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= Nickel =
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Introduction
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Nickel is a chemical element; it has symbol Ni and atomic number 28.
It is a silvery-white lustrous metal with a slight golden tinge.
Nickel is a hard and ductile transition metal. Pure nickel is
chemically reactive, but large pieces are slow to react with air under
standard conditions because a passivation layer of nickel oxide forms
on the surface that prevents further corrosion. Even so, pure native
nickel is found in Earth's crust only in tiny amounts, usually in
ultramafic rocks, and in the interiors of larger nickel-iron
meteorites that were not exposed to oxygen when outside Earth's
atmosphere.
Meteoric nickel is found in combination with iron, a reflection of the
origin of those elements as major end products of supernova
nucleosynthesis. An iron-nickel mixture is thought to compose Earth's
outer and inner cores.
Use of nickel (as natural meteoric nickel-iron alloy) has been traced
as far back as 3500 BCE. Nickel was first isolated and classified as
an element in 1751 by Axel Fredrik Cronstedt, who initially mistook
the ore for a copper mineral, in the cobalt mines of Los, Hälsingland,
Sweden. The element's name comes from a mischievous sprite of German
miner mythology, Nickel (similar to Old Nick). Nickel minerals can be
green, like copper ores, and were known as kupfernickel - Nickel's
copper - because they produced no copper.
Although most nickel in the earth's crust exists as oxides,
economically more important nickel ores are sulfides, especially
pentlandite. Major production sites include Sulawesi, Indonesia, the
Sudbury region, Canada (which is thought to be of meteoric origin),
New Caledonia in the Pacific, Western Australia, and Norilsk, Russia.
Nickel is one of four elements (the others are iron, cobalt, and
gadolinium) that are ferromagnetic at about room temperature. Alnico
permanent magnets based partly on nickel are of intermediate strength
between iron-based permanent magnets and rare-earth magnets. The metal
is used chiefly in alloys and corrosion-resistant plating.
About 68% of world production is used in stainless steel. A further
10% is used for nickel-based and copper-based alloys, 9% for plating,
7% for alloy steels, 3% in foundries, and 4% in other applications
such as in rechargeable batteries, including those in electric
vehicles (EVs). Nickel is widely used in coins, though nickel-plated
objects sometimes provoke nickel allergy. As a compound, nickel has a
number of niche chemical manufacturing uses, such as a catalyst for
hydrogenation, cathodes for rechargeable batteries, pigments and metal
surface treatments. Nickel is an essential nutrient for some
microorganisms and plants that have enzymes with nickel as an active
site.
Atomic and physical properties
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Nickel is a silvery-white metal with a slight golden tinge that takes
a high polish. It is one of only four elements that are ferromagnetic
at or near room temperature; the others are iron, cobalt and
gadolinium. Its Curie temperature is 355 °C, meaning that bulk nickel
is non-magnetic above this temperature. The unit cell of nickel is a
face-centered cube; it has lattice parameter of 0.352 nm, giving an
atomic radius of 0.124 nm. This crystal structure is stable to
pressures of at least 70 GPa. Nickel is hard, malleable and ductile,
and has a relatively high electrical and thermal conductivity for
transition metals. The high compressive strength of 34 GPa, predicted
for ideal crystals, is never obtained in the real bulk material due to
formation and movement of dislocations. However, it has been reached
in Ni nanoparticles.
Electron configuration dispute
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Nickel has two atomic electron configurations, [Ar] 3d(8) 4s(2) and
[Ar] 3d(9) 4s(1), which are very close in energy; [Ar] denotes the
complete argon core structure. There is some disagreement on which
configuration has the lower energy. Chemistry textbooks quote nickel's
electron configuration as [Ar] 4s(2) 3d(8), also written [Ar] 3d(8)
4s(2). This configuration agrees with the Madelung energy ordering
rule, which predicts that 4s is filled before 3d. It is supported by
the experimental fact that the lowest energy state of the nickel atom
is a 3d(8) 4s(2) energy level, specifically the 3d(8)((3)F) 4s(2)
(3)F, 'J' = 4 level.
