Mercury Residues Research Articles

Evidence for changes in the conformational status of rat liver microsomal glucose-6-phosphate:phosphohydrolase during detergent-dependent membrane modification. Effect of p-mercuribenzoate and organomercurial agarose gel on glucose-6-phosphatase of native and detergent-modified microsomes.

Comparative studies investigating influences of temperature and time of preincubation on the interactions of an organomercurial agarose gel and p-mercuribenzoate with glucose-6-phosphatase of native and Triton X-114-modified rat liver microsomes were carried out. The effect of p-mercuribenzoate on glucose 6-phosphate hydrolysis is a result of two processes, a moderate membrane perturbation connected with release of some latency and temperature- and time-dependent inhibition of the catalytic activity. Short-term preincubation with both organic mercurials at 37 degrees C is a necessary condition for the entire inhibition of the enzyme activity of native as well as of Triton X-114-modified microsomes. A binding site of the phosphohydrolase itself is accessible to p-mercuribenzoate and the phenyl mercury residue of the affinity gel from the cytoplasmic surface even in native microsomes. Kinetic analyses reveal a formally competitive mechanism of inhibition using native microsomes, but the kinetic picture changes to a noncompetitive pattern of Lineweaver-Burk plots when the inhibitor-loaded microsomes are modified optimally by Triton X-114. This behavior can be evaluated as the first convincing evidence for drastic changes of the conformational status of the phosphohydrolase during the membrane modification process. A combined conformational flexibility-substrate transport model characterizing the microsomal glucose-6-phosphatase as an integral channel-protein embedded within the hydrophobic interior of the membrane is proposed.

Methylmercury in Fish: A Review of Residue Levels, Fish Consumption and Regulatory Action in the United States

The dangers associated with the consumption of large amounts of methylmercury in fish are well recognized, and there is some evidence to suggest that methylmercury may be the cause of subtle neurological impairments when ingested at even low to moderate levels, particularly the prenatal and early childhood periods. This concern has prompted a continuing assessment of the risk of methylmercury toxicity among fish consumers in the United States as well as other countries. The toxicokinetics of methylmercury in humans are reviewed and used to estimate body burdens associated with toxic effects. To determine seafood consumption patterns among the continental U.S. population the Food and Drug Administration (FDA) has analyzed data from a diary study commissioned by the Tuna Research Foundation. Mercury residue levels in domestic fish sampled by the FDA were used to determine the level of exposure to methylmercury. Until evidence is presented that substantially lowers the known body burden of methylmercury which causes toxicity, calculations indicate that the current 1.0 ppm regulatory level provides adequate protection for the average fish consumer, for young children, and for a significant number of consumers exceeding the acceptable daily intake. However, additional studies are being carried out in a continuing process to ensure that safe levels of prenatal exposure to mercury residues in fish are maintained.

Methylmercury in fish: a review of residue levels, fish consumption and regulatory action in the United States.

The dangers associated with the consumption of large amounts of methylmercury in fish are well recognized, and there is some evidence to suggest that methylmercury may be the cause of subtle neurological impairments when ingested at even low to moderate levels, particularly the prenatal and early childhood periods. This concern has prompted a continuing assessment of the risk of methylmercury toxicity among fish consumers in the United States as well as other countries. The toxicokinetics of methylmercury in humans are reviewed and used to estimate body burdens associated with toxic effects. To determine seafood consumption patterns among the continental U.S. population the Food and Drug Administration (FDA) has analyzed data from a diary study commissioned by the Tuna Research Foundation. Mercury residue levels in domestic fish sampled by the FDA were used to determine the level of exposure to methylmercury. Until evidence is presented that substantially lowers the known body burden of methylmercury which causes toxicity, calculations indicate that the current 1.0 ppm regulatory level provides adequate protection for the average fish consumer, for young children, and for a significant number of consumers exceeding the acceptable daily intake. However, additional studies are being carried out in a continuing process to ensure that safe levels of prenatal exposure to mercury residues in fish are maintained.

