Iron

(From the Middle English iren) A white, malleable, ductile, metallic chemical element that can be readily magnetized and rusts rapidly in moist or salty air, forming mainly ferric oxide (Fe₂O₃) and ferric hydroxide (Fe(OH)₃). It is vital to plant and animal life; the average human contains about four grams, much of which circulates as hemoglobin in the blood. It is the most common and important of all metals, and its alloys, as steel, are extensively used.

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iron n.

Hardware, especially older and larger hardware of mainframe class with big metal cabinets housing relatively low-density electronics (but the term is also used of modern supercomputers). Often in the phrase big iron. Oppose silicon. See also dinosaur.

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.

Today's irons are heated electrically, but irons certainly predate the era of easily available electricity. Traditional irons were indeed slabs of iron (with a handle of wood or some other material that wouldn't burn your hand), heated on a hot stove.

The word iron can also more generally denote a tool used in a similar way to heat and shape things - for instance, a soldering iron is a metal tool with a handle that is heated to a high temperature to melt solder to join objects - or to describe a tool made of (or traditionally made of) iron.

A certain amount of iron in one's diet is crucial for good health; in addition to it being a key component of the hemoglobin in red blood cells, the body needs iron to create myoglobin for muscles and to produce white blood cells. It also plays an important role in biochemical processes to produce energy. Adult women need 12-15 milligrams of iron a day, men need 8-15 milligrams, and children need about 10.

Dietary iron deficiency is the main cause of anemia. The National Institutes of Health estimates that 20% of women, 50% of pregnant women, and 3% of men are iron deficient. Women suffer more from chronic iron deficiency due to regular iron loss from menstruation.

Typical syptoms of iron deficiency include fatigue, bad temper, pale complexion, brittle nails, and weakness. Low-level deficiency may cause no obvious symptoms. Children with iron deficiency have been found to suffer from learning problems, attention deficits, and growth problems, so it's especially important that kids get the iron they need. Foods that are naturally rich in iron include beans and peas, meats (especially red meats), dark green leafy vegetables, blackstrap molasses, and whole grains. Eating foods rich in vitamin C (such as orange juice) in the same meal helps your body absorb the iron.

However, if one consumes much past the recommended daily allowance for one's age, size, and activity level, this mineral becomes unhealthy and even outright poisonous.

There are over 3,500 cases of acute iron poisoning in the the U.S. alone each year. Just a few iron-containing supplement pills can be deadly to an infant or small child: a fatal dose can be 600 milligrams or more. Acute iron poisoning first causes irritation and ulceration of the stomach lining. Once the blood gets loaded with the excess iron, it causes widespread damage to the heart, kidneys, liver, brain, and lungs. The treatment for iron poisoning is to give the victim a chelation agent intravenously.

Lower doses of iron can cause chronic poisoning; this is most often seen in people who have a genetic tendency toward storing excessive amounts of iron (hemochromatosis). Some people with chronic iron poisoning find that their skin turns dark bronze or takes on a grayish hue. People may also suffer from fatigue, upset stomach, and intestinal pain. Eventually, chronic poisoning damages the internal organs, particularly the spleen, liver, and kidneys (the kidney damage causes a type of diabetes known as "bronze diabetes").

But even lower amounts of excess iron can cause subtle damage to the heart.

In the early 90s, medical researchers found that, in middle-aged men, having excessive stores of iron, as indicated by the presence of the protein ferritin in the blood serum, increases the risk of developing ischemic heart disease (IHD) which leads to heart attacks.

Iron evidently promotes the creation of free radicals, and free radicals promote the oxidation of lipids, and oxidized lipids are thought to cause hardening of the arteries (atherosclerosis). The researchers also found a link between elevated levels of ferritin and the consumption of meat, a typically iron-rich food.

The significance of this study is that men (and postmenopausal women) who consume large quantities of iron-rich foods could be putting themselves at risk of developing heart disease. Also, people with hemochromatosis are at risk even if they consume little iron-rich food.

So in order to reduce the risk of heart disease, many older people might need to cut back on iron intake, and it may be further necessary to actively remove iron in some people. "Active removal" might involve such things as prescribing chelating agents or perhaps even bleeding the patient.

People who get too much iron because of genes or diet can do a couple of things to keep themselves healthy:

1. Donate blood on a regular basis if your health allows
2. Don't consume iron-rich foods along with vitamin C, as the vitamin vastly improves absorbtion of the mineral
3. Drink tea -- the tannins in tea block iron absorbtion
4. Drink cranberry juice -- an oxalate in the juice also inhibits iron absorbtion
5. Get regular vigorous exercise. Exercise provides the double benefit of improving the heart's fitness and increasing iron excretion.

