Bromide
Encyclopedia
A bromide is a chemical compound containing bromide ion
, that is bromine
atom with effective charge
of −1. The class name can include ion
ic compounds such as caesium bromide
or covalent compounds such as sulfur dibromide.
(35 PSU
) with a concentration of around 65 mg/L, which is around 0.2% of all dissolved salt
s. Seafoods generally have high levels of bromide, while foods derived from land have variable amounts.
(HNO3), then silver nitrate
(AgNO3). A cream precipitate forms.
, were frequently used as sedatives in the 19th and early 20th century. Their use in over-the-counter sedatives and headache remedies (such as Bromo-Seltzer
) in the United States extended to 1975, when these bromides were withdrawn as ingredients, due to chronic toxicity
.
This use gave the word "bromide" its colloquial connotation of a boring cliché
, a bit of conventional wisdom
overused as a calming phrase, or verbal sedative
.
The bromide ion is antiepileptic, and bromide salts are still used as such, particularly in veterinary medicine. Bromide ion is excreted by the kidneys. The half-life of bromide in the human body (12 days) is long compared with many pharmaceuticals, making dosing difficult to adjust (a new dose may require several months to reach equilibrium). Bromide ion concentrations in the cerebrospinal fluid are about 30% of those in blood, and are strongly influenced by the body's chloride intake and metabolism.
Since bromide is still used in veterinary medicine (particularly to treat seizures in dogs) in the United States, veterinary diagnostic labs can routinely measure blood bromide levels. However, this is not a conventional test in human medicine in the U.S., since there are no FDA-approved uses for bromide, and it is no longer available in over-the-counter sedatives. Therapeutic bromide levels are measured in European countries like Germany, where bromide is still used therapeutically in human epilepsy.
Chronic toxicity from bromide can result in bromism
, a syndrome with multiple neurological symptoms. Bromide toxicity can also cause a type of skin eruption. See potassium bromide
.
Lithium bromide
was used as a sedative
beginning in the early 1900s, but it fell into disfavor in the 1940s when some heart patients died after using it as a salt substitute. Like lithium carbonate
and lithium chloride
it was used as treatment for bipolar disorder
.
, a haloperoxidase
enzyme which is able to use chloride, but preferentially uses bromide when available. Despite this use by the body, bromide is not known to be strictly necessary for life, as its functions may generally be replaced (though in some cases not as well) by chloride.
Bromide salts are also sometimes used in hot tub
s and spas as mild germicidal agents, using the action of an added oxidizing agent to generate in situ hypobromite
, in a similar fashion to the peroxidase in eosinophils.
The average concentration of bromide in human blood is 5.3±1.4 mg/L and varies with age and gender. Much higher levels may indicate exposure to brominated chemicals (e.g. methyl bromide). However, bromide occurs in relatively high concentration in seawater and many types of seafood, and bromide concentrations in the blood are heavily influenced by seafood contributions to the diet.
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
, that is bromine
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...
atom with effective charge
Electric charge
Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. Electric charge comes in two types, called positive and negative. Two positively charged substances, or objects, experience a mutual repulsive force, as do two...
of −1. The class name can include ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
ic compounds such as caesium bromide
Caesium bromide
Caesium bromide, , is an ionic compound of caesium and bromine. It has simple cubic p-type cubic crystallic structure, comparable to that of caesium chloride type with space group Pmm and lattice constant a = 0.42953 nm...
or covalent compounds such as sulfur dibromide.
Natural occurrence
Bromide is present in typical seawaterSeawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...
(35 PSU
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
) with a concentration of around 65 mg/L, which is around 0.2% of all dissolved salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
s. Seafoods generally have high levels of bromide, while foods derived from land have variable amounts.
Chemistry
One can test for a bromide ion by adding dilute nitric acidNitric acid
Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...
(HNO3), then silver nitrate
Silver nitrate
Silver nitrate is an inorganic compound with chemical formula . This compound is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides...
(AgNO3). A cream precipitate forms.
Medical uses
Bromide compounds, especially potassium bromidePotassium bromide
Potassium bromide is a salt, widely used as an anticonvulsant and a sedative in the late 19th and early 20th centuries, with over-the-counter use extending to 1975 in the United States. Its action is due to the bromide ion...
, were frequently used as sedatives in the 19th and early 20th century. Their use in over-the-counter sedatives and headache remedies (such as Bromo-Seltzer
Bromo-Seltzer
Bromo-Seltzer , is an antacid used to relieve pain occurring together with heartburn, upset stomach, or acid indigestion. Originally produced by inventor Isaac E...
) in the United States extended to 1975, when these bromides were withdrawn as ingredients, due to chronic toxicity
Chronic toxicity
Chronic toxicity is a property of a substance that has toxic effects on a living organism, when that organism is exposed to the substance continuously or repeatedly. Compared with acute toxicity.Two distinct situations need to be considered:...
.
This use gave the word "bromide" its colloquial connotation of a boring cliché
Cliché
A cliché or cliche is an expression, idea, or element of an artistic work which has been overused to the point of losing its original meaning or effect, especially when at some earlier time it was considered meaningful or novel. In phraseology, the term has taken on a more technical meaning,...
