ABC of Safety in the Biological Sciences




Arsenic is believed to cause toxicity by combining with sulphydryl (-SH) enzymes and interfering with cellular metabolism.34 Arsenic poisoning produces violent gastroenteritis, burning oesophageal pain, vomiting and copious watery or bloody diarrhoea. Later the skin becomes cold and clammy, blood pressure falls and weakness develops. Death is from circulatory failure with convulsions and coma being the terminal signs.34

Large doses of arsenic insufficient to cause death will induce restlessness, nausea, vomiting, headaches, dizziness, chills, cramps, irritability and variable paralysis that may progress over several weeks. Ventricular arrhythmia's may occur.

Inhalation of arsenic dust may cause acute pulmonary oedema, restlessness, dyspnoea, cyanosis with foamy sputum and rales. Exposure to arsine causes burning and stinging of the face and after 3-4 hours tightness of the chest, dysphagia, nausea, vomiting, diarrhoea and ventricular arrhythmia's. Later, pulmonary oedema, massive haemolysis, cyanosis, haemoglobinuria, renal failure and liver damage can all occur. At 10 ppm arsine rapidly causes delirium, coma and death.

Chronic poisoning produces the same effects but over a longer period with the central nervous system also becoming seriously affected. Polyneuritis, optic neuritis, anaesthesis and paraesthesia such as burning pains in hands and feet can all occur.

Treatment for acute arsenic poisoning34
1 Remove ingested arsenic by gastric lavage or emesis and follow with a saline cathartic.
2 Antidote: give Dimercaprol for two days then Penicillamine. This can be discontinued when the urine arsenic falls below 50 mg in 24 hours.
3 In addition treatment for dehydration, shock, pulmonary oedema, anuria and liver damage may be required In very severe cases haemodialysis may be necessary after Dimercaprol therapy to remove the combined Dimercaprol and arsenic.

Treatment for acute arsine poisoning
After arsine poisoning it is necessary to treat the haemolytic reaction. Exchange transfusions are useful to remove the haemoglobin-arsine complex and dialysis is required during the period of renal failure. Antidotes appear not to work.

Treatment for chronic poisoning
Remove from further exposure and give Dimercaprol or Penicillamine. Signs of arsenic intoxication disappear slowly.

In acute arsenic poisoning survival for more than one week is usually followed by complete recovery. With chronic arsenic poisoning recovery may require 6 months to 1 year.



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