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Minerals in Detail
Chemical Details | Description | Industrial Applications |
In Nature | Health Impacts | Daily Intake
IRON
Iron - chemical details
| Symbol | Fe |
| Atomic number | 26 |
| Atomic mass | 55.85 g.mol-1 |
| Electronegativity | 1.8 (according to Pauling) |
| Density | 7.8 g.cm-3 at 20°C |
| Melting point | 1536 °C |
| Boiling point | 2861 °C |
| Vanderwaals radius | 0.126 nm |
| Ionic radius | 0.076 nm (+2) |
| 0.064 nm (+3) |
| Isotopes | 8 |
| Electronic configuration | [ Ar ] 3d6 4s2 |
| Energy of first ionisation | 761 kJ.mol-1 |
| Energy of second ionisation | 1556.5 kJ.mol-1 |
| Energy of third ionisation | 2951 kJ.mol-1 |
| Standard potential | - 0.44 V (Fe2+/ Fe ) |
| 0.77 V ( Fe3+/ Fe2+) |
| Discovered | - The Ancients |
Chemical Details | Description | Industrial Applications |
In Nature | Health Impacts | Daily Intake
Iron - Description
Iron is a lustrous, ductile, malleable, silver-gray metal (group VIII of the periodic table). It is known to exist in four distinct crystalline forms. Iron
rusts in damp air, but not in dry air. It dissolves readily in dilute acids. Iron is chemically active and forms two major series of chemical compounds, the
bivalent iron (II), or ferrous, compounds and the trivalent iron (III), or ferric, compounds.
Chemical Details | Description | Industrial Applications |
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Iron - Industrial applications
Iron is the most used of all the metals, compromising 95 % of all the metal tonnage produced worldwide. Its applications go from food containers to cars,
from scredrivers to washing machines, from cargo ships to paper staples. For details on
industrial applications and impact on the environment see www.lenntech.com/Periodic-chart-elements/Fe-en.htm
Chemical Details | Description | Industrial Applications |
In Nature | Health Impacts | Daily Intake
Iron - In natural form
Iron is believed to be the tenth most abundant element in the universe. Iron is also the most abundant (by mass, 34.6%) element making up the Earth;
the concentration of iron in the various layers of the Earth ranges from high at the inner core to about 5% in the outer crust. Most of this iron is found
in various iron oxides, such as the minerals hematite, magnetite, and taconite. The earth's core is believed to consist largely of a metallic iron-nickel
alloy. Iron is essential to most living things, from micro-organisms to humans.
World production of new iron is over 500 million tonnes a year, and recycled iron add other 300 million tonnes. Economically workable reserves of iron ores
exceed 100 billion tonnes. The main mining areas are China, Brazil, Australia, Russia and Ukraine, with sizeable amounts also mined in the USA, Canada,
Venezuela, Sweden and India.
Chemical Details | Description | Industrial Applications |
In Nature | Health Impacts | Daily Intake
Iron - Impact on health
Iron is an essential part of hemoglobin; the red colouring agent of the blood that transports oxygen through our bodies.
Iron may cause conjunctivitis, choroiditis, and retinitis if it contacts and remains in the tissues. A more common problem for humans is iron deficency.
Iron is essential to nearly all known organisms. In cells, iron is generally stored in the centre of metalloproteins, because "free" iron -- which binds
non-specifically to many cellular components -- can catalyse production of toxic free radicals. Iron deficiency can lead to iron deficiency anemia.
In animals, plants, and fungi, iron is often incorporated into the heme complex. Heme is an essential component of cytochrome proteins, which mediate redox
reactions, and of oxygen carrier proteins such as hemoglobin, myoglobin, and leghemoglobin. Inorganic iron also contributes to redox reactions in the
iron-sulfur clusters of many enzymes, such as nitrogenase (involved in the synthesis of ammonia from nitrogen and hydrogen) and hydrogenase. Non-heme iron
proteins include the enzymes methane monooxygenase (oxidizes methane to methanol), ribonucleotide reductase (reduces ribose to deoxyribose; DNA biosynthesis),
hemerythrins (oxygen transport and fixation in marine invertebrates) and purple acid phosphatase (hydrolysis of phosphate esters).
