Classification of Irritants:

B) Irritants:

1) Agricultural: Organophosphorous compound (OPC) Poisoning

2) Inorganic: a) Non-metallic: Phosphorus, iodine, chlorine, bromine (Halogens) b) Metallic: Arsenic, antimony, copper, lead, mercury, silver, zinc. c) Mechanical: Powdered glass, diamond dust, hair, etc.

3) Organic: a) Vegetable: Castor oil, Croton oil, Calotropis, aloes, Abrus precatorius b) Animal: Snake and insect venom, cantharides, ptomaine

 

Q. Enlist a few poisons that can be absorbed through intact skin. [SUST - 17M]

Ans. Metallic poison ( Arsenic, Copper, Lead Mercury, Iron, etc)

Arsenic Poisoning:

Metallic arsenic (black colored) is not poisonous, as it is not absorbed from the alimentary canal. When volatilized by heat, arsenic unites with oxygen and forms a poisonous vapor of arsenic trioxide.

Arsenic Trioxide - A white, crystalline powder

 

Source of Arsenic (Ref. Nandy)

Arsenic soil, Sub-soil water, Some sea fish

 

Fatal Dose: 0.1 to 0.2 gm arsenic trioxide.

Fatal Period: 1-2 days

 

POISONOUS COMPOUNDS of Arsenic:

1. Arsenious oxide or arsenic trioxide 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.

2. Arsenic acid

3. Arsine (AsH3) or Arsenic hydride is a colorless gas with a garlic-like, non-irritating odor.

4. Sodium and potassium arsenate.

5. Copper arsenite (Scheele's green) and copper acetoarsenite (Paris green or emerald green).

6. Arsenic sulphide

7. Arsenic trichloride

8. Organic compounds, e.g., cacodylates, atoxyl, acetarson, tryparsamide, salvarsan, mepharsen, etc.

 

Use of Arsenic

• For preserving timber and skin against white ants.
• Fruit sprays
• Insecticides,
• Rat poisons,
• Flypapers (fly-killing sticky paper coated)
• Weed-killers,
• Calico- printing,
• Taxidermy (the art of preserving an animal body)
• Wallpapers and artificial flowers
• Sheep-dips (liquid formulation of insecticide & fungicide)
• As mordant in dyeing

 

Mechanism of Action :

Arsenic interferes with cellular respiration by combining with the sulphydryl (-SH) groups of mitochondrial enzymes, especially pyruvate oxidase, and certain phosphatase. Arsenate causes its toxicity by uncoupling mitochondrial oxidative phosphorylation. It interferes with glycolysis.

Its particular target is vascular endothelium, leading to increased permeability, tissue edema, and hemorrhage, especially in the intestinal canal. Locally it causes irritation of the mucous membranes and remotely depression of the nervous system.

 

 

Signs and Symptoms of Acute Arsenic Poisoning: (Ref. Reddy)

1. The Fulminant Type (Sudden & severe onset)

Cause death in 1-3 hours from shock and peripheral vascular failure.

All the capillaries are markedly dilated, especially in the splanchnic area with a marked fall of blood pressure.

 

2. The Gastroenteric Type: Common form of acute poisoning,

Sweetish metallic taste

GIT:

Constriction in the throat and difficulty in swallowing; burning and colicky pain in the esophagus, stomach, and bowel occur.

Intense thirst and severe vomiting

Tenesmus, pain, and irritation about the anus.

The stools are expelled frequently and involuntarily and are dark-colored, stinking, and bloody, but later become colorless, odorless, and watery resembling rice-water stools of cholera.

A garlicky odor of breath and feces may be noted.

Renal:

Oliguria, uremia; urine contains albumin, red cells, and casts, pain during micturition.

C.V.S.:

Acute circulatory collapse with vasodilation, increased vascular permeability, ventricular tachycardia, and ventricular fibrillation.

CNS:

Headache, vertigo, hyperthermia, tremors, convulsions, coma, and general paralysis.

Death is usually due to circulatory failure.

 

3) Narcotic Form

Gastrointestinal symptoms are very slight.

There is giddiness, formication (sense of insect crawling on the skin), and tenderness of the muscles

Delirium, coma, and death

 

Differential Diagnosis of Acute Arsenic Poisoning Cholera Acute gastroenteritis

 

 

Treatment in case of Acute Arsenic Poisoning: (Ref. Reddy)

 

Treatment of Acute Arsenic Poisoning (Easy Alternative)

1. Emetics is not recommended.

The stomach should be emptied and then thoroughly and repeatedly washed by the stomach tube with a large amount of lukewarm water.

2. Demulcent prevents absorption

3. Specific antidote for unabsorbed poison: Freshly prepared Ferric Oxide (converts toxic arsenic to non-toxic ferric arsenite)

4. Antidote: B.A.L (British Anti-Lewisite)/ Dimercaprol

5. Penicillamine may be used with BAL

6. Laxative: Magnesium sulphate may be used.

7. I/V Fluid: Glucose-saline with sodium bicarbonate is helpful to combat shock and improve alkali reserve.

8. Hemodialysis or exchange transfusion may be given in cases of renal failure.

 

 

Postmortem Appearances of Acute Arsenic Poisoning: (Ref Reddy)

External:

The eyeballs are sunken and the skin is cyanosed. The body may be shrunken due to dehydration.

