Mercury In Fish
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The presence of
mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...
in
fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
is a health concern for people who eat them, especially for women who are or may become pregnant, nursing mothers, and young children. Fish and
shellfish Shellfish is a colloquial and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater envir ...
concentrate mercury in their bodies, often in the form of methylmercury, a highly toxic
organomercury Organomercury refers to the group of organometallic compounds that contain mercury. Typically the Hg–C bond is stable toward air and moisture but sensitive to light. Important organomercury compounds are the methylmercury(II) cation, CH3Hg+; ...
compound. This element is known to
bioaccumulate Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated ...
in humans, so bioaccumulation in
seafood Seafood is any form of sea life regarded as food by humans, prominently including fish and shellfish. Shellfish include various species of molluscs (e.g. bivalve molluscs such as clams, oysters and mussels, and cephalopods such as octopus an ...
carries over into human populations, where it can result in
mercury poisoning Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rashe ...
. Mercury is dangerous to both natural
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
s and humans because it is a
metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...
known to be highly
toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...
, especially due to its
neurotoxic Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specificall ...
ability to damage the
central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...
. In human-controlled ecosystems of fish, usually done for market production of wanted seafood species, mercury clearly rises through the food chain via fish consuming small
plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
, as well as through non-food sources such as underwater sediment. Fish products have been shown to contain varying amounts of
heavy metals upright=1.2, Crystals of osmium, a heavy metal nearly twice as dense as lead">lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals are generally defined as ...
, particularly mercury and fat-soluble pollutants from
water pollution Water pollution (or aquatic pollution) is the contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water ...
. Species of fish that are long-lived and high on the
food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), det ...
, such as
marlin Marlins are fish from the family Istiophoridae, which includes about 10 species. A marlin has an elongated body, a spear-like snout or bill, and a long, rigid dorsal fin which extends forward to form a crest. Its common name is thought to deri ...
,
tuna A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max length: ...
,
shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...
,
swordfish Swordfish (''Xiphias gladius''), also known as broadbills in some countries, are large, highly migratory predatory fish characterized by a long, flat, pointed bill. They are a popular sport fish of the billfish category, though elusive. Swordfis ...
,
king mackerel The king mackerel (''Scomberomorus cavalla'') or kingfish, is a migratory species of mackerel of the western Atlantic Ocean and Gulf of Mexico. It is an important species to both the commercial and recreational fishing industries. Description T ...
and
tilefish 250px, Blue blanquillo, ''Malacanthus latovittatus'' Tilefishes are mostly small perciform marine fish comprising the family Malacanthidae. They are usually found in sandy areas, especially near coral reefs. Commercial fisheries exist for th ...
contain higher concentrations of mercury than others.
Cetaceans Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...
(
whales Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...
and
dolphins A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (t ...
) also bioaccumulate mercury and other pollutants, so populations which eat
whale meat Whale meat, broadly speaking, may include all cetaceans (whales, dolphins, porpoises) and all parts of the animal: muscle (meat), organs (offal), skin (muktuk), and fat (blubber). There is relatively little demand for whale meat, compared to ...
, such as the Japanese, Icelanders,
Norwegians Norwegians ( no, nordmenn) are a North Germanic ethnic group and nation native to Norway, where they form the vast majority of the population. They share a common culture and speak the Norwegian language. Norwegians are descended from the N ...
and the Faroese, are also vulnerable to mercury ingestion.


Biomagnification

The consumption of fish is by far the most significant source of ingestion-related mercury exposure in humans and animals.
Mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...
and
methyl mercury Methylmercury (sometimes methyl mercury) is an organometallic cation with the formula . It is the simplest organomercury compound. Methylmercury is extremely toxic, and its derivatives are the major source of organic mercury for humans. It is ...
are present in only very small concentrations in
seawater Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...
. However, they are absorbed, usually as methyl mercury, by
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
at the start of the
food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), det ...
. This algae is then eaten by fish and other organisms higher in the food chain. Fish efficiently absorb methyl mercury, but excrete it very slowly. Methyl mercury is not soluble and therefore not excreted. Instead, it accumulates, primarily in the
viscera In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a ...
, although also in the muscle tissue. This results in the
bioaccumulation Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated ...
of mercury, in a buildup in the
adipose Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular ...
tissue of successive
trophic level The trophic level of an organism is the position it occupies in a food web. A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it i ...
s:
zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
, small
nekton Nekton or necton (from the ) refers to the actively swimming aquatic organisms in a body of water. The term was proposed by German biologist Ernst Haeckel to differentiate between the active swimmers in a body of water, and the passive organisms t ...
, larger fish, and so on. The older that such fish become, the more mercury they may have absorbed. Anything that eats these fish within the
food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), det ...
also consumes the higher level of mercury that the fish have accumulated, including humans. This process explains why predatory fish such as
swordfish Swordfish (''Xiphias gladius''), also known as broadbills in some countries, are large, highly migratory predatory fish characterized by a long, flat, pointed bill. They are a popular sport fish of the billfish category, though elusive. Swordfis ...
and
shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...
s or birds like
osprey The osprey (''Pandion haliaetus''), , also called sea hawk, river hawk, and fish hawk, is a diurnal, fish-eating bird of prey with a cosmopolitan range. It is a large raptor reaching more than in length and across the wings. It is brown o ...
and
eagle Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, just ...
s have higher concentrations of mercury in their tissue than could be accounted for by direct exposure alone. Species on the food chain can amass body concentrations of mercury up to ten times higher than the species they consume. This process is called biomagnification. For example, herring contains mercury levels at about 0.1 parts per million, while shark contains mercury levels greater than 1 part per million.


