Pure metallic copper is not poisonous. Copper is soluble in water or liquid with pH less than 5.5. Hence food with pH less than 5.5 stored in copper utensils or cooked in copper vessels will cause poisoning.
Source – Copper and its chemical compounds are used in industries commercial centres, as fungicide, pesticide, household appliances.
Common toxic compounds – Copper subacetate (verdegris), copper sulphate (blue vitriol), copper chloride. In fact many compounds of copper, after ingestion, may get dissolved in the gastric juice, forming copper chloride.
Fatal dose – Copper subacetate – 15 gm., Copper sulphate – 30 gm.
Fatal period – Usually more than a day, may be upto 10 -12 days.
Signs and symptoms – These are nausea, vomiting with greenish blue vomitus which turns deep blue if treated with ammonia, diarrhoea, abdominal pain, urinary suppression, haematuria, jaundice due to damage of the liver, paralysis of limbs, increased fragility of the R.B.C., shock and respiratory distress due to haemolysis, anaemia with increased leucocyte count, coma.
In chronic poisoning cases there are G.I. tract disturbance, unhealthy gum with blue lining, jaundice, muscular weakness, paralysis of limbs. Hair contains copper.
Treatment – Stomach wash with 1% potassium ferroyanide. Castor oil purgative, Penicillamine (beta, beta-dimethyl cystine), B.A.L. in their usual doses.
Postmortem findings –
There are not many external signs on the dead body in acute poisoning cases. The mucus membrane of mouth and tongue may have bluish or greenish blue tinge.
Internally, the same discolouration is present in the mucus membrane of the oesophagus and stomach. The mucus membrane of the stomach is congested with desquamation and haemorrhage at places. Mucus membrane of the upper part of the small intestine shows signs of mild to moderate irritation. There are degenerative changes in the. liver and proximal tubules of the kidneys.
In chronic poisoning cases gums appear unhealthy with bluish lining. There is muscular atrophy. Liver and kidneys show varying degree of degeneration. In poisonings due to inhalation of vapours, signs of chronic pneumonitis may be there. Blood picture is altered with presence of premature cells in peripheral blood.
Medicolegal aspects –
Poisoning is mostly suicidal or accidental. Number of successful suicides are much less than attempts due to the emetic property of copper sulphate which is commonly used by the suicide, and is mostly vomited out. However, suicidal deaths with copper sulphate is not very infrequent in our country. Acute accidental poisoning occurs mostly in children who being attracted with the colour and glaze of the copper sulphate crystals, may chew them. It may also occur due to preservation and cooking of food and drink in copper container or utensils. Chronic poisoning occurs in industries and from commercial sources. Homicidal poisoning is not possible due to detectable colour and high fatal dose. Preparation of copper may be used for causing abortion and as cattle poison.
Chronic poisoning with copper may occur in the industrial environment and in domestic environment due to constant use of copper utensil or consumption of vegetables treated with copper sulphate solution as preservative or colouring agent.