Metals in sediments and benthic organisms in the Mersey estuary

Concentrations of twelve metals were determined in sediments, seaweed ( Fucus vesiculosus), winkles ( Littorina littorea), polychaetes ( Nereis diversicolor), suspension feeding bivalves ( Mytilus edulis, Cerastoderma edule) and deposit feeding bivalves ( Macoma balthica, Scrobicularia plana) collected from the Mersey estuary between April 1980 and June 1984. Sediments and organisms in the Mersey are moderately contaminated with most of the metals measured, but mercury concentrations are consistently higher than in other United Kingdom estuaries. Comparisons with other sites in the North West of England indicate that mercury residues in organisms, though primarily dependent on sediment concentrations, are also influenced by complexation with particulate organic matter which reduces the availability of mercury. The biological availability of arsenic in Mersey sediments is similarly influenced by complexation with iron oxyhydroxides. Nereis diversicolor and Macoma balthica are the most suitable indicator species in terms of abundance and widespread distribution along the estuary, and, for the majority of metals, tissue concentrations increase upstream, reflecting corresponding gradients in sediment contamination. However mid-estuarine peaks for tin, chromium copper and nickel in Nereis indicate more localised inputs to the estuary. Correlations between lead in sediments and organisms are poor; it is suggested that hydrophilic alkyl lead compounds may be the predominant biologically available forms. Progressive reductions in mercury contamination in sediments and mercury and lead in organisms have occurred in recent years, which coincide with efforts to reduce inputs of these metals to teh Mersey estuary.

A comparative toxicological study on pike ( Esox lucius L.) from the river Rhine and river Lahn

The influence of environmental pollutants on morphological and hepatic biochemical parameters of mature pike from the river Rhine and river Lahn was investigated. Liver content of aromatic organohalogen compounds in Rhine pike was up to 40 times higher than found in pike from the river Lahn. Lead and mercury residues in Rhine pike liver tissue were about twice as high as in Lahn pike. Copper and zinc contents were comparatively higher in Lahn pike. Cadmium occurred in about equal concentration in both groups. Interrelations between body weight and age, between body length and age, between body weight and body length and between liver weight and body weight in both pike groups revealed no influence by xenobiotics. Distribution pattern of hepatic porphyrins in the Rhine pike differed significantly from that in the Lahn pike. The in vitro activity of the hepatic uroporphyrinogen decarboxylase of pike from the river Rhine was markedly lower than in pike from the river Lahn.

Mercury emission from a cement factory and its influence on the environment

Mercury balance was investigated in a cement factory, measuring the mercury concentration in ingredients, fuels, cement and exhaust gases, etc. Daily mercury emission quantity from the factory was estimated to be 1.5 kg, originating mostly from limestone. Gaseous and particulate mercury concentrations in ambient air were 4.1–8.7 ng m −3 and 0.15–0.68 ng m −3, respectively. Particulate mercury concentrations are remarkably higher than the background ones. The influence of mercury emission estimated from the determined mercury levels in the leaves of indicator plants reaches up to 5 km at least from the source. The sum of the mercury quantity deposited from the atmosphere and that taken by leaves of plants in the area within a 5-km radius from the factory was calculated to be about 4% of the entire mercury emitted. The mercury residue was recognized in humus and surface soil in the forest near the factory.

Contaminant levels in colonial waterbirds from Green Bay and Lake Michigan, 1975?80

Residues of organochlorine pesticides, polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), polychlorinated styrenes (PCSs), and mercury were measured in the eggs of 10 species of colonial waterbirds nesting in areas around Green Bay or Lake Michigan from 1975 to 1980. Residues also were measured in the carcasses and brains of black-crowned night-herons (Nycticorax nycticorax). The highest residues were of PCBs, DDE, mercury, and dieldrin; for some species, levels of these chemicals possibly were high enough to have caused reproductive effects. Other organochlorine pesticides were found at low levels. Only trace amounts of PCSs and PBBs were found. Eggs of herring gulls (Larus argentatus) collected in 1977 from an island in Lake Michigan contained an average of 100 ppm PCBs and 33 ppm DDE; this was the most-contaminated species. Cattle egrets (Bubulcus ibis), the only bird that is not a fish eater, contained only small quantities of DDE and mercury.

Organochlorine and Mercury Residues in Young-of-the-Year Spottail Shiners from the Detroit River, Lake St. Clair, and Lake Erie

Young-of-the-year spottail shiners (Notropis hudsonius) were used as biomonitors to determine the spatial distribution (1982/83) and assess trend data for organochlorine and mercury residues. Significantly (p < 0.01) higher PCB residues were found in Detroit River spottail shiners than in collections from southwestern Lake St. Clair and northwestern Lake Erie. The highest PCB residues were found in the west bank collections from Michigan waters (912–2,997ng/g) compared to the mid-stream (96–290 ng/g) and east bank collections (153–316 ng/g). Chlordane residues were found to be elevated in all spottail shiner samples from urbanized areas. Octachlorostyrene and ∑ DDT residues were distributed uniformly within the study area, whereas mercury concentrations were found to be lower in spottail shiners from northwestern Lake Erie than in comparable samples from the Detroit River and southwestern Lake St. Clair. Residues for BHC, heptachlor, aldrin, and chlorinated benzenes were near their detection limits; mirex and chlorinated phenols were not detectable. Recent (1982/83) PCB residue levels in spottail shiners exceeded the IJC aquatic life objective (Great Lakes Water Quality Agreement of 1978) at all the sites sampled, except at Pike Creek in Lake St. Clair. PCB residues in spottail shiners from Pike Creek, Big Creek, and Leamington have declined significantly (p < 0.01) since the mid-seventies. Mercury and chlordane residues have decreased in spottail shiner samples from Leamington, but have remained virtually unchanged at Big Creek and Pike Creek.

