Poison: A chemical substance that, when administered, inhaled or taken orally, has the potential to cause harm to the human body.

History of Plant Poisons

The renowned Greek philosopher Socrates was murdered with water hemlock containing coniine, another notorious toxic chemical (c.479-399 BC).

Claudius, the Roman Emperor, was assassinated by his wife Agripinna, who used the Amanita, or death cap mushroom, expertly.

Mistletoe (Viscum album) has been known for its toxic qualities since ancient times. In pagan times, it was regarded as a sacred plant, especially by the Celts. An arrow composed of mistletoe was said to have killed the deity Baldr in Nordic mythology. Extracts taken from this plant is still in use for alternative treatment of cancer in certain places.

In ancient India, poisoned weapons were employed as a form of warfare.

Chanakya, also known as Kautilya (350-283 BC), was the first Maurya Emperor Chandragupta’s (340-293 BC) advisor and prime minister, and he proposed the hidden use of poisons / poisoned weapons for political benefit.

Forensic Significance of Plant Poisons

India, being a tropical nation, has a diverse and abundant flora that includes hundreds of species, some of which are quite toxic. The majority of people in rural regions rely on farms and gardens for their sustenance. Hence, Accidental poisoning occurs regularly.

Accidental poisoning include intake of harmful traditional medicines, poisonous milk from flowers. A large majority of cases of poisoning include children.

Used as stupefying agents i.e. certain plant poisons when mixed with substances like water, juice or sweets will bring down the logical capacity. Therefore, plant poisons are also used in burglary cases.

Botanical weapons in suicidal and homicidal purposes.

In some forensic cases, plant poisons can also be used as truth serum to make suspects reveal the truth.

Classification of Poison Based on Action

1.Neurotic– They primarily affect the central nervous system and spinal cord, with symptoms including headache, giddiness, delirium, stupor, coma, and convulsions. Eg: Strychnos nux vomica, Datura fastuosa, Cannabis sativa

2. Cardiac– These have an impact on cardiac function. Eg: Digitalis purpurea, Calotropis gigantean

3. Irritants– Pain in the abdomen, vomiting, and purging are some of the symptoms. Eg: Calotropis procera, Taxus baccata

4. Miscellaneous– Ergot (Claviceps purpurea), Oleander (Glycoside)

Most Common Indian Poisonous Plants

Datura (Deliriant & Cerebral poison)

• One of the most common wild plant found in India which mainly grows in garbage dumped areas.
• Varieties: Datura Stramonium (large white flowers), Datura fastuosa-Datura Niger (White flower plant in land areas), Datura alba (purple flower plant).
• The entire plant is toxic, but its seed and fruit are the most hazardous.
• Datura fruit-Greyish ash colour with almost 500 seeds in 1 fruit.
• Datura seed- Yellowish brown, kidney shaped.

Fatal dose: 1g (100-125 seeds), Fatal period: 24 hrs

Mode of action: It affects both the central and peripheral system.

• Small dose- Stimulates central nervous system
• Moderate dose- Causes somnolence
• Large dose-Delirium, depression, coma, death

Signs & symptoms–

• Hot as a hare- Body temperature rises to as high as 105-107 ℉.
• Red as a beet-Face becomes flushed and red
• Blind as a bat-Pupils get dilated, loss of vision
• Dry like a bone-Throat becomes dry and feeling of intense thirst
• Death due to respiratory failure

Treatment–

• Stomach wash/Pumping/ Gastric irrigation with KMNO4 (Potassium Permanganate) with weak solution of tanic acid.
• To counteract anticholinergic toxicity in extreme instances, physostigmine, a cholinesterase inhibitor, should be administered.

Detection test–

Vitali’s test, Mydriatic test, microscopic tests, Physiological tests etc.

Medico-legal aspects–

Homicide, suicidal, Accidental, Abortifacient

Calotropis ( gastrointestinal irritant, ocular toxicity, cardio-toxicity)

• Usually found in abandoned farmlands.
• Varieties- Calotropis gigantea (White to purple non-scented flowers), Calotropis procera ( White to pink scented flowers)
• Root bark and flower are the most toxic parts.
• Milky juice of the plant, madar juice can cause irritation, inflammation and if it is instilled into eyes, it can cause conjunctivitis which may lead to permanent loss of vision.
• Digoxin is an active component of Calotropis which affects the rate of heartbeat.

Fatal dose-Root bark powder-0.5-1g/day , flower powder-1-2g/day

Fatal period-6-12 hours

Signs & symptoms–

• If ingested, it may cause burning sensation in the mouth to oesophagus.
• Increased salivation, abdominal pain
• Dilated pupil, tetanic convulsions, coma, death
• Slow heart beat

Treatments–

• Stomach wash with warm water.
• Using Demulcents like mineral oil.
• Intravenous administration of glucose and saline.

Detection–

Frohde’s test, Conc. Sulphuric acid test, Conc. Hydrochloric acid test

Medico-legal aspects–

• In precise doses, it is used as a medicine.
• Accidental poisoning is very common.
• Abortifacient
• Used to create artificial bruise
• Commonly used cattle poison
• Used as an Infanticide poison

Oleander/Nerium Oleander (Cardiac congestion & toxicity, glycoside)

• A shrub or small tree used as an ornamental and landscape plant in temperate and subtropical regions across the world.
• Varieties-White, purple, yellow and pink coloured flowers
• All the parts of Oleander are poisonous but the stem, seeds and root are most toxic parts.
• Used in cancer treatment, ischemic stroke
• Active principles are cardiac glycosides (Oleandrin, nerin, folinerin and rosagenin)

Fatal dose– 5-15 leaves, 15-20g root, 10-15g stem

Fatal period-20-36 hrs

Signs & Symptoms–

• Vomiting and gastric irritation
• Bradyarrhythmias
• Tachyarrhythmias
• Heart attack
• Blurred vision
• Diarrhea
• Convulsions

Treatments–

• Antiemetics are used to manage severe vomiting, while plain saline is used to correct dehydration.
• Correction of hyper or hypokalemia
• Gastric decontamination using charcoal

Detection–

• HPLC/MS (high-performance liquid chromatography and mass spectrometry) may identify it in the blood.
• Digoxin immunoassay, liquid chromatography

Medico-legal aspects–

• Accidental ingestion especially by children
• Inhalation of smoke from fires that burn near oleander
• Livestock killing poison
• Rodent poison

There are many more plants which are toxic in nature. There are no true distinctions between a medicine and a poison, because a medicine in a toxic dosage is a poison, and a poison in a tiny dose can be a medication, implying that it all comes down to dose/quantity.