The Dangers of the Halogens In the Workplace

The halogens are highly reactive elements and can be harmful or even lethal in sufficient quantities. It’s surprising to think that something as benign as table salt contains chlorine, which in its elemental form, is a poisonous yellow gas. Small amounts of bromine are used in halogen light bulbs and iodine is essential to health.

The 5 halogens are:

  • Fluorine
  • Chlorine
  • Bromine
  • Iodine
  • Astatine

The halogens are nonmetals and are found in the environment only in compounds or as ions in many minerals and sea water. Their elemental name is derived from two Greek words, which when combined mean, ‘salt producing’. When combined with Hydrogen, the halogens form compounds called halides, a series of very strong acids, one of which is hydrochloric acid.

Fluorine

At room temperature, it is a pale yellowish- brown gas, one of the most reactive elements in existence. It is corrosive, poisonous, and highly toxic and even under cool, dark conditions, reacts explosively with hydrogen. Fluorine is so reactive that it is difficult to

find a container in which it can be stored safely. It is so powerful that if stored in ordinary laboratory glass, it can react, forming silicon tetrafluoride, a very toxic gas which if inhaled causes pulmonary edema which could lead to death. It must be handled with substances such as Teflon, extremely dry glass or metals, such as copper or steel, which form a protective layer of fluoride on their surface. Fluorine is very corrosive, burning the skin and eyes, and can cause respiratory problems if inhaled.

Chlorine

Is a highly toxic, pale greenish-yellow gas, which is about 2½ times as dense as air with a choking, disagreeably suffocating odor. The benign compound of chlorine and sodium has resulted in sodium chloride, our common but essential, table salt. Chlorine is a strong oxidizing agent and its container may explode if exposed to heat, igniting combustibles. It is used to produce many chemicals, including chloroform and carbon tetrachloride. It has been implicated in the destruction of the ozone layer in the atmosphere. Chlorine gas was first used as a weapon in World War I. It has reappeared in the Iraq War where chlorine bombs have been used by insurgents against the local population and coalition forces..

Bromine

Is a reddish-brown volatile liquid whose vapors are toxic and corrosive. It has a strong, disagreeable, choking odor, similar to chlorine. Its name is derived from a Greek word for’stench’ which aptly describes it. It is a powerful oxidizing agent and can explode violently if it contacts acetylene, ammonia, potassium, and quite a few other elements and compounds. It is very hazardous in contact with the skin, causing burns and blisters. If inhaled, its poisonous vapors can cause severe damage to the respiratory system.

Iodine

This grayish black solid is the least chemically active halogen. It is very corrosive and can cause dark staining of the skin, penetrating burns, irritation, and corneal damage to the eyes, which can lead to blindness. If inhaled, it is not as toxic as some of the other halogens but it can cause respiratory distress and may lead to severe respiratory problems. Iodine is a volatile solid that will explode if it comes in contact with bromine and certain other elements and compounds.

Astatine

This is the rarest occurring natural element and the scientists estimate that there is no more than 25 grams, less than an ounce, in the earth’s crust. It is radioactive and decomposes rapidly, making it difficult to study its properties. It exists in nature as a result of the decay of uranium and thorium.

After reviewing the properties of the halogens, it becomes very evident that they must be

handled carefully in the workplace. All of these elements present varying degrees of risk, ranging from the violent explosions of titanium tetrachloride to the dangers of dense clouds of hydrochloric acid gas.