Organochlorine pesticide, polychlorobiphenyl, and mercury residues in bald eagle eggs--1969-79--and their relationships to shell thinning and reproduction.

Bald eagle (Haliaeetus leucocephalus) eggs were collected in 14 States in 1969–79 and analyzed for organochlorine pesticides, polychlorobiphenyls, and mercury. Moderate shell thinning occurred in eggs from several areas. Eggs from the Chesapeake Bay area contained the highest residue levels of most organochlorines. DDE was detected in all eggs; other organochlorines were detected less frequently. Mercury levels were highest in eggs from Maine. Eight contaminants were significantly negatively correlated with shell thickness or reproduction at sampled breeding areas; DDE was most closely related to these factors. Production of young was near normal at breeding areas when DDE was ⩽3 ppm (wet weight); reproductive failure approached 100% for those breeding areas where DDE in eggs was >15 ppm. Five ppm DDE was associated with 10% shell thinning. The other contaminants that were associated with these factors were also highly correlated with DDE; their impact appeared minor in relation to those of DDE.

Residues of organochlorine insecticides, industrial chemicals, and mercury in eggs and in tissues taken from healthy and emaciated common loons, Ontario, Canada, 1968-1980.

Between 1968 and 1980, 98 eggs were collected from active nests of the common loon (Gavia immer) in Ontario. Residues of ⌆DDT and PCB declined over this period while dieldrin and Hg appeared unchanged. Eggs collected in 1969 and 1970 had significantly thinner shells than eggs from a collection made before 1947. Between 1969 and 1979, 215 common loon carcasses were collected across Ontario, the result of having been drowned or shot or having died of diseases or unknown causes. Chemical analyses of 174 carcasses taken from healthy birds showed that adult loons accumulated higher levels of organochlorine and Hg residues than did juveniles. Tissues with high fat contents contained higher organochlorine levels while kidney, liver, and feathers had the highest Hg levels. Thirty loons were found to be emaciated with visibly lesser amounts of body fat and significantly lower levels of lipids in pectoral muscle tissue. Organochlorine but not Hg residues were one to two orders of magnitude higher in the wet tissues of emaciated birds than healthy birds. Higher residues of organochlorine chemicals were found in the uropygial gland, the oil secreted by this gland and belly and back feathers of emaciated birds when compared to healthy birds. It was concluded that losses of organochlorine chemical residues could occur through this gland. While Hg levels in feathers were elevated, Hg did not accumulate in the uropygial gland or in the secreted oil and was not the route for Hg content in feathers. In emaciated birds, mean brain levels of ⌆DDT (primarily DDE) were between 25 and 49 Μg/g, dieldrin 0.5 to 1.2 Μg/g, PCB 39 to 63 Μg/g, and mercury 1.0 to 1.8 Μg/g. The mean brain levels in healthy birds were between 0.2 and 0.9 Μg/g ⌆DDT, 0.01 and 0.05 Μg/g dieldrin, 0.6 and 2.0 Μg/g PCB, and 0.4 and 0.6 Μg/g mercury.

Industrial effluents as a source of mercury contamination in terrestrial riparian vertebrates

Eight species of piscivorous and insectivorous birds and one species of bat collected along Virginia's North Fork of the Holston River contained elevated mercury residues. The ubiquitous occurrence of mercury in riparian insectivores implicates aquatic insects as a vehicle for spreading mercury contamination from one ecosystem to another and expands the ecological ramifications of mercury-contaminated industrial effluents.

Organochlorine and mercury residues in peregrine falcon eggs in France.

Sterile falcon eggs were analyzed for DDE, HCB, Total HCH, PCBs and mercury. Results show that contamination by PCBs was predominant with levels of 0.77-160 ppm fresh weight in 1974 and 0.096-1.2 ppm in 1975. Mercury levels were 0.1-0.3 ppm. (JMT)

Chronic toxicity and bioaccumulation of mercuric chloride in the fathead minnow ( Pimephales promelas)

