1. Toxicity in Humans by Ingestion of Colocasia esculenta (Elephant Ear) Audrey Medina Barry Sandall Loucia Jose Biology 445 May 04, 2007

2. What is Colocasia esculenta ? Herbaceous, flowering plant of the family Araceae. Herbaceous, flowering plant of the family Araceae. Commonly referred to as ‘Elephant Ear’ Commonly referred to as ‘Elephant Ear’ because of its large leaves resembling elephant ears. Grown in tropical areas as a staple food resource (taro) by many indo-asian countries Grown in tropical areas as a staple food resource (taro) by many indo-asian countries

3. Description Perinnial monocot Perinnial monocot Large, arrowhead-shaped leaves can grow to be 3’ X 2’ Large, arrowhead-shaped leaves can grow to be 3’ X 2’ Long stalk Long stalk Flowers are arranged in a spadix with green or yellow spathe Flowers are arranged in a spadix with green or yellow spathe Taro corms present in the root Taro corms present in the root similar in appearance to a yam or potato similar in appearance to a yam or potato

4. Distribution Native to tropical Polynesia and southeastern Asia Native to tropical Polynesia and southeastern Asia Grows naturally in tropical and subtropical areas but will grown in temperate climates as well Grows naturally in tropical and subtropical areas but will grown in temperate climates as well Introduced to United States, considered an invasive species in some areas Introduced to United States, considered an invasive species in some areas

5. Uses: Grown primarily as a vegetable food for its Grown primarily as a vegetable food for its edible corm Taro corms are used most Taro corms are used most famously in the Hawaiian dish known as poi. Also grown as a leaf vegetable for food. Also grown as a leaf vegetable for food. Popular in the United States for its foliage and used mainly for aesthetic purposes. Popular in the United States for its foliage and used mainly for aesthetic purposes.

6. Toxic Parts of Plant The entire plant is toxic! Leaf, stem, and root. SO WATCH OUT!!!

7. Signs and Symptoms If Ingested Raw : Intense burning and irritation of lips, mouth, tongue, and throat. Intense burning and irritation of lips, mouth, tongue, and throat. Vomiting Vomiting Diarrhea (Uncommon) Diarrhea (Uncommon) Base of tongue swells and can be fatal if swelling is large enough to block the air passage of the throat. Base of tongue swells and can be fatal if swelling is large enough to block the air passage of the throat. Death by asphyxiation! Death by asphyxiation!

8. Toxic Agent Elephant ear contains calcium oxalate crystals which are needle-shaped and arranged in compact bundles. Elephant ear contains calcium oxalate crystals which are needle-shaped and arranged in compact bundles. When chewed the crystals are ejected from specialized explosive ejector cells. When chewed the crystals are ejected from specialized explosive ejector cells. Needles get lodged in the lining of the mouth, tongue, and throat leading to local inflammatory reactions. Needles get lodged in the lining of the mouth, tongue, and throat leading to local inflammatory reactions.

9. Toxic Principle Calcium oxalate crystals-Raphides Oxalate is an unstable salt of oxalic acid Oxalate is an unstable salt of oxalic acid Oxalic acid is soluble in water, alcohol, and ether. Oxalic acid is soluble in water, alcohol, and ether. Composed of: Composed of: 2 carboxyl groups Creates dangerous Creates dangerous free-radicals in body.

10. Mechanism Needle fibers induce inflammatory response and edema in oral cavities and mucous membranes. Needle fibers induce inflammatory response and edema in oral cavities and mucous membranes. Can lead to aphyixiation Can lead to aphyixiation Calcium oxalate dissolves in the stomach to form oxalic acid. Calcium oxalate dissolves in the stomach to form oxalic acid. more readily absorbed into the more readily absorbed into the blood and circulation system. Very dangerous if ingested in large amounts Very dangerous if ingested in large amounts

11. Toxicity Oxalic acid can binds with calcium in the body resulting in hypocalcemia. Oxalic acid can binds with calcium in the body resulting in hypocalcemia. Can lead to muscle cramps, hypotension, bradycardia, and cardiac arrhythmia. Can lead to muscle cramps, hypotension, bradycardia, and cardiac arrhythmia. Binding of oxalic acid with calcium in the body can induce crystallization of calcium oxalate. Binding of oxalic acid with calcium in the body can induce crystallization of calcium oxalate. Calcium oxalate can build up in the body. Calcium oxalate can build up in the body. Major cause of kidney stones. Major cause of kidney stones. Can lead to liver and kidney failure and cause permanent damage. Can lead to liver and kidney failure and cause permanent damage.

12. Treatment and Other Precautions Calcium chloride and calcium gluconate should be administered for large ingestion of plant…why? Calcium chloride and calcium gluconate should be administered for large ingestion of plant…why? Calcium chloride and gluconate act by replenishing the calcium in the circulation, thus reducing the toxic effects. Calcium chloride and gluconate act by replenishing the calcium in the circulation, thus reducing the toxic effects. Providing extra calcium reduces the toxic danger of the Providing extra calcium reduces the toxic danger of the free oxalic radicals. As a precaution, Elephant Ear As a precaution, Elephant Ear should be eaten with milk or other foods rich in calcium.

13. Summary of Toxicity Oxalate crystals on plant cause extreme inflammatory immune response which may lead to death. Oxalate crystals on plant cause extreme inflammatory immune response which may lead to death. Minor gastrointestinal distresses to serious heart conditions can be caused by low calcium levels due to oxalic acid ingested from Colocasia esculenta. Minor gastrointestinal distresses to serious heart conditions can be caused by low calcium levels due to oxalic acid ingested from Colocasia esculenta. Kidney stones, major organ failure, Kidney stones, major organ failure, and tissue damage can also result from deposits of calcium oxalate, formed by oxalic acid binding calcium in the body.

14. Conclusions Colocasia esculenta (Elephant Ear, taro) can cause many toxic effects in humans with potential for serious damge or death. Colocasia esculenta (Elephant Ear, taro) can cause many toxic effects in humans with potential for serious damge or death. Colocasia esculenta should NEVER be eaten raw. Colocasia esculenta should NEVER be eaten raw. Proper cooking methods and precautions should be followed closely. Proper cooking methods and precautions should be followed closely. Calcium should be taken appropriately when ingesting. Calcium should be taken appropriately when ingesting.

15. Conclusions cont… Taro must be the most delicious dish in the world. Taro must be the most delicious dish in the world. Because, really, why the hell is anyone eating this thing? Because, really, why the hell is anyone eating this thing? Yummy! Yummy!

16. References Beaulieu, David. 2007. Elephant Ear Plants. About: Landscaping. <http://landscaping.about.com/od/unusualplants1/p/elephant_ears.htm> Kuhlken, R. 2002. Intensive Agricultural Landscapes of Oceania. Journal of Cultural Geography. 19: 161-195. Plant Profile: Colocasia esculenta. USDA Natural Resources Conservation Services. 2007. Plant Profile: Colocasia esculenta. USDA Natural Resources Conservation Services. 2007. Tagwireyi, D. and Ball D.E. 2001. The management of Elephant’s Ear poisoning. Human & Experimental Toxicology. 20: 189-192. Wagner, W. L., D. R. Herbst, and S. H. Sohmer. 1999. Manual of the Flowering Plants of Hawai‘i. Revised edition. Vol. 2. University of Hawaii Press/Bishop Museum Press. p. 1357.