However, each of these two configurations splits into several energy
levels due to fine structure, and the two sets of energy levels
overlap. The average energy of states with [Ar] 3d(9) 4s(1) is
actually lower than the average energy of states with [Ar] 3d(8)
4s(2). Therefore, the research literature on atomic calculations
quotes the ground state configuration as [Ar] 3d(9) 4s(1).
Isotopes
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The isotopes of nickel range in atomic weight from 48 u () to 82 u ().
Natural nickel is composed of five stable isotopes, , , , and , of
which is the most abundant (68.077% natural abundance).
Nickel-62 has the highest binding energy per nucleon of any nuclide:
8.7946 MeV/nucleon. Its binding energy is greater than both iron-56
and iron-58, more abundant nuclides often incorrectly cited as having
the highest binding energy. Though this would seem to predict nickel
as the most abundant heavy element in the universe, the high rate of
photodisintegration of nickel in stellar interiors causes iron to be
by far the most abundant.
Nickel-60 is the daughter product of the extinct radionuclide iron-60
(half-life 2.6 million years). Due to the long half-life of , its
persistence in materials in the Solar System may generate observable
variations in the isotopic composition of . Therefore, the abundance
of in extraterrestrial material may give insight into the origin of
the Solar System and its early history.
At least 26 nickel radioisotopes have been characterized; the most
stable are with half-life 76,000 years, (100 years), and (6 days).
All other radioisotopes have half-lives less than 60 hours and most
these have half-lives less than 30 seconds. This element also has one
meta state.
Radioactive nickel-56 is produced by the silicon burning process and
later set free in large amounts in type Ia supernovae. The shape of
the light curve of these supernovae at intermediate to late-times
corresponds to the decay via electron capture of to cobalt-56 and
ultimately to iron-56. Nickel-59 is a long-lived cosmogenic
radionuclide; half-life 76,000 years. has found many applications in
isotope geology. has been used to date the terrestrial age of
meteorites and to determine abundances of extraterrestrial dust in ice
and sediment. Nickel-78, with a half-life of 110 milliseconds, is
believed an important isotope in supernova nucleosynthesis of elements
heavier than iron. (48)Ni, discovered in 1999, is the most proton-rich
heavy element isotope known. With 28 protons and 20 neutrons, (48)Ni
is "doubly magic", as is (78)Ni with 28 protons and 50 neutrons. Both
are therefore unusually stable for nuclei with so large a
proton-neutron imbalance.
Nickel-63 is a contaminant found in the support structure of nuclear
reactors. It is produced through neutron capture by nickel-62. Small
amounts have also been found near nuclear weapon test sites in the
South Pacific.
Occurrence
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Nickel ores are classified as oxides or sulfides. Oxides include
laterite, where the principal mineral mixtures are nickeliferous
limonite, (Fe,Ni)O(OH), and garnierite (a mixture of various hydrous
nickel and nickel-rich silicates). Nickel sulfides commonly exist as
solid solutions with iron in minerals such as pentlandite and
pyrrhotite with the formula Fe9−xNixS8 and Fe7−xNixS6, respectively.
Other common Ni-containing minerals are millerite and the arsenide
niccolite.
Identified land-based resources throughout the world averaging 1%
nickel or greater comprise at least 130 million tons of nickel (about
the double of known reserves). About 60% is in laterites and 40% in
sulfide deposits.
On geophysical evidence, most of the nickel on Earth is believed to be
in Earth's outer and inner cores. Kamacite and taenite are naturally
occurring alloys of iron and nickel. For kamacite, the alloy is
usually in the proportion of 90:10 to 95:5, though impurities (such as
cobalt or carbon) may be present. Taenite is 20% to 65% nickel.
Kamacite and taenite are also found in nickel iron meteorites.
