Methylmercury concentrations

Kelly CA, Rudd JWM, St. Louis VL, Heyes A. 1995. Is total mercury concentration a good predictor of methylmercury concentration in aquatic systems Water Air Soil Pollut 80 715-724. 

Horvat M, Liang L, Azemaed S, Mandic V, Coquery M, and Viixeneuve J.-P (1997) Certification of total mercury and methylmercury concentrations in mussel homogenate (Mytilus edidis) reference material, IAEA-142. Fresenius J Anal Chem 358 411-418. 

Techniques for analysis of different mercury species in biological samples and abiotic materials include atomic absorption, cold vapor atomic fluorescence spectrometry, gas-liquid chromatography with electron capture detection, and inductively coupled plasma mass spectrometry (Lansens etal. 1991 Schintu etal. 1992 Porcella etal. 1995). Methylmercury concentrations in marine biological tissues are detected at concentrations as low as 10 pg Hg/kg tissue using graphite furnace sample preparation techniques and atomic absorption spectrometry (Schintu et al. 1992). 

Methylmercury compounds have induced abnormal sex chromosomes in the fruit fly (Drosophila melanogaster) (NAS 1978 Khera 1979). Earthworms (Eisenia foetida) exposed to soil containing methylmercury concentrations of 5.0 mg Hg/kg — typical of soil Hg levels near chloralkali plants — showed a significant reduction in the number of segments regenerated after 12 weeks, and contained... 

More research is needed on mercury removal technology. In the Florida Everglades, for example, using prototype wetlands of 1545 ha, removal of agricultural nutrients from stormwater reduced total mercury and methylmercury concentrations in water by as much as 70% in the first 2 years of operation moreover, total mercury concentrations in largemouth bass were about 0.1 mg Hg/kg FW muscle throughout the project site vs. 0.5 mg Hg/kg FW in adjacent areas (Miles and Fink 1998). 

Pokras, M.A., C. Hanley, and Z. Gordon. 1998. Liver mercury and methylmercury concentrations in New England common loons (Gavia immer). Environ. Toxicol. Chem. 17 202-204. 

Driscoll et al. (1994) have studied the mercury species relationships among water, sediments, and fish (yellow perch) in a series of Adirondack lakes in New York state, USA. In most lakes, approximately 10% of the total mercury loading was in the form of C2HsHg+. Mercury concentrations increased as pH fell, but the best correlation was found between [dissolved Al] and [dissolved Hg] suggesting that the same factors are responsible for mobilizing both these metals. Methylmercury concentrations correlated strongly with the dissolved organic carbon content in the water. Fish muscle tissue was analyzed for mercury and showed an increase with age. However, the study was unable to resolve the question of whether the principal source of mercury to these lakes was atmospheric deposition or dissolution from bedrock due to acid rains. 

Andren and Harris [54] have reported a methylmercury concentration of 0.02-0. lng Hg g 1 in unpolluted sediments by using a gas chromatograph with an electron capture detector. 

In several instances, biomonitoring data have confirmed health effects of environmental exposures and have validated public-health policies. For example, population data on blood lead concentrations that were associated with adverse health effects provided the impetus for the U.S. Environmental Protection Agency (EPA) regulations reducing lead in gasoline. Methylmercury concentrations in blood and hair that were correlated with neurodevelopmental effects provided the rationale for EPA s revision of the oral reference dose. In those examples, the biomonitored concentrations of chemicals could be shown to be related to adverse health effects because of the body of epidemiologic, toxicologic, and clinical... 

Gilmour, C.C., Reidel, GS., Ederington, M.C., Bell, J.T., Benoit, G.A., Gill, G.A., and Stordal, M.C. (1998) Methylmercury concentrations and production rates across a trophic gradient in the northern Everglades. Biogeochemistry 40, 327-345. 

Branfireun B. A., Bishop K., Roulet N. T., Granberg G., and Nilsson M. (2001) Mercury cycling in boreal ecosystems the long-term effect of acid rain constituents on peatland pore water methylmercury concentrations. Geophys. Res. Lett. 28(7), 1227-1230. 

Potential sources of human exposure to mercury include food contaminated with mercury, inhalation of mercury vapors in ambient air, and exposure to mercury through water, soil and sediment. Dietary intake is by far the most important source of exposure to mercury for the general population. Fish and other seafood products are the main source of methylmercury in the diet studies have shown that methylmercury concentrations in fish and shellfish are 10-100 times greater than in other foods, including cereals, potatoes, vegetables, fruits, meats, poultry, eggs, and milk. As of December 1998, mercury was the chemical contaminant responsible, at least in part, for the issuance of 1931 fish consumption advisories by 40 states, including the US territory of American Samoa. Almost 68% of all advisories issued in the United States are a result of mercury contamination in fish and shellfish. Advisories for mercury have increased steadily by 115% from 899 advisories in 1993 to 1931 advisories in 1998. The number of states that have issued mercury advisories also has risen steadily from 27 states in 1993 to 40 states in 1997, and remains at 40 states for 1998. Advisories for mercury increased nearly 8% from 1997 (1782 advisories) to 1998 (1931 advisories). 

The Gray (1995) PBPK model simulates the kinetics of methylmercury in the pregnant rat and fetus. The Gray model was developed to provide fetal and maternal organ methylmercury concentration-time profiles for any maternal dosing regimen. 

The model results for a total fetal methylmercury concentration of 0.79% 24 hours after maternal methylmercury dosing on Gd 19 compare favorably with published values of 0.6 and 0.88% for administered doses on Gd 19 and 20, respectively. 

The Pesticide and Chemical Contaminant Data Base for USFDA (1991/1992) reports the methylmercury concentration in catfish as 0.02 ppm. 

Recreational and Subsistence Fishers. Methylmercury concentrations in sport fish can be at least an order of magnitude higher than in commercial fish purchased in a supermarket (see Section 5.4.4). Therefore, recreational and subsistence fishers, including some Native American peoples who consume locally caught fish from mercury-contaminated waterbodies or consume long-lived predatory oceanic species such as shark and swordfish, can be exposed to higher mercury concentrations than individuals who consume similar amounts of commercially marketed fish from a variety of sources (Ebert et al. 1996 ... 

Native American populations that depend heavily on marine mammals are considered to be at higher risk than the general population. Wheatley and Paradis (1995a, 1995b) reported blood mercury levels in native peoples from 514 communities across Canada. Of these individuals, 23% had methylmercury blood levels >20 g/L (the WHO assessment level), while 1.6% of these individuals had blood levels >100 g/L (the WHO benchmark for at-risk populations). Native American populations in the western Arctic (Alaska) may be at similar risk as a result of their consumption of marine mammals, although no recent information on methylmercury concentrations in blood, hair or urine for these populations was... 

Braghiroli D, Parenti C, Di Bella M, et al. 1990. Follow-up of methylmercury concentration in brain areas of developing rats exposed during prenatal life using cold-vapor absorption spectrometry. Boll Chim Farm 129(7-8) 259-262. 

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