Chemically, salt is sodium chloride. All animals require some salt to survive.

In humans it plays a crucial role in maintaining health, being our main source of sodium and chloride ions. The sodium found in salt is essential for nerve and muscle function (including the heart). Additionally, it is involved in the regulation of fluids in the body and plays a role in the body’s control of blood pressure and volume. Chloride ions serve as important electrolytes by regulating blood pH and pressure. The chlorine from salt is also critical in the production of stomach acid, needed for digestion.

The Hazards of Chlorine

Pure chlorine is so dangerous that anyone attempting to rescue someone overcome by the gas should avoid breathing any exhaled air from the victim, as even that could cause chemical burns. Very brief exposure to a concentration of 1000 ppm may be fatal.

The Hazards of Sodium

Sodium in a putty-like substance that in contact with water releases flammable gases which may ignite spontaneously. To see such an explosion, view You Tube Demonstration and Large Scale Example. It also reacts violently to a broad range of other substances. Sodium can cause irreversible eye injury, skin burns, and deep, penetrating ulcers of the skin. Ingestion may cause gastrointestinal tract burns, and inhalation may result in severe irritation of the respiratory tract.

Sources

https://manoa.hawaii.edu/exploringourfluidearth/chemical/chemistry-and-seawater/salty-sea/weird-science-salt-essential-life

http://amp.generalair.com/MsdsDocs/PA4580S.pdf

https://www.fishersci.com/shop/msdsproxy?storeId=10652&productName=S2061LB