Nickel is commonly found in iron meteorites as the alloys kamacite and
taenite. Nickel in meteorites was first detected in 1799 by
Joseph-Louis Proust, a French chemist who then worked in Spain. Proust
analyzed samples of the meteorite from Campo del Cielo (Argentina),
which had been obtained in 1783 by Miguel Rubín de Celis, discovering
the presence in them of nickel (about 10%) along with iron.
Compounds
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The most common oxidation state of nickel is +2, but compounds of
{{chem2|Ni^{0}|}}, , and are well known, and the exotic oxidation
states and have been characterized.
Nickel(0)
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Nickel tetracarbonyl ), discovered by Ludwig Mond, is a volatile,
highly toxic liquid at room temperature. On heating, the complex
decomposes back to nickel and carbon monoxide:
:
This behavior is exploited in the Mond process for purifying nickel.
The related nickel(0) complex bis(cyclooctadiene)nickel(0) is a useful
catalyst in organonickel chemistry because the cyclooctadiene (or
'cod') ligands are easily displaced.
Nickel(I)
===========
Nickel(I) complexes are uncommon, but one example is the tetrahedral
complex . Many nickel(I) complexes have Ni-Ni bonding, such as the
dark red diamagnetic prepared by reduction of with sodium amalgam.
This compound is oxidized in water, liberating .
It is thought that the nickel(I) oxidation state is important to
nickel-containing enzymes, such as [[NiFe
Hydrogenase|[NiFe]-hydrogenase]], which catalyzes the reversible
reduction of protons to .
Nickel(II)
============
Nickel(II) forms compounds with all common anions, including sulfide,
sulfate, carbonate, hydroxide, carboxylates, and halides. Nickel(II)
sulfate is produced in large amounts by dissolving nickel metal or
oxides in sulfuric acid, forming both a hexa- and heptahydrate useful
for electroplating nickel. Common salts of nickel, such as chloride,
nitrate, and sulfate, dissolve in water to give green solutions of the
metal aquo complex .
The four halides form nickel compounds, which are solids with
molecules with octahedral Ni centres. Nickel(II) chloride is most
common, and its behavior is illustrative of the other halides.
Nickel(II) chloride is made by dissolving nickel or its oxide in
hydrochloric acid. It is usually found as the green hexahydrate, whose
formula is usually written . When dissolved in water, this salt forms
the metal aquo complex . Dehydration of gives yellow anhydrous .
Some tetracoordinate nickel(II) complexes, e.g.
bis(triphenylphosphine)nickel chloride, exist both in tetrahedral and
square planar geometries. The tetrahedral complexes are paramagnetic;
the square planar complexes are diamagnetic. In having properties of
magnetic equilibrium and formation of octahedral complexes, they
contrast with the divalent complexes of the heavier group 10 metals,
palladium(II) and platinum(II), which form only square-planar
geometry.
Nickelocene has an electron count of 20. Many chemical reactions of
nickelocene tend to yield 18-electron products.
Nickel(III) and (IV)
======================
Many Ni(III) compounds are known. Ni(III) forms simple salts with
fluoride or oxide ions. Ni(III) can be stabilized by σ-donor ligands
such as thiols and organophosphines.
Ni(III) occurs in nickel oxide hydroxide, which is used as the cathode
in many rechargeable batteries, including nickel-cadmium, nickel-iron,
nickel-hydrogen, and nickel-metal hydride, and used by certain
manufacturers in Li-ion batteries.
Ni(IV) remains a rare oxidation state and very few compounds are
known. Ni(IV) occurs in the mixed oxide .
Nickel(VI)
============
As of 2024, hexavalent nickel is known in the form of crystalline
Ni(BeCp)6. Notably it is not octahedral, instead adopting C3v
geometry.
History
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Unintentional use of nickel can be traced back as far as 3500 BCE.
