Poison Truths: From Symptoms to Postmortem_Forensic Toxicology

Poison Truths: From Symptoms to Postmortem_Forensic Toxicology

Introduction

Poison is any substance which, when introduced into the body in sufficient quantity, causes harmful effects or death by its chemical action. In forensic science, poisoning cases require detailed examination of the poison involved, its action on the body, symptoms before death, postmortem appearances, and laboratory toxicological findings. Poisons are broadly classified according to their action on the human body. The major types are corrosive poisons, irritant poisons, neurotic poisons, cardiac poisons, and asphyxiants.

 1. Corrosive Poisons

Meaning

Corrosives are substances that destroy tissues on contact by chemical action. They mainly affect the skin, mouth, esophagus, and stomach.

Examples

• Sulfuric acid
• Nitric acid
• Hydrochloric acid
• Caustic soda
• Caustic potash
• Phenol

Signs and Symptoms

• Immediate burning pain in mouth, throat, and stomach
• Difficulty in swallowing
• Excessive salivation
• Vomiting, often mixed with blood
• Shock
• Collapse
• Perforation of stomach in severe cases

Postmortem Changes

External

• Burns and stains around lips and mouth
• Black burns in sulfuric acid poisoning
• Yellow stains in nitric acid poisoning
• White or gray patches in alkali poisoning

Internal

• Corrosion of lips, tongue, throat, esophagus
• Perforation of stomach wall
• Softening and destruction of mucosa
• Dark brown or black stomach contents depending on poison

Toxicological Findings

• Strong acidic or alkaline reaction in stomach contents
• Chemical detection of acid radicals or alkalis
• Tissue destruction visible histologically
• Correlation with burned clothing or containers at scene

Forensic Importance

Mostly suicidal or accidental. Homicidal use is rare because of severe pain and obvious injuries.

 

2. Irritant Poisons

Meaning

Irritants cause inflammation of mucous membranes, especially gastrointestinal tract, leading to pain, vomiting, and diarrhea.

Examples

• Arsenic
• Mercury salts
• Phosphorus
• Copper sulfate
• Castor seeds
• Abrus seeds

Signs and Symptoms

• Burning pain in abdomen
• Vomiting
• Severe diarrhea
• Thirst
• Dehydration
• Muscle cramps
• Weakness
• Collapse

Postmortem Changes

External

• Dehydrated appearance
• Sunken eyes
• Cyanosis in severe poisoning

Internal

• Redness and inflammation of stomach and intestines
• Hemorrhages in mucosa
• Fatty degeneration of liver and kidneys
• Garlic smell in phosphorus poisoning

Toxicological Findings

• Detection of metals in viscera, hair, nails, blood, urine
• Chemical tests for arsenic, mercury, copper
• Histopathology showing organ damage

Forensic Importance

Can be homicidal, suicidal, or accidental. Arsenic has historical importance as a homicidal poison because it may resemble natural illness.

 

3. Neurotic Poisons

Meaning

Neurotic poisons act mainly on the central nervous system. They may depress, stimulate, or paralyze nerve centers.

Subtypes

• Cerebral depressants
• Deliriants
• Convulsants
• Spinal poisons

Examples

• Opium
• Morphine
• Alcohol
• Barbiturates
• Datura
• Strychnine
• Cannabis

 

A. Cerebral Depressants

Signs and Symptoms

• Drowsiness
• Slurred speech
• Pinpoint pupils (opioids)
• Slow breathing
• Unconsciousness
• Coma

Postmortem Changes

• Pulmonary edema
• Congested brain
• Cyanosis
• Froth at mouth sometimes

Toxicological Findings

• Detection in blood, urine, gastric contents
• Drug screening by chromatography or mass spectrometry

 

B. Deliriants (Example: Datura)

Signs and Symptoms

• Dilated pupils
• Dry mouth
• Hallucinations
• Restlessness
• Delirium
• Increased pulse

