In these slides, Professor Tagwireyi highlights on important aspects of ingestion of plants in the Araceae species as exemplified by "Elephant's Ear" ingestion. In addition the toxicology of poisoning from a few other toxic plants found in Zimbabwe is highlighted.

1. Elephant's Ear (DDT) 1
Plant Poisoning:Plant Poisoning:
Elephant’s Ear IngestionElephant’s Ear Ingestion
Dexter TagwireyiDexter Tagwireyi,,
BPharm(Hons), GradDipTox, MAppSc(Tox), PhDBPharm(Hons), GradDipTox, MAppSc(Tox), PhD
Drug & Toxicology Information ServiceDrug & Toxicology Information Service
Department of PharmacyDepartment of Pharmacy
University of ZimbabweUniversity of Zimbabwe

2. By the End of this Talk…
• Delegates must be able to describe the
clinical toxicology of exposure to
Elephant’s Ear plant
• Delegates must be able to identify few other
toxic plants and have an idea of their
toxicology
• Delegates must have learnt something
Elephant's Ear (DDT) 2

3. Elephant's Ear (DDT) 3
IntroductionIntroduction
• Ingestion of plants by kids (esp. toddlers)Ingestion of plants by kids (esp. toddlers)
common worldwidecommon worldwide
• inquisitive kidsinquisitive kids
• ‘‘experimentation’experimentation’
• hungerhunger
• otherother
• Number of plants potentially toxic - butNumber of plants potentially toxic - but
exposure appears more common with certainexposure appears more common with certain
species:species:
• AraceaeAraceae Family most common cause of symptomatic plantFamily most common cause of symptomatic plant
exposure in Zimbabwe and elsewhereexposure in Zimbabwe and elsewhere

4. Elephant's Ear (DDT) 4
Elephant’s Ear PlantElephant’s Ear Plant
• These are beautiful ornamental plants:These are beautiful ornamental plants:
– normally have large elephant shaped leavesnormally have large elephant shaped leaves
– normally green leaves, but may be other coloursnormally green leaves, but may be other colours
• A number of plant species are referred to asA number of plant species are referred to as
Elephant’s Ear, but normally:Elephant’s Ear, but normally:
– ColocasiaColocasia andand AlocasiaAlocasia spp.spp.
• Tubers are used as food in other communitiesTubers are used as food in other communities
• Related toRelated to DiffenbachiaDiffenbachia - including the- including the
toxicologytoxicology

5. Elephant's Ear (DDT) 5
ToxicologyToxicology
• All parts of the plant are toxic on exposureAll parts of the plant are toxic on exposure
• Plants contain calcium oxalate crystals which arePlants contain calcium oxalate crystals which are
needle-shaped in compact bundles (raphides)needle-shaped in compact bundles (raphides)
• Chewing leads to expulsion of calcium oxalateChewing leads to expulsion of calcium oxalate
crystals - lodge into mouth, tongue, throatcrystals - lodge into mouth, tongue, throat
On Chewing
Calcium oxalate crystal are ejected

6. Elephant's Ear (DDT) 6
ToxicologyToxicology
• The crystals lead to inflammation of theThe crystals lead to inflammation of the
oral cavity including the throat and severeoral cavity including the throat and severe
painpain
• Calcium oxalate is not readily absorbedCalcium oxalate is not readily absorbed
because it is ionisedbecause it is ionised
• In large doses, the hydrochloric acid in theIn large doses, the hydrochloric acid in the
GIT reacts with calcium oxalate to formGIT reacts with calcium oxalate to form
oxalic acid - freely absorbedoxalic acid - freely absorbed
• On absorption, oxalic acid leads toOn absorption, oxalic acid leads to
systematic effects of poisoningsystematic effects of poisoning

7. Elephant's Ear (DDT) 7
• Oxalic acid binds to calcium (Ca++) ions inOxalic acid binds to calcium (Ca++) ions in
the blood --- reduction of Ca++ ions --- thisthe blood --- reduction of Ca++ ions --- this
results in muscular and cardiac problemsresults in muscular and cardiac problems
• In kidneys, Ca++ binds to oxalic acidIn kidneys, Ca++ binds to oxalic acid
resulting in the formation of calciumresulting in the formation of calcium
oxalate crystals - - formation of stones - -oxalate crystals - - formation of stones - -
nephrotoxicity and other renal problemsnephrotoxicity and other renal problems
• Local inflammation as a result ofLocal inflammation as a result of
• direct effect of calcium oxalate on buccal liningdirect effect of calcium oxalate on buccal lining
• ‘‘breaking’ of mast cellsbreaking’ of mast cells
• proteolytic enzymes on grooves of crystalsproteolytic enzymes on grooves of crystals
• bradykinin-like substancesbradykinin-like substances

8. Elephant's Ear (DDT) 8
Toxic DoseToxic Dose
• Normally one bite is enough to ‘discourage’Normally one bite is enough to ‘discourage’
further mastication of the plantfurther mastication of the plant
• systemic effects rare, but have beensystemic effects rare, but have been
documented with the ingestion of largerdocumented with the ingestion of larger
quantities e.g.,quantities e.g.,
– the whole leafthe whole leaf
– one documented case for Zimbabwe (Tagwireyione documented case for Zimbabwe (Tagwireyi
& Ball, 2002)& Ball, 2002)