Bronzes from what is now Syria have been found to contain as much as
2% nickel. Some ancient Chinese manuscripts suggest that "white
copper" (cupronickel, known as 'baitong') was used there in 1700-1400
BCE. This Paktong white copper was exported to Britain as early as the
17th century, but the nickel content of this alloy was not discovered
until 1822. Coins of nickel-copper alloy were minted by Bactrian kings
Agathocles, Euthydemus II, and Pantaleon in the 2nd century BCE,
possibly out of the Chinese cupronickel.
In medieval Germany, a metallic yellow mineral was found in the Ore
Mountains that resembled copper ore. But when miners were unable to
get any copper from it, they blamed a mischievous sprite of German
mythology, Nickel (similar to 'Old Nick'), for besetting the copper.
They called this ore from German 'copper'. This ore is now known as
the mineral nickeline (formerly 'niccolite'), a nickel arsenide. In
1751, Baron Axel Fredrik Cronstedt tried to extract copper from
kupfernickel at a cobalt mine in the village of Los, Sweden, and
instead produced a white metal that he named 'nickel' after the spirit
that had given its name to the mineral. In modern German, Kupfernickel
or Kupfer-Nickel designates the alloy cupronickel.
Originally, the only source for nickel was the rare Kupfernickel.
Beginning in 1824, nickel was obtained as a byproduct of cobalt blue
production. The first large-scale smelting of nickel began in Norway
in 1848 from nickel-rich pyrrhotite. The introduction of nickel in
steel production in 1889 increased the demand for nickel; the nickel
deposits of New Caledonia, discovered in 1865, provided most of the
world's supply between 1875 and 1915. The discovery of the large
deposits in the Sudbury Basin in Canada in 1883, in Norilsk-Talnakh in
Russia in 1920, and in the Merensky Reef in South Africa in 1924 made
large-scale nickel production possible.
Coinage
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Aside from the aforementioned Bactrian coins, nickel was not a
component of coins until the mid-19th century.
Canada
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99.9% nickel five-cent coins were struck in Canada (the world's
largest nickel producer at the time) during non-war years from 1922 to
1981; the metal content made these coins magnetic. During the war
years 1942-1945, most or all nickel was removed from Canadian and US
coins to save it for making armor. Canada used 99.9% nickel from 1968
in its higher-value coins until 2000.
Switzerland
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Coins of nearly pure nickel were first used in 1881 in Switzerland.
United Kingdom
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Birmingham forged nickel coins in for trading in Malaysia.
United States
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In the United States, the term "nickel" or "nick" originally applied
to the copper-nickel Flying Eagle cent, which replaced copper with 12%
nickel 1857-58, then the Indian Head cent of the same alloy from 1859
to 1864. Still later, in 1865, the term designated the three-cent
nickel, with nickel increased to 25%. In 1866, the five-cent shield
nickel (25% nickel, 75% copper) appropriated the designation, which
has been used ever since for the subsequent 5-cent pieces. This alloy
proportion is not ferromagnetic.
The US nickel coin contains 0.04 oz of nickel, which at the April 2007
price was worth 6.5 cents, along with 3.75 grams of copper worth about
3 cents, with a total metal value of more than 9 cents. Since the face
value of a nickel is 5 cents, this made it an attractive target for
melting by people wanting to sell the metals at a profit. The United
States Mint, anticipating this practice, implemented new interim rules
on December 14, 2006, subject to public comment for 30 days, which
criminalized the melting and export of cents and nickels. Violators
can be punished with a fine of up to $10,000 and/or a maximum of five
years in prison. As of February 19, 2025, the melt value of a US
nickel (copper and nickel included) is $0.054 (108% of the face
value).
Current use
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In the 21st century, the high price of nickel has led to some
replacement of the metal in coins around the world. Coins still made
with nickel alloys include one- and two-euro coins, 5¢, 10¢, 25¢, 50¢,
and $1 U.S. coins, and 20p, 50p, £1, and £2 UK coins. From 2012 on the
nickel-alloy used for 5p and 10p UK coins was replaced with
nickel-plated steel. This ignited a public controversy regarding the
problems of people with nickel allergy.
