Toxicity in Humans by Ingestion of Toxicity in Humans by Ingestion of Colocasia esculenta Colocasia esculenta

(Elephant Ear)(Elephant Ear)

Audrey MedinaAudrey MedinaBarry SandallBarry SandallLoucia JoseLoucia JoseBiology 445Biology 445

May 04, 2007May 04, 2007

What is What is Colocasia esculentaColocasia 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 because of its large leaves resembling elephant ears.resembling elephant ears.

Grown in tropical areas as a staple food resource (taro) by Grown in tropical areas as a staple food resource (taro) by many indo-asian countries many indo-asian countries

DescriptionDescription Perinnial monocotPerinnial monocot

Large, Large, arrowhead-shaped leaves arrowhead-shaped leaves can growcan grow to be 3’ X 2’ to be 3’ X 2’

Long stalkLong stalk

Flowers are arranged in a spadix Flowers are arranged in a spadix with green or yellow spathewith green or yellow spathe

TaroTaro corms present in the rootcorms present in the root similar in appearance to a yam or similar in appearance to a yam or

potatopotato

DistributionDistribution Native to tropical Polynesia and southeastern AsiaNative to tropical Polynesia and southeastern Asia

Grows naturally in tropical and subtropical areas but will Grows naturally in tropical and subtropical areas but will grown in temperate climates as wellgrown in temperate climates as well

Introduced to United States, considered an invasive species in Introduced to United States, considered an invasive species in some areassome areas

Uses:Uses: Grown primarily as a vegetable food for its Grown primarily as a vegetable food for its

edible corm edible corm

TaroTaro corms are used most corms are used most

famously in the Hawaiian famously in the Hawaiian

dish known as poi.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 Popular in the United States for its foliage and used mainly for aesthetic purposes.mainly for aesthetic purposes.

Toxic Parts of PlantToxic Parts of Plant

The entire plant is toxic!The entire plant is toxic!

Leaf, stem, and root.Leaf, stem, and root.

SO WATCH OUT!!!SO WATCH OUT!!!

Signs and SymptomsSigns and Symptoms

If Ingested RawIf Ingested Raw::

Intense burning and irritation of lips, mouth, tongue, Intense burning and irritation of lips, mouth, tongue, and throat. and throat.

VomitingVomiting

Diarrhea (Uncommon)Diarrhea (Uncommon)

Base of tongue swells and can be fatal if swelling is Base of tongue swells and can be fatal if swelling is large enough to block the air passage of the throat.large enough to block the air passage of the throat.

Death by asphyxiation!Death by asphyxiation!

Toxic AgentToxic Agent

Elephant ear contains Elephant ear contains calcium oxalatecalcium oxalate crystals crystals which are needle-shaped and arranged in which are needle-shaped and arranged in compact bundles.compact bundles.

When chewed the crystals are ejected from When chewed the crystals are ejected from specialized explosive ejector cells. specialized explosive ejector cells.

Needles get lodged in the lining of the mouth, Needles get lodged in the lining of the mouth, tongue, and throat leading to local tongue, and throat leading to local inflammatory reactions.inflammatory reactions.

Toxic PrincipleToxic Principle

Calcium oxalateCalcium oxalate crystals- crystals-RaphidesRaphides

Oxalate is an unstable salt of oxalic acidOxalate is an unstable salt of oxalic acid

Oxalic acid is soluble in water, alcohol, and Oxalic acid is soluble in water, alcohol, and ether.ether.

Composed of:Composed of:2 carboxyl groups2 carboxyl groups

Creates dangerous Creates dangerous free-radicals in body.free-radicals in body.

MechanismMechanism Needle fibers induce inflammatory response and Needle fibers induce inflammatory response and

edema in oral cavities and mucous membranes.edema in oral cavities and mucous membranes. Can lead to aphyixiation Can lead to aphyixiation

Calcium oxalate dissolves in the stomach to form Calcium oxalate dissolves in the stomach to form oxalic acidoxalic acid..

more readily absorbed into the more readily absorbed into the

blood and circulation system.blood and circulation system.

