Poison in our Foods : Maleic Acid

  

In June 2013, Taiwan’s Food and Drug Administration found maleic acid in tapioca pearls produced by Taiwanese company Sunright Foods Corporation.   Soon afterwards, Singapore’s Agri-food and Veterinary Authority too found maleic acid in 11 starch-based products from Taiwan.  Malaysian Health Ministry followed suit by suspending the import of the 11 products.

Tapioca pearls are used in the popular bubble tea drink ( 珍珠奶茶 ), which too originated from Taiwan.

Maleic acid  顺丁烯二酸 (马来酸) is not an approved additive used in manufacturing food products.  Long term consumption of high levels of maleic acid may caused kidney damage.  However, occasional intake of maleic acid at a low dosage is not dangerous.  Industrial maleic acid can cause skin irritation and sensitization, as well as severe eye damage.

Maleic acid is a colourless crystalline, soluble in water and moderately toxic.  It is used as a detergent in surface cleaning, sizing agents in textile industry, photographical chemicals for quite-photo processing, making maleate salts in pharmaceutical industry, dying auxiliary, as an oil and fat preservative, and for hot melt adhesives.  In addition, it is also used to manufacture polyester resins, pesticides, tartaric acid, succinic acid, and DL-malic acid.

Poison in our Foods : Formaldehyde

Formaldehyde甲醛 is an organic compound with the formula CH₂O. It is the simplest form of aldehyde, hence its systematic name methanal.

A gas at room temperature, formaldehyde is colorless and has a characteristic pungent, irritating odor.  Commercial solutions of formaldehyde in water, commonly called formalin, were formerly used as disinfectants and for preservation of biological specimens.

In view of its widespread use, toxicity and volatility, exposure to formaldehyde is a significant consideration for human health.

Uses

Formaldehyde is used in photography, paints, explosives, as adhesive in making fiberboards, in textile industry to make fabrics crease-resistant, wet-strengthening for sanitary paper products, automobiles components, to make into foam for insulation, etc

It is also used as disinfectant in medical apparatus, for treatment for skin diseases, as treatment for parasites in aquarium, and in cosmetics and personal hygiene products to prevent bacterial growth.

Perhaps the most well known usage of formaldehyde is for preservation of human and animal tissues, and as a fixative for microscopy in histology.

International bans

In the EU, formaldehyde is banned from use in preservatives for liquide-cooling and processing systems, slimicides, metalworking-fuild preservatives, and antifouling products, under the Biocidal Product Directive.  The maximum allowed concentration of formaldehyde in finished products is 0.2%, and any product that exceeds 0.05% has to include a warning that the product contains formaldehyde.

In the United States, the allowable amount of formaldehyde emissions from these wood products to 0.09 ppm, in 2010 Formaldehyde Standards for Composite Wood Products Act.

In Canada, formaldehyde was declared a toxic substance by the 1999 Environmental Protection Act.

Contaminant in food

In the early 1900s, formaldehyde was added in fresh milk as a method of pasteurization.

In 2005, in Jakarta, Indonesia, the Indonesian government found that 60% of noodle shops in Jakarta had been serving noodles laced with formaldehyde.

In 2007, in Vietnam, formaldehyde was found in noodles of the national dish, Phở.  The food scares also involved dangerous banned pesticides in fruit and vegetable, and carcinogen in soy sauce.

In 2010, 2 Carefour hypermarkets in Jakarta were found to had sold cendol contained 10 ppm of formaldehyde.

In 2011, in Nokhon Rachasima, Thailand, a sizeable quantities of rotten chicken treated with formalin were discovered.  

In 2012, some 25 tonnes of mackerel fish worth 1 billion Rupiah ( @ 1 million USD ) imported from Pakistan to Batam, Indonesia were found laced with formaldehyde.

Health Effects

In humans, the ingestion of formaldehyde has been shown to cause vomiting, abdominal pain, dizziness, and in extreme cases can cause death; in addition, there is limited evidence of a carcinogenic effect.

Formaldehyde inhaled may cause headaches, a burning sensation in the throat, difficulty breathing, and asthmatic symptoms.

Poison in our Foods : Nitrite

In August 2011, surveillance conducted by Zhejiang Provincial Administration for Industry and Commerce found that excessive nitrite 亚硝酸盐 was present in culibose imported from Malaysia.  It was unsure how nitrite could occurred in bird’s nests燕窝. The Malaysian exporters claims no additives were added to bird’s nest, especially nitrite.

Experts says it is normal to have trace amount of nitrite in bird’s nest, but 4400 mg/kg is totally unacceptable.  Expert says nitrite may occure naturally due to chemical reaction.  Some studies suggested that It could be from the bird droppings, or other environmental contaminant.