Sources: personal research notes and various Medline articles

Approximately 70% of the iron found in the human body is defined as functional. The remainder can be subdivided into transport iron and storage iron. 80% of functional iron can be found in red blood cells, in the compound hemoglobin; the remaining 20% is found in myoglobin and intracellular respiratory enzymes such as cytochromes. 70-80% of storage iron is stored as ferritin in the liver, bone marrow, spleen, and skeletal muscles; a portion of the body's iron is stored instead as hemosiderin. Iron is transported through the bloodstream by the protein transferrin.

The amount of iron in the human body is regulated and balanced by gastrointestinal absorption, which maintains the amount of functional iron and establishes the ferritin and hemosiderin stores. The body's capacity for absorption is affected by the amount of iron that has already been stored, the body's rate of red blood cell production, the amount and kind of iron present in the body's diet, and the amount and kind of enhancer and inhibitor chemicals related to iron absorption present in said diet. Heme iron, present in meat, poultry, and fish, is 2 to 3 times more absorbable than non-heme iron, present in plant-based and iron-fortified foods. Beef liver, clams, oysters, red meats (preferably lean), kidneys, and eggs are all strong sources of heme iron; beans, wheat germ, whole grains, peas, nuts, dried fruits, leafy green vegetables (such as spinach), and of course food which has been fortified are all strong sources of non-heme iron. The chief enhancers for the absorption of non-heme iron are heme iron and vitamin C. Vitamin C can be found in broccoli, tomatoes, sweet potatoes and white potatoes, cantaloupe and citrus fruits. The chief inhibitors for the absorption of both heme and non-heme iron are polyphenols (found in certain vegetables), tannins (found in tea), phytates (found in bran), and calcium (found in dairy products).

The human body recycles iron when it breaks down red blood cells, but it does not retain the iron absolutely. Some (approximately 1 mg) iron gets lost daily in feces, skin cells and mucus, and a miniscule amount is lost through gastrointestinal blood loss. pathological losses of iron can frequently be attributed to sensitivity to cow's milk, peptic ulcer disease, inflammatory bowel disease, bowel cancer, and hookworm infections. Women of child-bearing age lose iron in their menses, averaging out to .3-.5 mg daily in those years. Women lose more iron during and after pregnancy, averaging out to 3 mg daily in that time). It therefore should not be surprising that women of child-bearing age are one of the demographics at highest risk for iron deficiency. Within that demographic category, women with minority ethnic backgrounds and/or who are from lower income brackets are at even higher risk.

SOURCES USED FOR THIS WRITEUP: www.cdc.gov/epo/mmwr/preview/mmwrhtml/00051880.htm, www.goaskalice.columbia.edu/0712.html.

I"ron (I"urn), n. [OE. iren, AS. Iren, Isen, Isern; akin to D. ijzer, OS. Isarn, OHG. Isarn, Isan, G. eisen, Icel. Isarn, jArn, Sw. & Dan. jern, and perh. to E. ice; cf. Ir. iarann, W. haiarn, Armor. houarn.]

1. (Chem.)

The most common and most useful metallic element, being of almost universal occurrence, usually in the form of an oxide (as hematite, magnetite, etc.), or a hydrous oxide (as limonite, turgite, etc.). It is reduced on an enormous scale in three principal forms; viz., cast iron, steel, and wrought iron. Iron usually appears dark brown, from oxidation or impurity, but when pure, or on a fresh surface, is a gray or white metal. It is easily oxidized (rusted) by moisture, and is attacked by many corrosive agents. Symbol Fe (Latin Ferrum). Atomic weight 55.9. Specific gravity, pure iron, 7.86; cast iron, 7.1. In magnetic properties, it is superior to all other substances.

⇒ The value of iron is largely due to the facility with which it can be worked. Thus, when heated it is malleable and ductile, and can be easily welded and forged at a high temperature. As cast iron, it is easily fusible; as steel, is very tough, and (when tempered) very hard and elastic. Chemically, iron is grouped with cobalt and nickel. Steel is a variety of iron containing more carbon than wrought iron, but less that cast iron. It is made either from wrought iron, by roasting in a packing of carbon (cementation) or from cast iron, by burning off the impurities in a Bessemer converter (then called Bessemer steel), or directly from the iron ore (as in the Siemens rotatory and generating furnace).

2.

An instrument or utensil made of iron; -- chiefly in composition; as, a flatiron, a smoothing iron, etc.