9. Elephant's Ear (DDT) 9
Clinical PresentationClinical Presentation
Local EffectsLocal Effects
• Pain in the mouth with inflammationPain in the mouth with inflammation
• Swelling of buccal mucosaSwelling of buccal mucosa
• Dysphagia, burning sensationDysphagia, burning sensation
• DysphoniaDysphonia
• Swelling of pharynx (cause of death inSwelling of pharynx (cause of death in
experimental animals)experimental animals)

10. Elephant's Ear (DDT) 10
Systematic Signs and SymptomsSystematic Signs and Symptoms
• these occur mainly as a result of a decreasethese occur mainly as a result of a decrease
in Ca++ ions in the body fluids and include:in Ca++ ions in the body fluids and include:
– muscular spasms and crampsmuscular spasms and cramps
– bradycardiabradycardia
– hypotensionhypotension
– arrhythmia'sarrhythmia's
– respiratory failure and bradypnoearespiratory failure and bradypnoea
– renal insufficiency (nephrotoxicity)renal insufficiency (nephrotoxicity)

11. Elephant's Ear (DDT) 11
ManagementManagement
• ABCs - if obstruction presentABCs - if obstruction present
• endotracheal intubation/tracheostomyendotracheal intubation/tracheostomy
• For local symptomsFor local symptoms
• rinse mouth with cold waterrinse mouth with cold water
• demulcent e.g., cold water, ice creamdemulcent e.g., cold water, ice cream
• simple analgesics e.g., paracetamolsimple analgesics e.g., paracetamol
• antacids may be usedantacids may be used
• ““the benefit of corticosteroids and/or antihistaminesthe benefit of corticosteroids and/or antihistamines
remains questionable - don’t use themremains questionable - don’t use them

12. Elephant's Ear (DDT) 12
• For systemic symptomatologyFor systemic symptomatology
– calcium gluconate and chloride may be given tocalcium gluconate and chloride may be given to
replenish calcium ion storesreplenish calcium ion stores
– give fluids to dissolve calcium oxalate crystalsgive fluids to dissolve calcium oxalate crystals
in the renal system as well as to prevent furtherin the renal system as well as to prevent further
crystalluriacrystalluria
– give other supportive therapy as deemedgive other supportive therapy as deemed
necessary according to the symptommatologynecessary according to the symptommatology
MonitorMonitor
• Airway, renal system and theAirway, renal system and the
cardiovascular systemcardiovascular system

13. References
• Tagwireyi D, Ball DE (2001). Management of Elephant’s
Ear Poisoning. Human & Experimental Toxicology 20 (4)
pp 189 - 192
Elephant's Ear (DDT) 13

14. Elephant's Ear (DDT) 14
May God Bless You All!!!May God Bless You All!!!

15. Elephant's Ear (DDT) 15
Other Common ToxicOther Common Toxic
PlantsPlants

16. Nerium Oleander
Elephant's Ear (DDT) 16

17. Nerium Oleander – White
Flowers
Elephant's Ear (DDT) 17

18. Thevetia peruviana
Elephant's Ear (DDT) 18

19. Highlights
• Toxic components cardiac glycosides
– Oleandrin, oleandroside and others (Thevetin A
and B for Thevetia peruviana
– Flowers pose hazard in accidental poisoning,
but all parts toxic
• Symptoms
– Nausea, vomiting, abdominal cramps and
bloody diarrhoea
– Confusion, dizziness, drowsiness, visual
disturbances
– Ventricular disarrythmias, tachyarrythmias,
bradycardia, heart block
Elephant's Ear (DDT) 19

20. Ricinus Communis
Elephant's Ear (DDT) 20

21. Highlights
• Toxicity due to ricin
– Lethal dose reported to be 4 – 8 seeds but rare
• Symptoms of overdose (2-4hrs…may be
delayed)
– Nausea, diarrhoea, abdominal pains
– Tachycardia, hypotension
– Seizures up to a week
– Beleeding disorders
Elephant's Ear (DDT) 21

22. Abrus Precatorius
Elephant's Ear (DDT) 22

23. Highlights
• Toxicity as a result of abrin
– Ingestion of a single seed could kill an adult??
• Toxicity similar to ricin
Elephant's Ear (DDT) 23

24. Jatropha curcas
Elephant's Ear (DDT) 24

25. Highlights
• Seeds contain curcin and carcinogenic
phorbol
• Symptoms
– Mainly GIT, emesis, nausea, vomiting,
diarrhoea
– Blood clotting disorders
Elephant's Ear (DDT) 25

26. Datura stramonium
Elephant's Ear (DDT) 26

27. Boophone disticha
Elephant's Ear (DDT) 27

28. Gloriosa superba
Elephant's Ear (DDT) 28

29. By the End of this Talk…
• Delegates must be able to describe the
clinical toxicology of exposure to
Elephant’s Ear plant
• Delegates must be able to identify few other
toxic plants and have an idea of their
toxicology
• Delegates must have learnt something
Elephant's Ear (DDT) 29

30. Also
• Raw tomatoes and leaves
• Raw potatos and leaves
• Pips of apples, plum seeds
• Cassava
• Other
Elephant's Ear (DDT) 30