Methylmercury concentrations increase by roughly a factor of 10 at each step through a food chain, and mehg fish tissue concentrations increase substantially with age. Prenatal exposure to methylmercury can produce various harmful neurological effects during embryonic development, and consumption of fish contaminated with mercury is the primary cause of human ingestion of methylmercury. Bakir f, damluji sf, aminzaki l, murtadha m, khalidi a, alrawi ny, tikriti s, dahahir hi, clarkson tw, smith jc, et al. Determination of methylmercury in fish by gc coupled with thermo scienti. Article information, pdf download for methylmercury in fish from the. Methylmercury mehg casrn 22967926 iris us epa, ord. This study examined methylmercury mehg concentrations in fish, the daily mehg. Methyl mercury in fish a case study on various samples collected from ganges river at west bengal article pdf available in environmental monitoring and assessment 1846. The following large fish have the highest levels of methylmercury, and should be avoided during pregnancy and breastfeeding. Exposure analysis of five fishconsuming populations for. Between 2000 and 2002, canned tuna was the mostconsumed. Graphic by leah burrowsseas the researchers hope that the minamata convention, an international treaty to reduce mercury emissions that was signed in 20 and enacted last year, will. Consumption of fish is the principal route of exposure to methylmercury.
Detection of mercury and methylmercury using icicpms method. Reducing mercury contamination of the fish in minnesotas lakes and streams is a high priority for the minnesota pollution control agency mpca. Determination of methylmercury in seafood 4 2 introduction mercury is an environmental contaminant present in fish and seafood mostly in the form of methylmercury. Total mercury and methylmercury in fish fillets, water. An exposure assessment for methylmercury from seafood for consumers in the united states pdf. Perspectives influencing fish consumption choices, environmental health perspectives, 120. Inorganic mercury discharged from various contaminants flows into seas, rivers, and streams, is converted to methylmercury by bacteria and plankton in water, is accumulated in pelagic organisms including fish and shellfish, and flows into humans through fish and shellfish intake by humans 1,6. However, tilefish from the atlantic ocean have lower average levels of methylmercury. In addition to elemental mercury, atmospheric mercury also exists as divalent mercury. Environmental protection agency, 20, national rivers and streams assessment 20082009a collaborative. Human health risks from methylmercury in fish are evaluated in terms of dose. Methylmercury definition of methylmercury by the free. Percentage of methylmercury in the muscle tissue of.
Humans and wildlife are exposed to mehg primarily through the consumption of contaminated fish, 1 particularly large predatory fish species such as tuna, swordfish, shark, and. Because this mercury poses a health threat, the minnesota. According to the scientific opinion of the european food safety agency efsa published in 2003 1, the major source of methylmercury intake in humans is fish. Introduction toxicological effects of methylmercury the national. For more on the health effects of methylmercury, see our earlier post. The highest percentages of fish tissue samples with hg concentrations that exceeded the criterion of 0. Methylmercury exposure, mercury levels in blood and hair, and health status in swedes consuming contaminated fish. If you do not have the adobe acrobat pdf reader, it is available for free download from adobe systems incorporated.
Methylmercury mehg is a highly toxic compound that. Methylmercury can accumulate in fish to concentrations that threaten human health1. States and tribes may use the criterion as the basis for establishing their water quality standards. Effects of prenatal and postnatal methylmercury exposure from. Methylmercury bioaccumulates with larger fish, which eat smaller.
It is also recommended to avoid tilefish from the gulf of mexico. Methylmercury exposure can attenuate the cardioprotective. Front matter toxicological effects of methylmercury the. Action level for mercury in fish, shellfish, crustaceans and other aquatic animals. Jul 19, 2018 percentage of methylmercury in the muscle tissue of freshwater fish varies with body size and age and among species. Mercury in the nations streamslevels, trends, and implications. Mercury is deposited on water and soil from the air and is converted to methylmercury by microorganisms. Eating fish is an important part of a healthy diet and is a good food choice for pregnancy. Online maps including fish advisories and calenviroscreen. Introduction toxicological effects of methylmercury the.