 

Traces of nitrite is also found naturally in some vegetables, eg. beetroot, broccoli, cabbage, carrot, celery, cucumber, lettuce, potato, spinach, tomato etc. 

Processed meat, such as sausages, smoked meats and fishes, fermented meats, hams, canned meats, etc and cheeses may contain nitrite not exceeding 200mg/kg.  

Nitrite are permitted preservatives in many countries for processed meat, but do not include bird’s nest.

Bird’s nest is a prized delicacies, especially for the Chinese.  Bird’s nest is produced by swiftlets, Aerodramus fuciphagus ( synonym Collocalia fuciphaga ), and German’s swiftlets, Aerodramus germani.  The swiftlets used a glutinous secretion to bind together materials for nest building, or construct a whole nest with it.  

Bird’s nests are among the most expensive animal products consumed by humans.  A 100g of bird’s nest cost about USD1,000.  bird’s nest is believed to be very nourishing and contains unknown properties.  It is claimed that bird’s nests can help maintain a youthful, radiant and wrinkle-free complexion.  

Bird’s nest has a translucent appearance.  It smells similar to the scent of egg white.  It contains mainly carbohydrates ( sialic acid, galactoamine, glucosamine, galactose, fucose ) , amino acids ( aspartic acid, blutamic acid, praline, threonine, valine, etc ) and minerals ( copper, iron, zinc, manganese, potassium, sodium, etc ). 

It is very disturbing that such a premium delicacy contains nitrites.  Nitrites, when consumed, will go into the blood stream and react with hemoglobin ( Hb ) to form methemoglobin ( metHb ).  MetHb cannot bind oxygen, which decrease the capacity of the blood to transport oxygen to body tissues, thus causing a condition known as methemoglobinemia.   Methemoglobinemia may cause bluish tinge on lips and skin, tiredness, coma and even death.  However, metHb formation is reversible.  Nitrite in blood is rapidly oxidized to nitrate, and excreted via the urinal tract.  

The China health authority thus announced the maximum of nitrite in bird’s nest to be 30mg/kg ,  adopted from the existing rule on processed meats.

Still, it is recommended that bird’s nest should be thoroughly washed and soaked before stewing.  Washing and soaking for few hours can in general remove substantial quantity of nitrite.  The water used for soaking should also be discarded and replace once or twice during the soaking process. 

Food Attack ! 金针

It is reported that daylily buds contain a natural toxic colchicine ( 秋水仙碱 ). Although colchicine is used as medicine, ingestion of excessive dose of colchicine may cause poisoning.


Symptoms starts 2 to 5 hours after ingestion, include burning in mouth and throat, fever, vomiting, diarrhea, abdominal pain and kidney failure.


Onset of multiple-system organ failure may occure within 24 to 72 hours. This includes hypovolemic shock due to extreme vascular damage and fluid loss through the GI tract, which may result in death.


Additionally, sufferers may experience kidney damage resulting in low urine output and bloody urine; low white blood cell counts, persisting for several days; anemia; muscular weakness; and respiratory failure.


Recovery may begin within 6 to 8 days. However, there is no specific antidote for colchicine.

Food Attack ! Liver

The liver of mammals, fowl, and fish are commonly eaten as food by humans.

Animal livers are rich in iron and Vitamin A.  However, very high doses of vitamin A have the potential to be toxic and can cause hypervitaminosis A, a dangerous disorder.  In 1913, Antarctic explores Douglas Mawson and Xavier Mertz were both poisoned, the latter fatally, from eating husky liver.  Inuit will not eat the liver of polar bears or seals as they contain so much vitamin A as to be poisonous to humans.

Poisoning is less likely from consuming oil-based vitamin A products and liver than from consuming water-based and solid preparations.

As vitamin A is fat-soluble, disposing of any excesses taken in through diet is much harder than with water-soluble vitamin B and C.  Vitamin A toxicity may lead to nausea, jaundice, irritability, anorexia , vomiting, blurry vision, headaches, hairloss, muscle and abdominal pain and weakness, drowsiness, and altered mental status.

In general, acute toxicity occurs at doses of 25,000IU/kg of body weight, with chronic toxicity at 4,000IU/kg of body weight daily for  6 – 15 months.  In people with renal failure, 4000 IU/kg can cause substantial damage.  Children can reach toxic levels at 1,500 IU/kg of body weight.

In addition, excessive alcohol intake can increase toxicity.

Unrelated to its vitamin content, the liver of the pufferfish,, which  is consumed in Japanese cuisine as fugu, , contains the highest concentration of neurotoxin which characterizes the species.  As a result, it is generally not eaten, and indeed consumption is forbidden by Japanese law.