Origins of mercury pollution


Terrestrial mercury pollution

There are three types of mercury emission:
anthropogenic Anthropogenic ("human" + "generating") is an adjective that may refer to: * Anthropogeny, the study of the origins of humanity Counterintuitively, anthropogenic may also refer to things that have been generated by humans, as follows: * Human im ...
, re-emission, and natural, including
volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ...
es and geothermal vents. Anthropogenic sources are responsible for 30% of all emissions, while natural sources are responsible for 10%, and re-emission accounts for the other 60%. While re-emission accounts for the largest proportion of emissions, it is likely that the mercury emitted from these sources originally came from anthropogenic sources. Anthropogenic sources include coal burning,
cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mix ...
production, oil refining,
artisan An artisan (from french: artisan, it, artigiano) is a skilled craft worker who makes or creates material objects partly or entirely by hand. These objects may be functional or strictly decorative, for example furniture, decorative art ...
and small-scale gold mining, wastes from consumer products,
dental amalgam Dental amalgam is a liquid mercury and metal alloy mixture used in dentistry to fill cavities caused by tooth decay. Low-copper amalgam commonly consists of mercury (50%), silver (~22–32%), tin (~14%), zinc (~8%) and other trace metals. ...
, the
chlor-alkali The chloralkali process (also chlor-alkali and chlor alkali) is an industrial process for the electrolysis of sodium chloride (NaCl) solutions. It is the technology used to produce chlorine and sodium hydroxide (caustic soda), which are commod ...
industry, production of
vinyl chloride Vinyl chloride is an organochloride with the formula H2C=CHCl. It is also called vinyl chloride monomer (VCM) or chloroethene. This colorless compound is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride (PVC ...
, and the mining,
smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a ch ...
, and production of
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
and other metals. The total amount of mercury released by mankind in 2010 was estimated to be 1,960 metric tons. The majority of this comes from coal burning and gold mining, accounting for 24% and 37% of total anthropogenic output respectively. Re-emission, the largest emitter, occurs in a variety of ways. It is possible for mercury that has been deposited in soil to be re-emitted into the
mercury cycle The mercury cycle is a biogeochemical cycle influenced by natural and anthropogenic processes that transform mercury through multiple chemical forms and environments. Mercury is present in the Earth's crust and in various forms on the Earth ...
via floods. A second example of re-emission is a
forest fire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire ...
; mercury that has been absorbed into
plant life Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...
is re-released into the
atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...
. While it is difficult to estimate the exact extent of mercury re-emission, it is an important field of study. 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. Mercury that has been released can find its way into the
ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...
s. A 2008 model estimated the total amount of deposition into the oceans that year to be 3,700 metric tons. It is estimated that
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...
s carry as much as 2,420 metric tons. Much of the mercury deposited in the oceans is re-emitted, however; as much as 300 metric tons is converted into methyl mercury. While only 13% of this finds its way into the food chain, that is still 40 metric tons a year. Much (an estimated 40%) of the mercury that eventually finds its way into fish originates with
coal-burning power plant A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity. Worldwide, there are about 8,500 coal-fired power stations totaling over 2,000 gigawatts capacity. They generate about a th ...
s and
chlorine production Chlorine gas can be produced by extracting from natural materials, including the electrolysis of a sodium chloride solution (brine) and other ways. Gas extraction Chlorine can be manufactured by the electrolysis of a sodium chloride solution (bri ...
plants. The largest source of mercury contamination in the United States is coal-fueled power plant emissions. Chlorine chemical plants use mercury to extract chlorine from salt, which in many parts of the world is discharged as mercury compounds in waste water, though this process has been largely replaced by the more economically viable membrane cell process, which does not use mercury. Coal contains mercury as a natural contaminant. When it is fired for electricity generation, the mercury is released as smoke into the atmosphere. Most of this mercury pollution can be eliminated if pollution-control devices are installed. Mercury in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
frequently comes from
power plants A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid. Many pow ...
, which release about 50% of the nation's mercury
emissions Emission may refer to: Chemical products * Emission of air pollutants, notably: **Flue gas, gas exiting to the atmosphere via a flue ** Exhaust gas, flue gas generated by fuel combustion ** Emission of greenhouse gases, which absorb and emit rad ...
. In other countries, such as
Ghana Ghana (; tw, Gaana, ee, Gana), officially the Republic of Ghana, is a country in West Africa. It abuts the Gulf of Guinea and the Atlantic Ocean to the south, sharing borders with Ivory Coast in the west, Burkina Faso in the north, and To ...
,
gold mining Gold mining is the extraction of gold resources by mining. Historically, mining gold from alluvial deposits used manual separation processes, such as gold panning. However, with the expansion of gold mining to ores that are not on the surface ...
requires mercury
compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fortified with defensive struct ...
s, leading to workers receiving significant quantities of mercury while performing their jobs. Such mercury from gold mines is specifically known to contribute to
biomagnification Biomagnification, also known as bioamplification or biological magnification, is any concentration of a toxin, such as pesticides, in the tissues of tolerant organisms at successively higher levels in a food chain. This increase can occur as a ...
in aquatic
food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), det ...
s. Elemental mercury often comes from
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...
power plants, and
oxidized Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
mercury often comes from
incinerator Incineration is a waste treatment process that involves the combustion of substances contained in waste materials. Industrial plants for waste incineration are commonly referred to as waste-to-energy facilities. Incineration and other high ...
s. Oil-fired power plants also contribute mercury to the environment. The
energy industry The energy industry is the totality of all of the industries involved in the production and sale of energy, including fuel extraction, manufacturing, refining and distribution. Modern society consumes large amounts of fuel, and the energy indu ...
therefore is a key player in the introduction of mercury into the
environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...
. When addressing the issue of reducing seafood mercury bioaccumulation on a global scale, it is important to pinpoint major energy producers and consumers whose exchange of energy may be the root of the problem.


Aquatic mercury pollution

The farming of aquatic organisms, known as
aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lot ...
, often involves
fish feed Manufactured feeds are an important part of modern commercial aquaculture, providing the balanced nutrition needed by farmed fish. The feeds, in the form of granules or pellets, provide the nutrition in a stable and concentrated form, enabling th ...
that contains mercury. A study by Jardine has found no reliable connection between mercury in fish food affecting aquaculture organisms or aquatic organisms in the wild. Even so, mercury from other sources may affect organisms grown through aquaculture. In
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
, farmed fish species, such as
bighead carp The bighead carp (''Hypophthalmichthys nobilis'') is a species of cyprinid freshwater fish native to East Asia, and is one of several Asian carps introduced into North America. It is one of the most intensively exploited fishes in fish farming, ...
, mud carp, and ''
Siniperca chuatsi ''Siniperca chuatsi'', the mandarin fish (,), is a species of freshwater ray-finned fish from the family Sinipercidae, the Oriental perches. It is the type species of the genus ''Siniperca'' (Chinese perches). Description ''Siniperca chautsi'' ...
'', carried 90% of total mercury content in all of the measured fish in a study by Cheng. This study also concluded that mercury bioaccumulates through food chains even in controlled aquaculture environments. Both total mercury and methyl mercury absorption was found to be derived from sediments containing mercury, not mainly from fish feed. The
Hawaii Institute of Marine Biology Hawaii ( ; haw, Hawaii or ) is a U.S. state, state in the Western United States, Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is ...
has noted that fish feed used in aquaculture often contains
heavy metals upright=1.2, Crystals of osmium, a heavy metal nearly twice as dense as lead">lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals are generally defined as ...
such as mercury,
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
, and
arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but ...
, and has dispatched these concerns to organizations such as the
Food and Agriculture Organization The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...
of the
United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and international security, security, develop friendly relations among nations, achieve international cooperation, and be ...
. Mercury can get into
freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
systems by point sources and extended flooding. In
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
, mercury poisoning in
Grassy Narrows Asubpeeschoseewagong First Nation (also known as Grassy Narrows First Nation or the ''Asabiinyashkosiwagong Nitam-Anishinaabeg'' in the Ojibwe language) is an Ojibwe First Nations band government who inhabit northern Kenora in Ontario, Canada ...
was likely caused by a spill at a
paper mill A paper mill is a factory devoted to making paper from vegetable fibres such as wood pulp, old rags, and other ingredients. Prior to the invention and adoption of the Fourdrinier machine and other types of paper machine that use an endless belt, ...
, which is a point source. Non-point sources include floods that create hospitable habitats for
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
that can convert mercury to methylmercury, which is the toxic form that bioaccumulates through aquatic
food web A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Another name for food web is consumer-resource system. Ecologists can broadly lump all life forms into one ...
s. The effects of these different sources of mercury have been studied at the
Experimental Lakes Area IISD Experimental Lakes Area (IISD-ELA, known as ELA before 2014) is an internationally unique research station encompassing 58 formerly pristine freshwater lakes in Kenora District Ontario, Canada. Previously run by Fisheries and Oceans Canada, ...
in
Ontario, Canada Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central C ...
, using research procedures including whole-lake ecosystem experiments and non-lethal fish muscle
biopsies A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a diseas ...
.