Mercury evaporates from rock, soil, and water into the air. Methylmercury, one organic form of mercury, can accumulate up the aquatic food chain. Fish were exposed to water containing either low 0. Fish that are older or that eat other fish can accumulate more methylmercury, which builds up in the fish meat. The highest percentages of fishtissue samples with hg concentrations that exceeded the criterion of 0. It affects the immune system, alters genetic and enzyme systems, and damages the nervous system, including coordination and the senses of touch, taste, and sight. Nov 29, 2012 inorganic mercury discharged from various contaminants flows into seas, rivers, and streams, is converted to methylmercury by bacteria and plankton in water, is accumulated in pelagic organisms including fish and shellfish, and flows into humans through fish and shellfish intake by humans 1,6. In general, large fish, fish that have long life spans, and fish that eat other fish are more likely to contain higher amounts of methylmercury. Bioaccumulation of mercury and methylmercury springerlink. Pdf methyl mercury in fish a case study on various.
The oft invoked lipid solubility of mmhg is an inadequate explanation because inorganic hg complexes, which are not bioaccumulated, are as lipid soluble as their mmhg analogs and, unlike other hydrophobic compounds, mmhg in fish resides in protein rather than fat tissue. Mercury is converted to methylmercury in aquatic systems by sulfate and ironreducing bacteria. Methylmercury is formed from inorganic mercury by the action of microbes that live in aquatic systems including lakes, rivers, wetlands, sediments, soils and the open ocean. Consumption of fish is the major route of exposure to methylmercury in the united states. Hgmethylmercury in fish, approximately 10% of the total mercury body burden was present in 1 l of blood in the first few days after exposure. The former, by luciana zimmermann and colleagues, showed in 20 that the methyl and ethylmercury entered cultured rat cells in roughly equal measure and display similar toxicities. But some people eat a lot of fish, every day or several meals per week, and thus can run a significant risk of overexposure to methylmercury. Methylmercury is of particular concern, because it is the toxic form of mercury found in fish. Human health criteria methylmercury the 2001 methylmercury human health criterion is a concentration of methylmercury in fish that epa calculated to protect human health. A field experiment was conducted to determine the degree to which fish accumulated methylmercury mehg via their food or via passive uptake from water through the gills. The comparable dangers of ethylmercury and methylmercury. The concentrations of mercury hg and methyl mercury mehg in sediment and tissues of barbus grypus and barbus esocinus fish species. Finescale dace phoxinus neogaeus were held in 2000 l enclosed pens floating in an undisturbed, oligotrophic lake in northwestern ontario. Mercury, in the form of methylmercury, is found in a myriad of fish species consumed by recreational and subsistence fishers around the world.
Recognizing and preventing overexposure to methylmercury. Mercury, a metal, is widely found in nature in rock and soil, and is washed into surface waters during storms. Hg that enters our oceans, lakes, and rivers is converted to methylmercury mehg by aquatic biota and bioaccumulates in aquatic food webs including fish and shellfish. Methylmercury concentrations in fish exceeded the u. Methylmercury, discharged into water from two chemical plants i. Mcdiarmid m, gardiner p and jack b 2008 the clinical content of preconception care. Methylmercury reported as hg in fishtissue samples collected for the state fish consumption advisory program was used to describe mehg foodweb accumulation and magnification in the reservoirs. Mercury and methylmercury in reservoirs in indiana usgs.
Sources of mercury pollution and the methylmercury. In inland china, rice, rather than fish, is the major pathway. Of the persistent bioaccumulative pollutants, only pcbs exhibit comparable bioconcentration factors. Methylmercury in fish comes from mercury in the aquatic environment. Mercury and methyl mercury concentration in sediment, benthic. Sources of mercury pollution and the methylmercury contamination of fish in minnesota. Introduction toxicological effects of methylmercury. Current advice regarding methylmercury from fish consumption is targeted to protect the developing brain and nervous system but adverse health effects are.
