Chromic Acid - Corrosive(Caustic) Poisons

Chromic Acid

It is a derivative of the metal chromium, being one of the hexavalent chromium compounds, while bivalent and trivalent compounds include chromic oxide, chromic phosphate, and chromic sulfate.

Clinical Features

The hexavalent compounds (chromium trioxide, the anhydride of chromic acid, chromates, dichromates, and polychromates) are corrosive in nature, and can cause oral burns and tissue ulceration.

Symptoms include vomiting, diarrhoea, GI bleeding, and manifestations of renal failure. Other features include intense gastrointestinal irritation or ulceration and corrosion, epigastric pain, vertigo, fever, muscle cramps, haemorrhagic diathesis, intravascular haemolysis, circulatory collapse, peripheral vascular collapse, liver damage, acute multisystem shock, coma, and even death, depending on the dose.

Bivalent and trivalent compounds are relatively non-toxic. Trivalent chromium is in fact an essential nutrient for glucose metabolism. However, prolonged chromic phosphate therapy in the form of intraperitoneal administration for early stage ovarian carcinoma can result in bowel perforation or obstruc-tion.

Occupational exposure to hexavalent chromium has been associated with an increased incidence of lung cancer.

Treatment

·            Chelation therapy with BAL may be helpful. Haemodialysis and exchange transfusion have also been successfully tried. Dimercapto-propane-sulfonic acid (DMPS) is a new drug with promising results.

·          Dichromates (sodium, potassium, and ammonium) are important hexavalent chromium compounds which display some significant differences when compared to other chro-mium compounds. Ingestion of dichromates can cause vertigo, abdominal pain, vomiting, convulsions, severe coagulopathy, intravascular haemolysis, and hepatorenal failure.

·             Chronic inhalation of chromate dust causes conjuncti-vitis, lacrimation, ulceration of nasal septum, and respiratory cancer.

Treatment of acute dichromate poisoning involves adminis-tration of BAL and large doses of ascorbic acid (IV). Stomach wash can also be done with a solution of ascorbic acid. There are reports of favourable results with N-acetylcysteine.