twelve occupationally unexposed referents participated in the study. Their mercury levels in kidney, liver and thyroid were measured using a technique based on excitation with partly plane polarized photons. The mercury levels in blood and urine were determined using atomic absorption spectrophotometry. The detection limit for mercury in the kidney was exceeded in nine of the exposed workers, but in none of the referents. The mean kidney mercury concentration (including estimates below the detection limits) was 24 mu g g-1 in the exposed workers, and 1 mu g g-1 in the referents. The association between mercury in the kidney and in urine was statistically significant, but it was unclear whether the relation was linear. The measurements on liver (n=10) and thyroid (n=8) in the exposed workers showed mercury levels below the detection limit. The study shows that it is now possible to measure the mercury concentrations in kidneys of occupationally exposed persons, using in vivo X-ray fluorescence. The estimated concentrations are in reasonable agreement with the limited human autopsy data, and the results of animal studies.

Fate and distribution of toxic heavy metals in some marine organisms from the eastern Adriatic coast

The paper reports on levels of heavy metals in some organisms from the eastern Adriatic coast and polluted areas near a big urban centre (Split area). Surprisingly high Hg and MeHg concentrations were found in sea bream (Pagellus erythrinus) and striped mullet (Mullus barbatus) from the south-eastern part of the Adriatic. The reason for the high levels are probably geochemical anomalies. Studies of total and organic mercury content in bivalves have also shown that the gills and hepatopancreas had high levels of accumulated mercury. Our results have shown that fish contain significantly higher concentrations of MeHg than mussel. High concentrations of these elements in fish may be a consequence of the methylation process in the visceral organs. Bacterial activity in the intestinal contents is most likely to be responsible for this methylation (Rudd et al., 1980).

The contents and chemical forms of mercury in sediments from Kagoshima Bay, in comparison with Minamata Bay and Yatsushiro Sea, southwestern Japan.

Sediments collected from Kagoshima Bay, Minamata Bay and Yatsushiro Sea were analyzed for organic mercury, mercury(II) oxide, mercury(II) sulfide and residual mercury through sequential extraction followed by cold vapor atomic absorption spectrometry. Results show that mercury(II) sulfide (38.4∼96.1%, geometric mean 71.4%) is the most prevalent mercury compound in the sediments followed by mercury(II) oxide (<0.9∼42.9%, geometric mean 5.65%). Organic mercury is present only in a very small quantity (0.21∼12.8%, geometric mean 2.55%). Residual mercury shows a wide range of content in the sediments (2.6∼44.3%, geometric mean 10.5%). The abnormally high mercury concentration observed in the sediment samples from Northern Kagoshima Bay is caused by the condensation of submarine fumarolic gases including elemental mercury and hydrogen sulfide, which are depositing in the surface sediments. This is in accord with the fact that mercury(II) sulfide is the most prevalent mercury compound there. Organic mercury content is high in the vicinity of the submarine fumarole, where mercury(II) sulfide content is very high.

Longitudinal study of workers exposed to mercury vapour at low concentrations: time course of inorganic and organic mercury concentrations in urine, blood, and hair.

Seven Japanese female workers exposed to mercury vapour at a concentration of < 0.02 mg Hg/m3 (8 h/day, 44 h/week) were examined for inorganic (I-Hg) and organic (O-Hg) mercury concentrations in urine, blood, and hair after 0, 4, 8, 17, and 23 months of exposure. Both I-Hg and O-Hg concentrations in urine and hair did not increase significantly even after 23 months of exposure. The concentration of I-Hg and O-Hg in plasma and O-Hg in erythrocytes, however, increased significantly after four months of exposure, and the high concentrations were maintained until the end of the study (23 months of exposure). Absence of a significant increase in the concentration of O-Hg in hair indicates that changes in concentrations of I-Hg and O-Hg in blood could be caused by the occupational exposure to mercury vapour. These results show clearly that mercury concentration in blood indicates the uptake of mercury compared with data from before employment with mercury. Even after 23 months of exposure to mercury vapour, however, urinary mercury concentration was not affected.

