Arsenic

Metallic arsenic is non-poisonous. Poisoning occurs due to its salts.
Poisonous compounds:
1} Arsenious oxide or arsenic trioxide {sankhya or somalkhar} – This is the most common form of arsenic used and is known as white arsenic or arsenic. It occurs in two forms:
a} White, smooth, heavy, crystalline powder.
b} White and opaque solid mass similar to porcelain.
It has no taste or smell and is sparingly soluble in water. When added to water, it floats on its surface` even though it is heavier than water. It sublimes on heating. Arsenic is used in fruit sprays, sheep-dips, weed killers, insecticides, rat poisons, fly papers, calico-printing, taxidermy, wall papers and artificial flowers, as mordant in dyeing and for preserving timber and skin against white ants.
2} Copper arsenite{Scheele’s green} and copper aceto-arsenite{paris green or emerald green}
3} Arsenic Acid
4} Sodium and Potassium arsenate.
5} Arsenic suplhide, orpiment and realgar.
6} Arsenic trichloride{butter of arsenic}
7} Arsine is a colowebsiteess gas with garlic-like non-irritating odour.
8} Organic compounds e.g. cacodytes, atoxyl, acetarsone, tryparsamide, salvarsan, mepharsen, etc.

Route :
Ingestion
Fatal Dose :
0.1 to 0.2 g. (180 mg. average)
Fatal Period :
One to two days
Mechanism of action :
1} Arsenic interferes with cellular respiration by combining with the sulphydryl groups of mitochondrial enzymes.
2} Its particular target is vascular endothelium, leading to increased permeability, tissue oedema and haemorrhage` especially in the intestinal canal.

Clinical Picture :
1} Acute poisoning
a. The Gastrointestinal form – It is the common form of acute poisoning and resembles bacterial food poisoning. Symptoms usually appear half to one hour after ingestion. There is sweetish metallic taste.
GIT – Constriction in the throat and difficulty in swallowing, burning and colicky pain in oesophagus, stomach and bowel. Intense thirst and severe vomiting which may be projectile are the constant symptoms. Purging is usually accompanied by pain, tenesmus and irritation about the anus. The stools are expelled frequently and involuntarily, and are dark coloured, stinking, and bloody` but later become colowebsiteess, odowebsiteess and watery resembling the rice water stools of cholera.
Liver- fatty infiltration
Kidney- oliguria, uraemia` urine contains albumin, red cells and casts. Pain during micturition.
CVS- Circulatory collapse with vasodilation, increased vascular permeability, ventricular tachycardia, ventricular fibrillation
CNS - headache, vertigo, hyperthermia, tremors, convulsions, coma, general paralysis.
Skin – delayed loss of hair, skin eruptions

b. The Narcotic Form – The GI symptoms are very slight. There is giddiness, formication and tenderness of muscles, delirium, coma and death. Rarely there is complete paralysis of the extremities.

c. Sub-acute Form- no diagnostic signs and symptoms except for peripheral neuritis. It results in unexplained death.

2. Chronic poisoning
There are 4 stages.

Stage I – Stage of nutritional and gastro-intestinal disturbances: weakness, loss of weight, loss of appetite, abdominal pain, constipation, red and soft gums and increased temperature.

Stage II – Stage of catarrhal changes: increased secretion from larynx and bronchi, hoarseness of voice, congested voice, photophobia, running nose, cough with expectoration, spasmodic cough.

Stage III – Stage of skin rashes: generalized uneven hyperpigmentation of palms and soles – ‘Rain-drop appearance’. Vasodilation causes ‘Milk and Roses’ complexion. Nails become brittle and have linear pigmentation. Transverse white ‘Mee’s Lines’ appear on finger nails. There is hyperkeratosis of palms and soles. There is alopecia.

Stage IV – Stage of CNS disturbances: peripheral neuritis and muscular atrophy especially of interosseal and intercostal muscles. Headache, tingling and numbness, muscle pain, bone marrow depression and muscle paralysis.

Treatment :
1} Emetics are not recommended.
2} The stomach should be emptied and then thoroughly and repeatedly washed by the stomach tube with a large amount of water and milk. It should be washed at intervals to remove iron compounds and adherent arsenic.
3} Butter and greasy substance prevent absorption.
4} Alkalis should not be given as they increase the solubility of arsenic.
5} Freshly prepared, hydrated ferric oxide orally in small doses converts toxic arsenic to non-toxic ferric oxide.
6} B.A.L. 400-800 mg on 1st day, 200-400 mg on 2nd and 3rd days in divided doses every 4 hours and 100-200 mg in two divided doses for 7-10 days or until urine level falls below 50 micrograms in a 24 hr. specimen.
7} Penicillamine may be used with BAL. 100 mg, kg daily upto 1-2 g. in four divided doses for 5 days.
8} Demulcents lessen irritation.
9} Castor oil or magnesium sulphate to prevent intestinal absorption of arsenic.
10} Glucose-saline with sodium bicarbonate is useful to combat shock and improve alkali reserve.
11} Haemodialysis or exchange transfusion may be given if necessary.
12} Chelation therapy is ineffective in arsine poisoning.

Arsenic

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