Controlling output of mercury pollution sources

A study that was led by scientists from Harvard University and U.S. Geological Survey has determined that in the next several decades there will be a 50 percent increase in mercury levels. The study also shows that the increases are connected through industrial emissions and are not natural as previously thought.However, by decreasing emissions from industrial plants, the possibility of decreasing the high level of mercury remains plausible. Several nations are currently implementing systems that will detect and therefore later be able to control the output of mercury into the atmosphere. Air pollution control devices (APCDs) have been implemented in
South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
as the
government A government is the system or group of people governing an organized community, generally a state. In the case of its broad associative definition, government normally consists of legislature, executive, and judiciary. Government is a ...
is starting to take inventory of mercury sources. Mercury pollution can also be removed by
electrostatic precipitator An electrostatic precipitator (ESP) is a filterless device that removes fine particles, like dust and smoke, from a flowing gas using the force of an induced electrostatic charge minimally impeding the flow of gases through the unit. In con ...
s (ESPs). Bag-based filters are also used in
factories A factory, manufacturing plant or a production plant is an industrial facility, often a complex consisting of several buildings filled with machinery, where workers manufacture items or operate machines which process each item into another. T ...
that may contribute mercury to the environment. Flue-gas desulfurization, normally used to eliminate
sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activ ...
, can also be used in conjunction with APCDs to remove additional mercury before exhausts are released into the environment. 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.


Health effects and outcomes


Disparate impacts

Mercury content in fish does not affect all populations equally. Certain ethnic groups, as well as young children, are more likely to suffer the effects of methyl mercury poisoning. In the United States, Wallace gathered data that indicated 16.9% of women who self-identify as Native American,
Asian Asian may refer to: * Items from or related to the continent of Asia: ** Asian people, people in or descending from Asia ** Asian culture, the culture of the people from Asia ** Asian cuisine, food based on the style of food of the people from Asi ...
,
Pacific Islander Pacific Islanders, Pasifika, Pasefika, or rarely Pacificers are the peoples of the list of islands in the Pacific Ocean, Pacific Islands. As an ethnic group, ethnic/race (human categorization), racial term, it is used to describe the original p ...
, or multiracial exceed the recommended
reference dose A reference dose is the United States Environmental Protection Agency's maximum acceptable oral dose of a toxic substance.Reference doses are most commonly determined for pesticides. The EPA defines an oral reference dose (abbreviated RfD) as: es ...
of mercury. A study done on children of the
Faroe Islands The Faroe Islands ( ), or simply the Faroes ( fo, Føroyar ; da, Færøerne ), are a North Atlantic island group and an autonomous territory of the Kingdom of Denmark. They are located north-northwest of Scotland, and about halfway bet ...
in the North Atlantic showed neurological problems stemming from mothers consuming
pilot whale Pilot whales are cetaceans belonging to the genus ''Globicephala''. The two extant species are the long-finned pilot whale (''G. melas'') and the short-finned pilot whale (''G. macrorhynchus''). The two are not readily distinguishable at sea, ...
meat during pregnancy (see
Whaling in the Faroe Islands Whaling in the Faroe Islands, or (from the Faroese terms , meaning pilot whale, and , meaning killing), is a type of drive hunting that involves herding various species of whales and dolphins, but primarily pilot whales, into shallow bays ...
). A 2020 NBER paper found that in coastal Colombia, those born during periods when fish catches have high mercury content have worse educational and labor market outcomes than those born during periods of low mercury content in fish.


Regulation and health

While various studies have shown high concentrations of mercury accumulated in fish, medical cases often go unreported and pose a difficulty in correlating mercury in fish with human poisoning. Environmental issues cover a broad range of areas, but medical cases that are associated with pollutants released into the environment by factories or construction areas cause
public health Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the det ...
issues that affect not only the environment but also human well-being. Substances poisonous to the
human body The human body is the structure of a Human, human being. It is composed of many different types of Cell (biology), cells that together create Tissue (biology), tissues and subsequently organ systems. They ensure homeostasis and the life, viabi ...
in a particular amount or dose may not cause any symptoms over time. While there are limits to how much of anything the body can have, mercury is a particular poison that produces immediate physical symptoms when the body has been accumulating it over a period of time. In the United States, the Environmental Protection Agency estimates the amount of mercury in human blood that is not likely to pose
fatal Fatal may refer to: * ''Fatal'' (album), by Hussein Fatal, 2002 * ''Fatal'' (film), a 2010 French film starring Michaël Youn and Stéphane Rousseau * '' F.A.T.A.L.'', a tabletop role-playing game released in 2003 * Fatal Recordings, a record ...
health outcomes. The agency is in charge of enforcing regulations and policies that cover a range of environmental topics. Analysis of blood mercury concentrations in childbearing women has documented that exposure to methyl mercury (MeHg) occurs primarily through the consumption of fish. The U.S. FDA highly recommends against pregnant women and young children consuming raw fish. Pregnant women and young children often lack strong immune systems and are more at risk for foodborne illnesses.