Fathead minnows ( Pimephales promelas) were exposed to various concentrations of mercuric chloride in water to determine its acute and chronic (including reproduction) toxicity and to measure bioaccimulalion. Mean LC 50 values of HgCl 2 for juvenile fatheads were 168, 112, 84, and 74 μg Hg/l at 4, 5, 6, and 7 days, respectively. Following 41 wk of exposure to 0.26 to 3.69 μg/l, females were significantly smaller than controls at all concentrations except 0.50 μg/l and males showed reduced growth at 3.69 μg/l. Over half of the fish at 2.01 and 3.69 μg/l were severely stunted and scoliosis was prevalent among these stunted fish. No spawning occurred at and above 1.02 μg/l and the number of spawning pairs was reduced at 0.26 and 0.50 μg/l resulting in total egg production of 46 and 54%, respectively, of control. Thirty-day growth of second-generation larvae (from transferred control embryos at and above 1.02 μg/l) was significantly reduced at all mercury concentrations tested. No effects on hatchability or larval survival were detected. Chronically-exposed fish accumulated mean whole body total mercury residues of 1.36 to 18,80 μg/g of tissue (wet weight) from 0.26 to 3.69 μg/l, respectively. Uptake appeared proportional to water concentration; bioconcentration factors varied between 4380 and 5680. The influence of diet on mercury toxicity and bioaccumulation was studied during two 60-day larval fathead exposures. Overall recuccd growth and possibly enhanced toxic effects occurred in larvae on the dry trout starter diet compared to larvae fed on Artemia. Mercury uptake appeared influenced by the severity of toxic effects.

DISTRIBUTION OF MERCURY RESIDUES FROM THE USE OF MERCURIAL FUNGICIDES ON GOLF COURSE GREENS

Soil samples taken from two golf courses with a long history of mercurial fungicide use for disease control showed mercury residues in excess of background levels to a maximum depth of 30 cm at one site and 60 cm at the other. Laterally, residues were found up to 30 m from the treated areas at both sides.

Simian virus 40 transcriptional complexes incorporate mercurated nucleotides into RNA in vitro.

Simian virus 40 Sarkosyl transcriptional complexes incorporated mercurated nucleotide precursors into preinitiated RNA chains. Synthesis with mercurated precursors was three- to fivefold slower than with nonmercurated nucleotides (12 to 20 pmol per 10(6) cells per h at 25 degrees C), and 50 to 70% of the RNA product bound specifically to sulfhydryl-agarose. The amount of mercurated CMP incorporated into RNA was measured by specific binding of [35S]cysteine to the mercury residues. More than 90% of the mercurated RNA hybridized to simian virus 40 DNA.

Organochlorine and mercury residues in snakes from Pilot and Spider Islands, Lake Michigan--1978.

Little is known about the chronic effects of environmental pollutants on snakes, but some investigators have suggested that snakes make good biological indicators of environmental contamination. Being carnivorous, snakes would be expected to carry fairly high contaminant loads as a result of food chain concentration. They are also generally more sedentary than many other vertebrates and should, therefore, be good indicators of pollutants in the area where they are collected. During the course of a contaminant study with waterfowl on several islands in Lake Michigan, we collected snakes in order to measure their organochlorine and mercury levels.

Residues and effects in mice after drilling wheat treated with chlorfenvinphos and an organomercurial fungicide

The use of the wood mouse ( Apodemus sylvaticus) as an indicator species to assess the effects of chlorfenvinphos and an organomercurial fungicide used as seed dressings on winter wheat have been investigated. Optimum assay conditions for measurement of glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, glutamate dehydrogenase, and sorbitol dehydrogenase in rodent plasma were developed for this study. The amount of surface grain and the chlorfen vinphos and total mercury residues on the surface grain declined with time after drilling. Wood mice were captured using a grid of small mammal traps placed over the surface of a field sown with treated winter wheat and also in adjacent woodland. No trend in mouse body total mercury was discernible after sowing unlike mouse gut chlorfenvinphos which declined with time. Mice trapped in the wood contained very low levels of chlorfenvinphos and total mercury unlike those mice trapped on the field. Plasma acetylcholinesterase and cholinesterase showed significant inhibition 10 days after drilling and liver nitrophenyl acetate esterase showed significant inhibition during the first 3 days after drilling in mice trapped on the field. This inhibition of esterase activities reflected the chlorfenvinphos residue in the gut contents of the mice. The enzyme changes further differentiated mice trapped on the field from those caught in the wood.

Organochlorine and mercury residues in wild mammals in southern Ontario, Canada 1973-74.

Organochlorine and mercury residues in wild mammals in southern Ontario, Canada 1973-74.

Mercury, chromium, lead and organochlorine pesticide residues in some food products of animal origin: A review

The authors present the results of several years' work in the field of food pollution. The research, which has been carried out on food products of animal origin marketed in the north of Italy, has established that the degree of contamination by heavy metals (mercury, chromium and lead) and organochlorine pesticides is generally lower than the tolerances suggested by the World Health Organisation.

Mercury residues in soil around a large coal-fired power plant

Mercury residues in soil around a large coal-fired power plant