Determination of a sitespecific reference dose for. Inorganic mercury hg discharged into lakes, rivers, and oceans is converted to methylmercury mehg by microorganisms and bioaccumulated up the aquatic food chain. Virtually all fish contain mercury at some level, and most of the mercury in fish is in the more toxic organic form, methylmercury. A toxicologicalepidemiologic evaluation of risks report from an expert group. Methylmercury is particularly damaging to developing embryos, which are five to ten times more sensitive than adults. Fish methylmercury concentrations are high in many reservoirs2 and acidic lakes3, and also in many remote lakes4. Methylmercury exposure and neurotoxicity toxicology jama. Methylmercury concentration in fish and riskbenefit. Pdf mercury and methylmercury bioaccessibility in swordfish. This methylmercury production has been primarily attributed to anaerobic bacteria in the sediment. By the early decades of the twentyfirst century, researchers had yet to determine, a doseeffect but they noted that people. Mercury and methylmercury bioaccessibility in swordfish article pdf available in food additives and contaminants part a chemistry, analysis, control, exposure and risk assessment 273.
Harvard study tracks methylmercury in seafood harvard gazette. In the case of the majority of fish with methylmercury concentrations below 0. Methylmercury is a neurotoxic environmental contaminant, for which fish is the main source of dietary exposure. The factors controlling the accumulation of mercury in fish are poorly understood. Hg methylmercury in fish, approximately 10% of the total mercury body burden was present in 1 l of blood in the first few days after exposure. Mercury contamination in riverine sediments and fish.
Because tuna has relatively higher concentrations of methylmercury, fluctuations in its consumption have a huge impact on u. Fish methylmercury concentrations are high in many reservoirs2 and. Human health risks from methylmercury in fish clarkson. Big head, pomfret, dace, mince, salmon, grey mullet, sole fillet and grass carp. Specifically, information has become available from three independent epidemiological studies indicating that methylmercury levels in the mother during pregnancy predict the probability of adverse.
Human exposure to mehg from contaminated fish and seafood can pose a variety of health risks. Methylmercury in fish from the southern baltic sea and coastal. Apart from methylmercury in fish, the remaining mercury is inorganic, although there is a report of ethylmercury being found in fish downstream of phenylmercury effluent. Microwaveassisted extraction protocol for analysis of total mercury and methylmercury in fish tissues. Significant concentrations of methylmercury in ocean water columns are strongly associated with nutrients and organic. Higher serum longchain omega3 fatty acid concentration, a marker for fish consumption, was beneficially associated with cardiac performance in middleaged and. Methylmercury is particularly damaging to developing embryos, which are.
This prospective study was carefully conducted and analyzed, included a large cohort of motherinfant pairs, and was relatively free of confounding factors. Increasingly, fish species, including the popular cod, are swimming out of reach of u. Methylmercury and human embryonic development the embryo. Methylmercury is commonly found in fish, both freshwater and saltwater. Methylmercury is present in fish from the great lakes and other waterbodies in michigan. Fy16 evaluation of factors influencing methylmercury. Methylmercury definition of methylmercury by merriamwebster. Its derivatives are the major source of organic mercury for humans.
Iris assessment plan for methylmercury scoping and problem formulation materials report jan 2001. Percentage of methylmercury in the muscle tissue of freshwater fish varies with body size and age and among species. This report is available online in portable document format pdf. Recognizing and preventing overexposure to methylmercury from. Methylmercury is highly toxic, especially to the developing nervous system, and it accumulates in the food web.
Human data from poisoning incidents and epidemiological studies have been used by expert committees to derive a guideline intake level for methylmercury, based on the susceptibility of the most sensitive lifestage, the developing fetus. Methylmercury from fish is readily absorbed by humans, with approximately 95% of an ingested dose transferred from the gastrointestinal tract. Among the types of fish covered in the tds study, 7 of were found to contain relatively low levels less than 100 gkg of methylmercury, i. Methylmercury determination in fish and seafood products. The exposures to methylmercury in this population result from chronic, multigenerational ingestion of contaminated fish. Fy16 evaluation of factors influencing methylmercury accumulation in south florida marshes annual report contract no.