Mercury in fish
Mercury is dangerous to both natural ecosystems and humans because it is a metal known to be highly toxic, especially due to its neurotoxic ability to damage the central nervous system.
Species of fish that are long-lived and high on the food chain, such as marlin, tuna, shark, swordfish, king mackerel and tilefish contain higher concentrations of mercury than others.
[7] This results in the bioaccumulation of mercury, in a buildup in the adipose tissue of successive trophic levels: zooplankton, small nekton, larger fish, and so on.
[8] This process explains why predatory fish such as swordfish and sharks or birds like osprey and eagles have higher concentrations of mercury in their tissue than could be accounted for by direct exposure alone.
Knowing how easily and how often previously emitted mercury can be released helps us learn how long it will take for a reduction in anthropogenic sources to be reflected in the environment.
Non-point sources include floods that create hospitable habitats for bacteria that can convert mercury to methylmercury, which is the toxic form that bioaccumulates through aquatic food webs.
The effects of these different sources of mercury have been studied at the Experimental Lakes Area in Ontario, Canada, using research procedures including whole-lake ecosystem experiments and non-lethal fish muscle biopsies.
Flue-gas desulfurization, normally used to eliminate sulfur dioxide, can also be used in conjunction with APCDs to remove additional mercury before exhausts are released into the environment.
[1] Even so, countries such as South Korea have only begun to use inventories of mercury sources, calling into question how fast anti-mercury measures will be put into factories.
In the United States, Wallace gathered data that indicated 16.9% of women who self-identify as Native American, Asian, Pacific Islander, or multiracial exceed the recommended reference dose of mercury.
[clarification needed] In the United States, the Environmental Protection Agency (EPA) estimates the amount of mercury in human blood that is not likely to pose fatal health outcomes.
Symptoms of exposure to high levels of methyl mercury include disturbed vision, hearing, and speech, lack of coordination, and muscle weakness.
[22][failed verification] Addressing the issues of fish consumption forces health officials to recognize the sources of mercury in the human body.
Exposure risk was assessed through a medical study, thus raising judicial issues of whether the public health of these groups is a priority in the United States.
Around 20% of the women selected, after hair and blood samples, were found to have exceeded the EPA-recommended reference dose of 0.1 micrograms of methyl mercury per kilogram of body weight.
Additionally, the study concluded that there was "no margin of safety for neuraldevelopmental effects in fetus[es]"[24] without removing the offending species of fish from the diets of the women.
Children exposed to mercury are particularly susceptible to poisoning since the ratio of food, water, and air intake versus individual body weight is much higher than that of adults.
One study shows "no significant differences in mercury levels in tuna, bluefish, and flounder as a function of type of store or economic neighborhood".
In Ghana, the local population traditionally consumes large quantities of fish, leading to potentially dangerous amounts of mercury in the bloodstream.
[29] A 2014 USGS survey of mercury levels in the United States water system found that methylmercury concentrations in fish were typically highest in wetland areas including the coastal plain streams in the Southeast.
[30][full citation needed] In the 1950s, inhabitants of the seaside town of Minamata, on Kyushu island in Japan, noticed strange behavior in animals.
It was found that the Chisso Corporation, a petrochemical company and maker of plastics such as vinyl chloride, had been discharging heavy metal waste into the sea for decades.
The American College of Obstetricians and Gynecologists noted that, considering all the dangers and benefits, the overall result of eating fish in the United States is likely to improve personal health rather than damage it.
[17] The College argues that the omega-3 polyunsaturated fatty acids found in fish have a health benefit that outweighs the harm from mercury or polychlorinated biphenyls.
[31] The Seychelles Child Development Study traced more than seven hundred mother-child pairs for nine years and found no neurological problems in the children resulting from both prenatal and postnatal methylmercury exposure.
Recently, the EU estimated the Mercury content in the topsoils based on a large Land Cover Survey named LUCAS.
The Minamata Convention, named after the Japanese city that suffered horribly from mercury pollution, has taken four years of negotiation but was finally adopted by delegates from over 140 countries.
[5] Because methyl mercury and high levels of elemental mercury can be particularly toxic to a fetus or young children, government agencies, including the EPA and FDA, recommend that women who are pregnant or plan to become pregnant within the next one or two years, as well as young children, avoid eating more than 6 ounces (170g, one average meal) of fish per week.
[21] In the United States, the FDA established an action level for methylmercury in commercial marine and freshwater fish that is 1.0 parts per million (ppm).
website (sponsored by Turtle Island Restoration Network, a non-profit organization) includes a calculator for determining mercury levels in fish.