World production
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An estimated 3.7 million tonnes (t) of nickel per year are mined
worldwide; Indonesia (2,200,000 t), the Philippines (330,000 t),
Russia (210,000 t), Canada (190,000 t), China (120,000 t), and
Australia (110,000 t) are the largest producers as of 2024. The
largest nickel deposits in non-Russian Europe are in Finland and
Greece. Identified land-based sources averaging at least 1% nickel
contain at least 130 million tonnes of nickel. About 60% is in
laterites and 40% is in sulfide deposits. Also, extensive nickel
sources are found in the depths of the Pacific Ocean, especially in an
area called the Clarion Clipperton Zone in the form of polymetallic
nodules peppering the seafloor at 3.5-6 km below sea level. These
nodules are composed of numerous rare-earth metals and are estimated
to be 1.7% nickel. With advances in science and engineering,
regulation is currently being set in place by the International Seabed
Authority to ensure that these nodules are collected in an
environmentally conscientious manner while adhering to the United
Nations Sustainable Development Goals.
The one place in the United States where nickel has been profitably
mined is Riddle, Oregon, with several square miles of nickel-bearing
garnierite surface deposits. The mine closed in 1987. The Eagle mine
project is a new nickel mine in Michigan's Upper Peninsula.
Construction was completed in 2013, and operations began in the third
quarter of 2014. In the first full year of operation, the Eagle Mine
produced 18,000 t. The Eagle mine produced 17,000 tons of nickel
concentrate in 2023. Other projects in the region include the
Marquette County nickel project, which received $145 million in
funding from the federal government in 2024, investments in work at
the Boulderdash and Roland mines, and the development of a third zone,
the Keel zone, at The Eagle mine.
Production
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Nickel is obtained through extractive metallurgy: it is extracted from
ore by conventional roasting and reduction processes that yield metal
of greater than 75% purity. In many stainless steel applications, 75%
pure nickel can be used without further purification, depending on
impurities.
Traditionally, most sulfide ores are processed using pyrometallurgical
techniques to produce a matte for further refining. Hydrometallurgical
techniques are also used. Most sulfide deposits have traditionally
been processed by concentration through a froth flotation process
followed by pyrometallurgical extraction. The nickel matte is further
processed with the Sherritt-Gordon process. First, copper is removed
by adding hydrogen sulfide, leaving a concentrate of cobalt and
nickel. Then, solvent extraction is used to separate the cobalt and
nickel, with the final nickel content greater than 86%.
A second common refining process is leaching the metal matte into a
nickel salt solution, followed by electrowinning the nickel from
solution by plating it onto a cathode as electrolytic nickel.
Mond process
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The purest metal is obtained from nickel oxide by the Mond process,
which gives a purity of over 99.99%. The process was patented by
Ludwig Mond and has been in industrial use since before the beginning
of the 20th century. In this process, nickel is treated with carbon
monoxide in the presence of a sulfur catalyst at around 40-80 °C to
form nickel carbonyl. In a similar reaction with iron, iron
pentacarbonyl can form, though this reaction is slow. If necessary,
the nickel may be separated by distillation. Dicobalt octacarbonyl is
also formed in nickel distillation as a by-product, but it decomposes
to tetracobalt dodecacarbonyl at the reaction temperature to give a
non-volatile solid.
Nickel is obtained from nickel carbonyl by one of two processes. It
may be passed through a large chamber at high temperatures in which
tens of thousands of nickel spheres (pellets) are constantly stirred.
The carbonyl decomposes and deposits pure nickel onto the spheres. In
the alternate process, nickel carbonyl is decomposed in a smaller
chamber at 230 °C to create a fine nickel powder. The byproduct carbon
monoxide is recirculated and reused. The highly pure nickel product is
known as "carbonyl nickel".
