SN2 SHORT NOTE 5M ★ High-yield

Describe copper sulphate poisoning.

Forensic Medicine · 2nd Professional — Para-Clinical

Sources and Action

Copper sulphate (blue vitriol, nila thotha, tuttha) is a blue crystalline irritant widely available in India as a fungicide and algicide, in tanneries and dyeing, and formerly in medicine as an emetic and astringent
It is used suicidally, and notably to procure abortion; it has also been used to adulterate food and vegetables, since a small quantity restores the green colour of stale produce — a practice that causes chronic low-level poisoning
Fatal dose about 15 to 30 g; fatal period 1 to 3 days
Mechanism — direct corrosive and irritant action on the gut; and systemically massive intravascular haemolysis, with methaemoglobinaemia, followed by acute renal failure and hepatic necrosis

Stage	Features
Immediate (local)	A characteristic metallic or astringent taste; burning pain in the mouth, throat and abdomen; and repeated vomiting of blue or green material, which is almost diagnostic and is the classical presenting sign
Within hours	Green or blue diarrhoea; dehydration and shock; salivation and a blue discolouration of the tongue and gums
12 to 48 hours — systemic	Intravascular haemolysis with haemoglobinuria; jaundice, which is both haemolytic and hepatic; methaemoglobinaemia with cyanosis; and hepatic necrosis
2 to 4 days	Acute renal failure from haemoglobinuric tubular necrosis, which is the usual cause of death; convulsions, coma and cardiovascular collapse
Chronic exposure	"Vineyard sprayer’s lung"; hepatic cirrhosis; and, in WILSON disease, the same picture arises from a genetic failure of copper excretion with the KAYSER-fleischer ring at the corneal margin

CLINICAL PEARL

Blue or green vomit is close to diagnostic, and it is the one poisoning that announces itself. Very few substances colour the vomit; copper sulphate does it reliably, and the metallic taste and blue-stained tongue complete the picture. The trap is what follows: the local symptoms settle, the patient appears to improve, and haemolysis and renal failure develop over the next two to four days.

Postmortem Findings and Treatment

Postmortem — blue or green staining of the mouth, tongue, oesophagus and stomach; the gastric mucosa congested, eroded and blue-green; the contents blue; the liver enlarged and jaundiced with centrilobular necrosis; and the kidneys swollen with haemoglobin casts. The lividity may be chocolate-brown from methaemoglobin
Treatment — gastric lavage cautiously (it is corrosive in concentration); demulcents such as milk and egg white; penicillamine or BAL as the chelator, with DMSA as an alternative; management of haemolysis with alkaline diuresis and transfusion; methylene blue for methaemoglobinaemia; and haemodialysis for renal failure, which is what most survivors require
Potassium ferrocyanide has been used as a chemical antidote to form insoluble copper ferrocyanide in the stomach

Medicolegal Aspects and Applied Aspects

Manner — suicidal is much the commonest in India; accidental in children and from contaminated food and adulterated vegetables; used as an abortifacient; and rarely homicidal, since the taste and colour make concealment difficult
Food adulteration with copper salts to green stale vegetables and sweets is an offence under the Food Safety and Standards Act, and produces chronic low-grade exposure in the population
Recognise the blue-green vomit and act on it; it is one of the few immediately diagnostic signs in toxicology
Do not be reassured by early improvement; haemolysis and renal failure develop at 2 to 4 days, and a patient discharged after the gastrointestinal phase may die at home
Monitor haemoglobin, renal function and methaemoglobin daily for several days, and arrange dialysis access early
Consider WILSON disease in a young person with unexplained hepatic failure and neurological signs; look for the Kayser-Fleischer ring, which is a bedside diagnosis
Preserve viscera and the vomit; copper is readily demonstrated and the quantity distinguishes therapeutic from toxic exposure
Copper sulphate is used to green stale vegetables, which is an offence under the Food Safety Act and a source of chronic exposure
Methylene blue treats the methaemoglobinaemia, and alkaline diuresis protects the kidney from the haemoglobin load

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