chromium(redirected from Element 24)
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a chemical element, atomic number 24, atomic weight 51.996. (See Appendix 6.) It is an essential dietary trace element, but hexavalent chromium is carcinogenic.
chromium 51 a radioactive isotope of chromium having a half-life of 27.7 days and decaying by electron capture, emitting gamma rays. It is used to label red blood cells for measurement of red cell mass or volume, survival time, and sequestration studies, and for the diagnosis of gastrointestinal bleeding, and is used to label platelets to study their survival. Symbol 51Cr.
A metallic element, atomic no. 24, atomic wt. 51.9961. A dietary essential bioelement. 51Cr (half-life of 27.70 days) is used as a diagnostic aid in many disorders (for example, gastrointestinal protein loss).
[G. chroma, color]
chromium/chro·mi·um/ (Cr) (kro´me-um) a chemical element, at. no. 24. It is an essential dietary trace element, but hexavalent chromium is carcinogenic.
chromium 51 a radioactive isotope of chromium having a half-life of 27.7 days and decaying by electron capture with emission of gamma rays (0.32 MeV); it is used to label red blood cells for measurement of mass or volume, survival time, and sequestration studies, for the diagnosis of gastrointestinal bleeding, and to label platelets to study their survival.
chromium trioxide chromic acid.
Etymology: Gk, chroma, color
a hard, brittle metallic element. Its atomic number is 24; its atomic mass is 51.99. It does not occur naturally in pure form but exists in combination with iron and oxygen in chromite, a mineral found chiefly in Africa, Albania, Russia, and Turkey. Chromium strongly resists corrosion and is used extensively to plate other metals, harden steel, and, in combination with other elements, form colored compounds. Stainless steels are more than 10% chromium and strongly resist rusting. Traces of chromium occur in plants and animals, and there is evidence that this element may be important in human nutrition, especially in carbohydrate metabolism. Some experts estimate that the safe and adequate daily intake of chromium ranges from 0.1 to 0.2 mg, depending on the age of the individual. Workers in chromite mines are susceptible to pneumoconiosis caused by the inhalation of chromite dust particles that lodge in the lung. Chromate salts have been identified as potential carcinogens. Chromium 51 isotope is used in blood studies.
chromiumA metallic element (atomic number 24; atomic number 51.99), which is an essential mineral that potentiates the action of insulin and is present in trace amounts in various enzymes; chromium is present in various foods including brewers’ yeast, whole grains, peanuts, wheat germ and skim milk.
A metallic element, atomic no. 24, atomic wt. 51.9961. A dietary essential bioelement, 51Cr (half-life of 27.70 days) is used as a diagnostic aid in many disorders (e.g., gastrointestinal protein loss).
[G. chrōma, color]
mineralsinorganic substances which are obtained in a well-balanced diet. The substances required in the largest amounts (sometimes known as macrominerals) are sodium, potassium, calcium, phosphorus and magnesium, and many others are essential in smaller amounts. Minerals are essential in all metabolic processes, from maintenance of cell volume and structure to muscle contraction and relaxation, regulation of acid-base equilibrium, protection from oxidative stress, bone metabolism, immune function and haemoglobin synthesis. No mineral supplements should be required for athletes who are consuming a well-balanced diet but they frequently take them, especially iron, magnesium and chromium. See Table 1.
|Name and chemical symbol||Reference nutrient intake (adults, per day)||Sources||Functions||Deficiency||Excess|
|Calcium Ca||700 mg||Milk and milk products, green vegetables, soya beans, white bread, hard water||Calcium deposits in soft tissue can occur, but probably not related to high intake|
|Chlorine Cl||3.4 g (as chloride)||Salt-containing foods||Unlikely with normal diet||As NaCl, risk factor for high blood pressure|
|Chromium Cr||25 μg||Vegetables, cereals, meats, vegetable oils, whole grains||Co-factor for some enzymes involved in glucose and energy metabolism|
|Copper Cu||900 μg||Meat, drinking water||Co-factor for some enzymes; intermediate in electron transfer during oxidative phosphorylation||Low activity of antioxidant enzymes||Very high intake can cause liver damage|
|Iodine I||140 μg||Seafood, iodized salt, milk and milk products, meat and eggs||Synthesis of thyroid hormones||Thyroid swelling (goitre) with hypothyroidism: low BMR, lethargy||Rarely any effect; may exacerbate some skin diseases|
|Iron Fe||Liver, kidney, red meat, egg yolk, wholegrains, pulses, dark green vegetables, dried fruit, treacle, cocoa, molasses||Component of haemoglobin, myoglobin and many enzymes||Can be toxic if very excessive. (from blood transfusions rather than from diet); gastrointestinal upset; may promote vascular disease|
|Fluoride F||3-4 mg||Drinking water, mostly as calcium fluoride; tea, seafood||May be important in maintenance of bone structure||Increased risk of tooth decay||Unlikely from dietary sources|
|Magnesium Mg||Cereals, milk, nuts, seeds, and green vegetables||Co-factor for enzymes essential in metabolism; role in calcium homeostasis; skeletal development; neuromuscular function||Uncommon; can occur with malabsorption or in chronic renal failure, when it accompanies hypocalcaemia||Unlikely from dietary sources|
|Phosphorus-P||550 mg (as phosphate)||Milk, cheese, yogurt, meat, poultry, grains, fish||Adenosine phosphate compounds vital in energy metabolism. With Ca in bones and teeth||Only in severe malnutrition; muscle weakness, bone pain, rickets, anorexia, anaemia||In treatment of osteoporosis or bone cancer with biphosphonates|
|Potassium K||3.5 g||Fruit, vegetables, meat, wholegrains||High ECF [K+] (hyperkalaemia) causes cardiac arrest|
|Selenium Se||Seafood, meat, grains, wheat flour||Key component in the endogenous antioxidant, glutathione peroxidase||Health implications of low intake in UK currently under DoH review. May cause abnormality of heart muscle||Excessive supplements: hair loss, skin rash, neurological disorder|
|Sodium Na||1.6 g||Mainly as salt: table salt, and in milk, meat, vegetables, sauces, pickles, processed foods, snacks, cheese||Major extracellular cation; linked to ECF volume, hence to blood volume and blood pressure. Component of bone mineral||Loss in sweat and diarrhoea; dilution in body fluids due to excess water intake. Weakness, cramp; faintness, confusion||Oedema, hypertension|
|Zinc Zn||Red meat, dairy products, eggs, wholegrains, peas, beans, nuts, lentils|
n an essential mineral that is associated with glucose tolerance, high cholesterol, blocked arteries, glaucoma, obesity, diabetes, and hypoglycemia. Not for use by chil-dren or pregnant or nursing women. Also called
chromium picolinate, chromium polynicotinate, or
chromium picolinate, chromium polynicotinate, or
A metallic element and essential dietary bioelement; used as diagnostic aid in many disorders (e.g., gastrointestinal protein loss).
[G. chroma, color]
a chemical element, atomic number 24, atomic weight 51.996, symbol Cr. See Table 6.
chromium nutritional deficiency
possibly causally related to the onset of diabetes mellitus in primates.
possibly carcinogenic in humans. See also chromate.