Iron distribution is heavily regulated in mammals, partly because iron has a high potential for biological toxicity. Iron distribution is also regulated
because many bacteria require iron, so restricting its availability to bacteria (generally by sequestering it inside cells) can help to prevent or limit
infections. This is probably the reason for the relatively low amounts of iron in mammalian milk. A major component of this regulation is the protein
transferrin, which binds iron absorbed from the duodenum and carries it in the blood to cells.1
Iron provided by dietary supplements is often found as iron (II) fumarate, although iron sulfate is cheaper and is absorbed equally well. Elemental iron,
despite being absorbed to a much smaller extent (stomach acid is sufficient to convert some of it to ferrous iron), is often added to foods such as
breakfast cereals or "enriched" wheat flour (where it is listed as "reduced iron" in the list of ingredients). Iron is most available to the body when
chelated to amino acids - iron in this form is ten to fifteen times more bioavailable2 than any other.
Iron can be found in meat, whole meal products, potatoes and vegetables. The human body absorbs iron in animal products faster than iron in plant products.
While a man needs an average daily intake of 7 mg of iron and a woman 11 mg, a normal diet will generally provided all that is needed.
Chemical Details | Description | Industrial Applications |
In Nature | Health Impacts | Daily Intake
Iron - Recommended daily & maximum intake
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Risk free |
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intake? |
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Food sources? |
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Result of overdose? |
| Age Group |
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RDA |
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Limit |
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Infants
0-6 mo
7-12 mo
Children
1-3 y
4-8 y
Males
9-13 y
14-18 y
19-30 y
31-50 y
50-70 y
> 70 y
Females
9-13 y
14-18 y
19-30 y
31-50 y
50-70 y
> 70 y
Pregnancy
< 19 y
19-30 y
31+ y
Lactation
< 19 y
19-30 y
31+ y |
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(mg/d)
0.27
11.0
7.0
10.0
8.0
11.0
8.0
8.0
8.0
8.0
8.0
15.0
18.0
18.0
8.0
8.0
27.0
27.0
27.0
10.0
9.0
9.0 |
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(mg/d)
40.0
40.0
40.0
40.0
40.0
45.0
45.0
45.0
45.0
45.0
40.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0 |
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Fruits
Grain
Meat
Poultry
Vegetables |
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Gastrointestinal distress (stomach cramps) |
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Explanations:
ND = Not determinable. There is either insufficient data on adverse effects and/or concern with the body's ability to handle excess amounts. In most
instances it is wise not to supplement for this particular element, but to rely on diet to provide sufficient quantities.
RDA = Recommended Dietary Allowance. May be used as a goal for daily intake. RDAs are set at a level that should meet the needs of 97-98% of all individuals.3, 4, 5, 6
Limit = The maximum level of daily nutrient intake from all sources that is highly likely to pose no risk of adverse effects.3, 4, 5, 6
References:
- Rouault, T. (2003). How Mammals Acquire and Distribute Iron Needed for Oxygen-Based Metabolism. http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0000079&ct=1. Retrieved 24 Sep 2008.
- Pineda, O., & Ashmead, H. (2001). Effectiveness of treatment of iron-deficiency anemia in infants and young children with ferrous bis-glycinate chelate. Nutrition 17 (5): 381–4.
- Standing Committee on the Scientific Evaluation of Dietary Reference Intakes (1997). Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D, and Fluoride. Food and Nutrition Board: Institute of Medicine.
- Standing Committee on the Scientific Evaluation of Dietary Reference Intakes (1998). Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6,
Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Food and Nutrition Board: Institute of Medicine.
- Standing Committee on the Scientific Evaluation of Dietary Reference Intakes (2000). Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Food and Nutrition Board: Institute of Medicine.
- Standing Committee on the Scientific Evaluation of Dietary Reference Intakes (2001). Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Food and Nutrition Board: Institute of Medicine.
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