Poison Ivies

THE OLEANDER, A staple of Indian gardens, is known as much for the beautiful clusters of flowers it produces all year round as for its toxicity. A hardy, quick-proliferating ornamental shrub with leathery leaves that is often trained as a small tree, Nerium odorum, known as kaner in Hindi and arali in Tamil, is in fact one of the top botanical poisons consumed for self-harm in South India. Now, a young woman’s death by accidental poisoning from chewing oleander leaves has prompted two Kerala government-run temple boards to ban the offering of oleander flowers—both to the deity as naivedya and to devotees as prasadam. On April 28, 24-year-old Surya Surendran, a nursing graduate, collapsed at Kochi International Airport after unwittingly consuming oleander growing near her house in Alappuzha. She died the following day, her death coming as a warning to gardeners and plant enthusiasts who grow these plants with little regard for the potent cardiac toxins they contain. The oleander’s cousin, Thevetia peruviana, which produces lush yellow flowers, is just as toxic. “The oleander, the beautiful sweet-scented oleander, was in profusion—deep red, pure white, pink and variegated, with single and double blossoms. I rooted up many clusters of this beautiful shrub in the grounds, fearing the horses and cows might eat the leaves, which are poisonous. Hindoo women, when tormented by jealousy, have recourse to this poison for self-destruction,” wrote Fanny Parkes, a Welsh travel writer who lived in Calcutta, and later in Ahmedabad between 1822 and 1846.

ALL PARTS OF THE plant are poisonous, especially the leaves, stem, seeds, and root. The following active toxins are present—oleandrin, neriin, folinerin, rosagenin, and digitoxigenin. These are cardiac glycosides and have digoxin-like effects, acting by inhibiting the sodium-potassium-adenosine triphosphatase (Na-K-ATPase) pump. Leaves also contain oxalates. 15g of the root or 5-15 leaves can be fatal if consumed,” note Dr VV Pillay and Dr Anu Sasidharan of the Department of Forensic Medicine and Toxicology and the Poison Control Centre (PCC) at Amrita School of Medicine, Kochi, in a 2019 paper on oleander and datura poisoning. The PCC is one of the few in the country to be recognised by the World Health Organization. A PCC established at the All India Institute of Medical Sciences in Delhi a few years ago appears to be defunct as calls to the helpline number went unanswered.

Datura, a wild shrub that grows wantonly and contains atropine, scopolamine and hyoscyamine, is an infamous hallucinogen that causes delirium. Unlike oleander, it is only lethal in high doses and is therefore emerging as a cheap adulterant to cut cannabis with, says Dr CB Jani, a professor of forensic medicine and toxicology. “Oleander poisoning by accident is rare because all parts of the plant are bitter to taste. There are other noxious plants causing deaths and hospitalisations that need our attention, including Datura metel, and Jatropha curcas, a plant that is being grown for its potential to yield biodiesel, but whose seed resembles fresh groundnut and is therefore attractive to children,” says Dr Jani. Commonly known as ratanjot, jatropha contains curcin, ricin and cyanic acid. Another oilseed, castor (Ricinus communis), a common crop across India—India is in fact the world’s leading producer of castor—is a natural source of ricin, a toxic ribosome-inactivating protein that has held the fascination of the world for decades, with several reported attempts to exploit its toxic potential for biological warfare. The Bulgarian dissident writer Georgi Markov is thought to have been poisoned to death by ricin in 1978. Luckily, castor oil, which is commercially and therapeutically valuable, is safe for human use and castor seed is toxic only when crushed and ingested. “Ricin is a cheap but slow poison, causing abdominal pain, severe dehydration and bloody diarrhoea. If untreated, it can lead to death in about 72 hours,” says Minakshi Mahajan, a professor of botany at Fergusson College in Pune, who led an experiment to make ricin in her lab—“a fairly simple process”, she says. The fatal oral dose of ricin in humans is estimated to range from 1 to 20mg/kg, or 5 to 10 beans. “We don’t know enough about how unprocessed castor, too, can affect humans. A student of mine experienced vomiting and nausea after visiting castor plantations in Gujarat during harvest,” says Mahajan. Castor seed meal/cake, while highly toxic, is a great nitrogenous fertiliser and pest repellent and readily available for Rs 200 a kg or less at gardening stores and online. The high cytotoxicity of ricin is being studied for eliminating diseased cells and has been experimentally used to treat cancer.

Indeed, throughout history, the most noxious of plants have been used to preserve and prolong life as much as to end it. In his 2016 book Toxic Histories: Poison and Pollution in Modern India, David Arnold notes that ancient and medieval India’s “medical traditions can be categorised as being as much systems of toxicology—or poison management—as of therapeutics. As stated in the Caraka Samhita, ‘Even acute poison is converted into an excellent medicine by the right method of preparation; while even a good medicine may act as an acute poison if improperly administered’.” In The Materia Medica of the Hindus, first published in 1870, civil medical officer and Ayurveda expert Udoy Chand Dutt writes of nine virulent poisons mentioned in most Ayurvedic texts: vatsanabha, haridra, saktu, pradipana, saurashtrika, sringi, kalakuta, halahala and brahmaputra.“Thesecannotallbeidentifiedat present. Most of them are apparently varieties of aconite,” he writes, before detailing “minor poisons”, among them opium, seeds of gunja (Abrus precatorius), datura, roots of Nerium odorum (oleander) and Gloriosa superba (flame lily) and the milky juices of Calotropis gigantea (arka or erukkampoo) and Euphorbia neriifolia (Indian spurge tree).

