Toxicity
Halogens are very reactive elements and their toxicity derives from their strong oxidant properties. Fluorine is the most toxic and dangerous of the halogens, capable of killing a person within seconds. Chlorine is also toxic, and can kill a person if inhaled in an enclosed area. Bromine is less reactive and toxic than Chlorine however, being a liquid at standard temperature and pressure, it is much more dense yet still behaves as a fuming liquid. Contact with molecular Bromine can be fatal. Bromine's increased reactivity with water can also lead to the formation of a higher quantity of acids in the lungs than those that might be formed with Chlorine. Iodine is the least dangerous of the halogens and will rarely kill a person if its vapor is inhaled however ingestion can be fatal even at a low dose (28 mg/kg).
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