In Vivo Measurements of Mercury Using X-Ray Fluorescence Analysis

Abstract In this study we present the results of in vivo measurements of the mercury concentration in organs of occupationally exposed persons by the use of X-ray fluorescence analysis (XRF). The mercury concentration in the right kidney was measured in 20 occupationally exposed workers and 12 referents. The detection limit for the individual persons varied with the kidney depth (mean 26 μg/g, range 12-45 μg/g), was exceeded in nine of the exposed workers but in none of the referents. The mean kidney mercury concentration (including estimated concentration values below the detection limit) was 24 μg/g in the group of exposed workers (group MDC 5 μg/g) and for the group of referents no detectable concentration (mean 1 μg/g) was found (group MDC 6 μg/g). The mean urinary mercury excretions for the two groups were 34 and 1.7 μg per g creatinine. X-ray fluorescence measurements made on liver (n = 10) and thyroid (n = 8), in some of the exposed workers, revealed no measurable mercury concentrations.

The relationship between mercury concentration in human organs and different predictor variables

Samples from different tissues were collected from autopsies of individuals of the general population of the Stockholm area, Sweden. The samples were analysed for total mercury content using radiochemical neutron activation analysis. Average concentrations of mercury in occipital cortex, abdominal muscle, pituitary gland and kidney cortex were, 10.6 (2.4–28.7), 3.3 (0.9–5.4), 25.0 (6.3–77) and 229 (21.1–810) μg/kg wet weight, respectively. Possible predictor variables for mercury concentrations were tested in multiple linear regression models. An effect of a number of tooth surfaces with amalgam was seen in occipital lobe cortex, abdominal muscle and pituitary gland, but not in kidney cortex. In occipital lobe cortex and abdominal muscle, concentrations of mercury increased with age. Explanation discussed include: that a significant fraction of the mercury retained from amalgam fillings has a very long biological half-life; a decreasing capacity of mercury excretion with age; or higher fish consumption in the older individuals. In kidney cortex mercury concentrations decreased with age. The reason for this remains unclear, but it might indicate a decreasing capacity of mercury excretion with age. Chronic alcohol abuse was associated with decreased concentrations of mercury in occipital cortex.

Total and organic mercury in North Atlantic fin whales: Distribution Pattern and Biological Related Changes

Total and organic mercury concentrations were determined in muscle, liver and kidney of thirty-six fin whales ( Balaenoptera physalus) of the Northeast Atlantic. Age, sex and length relationships for both forms of metal were examined. Tissue concentrations were lower than those of toothed whales and seals. A slight increase with age was observed for total mercury concentrations in muscle and liver and organic mercury concentrations in liver, which suggests a low rate of excretion for the metal, even at low concentrations. No differences between sexes were found regarding mercury concentrations, nor to their accumulation pattern.

Factors Affecting Blood Mercury Concentrations in Practicing Dentists

It has been suggested that mercury vapor may be transformed into highly toxic organomercury compounds by micro-organisms in the oral cavity and gastrointestinal tract. If this hypothesis is correct, practicing dentists might be expected to have concentrations of organic mercury in their blood higher than that found in non-dentists. Blood mercury concentrations of practicing dentists and non-dentists were determined by means of cold-vapor atomic absorption spectrophotometry. Potential sources of mercury exposure were identified in both dentists and non-dentists through a questionnaire completed at the time of sampling. Concentrations of total and inorganic blood mercury were significantly higher in dentists than in non-dentists. The organomercury concentrations of the two groups were not statistically different (p greater than or equal to 0.05). The high concentration of inorganic mercury in the blood of dentists was not related to the organomercury level, suggesting that biotransformation of inorganic mercury to organomercury does not occur in vivo. However, the concentration of blood organomercury was positively correlated with the frequency of fish consumption. There was no correlation between the number of amalgam restorations and the concentration of inorganic blood mercury for both groups. Accidental mercury spills in the dental operatory may contribute most to the concentration of inorganic blood mercury in the blood of dentists.