Postmortem Changes

• Congestion of brain and organs
• Dilated pupils may persist

Toxicological Findings

• Detection of atropine-like alkaloids in viscera

C. Convulsants (Example: Strychnine)

Signs and Symptoms

• Severe muscular spasms
• Opisthotonus
• Consciousness preserved till late stage
• Death due to respiratory failure

Postmortem Changes

• Congestion
• Cyanosis
• Signs of asphyxia

Toxicological Findings

• Detection of alkaloid in stomach contents and tissues

Forensic Importance

Often suicidal, accidental overdose, or drug abuse related.

 

4. Cardiac Poisons

Meaning

These poisons primarily affect the heart by altering rhythm, contractility, or conduction.

Examples

• Digitalis
• Oleander
• Aconite
• Nicotine in high dose

Signs and Symptoms

• Irregular pulse
• Chest pain
• Vomiting
• Sweating
• Weakness
• Sudden collapse
• Fatal arrhythmias

Postmortem Changes

• Congestion of organs
• Fluid blood
• No specific gross findings in many cases

Toxicological Findings

• Detection in blood and viscera
• ECG history before death may help
• Plant toxins identified in biological samples

Forensic Importance

Can be suicidal, accidental, or homicidal by mixing in food or medicine.

 

5. Asphyxiant Poisons

Meaning

These poisons interfere with oxygen supply, transport, or utilization leading to suffocation at cellular level.

Examples

• Carbon monoxide
• Cyanide
• Hydrogen sulfide
• Carbon dioxide in confined spaces

 

A. Carbon Monoxide

Signs and Symptoms

• Headache
• Dizziness
• Nausea
• Confusion
• Unconsciousness
• Death in closed spaces

Postmortem Changes

• Bright cherry red postmortem lividity
• Pink skin
• Congested organs

Toxicological Findings

• Raised carboxyhemoglobin level in blood

 

B. Cyanide

Signs and Symptoms

• Rapid collapse
• Breathlessness
• Convulsions
• Coma
• Very rapid death

Postmortem Changes

• Bright red blood
• Bitter almond smell in some cases
• Congestion

Toxicological Findings

• Detection of cyanide ions in blood and stomach contents

 

C. Hydrogen Sulfide

Signs and Symptoms

• Eye irritation
• Respiratory distress
• Collapse

Postmortem Changes

• Greenish discoloration
• Pulmonary edema

Toxicological Findings

• Sulfide detection in tissues

Forensic Importance

Common in industrial accidents, fires, enclosed spaces, and suicides.

6. Miscellaneous Poisons

Pesticides (Organophosphorus Compounds)

Signs and Symptoms

• Salivation
• Sweating
• Pinpoint pupils
• Vomiting
• Muscle twitching
• Respiratory failure

Postmortem Changes

• Froth at mouth and nostrils
• Pulmonary edema
• Characteristic odor

Toxicological Findings

• Low cholinesterase level in blood
• Chemical detection in viscera

 

Alcohol

Signs and Symptoms

• Impaired judgment
• Incoordination
• Slurred speech
• Coma in overdose

Postmortem Changes

• Gastritis
• Congestion
• Pulmonary edema

Toxicological Findings

• Blood alcohol estimation

 

General Forensic Toxicological Procedure

In suspected poisoning, the following are preserved:

• Stomach and contents
• Small intestine and contents
• Liver
• Kidney
• Blood
• Urine
• Preservative samples

Analysis is done using:

• Chromatography
• Spectroscopy
• Immunoassay
• Mass spectrometry

 

Conclusion

Each poison produces characteristic clinical effects, postmortem changes, and toxicological findings. Some poisons show obvious external injuries, while others leave only subtle internal evidence. Therefore, forensic investigation of poisoning depends on scene examination, autopsy findings, laboratory analysis, and case history. Proper understanding of each type of poison helps determine the cause, manner, and circumstances of death.