VeryVery dangerous if ingested in large amounts dangerous if ingested in large amounts

ToxicityToxicity

Oxalic acid can binds with calcium in the body Oxalic acid can binds with calcium in the body resulting in hypocalcemia. resulting in hypocalcemia. Can lead to muscle cramps, hypotension, bradycardia, and Can lead to muscle cramps, hypotension, bradycardia, and

cardiac arrhythmia.cardiac arrhythmia.

Binding of oxalic acid with calcium in the body can Binding of oxalic acid with calcium in the body can induce crystallization of induce crystallization of calcium oxalatecalcium 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 Can lead to liver and kidney failure and cause permanent

damage.damage.

Treatment and Other PrecautionsTreatment and Other Precautions

Calcium chloride and calcium gluconate should be Calcium chloride and calcium gluconate should be administered for large ingestion of plant…why?administered for large ingestion of plant…why? Calcium chloride and gluconate act by replenishing the Calcium chloride and gluconate act by replenishing the

calcium in the circulation, thus reducing the toxic effects.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.free oxalic radicals.

As a precaution, Elephant Ear As a precaution, Elephant Ear should be eaten with milk or should be eaten with milk or other foods rich in calcium. other foods rich in calcium.

Summary of Toxicity Summary of Toxicity Oxalate crystals on plant cause extreme inflammatory immune Oxalate crystals on plant cause extreme inflammatory immune

response which may lead to death.response which may lead to death.

Minor gastrointestinal distresses to serious heart conditions Minor gastrointestinal distresses to serious heart conditions can be caused by low calcium levels due to oxalic acid can be caused by low calcium levels due to oxalic acid ingested from ingested from Colocasia esculentaColocasia esculenta..

Kidney stones, major organ failure, Kidney stones, major organ failure, and tissue damage can also result and tissue damage can also result from deposits of calcium oxalate, from deposits of calcium oxalate, formed by oxalic acid binding formed by oxalic acid binding calcium in the body.calcium in the body.

ConclusionsConclusions Colocasia esculenta (Elephant Ear, taro) cColocasia esculenta (Elephant Ear, taro) can cause many an cause many

toxic effects in humans with potential for serious damge or toxic effects in humans with potential for serious damge or death.death.

Colocasia esculenta Colocasia esculenta should NEVER be eaten raw. should NEVER be eaten raw.

Proper cooking methods and precautions should be followed Proper cooking methods and precautions should be followed closely.closely.

Calcium should be taken appropriately when ingesting. Calcium should be taken appropriately when ingesting.

Conclusions cont… Conclusions cont…

Taro must be the most delicious dish in the Taro must be the most delicious dish in the world.world.

Because, really, why the hell is anyone eating Because, really, why the hell is anyone eating this thing?this thing?

Yummy!Yummy!

ReferencesReferences

Beaulieu, David. 2007. Elephant Ear Plants. Beaulieu, David. 2007. Elephant Ear Plants. About: LandscapingAbout: Landscaping. . <http://landscaping.about.com/od/unusualplants1/p/elephant_ears.htm><http://landscaping.about.com/od/unusualplants1/p/elephant_ears.htm>

Kuhlken, R. 2002. Intensive Agricultural Landscapes of Oceania. Kuhlken, R. 2002. Intensive Agricultural Landscapes of Oceania. Journal of Journal of Cultural GeographyCultural Geography. 19: 161-195.. 19: 161-195.

Plant Profile: Plant Profile: Colocasia esculenta . USDA Natural Resources Conservation Colocasia esculenta . USDA Natural Resources Conservation Services. Services. 2007.2007. < <http://plants.usda.gov/java/profile?symbol=COES>http://plants.usda.gov/java/profile?symbol=COES>

Tagwireyi, D. and Ball D.E. 2001. The management of Elephant’s Ear Tagwireyi, D. and Ball D.E. 2001. The management of Elephant’s Ear poisoning. poisoning. Human & Experimental ToxicologyHuman & Experimental Toxicology. 20: 189-192.. 20: 189-192.

Wagner, W. L., D. R. Herbst, and S. H. Sohmer. 1999. Wagner, W. L., D. R. Herbst, and S. H. Sohmer. 1999. Manual of the Flowering Manual of the Flowering Plants of Hawai‘i. Revised editionPlants of Hawai‘i. Revised edition. . Vol. 2. University of Hawaii Press/Bishop Vol. 2. University of Hawaii Press/Bishop Museum Press. p. 1357. Museum Press. p. 1357.