Internal:

The mouth, pharynx, and esophagus are usually not affected, but in some cases are inflamed or ulcerated.

The lesions are mainly found in the stomach. The mucosa is swollen, edematous, and red either generally or in patches. There may be lines of redness running along the walls or curved lines of sub-mucous hemorrhages.

The stomach mucosa resembles red velvet.

The small intestine appears flaccid and contains large flakes of mucus with very little fecal matter. The mucosa is pale-violet and shows signs of inflammation with sub-mucous hemorrhages along its whole length.

Sometimes, arsenic penetrates through the walls of the stomach and appears in the liver, omentum, and endocardium. If putrefaction has taken place, yellow streaks will be found in the sub-peritoneal layer of the stomach.

The liver, spleen, and kidneys are congested, enlarged, and show cloudy swelling and occasionally fatty change. The lungs are congested with sub-pleural ecchymoses.

There may be edema of the brain with patchy necrosis or hemorrhagic encephalitis. The meninges are congested.

Red velvety appearance (Characteristics sign of post mortem finding of arsenic Poisoning) Postmortem finding of acute arsenic Poisoning - stomach mucosa resembles red velvet.

 

 

Chronic Arsenic Poisoning:

It may be due to accidental ingestion of repeated small doses by those working with the metal, or by taking food or drink in which there are traces of the drug.

 

Signs & Symptoms of Chronic Arsenic Poisoning (Ref Reddy)

Arsenic is teratogenic and can result in lung and skin cancer, leukemia, etc.,

 

For Easy To Remember

Signs & symptoms of chronic arsenic Poisoning (Ref Parikh/6th/ 9.11-9.12)

A. Nutritional & GIT disturbance

• Earliest sign is gradual emaciation.
• Loss of appetite
• Nausea, vomiting
• Diarrhea

B. Skin rashes

• Hyper keratosis of both palm & sole

• Raindrop type pigmentation (milky-rose complexion): After long exposure, there may be patchy brown pigmentation of the skin.
• Loss of hair
• Brittle nail
• Aldrich-Mess line: White bands across nails of the finger

C. Nervous disturbance

• Tingling & numbness of the extremities
• Peripheral neuritis with itching

 

Note:

Mess line: Chronic arsenic poisoning Burtonian line: Lead poisoning

 

Treatment of Chronic Arsenic Poisoning

• Removing the patient from the source of exposure
• Administration of B.A.L/dimercaprol

 

 

POSTMORTEM APPEARANCES of Chronic Arsenic Poisoning:

• The stomach may show chronic gastritis.
• Patchy hemorrhagic gastritis with acute and chronic erosions
• The small intestine is dilated and reddened with thickened mucosa.
• Liver may be fatty or there may be severe necrosis or jaundice.
• Kidneys show tubular necrosis.

 

 

Arsenic is popular homicidal poison because

1. Cheap, & easily obtained,
2. Colorless, No smell, No taste,
3. Small quantity is required to cause death,
4. Can be easily administered with food or drink,
5. Onset of symptoms is gradual,
6. Symptoms simulate those of cholera.

 

Disadvantages are:

1) It delays putrefaction

2) Can be detected in completely decomposed bodies.

3) Can be found in bones, hair, and nails for several years.

4) Can be detected in charred bones or ashes.

 

Arsenicosis: Chronic arsenic poisoning

It is a chronic condition arising from prolonged ingestion of arsenic above a safe dose for at least 6 months, usually manifested by characteristics skin lesions of & melanosis and or keratosis with or without the involvement of internal organs.

 

Arsenophagists:
Some people take arsenic daily as a tonic or as an aphrodisiac, and they acquire tolerance up to 0.3 g. or more in one dose. Such people are known as arsenophagists.

 

Causes of Death in Arsenic Poisoning (Ref. Nandy)

Acute	Chronic
Dehydration & circulatory collapse Potassium & other electrolytes loss Hepatic failure Toxic encephalopathy	Hepatic failure Damage of kidney Toxic encephalopathy Intercurrent infection

 

In death due to acute arsenic poisoning, arsenic values in the liver and blood in excess of one mg. % are usually present.

X-ray may show the presence of arsenic in the G.I. tract.

 

What is the result of ingestion of massive doses of arsenic? (Ref Selima Reza)

Death may occur due to shock, in this condition, gastrointestinal symptoms are absent. So, postmortem examination is insignificant. In chemical examination may be detected in the viscera.

 

Postmortem Imbibition of Arsenic: (NTK)

In exhumations, the possibility of imbibition of arsenic from the stomach into neighboring viscera and also contamination from the surrounding earth should be remembered.

Arsenic absorbed during life is usually in soluble salt form.

Arsenic found in the soil is usually an insoluble salt. Keratin tissues absorb arsenic by contamination from outside. The concentration in hair and nails thus contaminated is likely to be much greater than the concentration of arsenic in the contaminating fluid.

If arsenic is introduced into the stomach after death, the transudation occurs into the organs of the left side before those of the right and the signs of inflammation and ulceration are absent.

 

DISTRIBUTION:
Arsenic is normally present in almost all tissues. It can appear in hair and nails within hours of ingestion. Estimates of the time of exposure can be made by measuring the distance of Mee's lines from the base of the nails or the length of hair from its growth site.