Market value
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The market price of nickel surged throughout 2006 and the early months
of 2007; , the metal was trading at US$52,300/tonne or $1.47/oz. The
price later fell dramatically; , the metal was trading at
$11,000/tonne, or $0.31/oz. During the 2022 Russian invasion of
Ukraine, worries about sanctions on Russian nickel exports triggered a
short squeeze, causing the price of nickel to quadruple in just two
days, reaching US$100,000 per tonne. The London Metal Exchange
cancelled contracts worth $3.9 billion and suspended nickel trading
for over a week. Analyst Andy Home argued that such price shocks are
exacerbated by the purity requirements imposed by metal markets: only
Grade I (99.8% pure) metal can be used as a commodity on the
exchanges, but most of the world's supply is either in ferro-nickel
alloys or lower-grade purities. In 2024, the average nickel price is
estimated by the London Metal Exchange (LME) to be $15,328 per metric
ton, 7.7% less than it was in 2023. At the end of 2024, the price
reached its lowest levels since 2020.
Applications
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Global use of nickel is currently 68% in stainless steel, 10% in
nonferrous alloys, 9% electroplating, 7% alloy steel, 3% foundries,
and 4% other (including batteries).
Nickel is used in many recognizable industrial and consumer products,
including stainless steel, alnico magnets, coinage, rechargeable
batteries (e.g. nickel-iron), electric guitar strings, microphone
capsules, plating on plumbing fixtures, and special alloys such as
permalloy, elinvar, and invar. It is used for plating and as a green
tint in glass. Nickel is preeminently an alloy metal, and its chief
use is in nickel steels and nickel cast irons, in which it typically
increases the tensile strength, toughness, and elastic limit. It is
widely used in many other alloys, including nickel brasses and bronzes
and alloys with copper, chromium, aluminium, lead, cobalt, silver, and
gold (Inconel, Incoloy, Monel, Nimonic).
Nickel is traditionally used for Kris production in Southeast Asia.
Because nickel is resistant to corrosion, it was occasionally used as
a substitute for decorative silver. Nickel was also occasionally used
in some countries after 1859 as a cheap coinage metal (see above), but
in the later years of the 20th century, it was replaced by cheaper
stainless steel (i.e., iron) alloys, except in the United States and
Canada.
Nickel is an excellent alloying agent for certain precious metals and
is used in the fire assay as a collector of platinum group elements
(PGE). As such, nickel can fully collect all six PGEs from ores, and
can partially collect gold. High-throughput nickel mines may also do
PGE recovery (mainly platinum and palladium); examples are Norilsk,
Russia and the Sudbury Basin, Canada.
Nickel foam or nickel mesh is used in gas diffusion electrodes for
alkaline fuel cells.
Nickel and its alloys are often used as catalysts for hydrogenation
reactions. Raney nickel, a finely divided nickel-aluminium alloy, is
one common form, though related catalysts are also used, including
Raney-type catalysts.
Nickel is naturally magnetostrictive: in the presence of a magnetic
field, the material undergoes a small change in length. The
magnetostriction of nickel is on the order of 50 ppm and is negative,
indicating that it contracts.
Nickel is used as a binder in the cemented tungsten carbide or
hardmetal industry and used in proportions of 6% to 12% by weight.
Nickel makes the tungsten carbide magnetic and adds
corrosion-resistance to the cemented parts, though the hardness is
less than those with cobalt binder.
, with a half-life of 100.1 years, is useful in krytron devices as a
beta particle (high-speed electron) emitter to make ionization by the
keep-alive electrode more reliable. It is being investigated as a
power source for betavoltaic batteries.
Around 27% of all nickel production is used for engineering, 10% for
building and construction, 14% for tubular products, 20% for metal
goods, 14% for transport, 11% for electronic goods, and 5% for other
uses.
In 2025, QuesTek Innovations and Stoke Space developed a nickel-based
superalloy for additive manufacturing and extreme high-pressure,
high-temperature oxygen environments. Its characteristics allow the
material to be used for fully reusable spacecraft launch systems, it
can withstand the full-flow staged combustion rocket engine Zenith.