Vitamin A content of various animal liver :

Liver of,	IU / 100g
foie gras	3,333
chicken	13,328
pig	17,997
lamb	24,945
cow	31,714

note : An IU ( International Unit ) equals to 0.3 μg of retinol or 0.6 μg of β-carotene

Recommended Dietary Allowance by USDA :

Life Stage Group	RDA	Upper Limit
	μg/day	μg/day
Infants
0–6 months	400	600
7–12 months	500	600
Children
1–3 years	300	600
4–8 years	400	900
Males
9–13 years	600	1700
14–18 years	900	2800
19 - >70 years	900	3000
Females
9–13 years	600	1700
14–18 years	700	2800
19 - >70 years	700	3000
Pregnancy
<19 years	750	2800
19 - >50 years	770	3000
Lactation
<19 years	1200	2800
19 - >50 years	1300	3000

Source :

Wikipedia

USDA Nutrient Data Laboratory

USDA National Agricultural Library

Food Attack ! Starfruits

Star fruit is the fruit of Averrhoa carambola, a perennial tree in the family Oxalidaceae. It was originated from South Asia, distributed all over S.E.Asia, the South Pacific, parts of East Asia, and tropical America.

The fruit starts out green, and goes to yellow as it ripens, though it can be eaten at both stags. The flesh is crunchy, slightly tart, acidic, sweet taste, reminiscent of pineapples, apples and sometimes kiwi fruit.

Health Benefits

Star fruit is rich in antioxidants and vitamin C and low in sugar, sodium and acid.

Regular consumption of the fruit is believes to help regulate blood pressure, reduce cholesterol levels and lower risk of cardiovascular problems.

Health Risks

However, people with kidney problem are not advised to consume the fruit. Star fruit contains oxalic acid which can combine with minerals to form tiny crystals known as oxalates. A problematic kidney may not be able to efficiently excrete the oxalate, of which may get lodged in the stomach, kidneys and bladder as ‘stones’. ( 80% of kidney stones derive from calcium oxalate ).

Bonding of calcium, iron, sodium, magnesium or potassium will deprive the body of the essential minerals. However, the some researches confirm that nutrient deprivation by oxalic acid is relatively small.

Clinical symptoms and outcomes of uraemic patients ingesting star fruit are quite variable and may progress to death. The most common symptoms are persistent and intractable hiccups, vomiting, variable degrees of disturbed consciousness, decreased muscle power, limb numbness, paresis, insomnia, parenthesis, and even seizures. Patients with severe intoxication who were not treated with peritoneal dialysis may not survive.(1)

To avoid acute oxalate nephropathy, pure sour star fruit juice should not be consumed in large amount, especially on an empty stomach or in a dehydrated state.(2)

Source :

1. Miguel et al, Intoxication by Star fruit in 32 Uraemic Patients, Nephrol Dial Transplant (2003) 18:120-125

2. Chen CL, Fang HC, Chou KJ, Wang JS, Chung HM. Acute Oxalate Nephropathy after Ingestion of Star Fruit. Am J Kidney Dis. 2001 Feb;37(2):418-22.

What is Oxalic Acid ?

Oxalic acid is an organic compound with molecular formula C₂H₂O₄. It s relatively strong acid, about 3,000 times stronger than vinegar. Oxalic acid is colorless, organic compound that occurs naturally in plants, animals and in humans. It is an important element, even essential, to maintain and to stimulate peristaltic motion.

How Many is Star Fruit Enough ?

A low oxalate diet should provide less than 50mg oxalate per day. In general, oxalic acid is found in higher concentrations in dark-green leafy vegetables such as spinach and beetroot. Tea, chocolate and other cocoa products have more oxalic acid even compare to star fruit.

It is certainly one shouldn’t avoid eating vegetable just because the present of small amount of oxalic acid. The amount of oxalic acid is too small to do harm to our body.

How Many Star Fruit is Fatal ?

In humans, oxalic acid has an oral LD_Lo of 0.6g/kg. LD_Lo is the lowest dosage per unit bodyweight of a substance known to have resulted in fatality in a particular animal species.

Star fruit contains some 958mg/100g of oxalic acid. Meaning that limit per day for an average man of 60kg body weight is 4 medium size star fruit.

Puerto Rican technologist found the oxalic acid content of ripe star fruit to average 5g/1liter of juice. Again, a simple calculation shows that an average man of 60kg body weight needs to drink 7.2liter of pure star fruit juice to get himself killed. 7.2liter of pure star fruit is certainly an exorbitant amount !