My young soldier, put up your iron.
Shak.

3. pl.

Fetters; chains; handcuffs; manacles.

Four of the sufferers were left to rot in irons.
Macaulay.

4.

Strength; power; firmness; inflexibility; as, to rule with a rod of iron.

Bar iron. See Wrought iron (below). --
Bog iron, bog ore; limonite. See Bog ore, under Bog. --
Cast iron (Metal.), an impure variety of iron, containing from three to six percent of carbon, part of which is united with a part of the iron, as a carbide, and the rest is uncombined, as graphite. It there is little free carbon, the product is white iron; if much of the carbon has separated as graphite, it is called gray iron. See also Cast iron, in the Vocabulary. --
Fire irons. See under Fire, n. --
Gray irons. See under Fire, n. --
Gray iron. See Cast iron (above). --
It irons (Naut.), said of a sailing vessel, when, in tacking, she comes up head to the wind and will not fill away on either tack. --
Magnetic iron. See Magnetite. --
Malleable iron (Metal.), iron sufficiently pure or soft to be capable of extension under the hammer; also, specif., a kind of iron produced by removing a portion of the carbon or other impurities from cast iron, rendering it less brittle, and to some extent malleable. --
Meteoric iron (Chem.), iron forming a large, and often the chief, ingredient of meteorites. It invariably contains a small amount of nickel and cobalt. Cf. Meteorite. --
Pig iron, the form in which cast iron is made at the blast furnace, being run into molds, called pigs. --
Reduced iron. See under Reduced. --
Specular iron. See Hematite. --
Too many irons in the fire, too many objects requiring the attention at once. --
White iron. See Cast iron (above). --
Wrought iron (Metal.), the purest form of iron commonly known in the arts, containing only about half of one per cent of carbon. It is made either directly from the ore, as in the Catalan forge or bloomery, or by purifying (puddling) cast iron in a reverberatory furnace or refinery. It is tough, malleable, and ductile. When formed into bars, it is called bar iron.

© Webster 1913

I"ron (I"urn), a. [AS. Iren, Isen. See Iron, n.]

1.

Of, or made of iron; consisting of iron; as, an iron bar, dust.

2.

Resembling iron in color; as, iron blackness.

3.

Like iron in hardness, strength, impenetrability, power of endurance, insensibility, etc.; as:

(a)

Rude; hard; harsh; severe.

Iron years of wars and dangers.
Rowe.

Jove crushed the nations with an iron rod.
Pope.

(b)

Firm; robust; enduring; as, an iron constitution.

(c)

Inflexible; unrelenting; as, an iron will.

(d)

Not to be broken; holding or binding fast; tenacious. "Him death's iron sleep oppressed." Philips.

⇒ Iron is often used in composition, denoting made of iron, relating to iron, of or with iron; producing iron, etc.; resembling iron, literally or figuratively, in some of its properties or characteristics; as, iron-shod, iron-sheathed, iron-fisted, iron-framed, iron-handed, iron-hearted, iron foundry or iron-foundry.

Iron age.
(a) (Myth.) The age following the golden, silver, and bronze ages, and characterized by a general degeneration of talent and virtue, and of literary excellence. In Roman literature the Iron Age is commonly regarded as beginning after the taking of Rome by the Goths, A. D. 410.
(b) (Archæol.) That stage in the development of any people characterized by the use of iron implements in the place of the more cumbrous stone and bronze. --
Iron cement, a cement for joints, composed of cast-iron borings or filings, sal ammoniac, etc. --
Iron clay (Min.), a yellowish clay containing a large proportion of an ore of iron. --
Iron cross, a Prussian order of military merit; also, the decoration of the order. --
Iron crown, a golden crown set with jewels, belonging originally to the Lombard kings, and indicating the dominion of Italy. It was so called from containing a circle said to have been forged from one of the nails in the cross of Christ. --
Iron flint (Min.), an opaque, flintlike, ferruginous variety of quartz. --
Iron founder, a maker of iron castings. --
Iron foundry, the place where iron castings are made. - - Iron furnace, a furnace for reducing iron from the ore, or for melting iron for castings, etc.; a forge; a reverberatory; a bloomery. --
Iron glance (Min.), hematite. --
Iron hat, a headpiece of iron or steel, shaped like a hat with a broad brim, and used as armor during the Middle Ages. --
Iron horse, a locomotive engine. [Colloq.] --
Iron liquor, a solution of an iron salt, used as a mordant by dyers. --
Iron man (Cotton Manuf.), a name for the self-acting spinning mule. --
Iron