Dangers of Oxalic Acid
The use of oxalic acid is advocated by a number of members, but I felt compelled to put up a few notes about its use and possible toxic effects.
This is not meant to be a definitive guide, nor is it intended to be used as a kind of safety data sheet, but merely to alert those who have or are going to use oxalic acid as to its effects on the body, and precautions that should be taken.
Just because it is readily available doesn’t mean it should not be treated with respect !!!
It cannot be stressed too strongly that oxalic acid is an aggressive substance and needs to be treated with respect. Acid resistant gloves and goggles should be worn and an apron of the type used by mortuary attendants, along with wellington boots that have the tops covered by gaiters so that any falling liquid cannot fall into the boot. A respirator that has specialised organic acid filtering will be required in cases where the acid is sprayed or vapourised. Oxalic acid is also poisonous to humans by ingestion.
Health Factors
Corrosive to tissue… When ingested, causing sore throat, burning sensation, abdominal pain, vomiting, diarrhoea, passing stools with blood, drowsiness, loss of feeling in fingers and toes. Oxalic acid removes calcium from the blood causing kidney damage as the calcium is removed from the blood in the form of calcium oxalate. The calcium oxalate then obstructs the kidney tubules.
Harmful if inhaled… Can cause severe irritation and burns to nose, throat, and respiratory tract. Irritations of mucous membranes, eye discomfort and burns, blue colouration of lips, fingernails or skin, shock, collapse, convulsions, kidney damage, pulmonary oedema.
Toxic… May cause burns, nausea, gastroenteritis, vomiting, shock and convulsions. May cause renal damage, as evidenced by blood in urine. Estimated fatal dose for humans is 5 to 15 grams.
Skin Contact… Can cause severe irritation and skin burns. May be absorbed through the skin.
Eye Contact… Oxalic acid is an extreme eye irritant by virtue of being corrosive and physically abrasive.
Chronic Exposure… Causes inflammation of the upper respiratory tract. Prolonged skin contact can cause dermatitis, cyanosis of the fingers and ulceration. May cause kidney damage.
Pre-existing Conditions… Exacerbates pre-existing skin disorders or eye problems, kidney problems or respiratory complaints.
NIOSH (IDLH) Immediately Dangerous To Life or Health Concentration, 500 mg/m3
First Aid Measures
Inhalation… Remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Call a doctor immediately.
Ingestion… DO NOT INDUCE VOMITING! Give large quantities of limewater or milk to drink. Never give anything by mouth to an unconscious person. Call a doctor immediately.
Skin Contact… In cases of contact, wipe off excess from skin then immediately flush skin with high volumes of water for at least 15 minutes while removing all contaminated clothing and shoes. Wash clothing thoroughly before reuse unless obviously damaged. Call a doctor or physician immediately.
Eye Contact… Immediately flush eyes with a gentle flow of a copious amount of water for at least 15 minutes, lifting lower and upper eyelids occasionally. Call a doctor immediately.