Medical cases and exposure to mercury

In the United States, the
EPA The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...
provides advice about the levels of mercury that are non-fatal in humans. Symptoms of exposure to high levels of methyl mercury include disturbed
vision Vision, Visions, or The Vision may refer to: Perception Optical perception * Visual perception, the sense of sight * Visual system, the physical mechanism of eyesight * Computer vision, a field dealing with how computers can be made to gain un ...
,
hearing Hearing, or auditory perception, is the ability to perceive sounds In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psycholog ...
, and speech, lack of coordination, and
muscle weakness Muscle weakness is a lack of muscle strength. Its causes are many and can be divided into conditions that have either true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, includi ...
. Medical studies have examined the correlation of fish consumption and health issues. American studies have presented evidence of fish consumption and its effects on
child development Child development involves the Human development (biology), biological, developmental psychology, psychological and emotional changes that occur in human beings between birth and the conclusion of adolescence. Childhood is divided into 3 stages o ...
.
Longitudinal studies A longitudinal study (or longitudinal survey, or panel study) is a research design that involves repeated observations of the same variables (e.g., people) over short or long periods of time (i.e., uses longitudinal data). It is often a type of obs ...
agree that human activities release mercury that accumulates in
marine life Marine life, sea life, or ocean life is the plants, animals and other organisms that live in the salt water of seas or oceans, or the brackish water of coastal estuaries. At a fundamental level, marine life affects the nature of the planet. M ...
. Addressing the issues of fish consumption forces health officials to recognize the sources of mercury in the human body. Specific Native American tribes are vulnerable to a high exposure of mercury. Studies have determined that these native peoples in the United States suffer more from mercury
poisoning A poison can be any substance that is harmful to the body. It can be swallowed, inhaled, injected or absorbed through the skin. Poisoning is the harmful effect that occurs when too much of that substance has been taken. Poisoning is not to ...
and illness than any other
cohort Cohort or cohortes may refer to: * Cohort (educational group), a group of students working together through the same academic curriculum * Cohort (floating point), a set of different encodings of the same numerical value * Cohort (military unit ...
group in the country. This is due to the fact that fish is a main source of protein. Exposure risk was assessed through a medical study, thus raising
judicial The judiciary (also known as the judicial system, judicature, judicial branch, judiciative branch, and court or judiciary system) is the system of courts that adjudication, adjudicates legal disputes/disagreements and interprets, defends, and app ...
issues of whether the
public health Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the det ...
of these groups is a priority in the United States.


Work and exposure

Most cases that arise are due to work exposure or medicinal poisoning.
Environmental justice Environmental justice is a social movement to address the unfair exposure of poor and marginalized communities to harms from hazardous waste, resource extraction, and other land uses.Schlosberg, David. (2007) ''Defining Environmental Justic ...
advocates can relate these mercury cases to the unregulated amount of mercury that enters the environment. Workers can be exposed to mercury through the manufacture of fluorescent tubes,
chloralkali The chloralkali process (also chlor-alkali and chlor alkali) is an industrial process for the electrolysis of sodium chloride (NaCl) solutions. It is the technology used to produce chlorine and sodium hydroxide (caustic soda), which are comm ...
, or
acetaldehyde Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is a colorless liquid or gas, boiling near room temperature. It is one of the mos ...
among other products.
Anthropogenic Anthropogenic ("human" + "generating") is an adjective that may refer to: * Anthropogeny, the study of the origins of humanity Counterintuitively, anthropogenic may also refer to things that have been generated by humans, as follows: * Human im ...
sources and places where mercury is released or used as a solid or vapor puts these has caused
fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...
,
dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a common medical c ...
,
hyperhidrosis Hyperhidrosis is a condition characterized by abnormally increased sweating, in excess of that required for regulation of body temperature. Although primarily a benign physical burden, hyperhidrosis can deteriorate quality of life from a psychologi ...
, chest congestion, and loss of motor skills. When taken to the hospital, the
neurotoxicity Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specificall ...
levels had already exceeded the maximum amounts. Over-the-counter medicines have been shown to have traces of mercurous chloride. Medical research reported that the children who received doses of these medicines experienced physical symptoms such as "
drooling Drooling, or slobbering, is the flow of saliva outside the mouth. Drooling can be caused by excess production of saliva, inability to retain saliva within the mouth (incontinence of saliva), or problems with swallowing (dysphagia or odynophagia ...
, irregular arm movements, and impaired gait". Exposures to this result in severe physical impairments unregulated chemicals that are put in products. The intake of
laxatives Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lub ...
that contained about 120 mg of mercurous chloride has also been cases of mercury's toxicity. Even in countries, such as
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...
, that have phased out mercury in the dental industry and manufacturing, lingering quantities of mercury still exist in
lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...
s and coastal areas. Moreover, global contributions of mercury to the environment also affect that country. A study in Sweden selected 127 women who had a high level of fish consumption. Around 20% of the women selected, after
hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and f ...
and
blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the c ...
samples, were found to have exceeded the
EPA The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...
's recommended
reference dose A reference dose is the United States Environmental Protection Agency's maximum acceptable oral dose of a toxic substance.Reference doses are most commonly determined for pesticides. The EPA defines an oral reference dose (abbreviated RfD) as: es ...
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 s without removing the offending species of fish from the diets of the women. This indicates that families intending to raise children should be especially careful about exposing their unborn babies to toxic mercury via fish. Children exposed to mercury are particularly susceptible to
poisoning A poison can be any substance that is harmful to the body. It can be swallowed, inhaled, injected or absorbed through the skin. Poisoning is the harmful effect that occurs when too much of that substance has been taken. Poisoning is not to ...
since the ratio of food, water, and air intake versus individual body weight is much higher than that of
adult An adult is a human or other animal that has reached full growth. In human context, the term ''adult'' has meanings associated with social and legal concepts. In contrast to a " minor", a legal adult is a person who has attained the age of major ...
s. Additionally, children undergo fast growth that causes them to be more susceptible to damaging exposure to methylmercury, as well as the long term consequences of such exposure during
childhood development Child development involves the biological, psychological and emotional changes that occur in human beings between birth and the conclusion of adolescence. Childhood is divided into 3 stages of life which include early childhood, middle childhood, ...
. Young age plays an important role in terms of damage caused by mercury, and much literature on mercury focuses on
pregnant women Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ca ...
and specific precautions designed to prevent youth mercury exposure. Prenatal methylmercury exposure does cause
behavioral Behavior (American English) or behaviour (British English) is the range of actions and mannerisms made by individuals, organisms, systems or artificial entities in some environment. These systems can include other systems or organisms as well ...
problems in infants and worsened
cognitive Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...
test performance. Additionally, Hughner estimates that 250,000 women may be exposing their unborn babies to levels of methyl mercury above recommended federal levels. Economically, there does not seem to be a difference in mercury exposure based on
socioeconomic Socioeconomics (also known as social economics) is the social science that studies how economic activity affects and is shaped by social processes. In general it analyzes how modern societies progress, stagnate, or regress because of their local ...
bracket and the ability to buy
fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
from the market. One study shows "no significant differences in mercury levels in
tuna A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max length: ...
,
bluefish The bluefish (''Pomatomus saltatrix'') is the only extant species of the family Pomatomidae. It is a marine pelagic fish found around the world in temperate and subtropical waters, except for the northern Pacific Ocean. Bluefish are known as ta ...
, and
flounder Flounders are a group of flatfish species. They are demersal fish, found at the bottom of oceans around the world; some species will also enter estuaries. Taxonomy The name "flounder" is used for several only distantly related species, thou ...
as a function of type of store or economic neighborhood".