, a bit of conventional wisdom
Conventional wisdom
Conventional wisdom is a term used to describe ideas or explanations that are generally accepted as true by the public or by experts in a field. Such ideas or explanations, though widely held, are unexamined. Unqualified societal discourse preserves the status quo. It codifies existing social...
overused as a calming phrase, or verbal sedative
Sedative
A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....
.
The bromide ion is antiepileptic, and bromide salts are still used as such, particularly in veterinary medicine. Bromide ion is excreted by the kidneys. The half-life of bromide in the human body (12 days) is long compared with many pharmaceuticals, making dosing difficult to adjust (a new dose may require several months to reach equilibrium). Bromide ion concentrations in the cerebrospinal fluid are about 30% of those in blood, and are strongly influenced by the body's chloride intake and metabolism.
Since bromide is still used in veterinary medicine (particularly to treat seizures in dogs) in the United States, veterinary diagnostic labs can routinely measure blood bromide levels. However, this is not a conventional test in human medicine in the U.S., since there are no FDA-approved uses for bromide, and it is no longer available in over-the-counter sedatives. Therapeutic bromide levels are measured in European countries like Germany, where bromide is still used therapeutically in human epilepsy.
Chronic toxicity from bromide can result in bromism
Bromism
Bromism is the syndrome which results from the long-term use of the potassium bromide based sedatives. Bromism was once a very common disorder being responsible for 5-10% of psychiatric hospital admissions. It is now an uncommon disorder due to bromide being withdrawn from clinical use in many...
, a syndrome with multiple neurological symptoms. Bromide toxicity can also cause a type of skin eruption. See potassium bromide
Potassium bromide
Potassium bromide is a salt, widely used as an anticonvulsant and a sedative in the late 19th and early 20th centuries, with over-the-counter use extending to 1975 in the United States. Its action is due to the bromide ion...
.
Lithium bromide
Lithium bromide
Lithium bromide, or LiBr, is a chemical compound of lithium and bromine. Its extreme hygroscopic character makes LiBr useful as a desiccant in certain air conditioning systems.-Production and properties:...
was used as a sedative
Sedative
A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....
beginning in the early 1900s, but it fell into disfavor in the 1940s when some heart patients died after using it as a salt substitute. Like lithium carbonate
Lithium carbonate
Lithium carbonate is a chemical compound of lithium, carbon, and oxygen with the formula Li2CO3. This colorless salt is widely used in the processing of metal oxides and has received attention for its use in psychiatry. It is found in nature as the rare mineral zabuyelite.-Properties:Like almost...
and lithium chloride
Lithium chloride
Lithium chloride is a chemical compound with the formula LiCl. The salt is a typical ionic compound, although the small size of the Li+ ion gives rise to properties not seen for other alkali metal chlorides, such as extraordinary solubility in polar solvents and its hygroscopic...
it was used as treatment for bipolar disorder
Bipolar disorder
Bipolar disorder or bipolar affective disorder, historically known as manic–depressive disorder, is a psychiatric diagnosis that describes a category of mood disorders defined by the presence of one or more episodes of abnormally elevated energy levels, cognition, and mood with or without one or...
.
In biology
Bromide is needed by eosinophils (white blood cells of the granulocyte class, specialized for dealing with multi-cellular parasites), which use it to generate antiparasitic brominating compounds by the action of eosinophil peroxidaseEosinophil peroxidase
Eosinophil peroxidase is a haloperoxidase enzyme that in humans is encoded by the EPX gene. The enzyme is a heterodimeric 71-77 kD peroxidase consisting of a heavier glycosylated chain and a lighter nonglycosylated chain...
, a haloperoxidase
Haloperoxidase
Haloperoxidases are peroxidases that are able to mediate the oxidation of halides by hydrogen peroxide. Both halides and hydrogen peroxide are widely available in the environment....
enzyme which is able to use chloride, but preferentially uses bromide when available. Despite this use by the body, bromide is not known to be strictly necessary for life, as its functions may generally be replaced (though in some cases not as well) by chloride.
Bromide salts are also sometimes used in hot tub
Hot tub
A hot tub is a large tub or small pool full of heated water and used for soaking, relaxation, massage, or hydrotherapy. In most cases, they have jets for massage purposes. Hot tubs are usually located outdoors, and are often sheltered for protection from the elements, as well as for privacy....
s and spas as mild germicidal agents, using the action of an added oxidizing agent to generate in situ hypobromite
Hypobromite
The hypobromite ion, also called alkaline bromine water, is BrO−. Bromine is in the +1 oxidation state. Hypobromite is the bromine compound analogous to hypochlorites found in common bleaches, and in immune cells...
, in a similar fashion to the peroxidase in eosinophils.
The average concentration of bromide in human blood is 5.3±1.4 mg/L and varies with age and gender. Much higher levels may indicate exposure to brominated chemicals (e.g. methyl bromide). However, bromide occurs in relatively high concentration in seawater and many types of seafood, and bromide concentrations in the blood are heavily influenced by seafood contributions to the diet.