Chloride Iodide A bromide ion is the negatively charged form (Br−) of the element bromine, a member of the halogens group on the periodic table.

[8] Some brominated flame retardants were identified as persistent, bioaccumulative, and toxic to both humans and the environment and were suspected of causing neurobehavioral effects and endocrine disruption.

However, it fell into disfavour in the 1940s due to the rising popularity of safer and more efficient sedatives (specifically, barbiturates) and when some heart patients died after using a salt substitute (see lithium chloride).

From 1954 - 1977, the Australian biochemist Shirley Andrews was researching safe ways to use lithium for the treatment of manic depressive illnesses while working at the Royal Park Psychiatric Hospital in Victoria.

While conducting this research she discovered that bromide caused symptoms of mental illness, leading to a major reduction in its usage.

Their use in over-the-counter sedatives and headache remedies (such as Bromo-Seltzer) in the United States extended to 1975 when bromides were withdrawn as ingredients due to chronic toxicity.

The half-life of bromide in the human body (12 days) is long compared with many pharmaceuticals, making dosing challenging to adjust.

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.

[18] In one specialized report, bromide is an essential cofactor in the peroxidising catalysis of sulfonimine crosslinks in collagen IV.

[20] The average concentration of bromide in human blood in Queensland, Australia, is 5.3±1.4 mg/L and varies with age and gender.