By nation

Certain
countries A country is a distinct part of the world, such as a state (polity), state, nation, or other polity, political entity. It may be a sovereign state or make up one part of a larger state. For example, the country of Japan is an independent, so ...
have
cultural Culture () is an umbrella term which encompasses the social behavior, institutions, and Social norm, norms found in human Society, societies, as well as the knowledge, beliefs, arts, laws, Social norm, customs, capabilities, and habits of the ...
differences that lead to more fish consumption and therefore more possible exposure to
seafood Seafood is any form of sea life regarded as food by humans, prominently including fish and shellfish. Shellfish include various species of molluscs (e.g. bivalve molluscs such as clams, oysters and mussels, and cephalopods such as octopus an ...
methylmercury. In
Ghana Ghana (; tw, Gaana, ee, Gana), officially the Republic of Ghana, is a country in West Africa. It abuts the Gulf of Guinea and the Atlantic Ocean to the south, sharing borders with Ivory Coast in the west, Burkina Faso in the north, and To ...
, the local population traditionally consumes large quantities of fish, leading to potentially dangerous amounts of mercury in the
bloodstream The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
. In the Amazonian Basin, during the
rainy season The rainy season is the time of year when most of a region's average annual rainfall occurs. Rainy Season may also refer to: * ''Rainy Season'' (short story), a 1989 short horror story by Stephen King * "Rainy Season", a 2018 song by Monni * ''T ...
,
herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
fish dominate the diet of 72.2% of the women selected from a particular Amazonian
village A village is a clustered human settlement or community, larger than a hamlet but smaller than a town (although the word is often used to describe both hamlets and smaller towns), with a population typically ranging from a few hundred to ...
. Analysis also shows increase of mercury content in the hair of humans who eat fish on a daily basis in the Amazon. The most serious case of mercury poisoning in recent history was in the Japanese city of
Minamata is a city located in Kumamoto Prefecture, Japan. It is on the west coast of Kyūshū and faces Amakusa islands. Minamata was established as a village in 1889, re-designated as a town in 1912 and grew into a city in 1949. As of March 2017, the ...
, in the 1950s. Minamata poisoning demonstrated that significant
prenatal Prenatal development () includes the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal devel ...
and
postnatal The postpartum (or postnatal) period begins after childbirth and is typically considered to end within 6 weeks as the mother's body, including hormone levels and uterus size, returns to a non-pregnant state. The terms puerperium, puerperal perio ...
exposure to high levels of methylmercury caused serious neurological problems. Minamata victims also showed higher than normal signs of
psychiatric disease A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitti ...
s, along with those
disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
s being caused by underlying neurological issues. 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. Fish methylmercury levels were also high in the Western US, but only in streams that had been mined for mercury or gold.


Minamata disease

In the 1950s, inhabitants of the seaside town of
Minamata is a city located in Kumamoto Prefecture, Japan. It is on the west coast of Kyūshū and faces Amakusa islands. Minamata was established as a village in 1889, re-designated as a town in 1912 and grew into a city in 1949. As of March 2017, the ...
, on
Kyushu is the third-largest island of Japan's five main islands and the most southerly of the four largest islands ( i.e. excluding Okinawa). In the past, it has been known as , and . The historical regional name referred to Kyushu and its surroun ...
island in Japan, noticed strange behavior in animals. Cats would exhibit nervous tremors, dance, and scream. Within a few years, this was observed in other animals; birds would drop out of the sky. Symptoms were also observed in fish, an important component of the diet, especially for the poor. When human symptoms started to be noticed around 1956 an investigation began. Fishing was officially banned in 1957. It was found that the
Chisso Corporation The , since 2012 reorganized as JNC (Japan New Chisso), is a Japanese chemical company. It is an important supplier of liquid crystal used for LCDs, but is best known for its role in the 34-year-long pollution of the water supply in Minamata, Ja ...
, a
petrochemical Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sou ...
company and maker of
plastics Plastics are a wide range of synthetic polymers, synthetic or semi-synthetic materials that use polymers as a main ingredient. Their Plasticity (physics), plasticity makes it possible for plastics to be Injection moulding, moulded, Extrusion, e ...
such as
vinyl chloride Vinyl chloride is an organochloride with the formula H2C=CHCl. It is also called vinyl chloride monomer (VCM) or chloroethene. This colorless compound is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride (PVC ...
, had been discharging heavy metal waste into the sea for decades. They used mercury compounds as catalysts in their syntheses. It is believed that about 5,000 people were killed and perhaps 50,000 were to some extent poisoned by mercury.
Mercury poisoning Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rashe ...
in Minamata, Japan, is now known as
Minamata disease Minamata disease is a neurological disease caused by severe mercury poisoning. Signs and symptoms include ataxia, numbness in the hands and feet, general muscle weakness, loss of peripheral vision, and damage to hearing and speech. In extrem ...
.