Aconitum ferox or bish, which was used to treat cholera in the 1900s along with heavy metals, continues to be an important Ayurvedic ingredient that is indicated as an antipyretic, an analgesic, an anti-rheumatic and an appetiser—a cureall, really. This vicious arrow poison derived from a beautiful plant that is also known as monkshood and wolfsbane precipitated Shakespearean plots and felled armies, but its use in native medicine has meant that it continues to cause accidental poisonings. In 2015, doctors at Dr SN Medical College in Jodhpur reported a case of aconite poi­soning by self-medication with Ayurvedic drugs. The 55-year-old patient, who had slipped into ventricular tachycardia, was lucky to make a full recovery, for 2mg of pure aconite, or a few grams of the plant, is potent enough to kill a man. Alarmingly, vatsanabha, derived from aconite, is an important ingredient in a formulation known as Mahashankha vati, an Ayurvedic OTC drug marketed as a digestive. It is also found in other classical Ayurvedic formula­tions, including Mrutunjaya rasa, Saubhagya vati, Rambana rasa, Kaphaketu rasa and Sanjeevani vati. Traditionally, druggists supposedly detoxified aconite root by submerging it in cow urine and milk for several days, but the line between life and death remains razor-thin when it comes to aconite.

Perhaps the most sensational use of aconite in recent times has been by Lakhvir Kaur Singh, an Indian-origin woman from West London who is serving a life sentence for murdering her former lover Lakhvinder Cheema by lacing his curry with aco­nite in 2009. Another tropical botanical toxin that had captivated the Victorian world, strychnine, an alkaloid that occurs in the Strychnos nux-vomica tree, is now rarely used, except as rat poison— and in an esoteric Unani formulation called hudar, a capsule for elevating blood pressure. Strychnine’s dramatic mode of action— causing violent convulsions and prolonged death—made it an Agatha Christie favourite and won pride of place in an Arthur Conan Doyle mystery, but the poison is so bitter that a homicide would be hard to pull off. Alkaloids produced by plants are in fact not suited for homicides, says Dr Anil Aggrawal, a forensic medicine and toxicology expert who has testified as a medical wit­ness in hundreds of cases across the world, even travelling to the UK to investigate the scene of crime once. They are the plant’s defence mechanism against predators, but many organisms have evolved to survive such poisons—the oleander hawk-moth, for instance, and the grey langur, which eats the fruits of the strychnine tree. “There is no plant poison that can go undetected today, but the need of the hour is to set up poison control centres to help medical practitioners react in cases of accidental poisoning,” says Dr Aggrawal, who has literally written the book on toxicology.

With the ubiquity of organophosphates now, toxic plants are no longer the go-to suicide weapon in rural India, says Dr Ravindra Deokar, who runs a journal on toxicology. “With pesticides, you know it’s certain death, and not a case of vomiting and stomach pumping. The issue today is that there is less awareness about plants and about their medicinal as well as toxic properties. Accidental poisonings, even if not fatal, are becoming more common,” he says. Arnold points out that “the medi­cal literature of the nineteenth century is replete with references to Indians who fell ill or died as a result not of homicidal poi­soning with arsenic or aconitum but from the supposedly therapeutic use of danger­ous drugs like nux vomica or oleander root in tonics, elixirs, aphrodisiacs and putative cures for venereal disease, or from acciden­tal poisoning, caused by eating seeds, fruits and roots that they mistakenly thought to be harmless or which, from poverty and desperation, they took the calculated risk of eating”. Even now, the flowers of calotropis, a giant weed that is also known as milk­weed due to its milky sap, are used to make tassels and garlands for Lord Ganesha. The leaves are used in bathing rituals on ratha saptami. Solanum nigrum, or manathakkali, a climber with berries, is a popular green vegetable in South India that can be toxic when eaten raw due to its solanine content. There are accidents waiting to happen in every garden patch. So the next time you browse Instagram gardening feeds with tape-à-l’oeil philodendrons and monsteras with gorgeous fenestrations, pause to read about the calcium oxalate crystals present in these leaves that can be toxic to pets. When you pick up a periwinkle from the nursery, look up vinca alkaloids, which are known to have cytotoxic effects that can arrest the division of cells and cause cell death. Don’t plant lilies, pretty as they are, in a kitchen garden where they can be mis­taken for edible tubers. Grow oleanders if you must, and live dan­gerously, knowing well what lies beneath the sweet fragrance.

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