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Minerals in Detail
Chemical Details | Description | Industrial Applications |
In Nature | Health Impacts | Daily Intake
CHROMIUM
Chromium - chemical details
| Symbol | Cr |
| Atomic number | 24 |
| Atomic mass | 51.996 g.mol-1 |
| Electronegativity | 1.6 |
| Density | 7.19 g.cm-3 at 20°C |
| Melting point | 1907 °C |
| Boiling point | 2672 °C |
| Vanderwaals radius | 0.127 nm |
| Ionic radius | 0.061 nm (+3) ; 0.044 nm (+6) |
| Isotopes | 6 |
| Electronic configuration | [ Ar ] 3d4 4s2 |
| Energy of first ionisation | 651.1 kJ.mol-1 |
| Energy of second ionisation | 1590.1 kJ.mol-1 |
| Energy of second ionisation | 2987 kJ.mol-1 |
| Standard potential | - 0.71 V (Cr3+ / Cr ) |
| Discovered | 1797 - Louis Vauquelin |
Chemical Details | Description | Industrial Applications |
In Nature | Health Impacts | Daily Intake
Chromium - Description
Chromium is a lustrous, brittle, hard metal. Its colour is silver-gray and it can be highly polished. It does not tarnish in air, when heated it burns and
forms chromic oxide, which is green in colour. Chromium is unstable in oxygen, it immediately produces a thin oxide layer that is impermeable to oxygen and
protects the metal below.
Chemical Details | Description | Industrial Applications |
In Nature | Health Impacts | Daily Intake
Chromium - Industrial applications
Among the main industrial uses of Chromium are in alloys such as stainless steel, in chrome plating and in metal ceramics. For details on industrial
applications and impact on the environment see www.lenntech.com/Periodic-chart-elements/Cr-en.htm
Chemical Details | Description | Industrial Applications |
In Nature | Health Impacts | Daily Intake
Chromium - In natural form
Chromium is mined as chromite (FeCr2O4) ore. Chromium ores are mined today in South Africa, Zimbabwe, Finland, India, Kazakihstan and the Philippines. A
total of 14 million tonnes of chromite ore is extracted. Reserves are estimated to be of the order of 1 billion tonnes. There are additional (currently)
unexploited deposits in Greenland, Canada and the USA.
Chemical Details | Description | Industrial Applications |
In Nature | Health Impacts | Daily Intake
Chromium - Impact on health
Chromium is implicated in maintenance of blood sugar, prevention of atherosclerosis, and control of cholesterol levels. Human studies suggest that a
particular form of chromium known as chromium picolinate, enhances insulin sensitivity, glucose removal, and may improve lipid ratios in obese and type 2
diabetics.1 Additionally, it is suggested that chromium has a potential beneficial antioxidant effect in patients with
type 2 diabetes when combined with zinc and copper supplementation.2
For most people eating food that contains chromium(III) is the main route of chromium uptake, as chromium(III) occurs
naturally in many vegetables, fruits, meats, yeasts and grains. Various ways of food preparation and storage may alter the chromium contents of food. When
food in stored in steel tanks or cans chromium concentrations may rise. Chromium(III) is an essential nutrient for humans and shortages may cause heart
conditions, disruptions of metabolisms and diabetes. But the uptake of too much chromium(III) can cause health effects as well, for instance skin rashes.
People can be exposed to chromium through breathing, eating or drinking and through skin contact with chromium or chromium compounds. The level of chromium
in air and water is generally low. In drinking water the level of chromium is usually low as well, but contaminated well water may contain the dangerous
chromium(IV) - hexavalent chromium.
Chromium(VI) is a danger to human health, mainly for people who work in the steel and textile industry. People who smoke tobacco also have a higher chance
of exposure to chromium. Chromium(VI) is known to cause various health effects. When it is a compound in leather products, it can cause allergic reactions,
such as skin rash. After breathing it in chromium(VI) can cause nose irritations and nosebleeds. Other health problems that are caused by chromium(VI)
include skin rashes, upset stomaches and ulcers, respiratory problems, Weakened immune systems, kidney and liver damage, alteration of genetic material,
lung cancer, and even death.
Chemical Details | Description | Industrial Applications |
In Nature | Health Impacts | Daily Intake
Chromium - 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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(ug/d)
0.2
5.5
11.0
15.0
25.0
35.0
35.0
35.0
30.0
30.0
21.0
24.0
25.0
25.0
20.0
20.0
29.0
30.0
30.0
44.0
45.0
45.0 |
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(ug/d)
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND |
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Certain cereals
Fish
Meats
Poultry |
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Chronic renal (kidney) failure |
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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:
- Cefalu, W., Wang, Z., Zhang, X., Baldor, L., & Russell, J. (2002). Oral chromium picolinate improves carbohydrate and lipid metabolism and enhances skeletal muscle Glut-4 translocation in obese, hyperinsulinemic (JCR-LA corpulent) rats. J Nutr 2002 Jun;132(6):1107-14
- Anderson, R., Roussel, A., Zouari, N., Mahjoub, S., Matheau, J., & Kerkeni, A. (2001). Potential antioxidant effects of zinc and chromium supplementation in people with type 2 diabetes mellitus. J Am Coll Nutr 2001 Jun;20(3):212-8
- 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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