Raney nickel is widely used for hydrogenation of unsaturated oils to
make margarine, and substandard margarine and leftover oil may contain
nickel as a contaminant. Forte et al. found that type 2 diabetic
patients have 0.89 ng/mL of Ni in the blood relative to 0.77 ng/mL in
control subjects.
Nickel titanium is an alloy of roughly equal atomic percentages of its
constituent metals which exhibits two closely related and unique
properties: the shape memory effect and superelasticity.
Biological role
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It was not recognized until the 1970s, but nickel is known to play an
important role in the biology of some plants, bacteria, archaea, and
fungi. Nickel enzymes such as urease are considered virulence factors
in some organisms. Urease catalyzes hydrolysis of urea to form ammonia
and carbamate. NiFe hydrogenases can catalyze oxidation of to form
protons and electrons; and also the reverse reaction, the reduction of
protons to form hydrogen gas. A nickel-tetrapyrrole coenzyme, cofactor
F430, is present in methyl coenzyme M reductase, which can catalyze
the formation of methane, or the reverse reaction, in methanogenic
archaea (in +1 oxidation state).
One of the carbon monoxide dehydrogenase enzymes consists of an
Fe-Ni-S cluster.
Other nickel-bearing enzymes include a rare bacterial class of
superoxide dismutase and glyoxalase I enzymes in bacteria and several
eukaryotic trypanosomal parasites (in other organisms, including yeast
and mammals, this enzyme contains divalent ).
Dietary nickel may affect human health through infections by
nickel-dependent bacteria, but nickel may also be an essential
nutrient for bacteria living in the large intestine, in effect
functioning as a prebiotic. The US Institute of Medicine has not
confirmed that nickel is an essential nutrient for humans, so neither
a Recommended Dietary Allowance (RDA) nor an Adequate Intake have been
established. The tolerable upper intake level of dietary nickel is 1
mg/day as soluble nickel salts. Estimated dietary intake is 70 to 100
μg/day; less than 10% is absorbed. What is absorbed is excreted in
urine. Relatively large amounts of nickel - comparable to the
estimated average ingestion above - leach into food cooked in
stainless steel. For example, the amount of nickel leached after 10
cooking cycles into one serving of tomato sauce averages 88 μg.
Nickel released from Siberian Traps volcanic eruptions is suspected of
helping the growth of 'Methanosarcina', a genus of euryarchaeote
archaea that produced methane in the Permian-Triassic extinction
event, the biggest known mass extinction.
Toxicity
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The major source of nickel exposure is oral consumption, as nickel is
essential to plants. Typical background concentrations of nickel do
not exceed 20 ng/m(3) in air, 100 mg/kg in soil, 10 mg/kg in
vegetation, 10 μg/L in freshwater and 1 μg/L in seawater.
Environmental concentrations may be increased by human pollution. For
example, nickel-plated faucets may contaminate water and soil; mining
and smelting may dump nickel into wastewater; nickel-steel alloy
cookware and nickel-pigmented dishes may release nickel into food. Air
may be polluted by nickel ore refining and fossil fuel combustion.
Humans may absorb nickel directly from tobacco smoke and skin contact
with jewelry, shampoos, detergents, and coins. A less common form of
chronic exposure is through hemodialysis as traces of nickel ions may
be absorbed into the plasma from the chelating action of albumin.
The average daily exposure is not a threat to human health. Most
nickel absorbed by humans is removed by the kidneys and passed out of
the body through urine or is eliminated through the gastrointestinal
tract without being absorbed. Nickel is not a cumulative poison, but
larger doses or chronic inhalation exposure may be toxic, even
carcinogenic, and constitute an occupational hazard.
