Acetic acid is the most important organic acid. It is present in vinegar, which is a common household acid and is used mainly in cooking purposes. In industries, it is used in the manufacture of plastics, paints, solvents, paper, textile and fabrics.

This compound is known to be a simple carboxylic acid, and is also known as ethanoic acid. It naturally results from the fermentation of ethanol, an alcohol. Its chemical formula is CH3COOH. The last hydrogen attached to the oxygen is given off in aqueous solutions giving the compound an acidic nature. It is classified, however, as a weak acid because it does not completely dissociate or separate in its component ions in water. The acid occurs in biochemical systems and is seen as a metabolic product during the breakdown of glucose. Acetic acid occurs naturally in dilute amounts, but in industries it is synthesized in more concentrated forms. The pure form of it is called glacial acetic acid because of the resemblance to ice. The solid acid melts at 16.7 degrees Celsius.

Dilute concentrations of the acid are safe. For instance, vinegar contains about five percent (5%) by mass of acetic acid and this is generally harmless. At higher concentrations, say at least ten percent (10%) the acid becomes an irritant. It is a known lachrymator which means it induces secretion of tears when gets in contact with eyes and can also cause soreness and conjunctivitis. In severe exposures, corneal damage may occur and this leads to blindness. It is a skin irritant and causes discoloration, itching, burns and blisters, and thickening of the skin. It does not happen quite quickly and my take a few hours after the skin gets in contact with the acid for the signs of irritation to manifest. Upon inhalation the organic acid irritates the nasal, throat and bronchial lining. Mucus secretions along the lining produces fluid build up, thus, leading to edemas in the respiratory organs like the pharynx and the lungs. Breathing may be adversely affected, such that the exposed person may suffer from shortness of breath and dizziness. The acid fumes can cause inflammation on the bronchial lining (bronchitis). Ingestion of the highly concentrated acid erodes the teeth enamel, causes burns, abdominal pains, perforation of the gastrointestinal lining, vomiting and diarrhea. Upon gaining entry in the blood stream, dangerous levels of this acid lead to destruction of red blood cells known as hemolysis. This breakdown frees the red pigment called hemoglobin which becomes excreted in the urine (hemoglobinuria). Kidney failure and shock may result.

Concentrations above 25% is considered corrosive, while at concentrations higher than 90% it becomes a flammable acid and may react violently upon exposure to air at warm temperatures (above 39 degrees Celsius). Therefore handling the substance at high concentrations should be done with the proper precautionary measures. The following are the first aid measures upon exposure to the acid.

1. Upon inhalation, immediately move the person to a safe area where there is open, fresh air. Seek medical assistance right away, especially if the victim has lost consciousness.

2. When the skin gets in contact with concentrated acid, wash the affected region with running water to reduce burning sensation and further irritation. Call medical help and take off contaminated clothes.

3. In case of eye contact, flush the affected eye with clean running water for ten minutes (eyelids should be held open during this procedure). Do not hesitate to call for medical help.

4. When accidentally swallowed, allow the victim to drink plenty of water if he or she is conscious. Never allow him or her to take in water or any liquid orally when he or she is too weak or unconscious. Do not induce vomiting and do not give any fluid or substance other than water. Call a medical professional right away.

Wear the prescribed uniform when handling acetic acid in laboratories or industrial areas. Do not handle the substance without wearing the appropriate nitrile rubber gloves. Always ensure the proper ventilation in the area.