Seafood consumption benefits

The
American College of Obstetricians and Gynecologists The American College of Obstetricians and Gynecologists (ACOG) is a professional association of physicians specializing in obstetrics and gynecology in the United States. Several Latin American countries are also represented within Districts of ...
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. 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 biphenyl Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act in 1979 and internationally by t ...
s. Even so, the College suggested limiting fish consumption for pregnant women. A risk-benefit study weighing the risks of mercury consumption against the benefits derived from fish in Alaska showed that the benefits outweigh the risks when consuming salmon for both cardiovascular health and infant neurological development, and that methyl mercury data for non-oily fish need to be of high quality before relative risk can be reliably identified. The
Seychelles Seychelles (, ; ), officially the Republic of Seychelles (french: link=no, République des Seychelles; Creole: ''La Repiblik Sesel''), is an archipelagic state consisting of 115 islands in the Indian Ocean. Its capital and largest city, V ...
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. A study done with marketed fish in
Oman Oman ( ; ar, عُمَان ' ), officially the Sultanate of Oman ( ar, سلْطنةُ عُمان ), is an Arabian country located in southwestern Asia. It is situated on the southeastern coast of the Arabian Peninsula, and spans the mouth of t ...
concluded that, except in a few rare cases, the fish available for consumption had lower levels of mercury than limits defined by various health organizations. Some, citing these studies, have suggested the creation of place-based consumption advisories.Loring, Philip A., and Lawrence K. Duffy, (2011) "Managing Environmental Risks: The Benefits of a Place-Based Approach." Remote and Rural Health, Vol. 11(3), p.1800, However place-based approaches do not take into account cases of severe mercury poisoning, such as that found in
Minamata disease Minamata disease is a neurological disease caused by severe mercury poisoning. Signs and symptoms include ataxia, numbness in the hands and feet, general muscle weakness, loss of peripheral vision, and damage to hearing and speech. In extrem ...
.
Selenium Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, ...
is an element that is known to counteract some of the dangers of ingesting mercury. Multiple studies have been done, such as those in
New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...
and
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...
, that take into account selenium as well as mercury levels. Fish often do contain selenium in conjunction with bioaccumulated mercury, which may offset some of the dangers associated with the mercury ingested.


Levels of contamination


Most-contaminated fish species

The danger level from consuming fish depends on species and size. Size is the best predictor of increased levels of accumulated mercury.
Shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...
s, such as the
mako shark ''Isurus'' is a genus of mackerel sharks in the family Lamnidae, commonly known as the mako sharks. Description The two living species are the common shortfin mako shark (''I. oxyrinchus'') and the rare longfin mako shark (''I. paucus''). They ...
, have very high levels of mercury. A study on
New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...
coastal fish Coastal fish, also called inshore fish or neritic fish, inhabit the sea between the shoreline and the edge of the continental shelf. Since the continental shelf is usually less than deep, it follows that pelagic coastal fish are generally epi ...
indicated that one third of the sampled fish had levels of mercury above 0.5
parts per million In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they ...
, a level that could pose a human health concern for
consumer A consumer is a person or a group who intends to order, or uses purchased goods, products, or services primarily for personal, social, family, household and similar needs, who is not directly related to entrepreneurial or business activities. T ...
s who regularly eat this fish. Another study of marketplace fish caught in waters surrounding
Southern Italy Southern Italy ( it, Sud Italia or ) also known as ''Meridione'' or ''Mezzogiorno'' (), is a macroregion of the Italian Republic consisting of its southern half. The term ''Mezzogiorno'' today refers to regions that are associated with the peop ...
showed that, undoubtedly, greater fish weight leads to additional mercury found in fish body tissues. Moreover, the concentration, measured in
milligram The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially. ...
s of mercury per
kilogram The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially ...
of fish, steadily increases with the size of the fish.
Anglerfish The anglerfish are fish of the teleost order Lophiiformes (). They are bony fish named for their characteristic mode of predation, in which a modified luminescent fin ray (the esca or illicium) acts as a lure for other fish. The luminescence ...
off the coast of Italy were found with concentrations as high as 2.2 milligrams of mercury per kilogram, higher than the recommended limit of 1 milligram of mercury per kilogram. Annually,
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...
catches approximately a third of its fish from the
Adriatic Sea The Adriatic Sea () is a body of water separating the Italian Peninsula from the Balkan Peninsula. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto (where it connects to the Ionian Sea) to t ...
, where these anglerfish were found. Fish that consume their
prey Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...
in a certain manner may contain much higher concentrations of mercury than other species.
Grass carp The grass carp (''Ctenopharyngodon idella'') is a species of large herbivorous freshwater fish in the family Cyprinidae, native to the Pacific Far East, with a native range stretching from northern Vietnam to the Amur River on the Sino-Russian ...
off the coast of China hold far less internal mercury than do
bighead carp The bighead carp (''Hypophthalmichthys nobilis'') is a species of cyprinid freshwater fish native to East Asia, and is one of several Asian carps introduced into North America. It is one of the most intensively exploited fishes in fish farming, ...
. The reason for this is that bighead carp are
filter feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...
s, while grass carp are not. Thus, bighead carp gather more mercury by eating large amounts of small plankton, as well as sucking up sediments that collect a sizable amount of methyl mercury. US government scientists tested fish in 291 streams around the country for mercury contamination. They found mercury in every fish tested, according to the study by the
U.S. Department of the Interior The United States Department of the Interior (DOI) is one of the executive departments of the U.S. federal government headquartered at the Main Interior Building, located at 1849 C Street NW in Washington, D.C. It is responsible for the mana ...
. They found mercury even in fish of isolated rural waterways. Twenty-five percent of the fish tested had mercury levels above the safety levels determined by the
U.S. Environmental Protection Agency The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...
for people who eat the fish regularly.


Legislation


Japan

Since the
Minamata disaster Minamata disease is a neurological disease caused by severe mercury poisoning. Signs and symptoms include ataxia, numbness in the hands and feet, general muscle weakness, loss of peripheral vision, and damage to hearing and speech. In extreme ca ...
,
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
has improved on its
mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...
regulation. During the 1970s Japan made strides to reduce mercury demand and production. Chief among these efforts was the reduction of inorganic mercury produced by mines. It was halted by 1974, and demand fell from 2,500 tons per year in 1964, its peak, to 10 tons per year in recent years. Since these initial strides, Japan has introduced a list of regulations governing the mercury content of a variety of materials. Regulation of these potential sources of pollution reduces the amount of mercury that ends up in
fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
and, through
biomagnification Biomagnification, also known as bioamplification or biological magnification, is any concentration of a toxin, such as pesticides, in the tissues of tolerant organisms at successively higher levels in a food chain. This increase can occur as a ...
, in
humans Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
. In addition to enacting
legislation Legislation is the process or result of enrolled bill, enrolling, enactment of a bill, enacting, or promulgation, promulgating laws by a legislature, parliament, or analogous Government, governing body. Before an item of legislation becomes law i ...
controlling the mercury levels in potential pollutants, Japan has directly influenced the
environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...
by issuing regulations setting acceptable levels of environmental mercury
pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...
. It is Japan's goal to promote international mercury legislation in hopes of preventing any country from experiencing what it did. Despite Japan's extensive regulation and experience with mercury-based disasters, there is still little information provided to the public. The Japanese Federal Fish Advisory's recommendations are less strict than those in
America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
.