Nickel compounds are classified as human carcinogens based on
increased respiratory cancer risks observed in epidemiological studies
of sulfidic ore refinery workers. This is supported by the positive
results of the NTP bioassays with Ni sub-sulfide and Ni oxide in rats
and mice. The human and animal data consistently indicate a lack of
carcinogenicity via the oral route of exposure and limit the
carcinogenicity of nickel compounds to respiratory tumours after
inhalation. Nickel metal is classified as a suspect carcinogen; In the
rodent inhalation studies with various nickel compounds and nickel
metal, increased lung inflammations with and without bronchial lymph
node hyperplasia or fibrosis were observed. In rat studies, oral
ingestion of water-soluble nickel salts can trigger perinatal
mortality in pregnant animals. Whether these effects are relevant to
humans is unclear as epidemiological studies of highly exposed female
workers have not shown adverse developmental toxicity effects.
People can be exposed to nickel in the workplace by inhalation,
ingestion, and contact with skin or eye. The Occupational Safety and
Health Administration (OSHA) has set the legal limit (permissible
exposure limit) for the workplace at 1 mg/m(3) per 8-hour workday,
excluding nickel carbonyl. The National Institute for Occupational
Safety and Health (NIOSH) sets the recommended exposure limit (REL) at
0.015 mg/m(3) per 8-hour workday. At 10 mg/m(3), nickel is immediately
dangerous to life and health. Nickel carbonyl is an extremely toxic
gas. The toxicity of metal carbonyls is a function of both the
toxicity of the metal and the off-gassing of carbon monoxide from the
carbonyl functional groups; nickel carbonyl is also explosive in air.
Sensitized persons may show a skin contact allergy to nickel known as
a contact dermatitis. Highly sensitized persons may also react to
foods with high nickel content. Patients with pompholyx may also be
sensitive to nickel. Nickel is the top confirmed contact allergen
worldwide, partly due to its use in jewelry for pierced ears. Nickel
allergies affecting pierced ears are often marked by itchy, red skin.
Many earrings are now made without nickel or with low-release nickel
to address this problem. The amount allowed in products that contact
human skin is now regulated by the European Union. In 2002,
researchers found that the nickel released by 1 and 2 euro coins, far
exceeded those standards. This is believed to be due to a galvanic
reaction. Nickel was voted Allergen of the Year in 2008 by the
American Contact Dermatitis Society. In August 2015, the American
Academy of Dermatology adopted a position statement on the safety of
nickel: "Estimates suggest that contact dermatitis, which includes
nickel sensitization, accounts for approximately $1.918 billion and
affects nearly 72.29 million people."
Reports show that both the nickel-induced activation of
hypoxia-inducible factor (HIF-1) and the up-regulation of
hypoxia-inducible genes are caused by depletion of intracellular
ascorbate. The addition of ascorbate to the culture medium increased
the intracellular ascorbate level and reversed both the metal-induced
stabilization of HIF-1- and HIF-1α-dependent gene expression.
External links
======================================================================
* [
https://www.periodicvideos.com/videos/028.htm Nickel video] from
the 'Periodic Videos' series (University of Nottingham)
* [
https://www.cdc.gov/niosh/npg/npgd0445.html Nickel] entry (last
reviewed October 30, 2019) in the 'NIOSH Pocket Guide to Chemical
Hazards' published by the CDC's National Institute for Occupational
Safety and Health
* [
https://www.atsdr.cdc.gov/toxprofiles/tp15.pdf Toxicological
Profile for Nickel (draft for public comment)] (PDF) (August 2023) -
422-page report from the United States Department of Health and Human
Services, Public Health Service, Agency for Toxic Substances and
Disease Registry
* [
https://www.bbc.com/news/magazine-32749262 The metal that brought
you cheap flights], BBC News (2015)
License
=========
All content on Gopherpedia comes from Wikipedia, and is licensed under CC-BY-SA
License URL:
http://creativecommons.org/licenses/by-sa/3.0/
Original Article:
http://en.wikipedia.org/wiki/Nickel
