How to Prevent Cassava Cyanide Poisoning

Last Updated on November 16, 2020 by marvz

My father told me not to mess with wild cassava. It’s poisonous. He was uprooting every wild kamoteng kahoy he found. And, didn’t even dare to feed it to our farm animals.

What he was saying is true. Cassava is a poisonous crop. It can kill if not properly prepared before eating.

What is cassava?

Cassava, Manihot esculenta, is an edible tuberous root. It’s resistant to drought, diseases, and pests. It’s a major source of carbohydrates in tropical areas.

Cassava is also known as balinghoy and kamoteng kahoy. Popular for making cassava flour,  cassava cake, and cassava balls – karyoka.

Incidences of Kamoteng Kahoy – Cassava – Poisoning

These are a few local cases of cassava poisoning reported by GMA News TV. You’ll surely find more if you dig the internet deeper.

August 6, 2013. A lad of Camarines Sur died after eating boiled kamoteng kahoy. The lad experienced diarrhea, vomiting, and fever.

December 11, 2014.  Don Marcelino, Davao Occidental. Forty-nine students were poisoned after eating cassava balls – karyoka. They experienced symptoms such as vomiting and dizziness. All students were safe after hospitalization.

Nov 19, 2014. Benguet Abra. Siblings were poisoned after eating wild lima beans and kamoteng kahoy. One died. They experienced loss of senses, vomiting, and darkening of lips.

Jan 8, 2016, Cebu. A five-year-old boy died after eating cassava cake. He had vomiting and stomach ache.

Why do cassava cause poisoning?

Cassava contains cyanogenic glycosides, which can result in fatal cyanide poisoning if not properly detoxified by soaking, drying, and scraping before being consumed.

If cassava causes poisoning, then why do people keep growing the crop?

Like rice, cassava is an excellent source of carbohydrate. However, rice relies heavily on irrigation,  cannot stand drought, and destroyed easily by harsh weather conditions.

Because cassava is resistant to drought, pests, and diseases, many rely on cassava as their food source.

Bad effects of  pure cassava diet

Eating cassava – balinghoy – in a large amount or monotonous cassava diet can lead to acute cassava poisoning.

Also, leads to long-term effects, including paralytic diseases such as tropical ataxic neuropathy and konzo, a neurologic disease characterized by sudden onset of irreversible, nonprogressive spastic paralysis.

What is the safe level of cyanide in cassava?

CDC. The recommended safe level is 10 ppm or 10 mg/kg.

What is the lethal dose of cyanide for humans?

According to Centre for Food Safety of Hongkong, the lethal dose of hydrogen cyanide for humans is 0.5-0.35/kg/body weight. Youth is vulnerable due to smaller body size.

What are the symptoms of cassava poisoning?

Poisoning may begin 4-6 hours after a meal. Common signs and symptoms of cassava poisoning include:

  1. Dizziness
  2. Vomiting
  3. Tachypnea – rapid breathing of more than 20 breaths per minute.
  4. Syncope – fainting or passing out.
  5. Tachycardia – rapid heartbeat, over 100 beats per minute.

In addition, more detailed symptoms are listed in the Management of Poisoning – A Handbook for Health Care Workers (ILO, WHO, 1997). Depending on severity, symptoms appear within 1-2 hours if cyanide is swallowed with food.

1. Symptoms of mild poisoning

  1. burning tongue and mouth, if cyanide is swallowed
  2. dizziness
  3. throbbing headache
  4. anxiety
  5. palpitations
  6. confusion
  7. fast breathing
  8. vomiting

2. Symptoms of moderate poisoning

  1. difficulty in breathing
  2. chest pain
  3. drowsiness
  4. short periods of unconsciousness

3. Symptoms of severe poisoning

Severe poisoning can be deadly within minutes. Symptoms include:

  1. deep coma
  2. slow pulses
  3. low blood pressure
  4. large pupils
  5. breathing stops

4. Symptoms of chronic poisoning

Cassava poisoning may cause lasting conditions – chronic- such as:

  1. numbness and pain of legs
  2. loss of sight
  3. difficulty in coordination
  4. swollen thyroid gland

Long term exposure to improperly prepared cassava diet may lead to chronic conditions.

What are the antidotes of cassava cyanide poisoning?

These cyanide antidotes should be given only by doctors. Don’t attempt to administer it on your own. A little misstep may cause more harm. Also, have bad effects if the person has not been poisoned with cyanide.

1. Moderate to severe poisoning

  1. Sodium thiosulfate
  2. Dicobalt edetate
  3. Sodium nitrite
  4. 4-Dimethylaminophenol
  5. Hydroxocobalamin

2. Mild poisoning

Bed rest. Give oxygen if needed.

3. Chronic poisoning

Chronic poisoning symptoms are permanent.

World Health Organization does not recommend planting wild cultivars

Wild cassava has high cyanide. About 2,000 ppm dry weight. It’s 200 times higher than the safe level of 10 ppm.

In addition. Wild cassava is more bitter than sweet cultivar. So they have a lower price.

However, wild cassava has a greater yield, higher resistance to pests, and can be left longer in soil. Making it more attractive to farmers.

Center for Food Safety of Hongkong said sweet cassava has 50mg/kg/fresh weight, while bitter variety may have 400mg.

How to remove poisonous cyanide out of cassava?

Sweet cassava has less cyanide, up to 100 ppm dry weight. Or, 50mg fresh weight.  It can be made safe for consumption by thorough cooking.

For full detoxification that promotes enzymatic degradation of cyanogenic glycosides. The process involves:

  1. peeling the tubers
  2. soaking them in water for 4–6 days
  3. sun-drying or roasting.
  4. scrape the outer layer
  5. then grind the rest into flour.

What will happen if the detoxification process is inadequate?

If any of the processes is too short, detoxification will be incomplete. The cyanide will remain potent.

Weeks of rains or seasons of drought may hamper the detox process. Sometimes, processors and traders may intentionally deviate from procedure to save on cost.

How to know if cassava and products have a potent amount of cyanide?

Matema LE Imakumbili, 2019, mentioned the picrate paper method to determine cassava cyanide content.

The method relies on natural enzymes to breakdown the cyanogenic glucosides, linamarine. It liberates hydrogen cyanide, which darkens the picrate paper.

Physical difference between bitter and sweet cassava?

When processed as flour, the wild cassava is pure white while the sweet cultivar is creamy colored.

According to USDA, bitter variety is identifiable through taste and smell. Although it’s not a valid system for assessing the root crop’s cyanide content.

How can I ensure safety?

Cassava can be poisonous, but you don’t have to hold yourself. Eat cassava products all you want.

If you have direct access to cassava roots, ensure that what you get is a sweet variety. Although bitter or wild cassava is rarely cultivated, it’s better safe than sorry.

Buy only from reliable sources. It’s not wrong to ask how the product is prepared or where it came from.

If you’re a manufacturer, ensure that every product you release is well prepared. Get a cyanide testing kit if possible. A better option is securing a safety certificate from an authorized laboratory.

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