United States

The United States has regulated mercury emissions under the authority of the Clean Air Act. The
Environmental Protection Agency A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...
(EPA) first attempted to regulate power plant mercury emissions with the ''Clean Air Mercury Rule'' in 2005. The
George W. Bush administration George W. Bush's tenure as the 43rd president of the United States began with his first inauguration on January 20, 2001, and ended on January 20, 2009. Bush, a Republican from Texas, took office following a narrow victory over Democratic ...
intended for the regulation to use a cap-and-trade system to control emissions across multiple industries. The rule was challenged in litigation, and in 2008 the U.S. Court of Appeals for the District of Columbia Circuit vacated the rule, stating that EPA had improperly excluded power plants from designation as emitting
hazardous air pollutants Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different types ...
. EPA subsequently classified mercury emissions from power plants as hazardous under section 112 of the Clean Air Act. The 2012 ''Mercury and Air Toxics Standards'' (MATS) regulation, issued by the
Barack Obama administration Barack Obama's tenure as the 44th president of the United States began with his first inauguration on January 20, 2009, and ended on January 20, 2017. A Democrat from Illinois, Obama took office following a decisive victory over Republican ...
, targets airborne mercury emissions from power plants and other stationary sources. Airborne mercury is dissolved in the oceans, where
microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
s convert waterborne mercury into
methyl mercury Methylmercury (sometimes methyl mercury) is an organometallic cation with the formula . It is the simplest organomercury compound. Methylmercury is extremely toxic, and its derivatives are the major source of organic mercury for humans. It is ...
, which enters the
food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), det ...
and is stored in fish tissue. EPA stated that the MATS regulation would prevent about 90% of power plant mercury. The agency estimated the total expected health benefits are estimated at $37 billion–$90 billion by 2016. EPA estimated the economic cost at $9.6 billion annually.. In 2020 the
Trump administration Donald Trump's tenure as the List of presidents of the United States, 45th president of the United States began with Inauguration of Donald Trump, his inauguration on January 20, 2017, and ended on January 20, 2021. Trump, a Republican Party ...
weakened the MATS rule by disavowing EPA's previous calculations and justifications, thereby making the rule subject to legal challenges. European Union In EU, the regulation (EU) 2017/852 covers the full life cycle of mercury. This legislation prohibits the manufacture, export and import of a large range of mercury-added products; puts an end to all uses of mercury catalysts and large electrodes in industrial processes and reduces the use of and pollution from dental amalgamRecently, the EU estimated the Mercury content in the topsoils based on a large Land Cover Survery named LUCAS. The mercury content in EU topsoils has a median of 38 μg per Kg with a total content of around 45,000 tons in the 0–20 cm of EU.


International

Legislation on a global scale is believed by some to be needed for this issue because mercury pollution is estimated to be so far-reaching. Pollution from one country does not stay localized to that country. Despite the need by some,
international regulation International regulation is regulation that occurs at the international level, often exercised by international organizations. An advantage of international regulation is that it allows localities and the individuals in them to be held accountable f ...
has been slow to take off. The first forms of international legislation appeared in the 1970s, beginning as agreements about shared bodies of water. The next step was the Stockholm Declaration, which urged countries to avoid polluting the oceans by dumping. The 1972
Oslo Convention The Convention for the Prevention of Marine Pollution by Dumping from Ships and Aircraft also called the Oslo Convention was an international agreement designed to control the dumping of harmful substances from ships and aircraft into the sea. ...
and the 1974 Paris Convention were adopted by parts of
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
. Both lessened polluting the ocean with mercury, the former by banning the dumping of
ship A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished ...
s and
aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
into the ocean and the latter by obligating participants to reduce land-based pollution on coastlines. The first real global legislation regarding mercury pollution was the
Basel Convention The Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal, usually known as the Basel Convention, is an international treaty that was designed to reduce the movements of hazardous waste between nations ...
of 1989. This convention attempts to reduce the movement of mercury across borders and primarily regulates the
import An import is the receiving country in an export from the sending country. Importation and exportation are the defining financial transactions of international trade. In international trade, the importation and exportation of goods are limited ...
and
export An export in international trade is a good produced in one country that is sold into another country or a service provided in one country for a national or resident of another country. The seller of such goods or the service provider is an ...
of
toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...
chemicals, including mercury. In 1998 the Convention on Long-Range Transboundary Air Pollution was adopted by most of the
European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been des ...
, the United States, and
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
. Its primary objective is to cut emissions of
heavy metals upright=1.2, Crystals of osmium, a heavy metal nearly twice as dense as lead">lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals are generally defined as ...
. The convention is the largest international agreement on mercury established to date. In the early 21st century, the focus of mercury regulation has been on voluntary programs. The next phase in legislation is a global effort, and this appears to be what the Minamata Convention hopes to accomplish. The
Minamata Convention The Minamata Convention on Mercury is an international treaty designed to protect human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds. The convention was a result of three years of meetin ...
, 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. The convention will come into power after 50 countries have signed it. The Minamata Convention will require all participants to eliminate, where possible, the release of mercury from small-scale
gold mining Gold mining is the extraction of gold resources by mining. Historically, mining gold from alluvial deposits used manual separation processes, such as gold panning. However, with the expansion of gold mining to ores that are not on the surface ...
. It will also require a sharp reduction in emission from
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...
burning.


Current advice

The complexities associated with mercury transport and environmental fate are described by USEPA in their 1997 Mercury Study Report to Congress. Because methyl mercury and high levels of elemental mercury can be particularly toxic to a fetus or young children, organizations such as the U.S. 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 Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
per week. In the United States, the FDA has an action level for methylmercury in commercial marine and freshwater fish that is 1.0 parts per million (ppm). In Canada, the limit for the total of mercury content is 0.5 ppm. The Got Mercury? website includes a calculator for determining mercury levels in fish. Species with characteristically low levels of mercury include
shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...
,
tilapia Tilapia ( ) is the common name for nearly a hundred species of cichlid fish from the coelotilapine, coptodonine, heterotilapine, oreochromine, pelmatolapiine, and tilapiine tribes (formerly all were "Tilapiini"), with the economically most ...
,
salmon Salmon () is the common name for several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the family (biology), family Salmonidae, which are native to tributary, tributaries of the ...
,
pollock Pollock or pollack (pronounced ) is the common name used for either of the two species of North Atlantic marine fish in the genus ''Pollachius''. ''Pollachius pollachius'' is referred to as pollock in North America, Ireland and the United Kingd ...
, and
catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...
(FDA March 2004). The FDA characterizes shrimp, catfish, pollock, salmon,
sardines "Sardine" and "pilchard" are common names for various species of small, oily forage fish in the herring family Clupeidae. The term "sardine" was first used in English during the early 15th century, a folk etymology says it comes from the I ...
, and canned light tuna as low-mercury seafood, although recent tests have indicated that up to 6 percent of canned light tuna may contain high levels. A study published in 2008 found that mercury distribution in tuna meat is inversely related to the lipid content, suggesting that the lipid concentration within edible tuna tissues has a diluting effect on mercury content. These findings suggest that choosing to consume a type of tuna that has a higher natural fat content may help reduce the amount of mercury intake, compared to consuming tuna with a low fat content. Also, many of the fish chosen for
sushi is a Japanese cuisine, Japanese dish of prepared , usually with some sugar and salt, accompanied by a variety of , such as seafood, often raw, and vegetables. Styles of sushi and its presentation vary widely, but the one key ingredient is " ...
contain high levels of mercury. According to the
US Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food s ...
(FDA), the risk from mercury by eating fish and shellfish is not a health concern for most people. However, certain seafood might contain levels of mercury that may cause harm to an unborn baby (and especially its brain development and nervous system). In a young child, high levels of mercury can interfere with the development of the nervous system. The FDA provides three recommendations for young children, pregnant women, and women of child-bearing age: # Do not eat
shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...
,
swordfish Swordfish (''Xiphias gladius''), also known as broadbills in some countries, are large, highly migratory predatory fish characterized by a long, flat, pointed bill. They are a popular sport fish of the billfish category, though elusive. Swordfis ...
,
king mackerel The king mackerel (''Scomberomorus cavalla'') or kingfish, is a migratory species of mackerel of the western Atlantic Ocean and Gulf of Mexico. It is an important species to both the commercial and recreational fishing industries. Description T ...
, or
tilefish 250px, Blue blanquillo, ''Malacanthus latovittatus'' Tilefishes are mostly small perciform marine fish comprising the family Malacanthidae. They are usually found in sandy areas, especially near coral reefs. Commercial fisheries exist for th ...
(Gulf of Mexico) because they might contain high levels of mercury. # Eat up to 12 ounces (2 average meals of 170 g each) a week of a variety of fish and
shellfish Shellfish is a colloquial and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater envir ...
that are lower in mercury. Five of the most commonly eaten fish and shellfish that are low in mercury are:
shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...
, canned light tuna,
salmon Salmon () is the common name for several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the family (biology), family Salmonidae, which are native to tributary, tributaries of the ...
,
pollock Pollock or pollack (pronounced ) is the common name used for either of the two species of North Atlantic marine fish in the genus ''Pollachius''. ''Pollachius pollachius'' is referred to as pollock in North America, Ireland and the United Kingd ...
, and
catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...
. Another commonly eaten fish,
albacore The albacore (''Thunnus alalunga''), known also as the longfin tuna, is a species of tuna of the order Perciformes. It is found in temperate and tropical waters across the globe in the epipelagic and mesopelagic zones. There are six distinct sto ...
or ("white") tuna depending on its origin might have more mercury than canned light tuna. So, when choosing your two meals of fish and shellfish, it is recommended that you should not eat more than up to 6 ounces (one average meal) of albacore tuna per week. # Check local advisories about the safety of fish caught by family and friends in your local lakes, rivers, and coastal areas. If no advice is available, eat up to 6 ounces (one average meal of 170 g) per week of fish you catch from local waters, but consume no other fish during that week. Research suggests that selenium content in fish is protective against the toxic effects of methylmercury content. Fish with higher ratios of selenium to methylmercury (Se:Hg) are better to eat since the selenium binds to the methylmercury allowing it to pass through the body un-absorbed. In 2012 the
European Food Safety Authority The European Food Safety Authority (EFSA) is the agency of the European Union (EU) that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain. EFSA was established in February 2002, ...
(EFSA) reported on chemical contaminants they found in the food of over 20 European countries. They established that fish meat and fish products were primarily responsible for methylmercury in the diet of all age classes. Particularly implicated were swordfish, tuna, cod, pike, whiting and hake. The EFSA recommend a tolerable weekly intake for methylmercury of 1.3 μg/kg body weight.


See also

* '' Diagnosis Mercury: Money, Politics and Poison'' *
Mercury pollution in the ocean Mercury is a toxic heavy metal that cycles through the atmosphere, water, and soil in various forms to different parts of the world. Due to this natural cycle, irrespective of which part of the world releases mercury it could affect an entirely d ...
* Mercury in tuna *
Safe Harbor Certified Seafood Safe Harbor Certified Seafood is the first brand developed under San Rafael, California based Micro Analytical Systems, Inc. (MASI). Seafood bearing the Safe Harbor seal is tested for overall mercury content to be under the FDA's action level of ...
*
Whale meat Whale meat, broadly speaking, may include all cetaceans (whales, dolphins, porpoises) and all parts of the animal: muscle (meat), organs (offal), skin (muktuk), and fat (blubber). There is relatively little demand for whale meat, compared to ...


References


Additional sources

* Kidd K and Batchelar K (2011
"Mercury"
In: Wood CM, Farrell AP and Brauner CJ, ''Fish Physiology: Homeostasis and Toxicology of Non-Essential Metals'', pp. 238–297. Academic Press. . * *


External links



The NRDC created the chart below as a guideline to how much tuna can be eaten by children, pregnant women or women wanting to conceive, based on their weight.

Bulletin No. 6 June 15, 2001 Mercury and National Fish Advisories Statement from Alaska Division of Public Health

* ttps://www.fda.gov/food/environmental-contaminants-food/mercury-levels-commercial-fish-and-shellfish-1990-2012 FDA - Mercury Levels in Commercial Fish and Shellfish (1990-2012)br>Federal Study Shows Mercury In Fish Widespread, InescapableEDF - Healthy Sushi selectorEDF - Find a healthy fish for consumptionEDF - Smart and healthy choices when consuming seafoodMercury Awareness Program Highlighted on Pacifica Radio , Turtle Island Restoration Network
A Mercury Calculator from Got Mercury?
Fish, Mercury & Nutrition: The Net Effects
Documentary produced by
Prairie Public Television Prairie Public Television is a state network of public television stations operated primarily by Prairie Public Broadcasting. It comprises all of the PBS member stations in the U.S. state of North Dakota. The state network is available via fla ...
{{DEFAULTSORT:Mercury In Fish Environmental impact of fishing Mercury (element)