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KARACHI, June 2: As the hustle and bustle at the Super Highway’s Sabzi Mandi, Karachi’s prime source of fruit and vegetable supplies, gradually subsides with wholesalers taking their stocks for the day, activity begins around 10am at a specific area reserved for mango trading. A number of workers, least bothered by the pungent smell that fills the area, are busy putting small packets in hundreds of crates, two in each, containing fresh green mangoes.

“This is ‘carpet.’ By the time the fruit will be transported to different markets in the country, it will have ripened and will fetch a good price,” says Mohammad Abrar, who does a whole variety of jobs at the mandi and earns Rs200 to Rs300 daily. About 300 to 400 trucks carrying around 8,000 tons of mangoes arrive every day at the mandi these days. The supplies will increase to about 20,000 tons by June 15.

Babu Chaman, who has been involved in the mango trade for generations, explains that what the worker was referring to as ‘carpet’ is actually calcium carbide. “The entire stocks of mangoes coming from Hyderabad, Mirpurkhas and Tando Allahyar, the areas first to witness mango harvesting in the country, these days are being treated with the chemical agent since mangoes are not ripe. The harvesting later begins in Tando Mohammad Khan, Hala, Matiari, Nawabshah, Tharooshah, Naushehro Feroz, followed by Rahimyar Khan, Multan and other areas in Punjab.”

Talking about the large-scale use of calcium carbide as a fruit ripening agent, Haji Mohammed Shahjehan, President of the Falahi Anjuman Wholesale Fruit and Vegetable Market, said that decades ago onions were used for the same purpose. In case of bananas, however, kilns were the norm.

“People turned to calcium carbide because the method was cost-efficient, easier and gave excellent results. Today, fruit matured with the help of calcium carbide are preferred as the fruit evenly ripens in this way and is neither too soft nor too hard. If fruit is left on trees, there are risks that it will get damaged due to weather conditions and subsequently cause losses to farmers besides affecting our business.”

The chemical compound – in the form of small blackish and white lumps – is wrapped in paper packets and placed inside a crate of about 27 mangoes. It is then closed and opened after 24 hours when the fruit is ripe. Babu Chaman, along with other fruit traders, claims that the chemical doesn’t cause any harm to the quality of fruit, but instead enhances its colour and taste.

“Traders transporting fruit from the interior of Sindh and Punjab to the city are not responsible for any chemical treatment. It’s the wholesale buyers and retailers throughout the country who use calcium carbide according to their own requirements. However, our long association with the business tells us that the chemical doesn’t cause any harm to the fruit’s quality. Rather, it enhances its taste and makes it a marketable commodity by ripening it and turning its colour yellow.”

Talking about the use of the chemical agent in the interior of Sindh, Nizam Din Memon, a mango grower, said that it was essential to get a good price of the commodity. “Many farmers selling their produce to different markets in the country ripen fruit with this method to get a good price. The chemical is easily available. About one kilogram of calcium carbide is enough to ripen 15 to 16 crates of mangoes.”

However, he didn’t agree with the notion that the chemical improved the fruit’s quality. “There is not only a difference of taste, but also of size. The mangoes do not properly ripen; some get too soft and some remain raw from inside, though their colour may change.”

A survey of the mandi revealed that the cheap chemical compound is also used for ripening many other fruit including apricots, bananas, papayas, plums and Japanese fruit, while the exceptions include apples, grapes, pomegranates and melons. Fruit traders claim that the use of calcium carbide reduces as mature produce starts arriving with the passage of time. For instance, they maintain, plums and peaches are not being ‘treated’ these days as the fruit is already mature when it reaches the market.

About the price of the chemical agent, Lala Jan, a shopkeeper at the mandi, said it was being sold at Rs90 to Rs100 per kg these days and he managed to sell 100 to 90 kilograms every day.

What is calcium carbide?

A banned ripening chemical agent in many countries, including India, calcium carbide is openly and commonly used for ripening fruit in Pakistan. A very strong reactive chemical, calcium carbide has carcinogenic properties and is used in gas welding for steel goods.

About the use of the chemical agent in fruit ripening, Dr Abid Hasnain of Karachi University’s department of food science and technology said that when calcium carbide comes in contact with moisture, it produces acetylene gas, which is quite similar in reaction to the natural ripening agents produced by fruit known as ethylene.

“Acetylene acts like ethylene and accelerates the ripening process. It’s an artificial way of ripening fruit and, therefore, not advisable. People must wash all types of fruit before consumption, or else it will burn their skin and will cause other health problems.”

In developed countries, he said, ripening chambers were set up at processing plants, where fruit is treated with controlled purified gases, usually artificial ethylene.

“All safety precautions are observed and there is no question of harmful residues since fruit does not come in direct contact with any chemicals.”

This reporter contacted different educational and research institutions in the country, including the Pakistan Council of Scientific and Industrial Research, to find a local study on the subject, but failed. There are, however, some studies available on the internet. One such study is Calcium carbide poisoning via food in childhood, conducted at the medical faculty of Erciyes University, Kayseri, Turkey in 2005.

The research states: “The fast ripening of fruit means they may contain various harmful properties. A commonly used agent in the ripening process is calcium carbide, a material most commonly used for welding purposes. Calcium carbide treatment of food is extremely hazardous because it contains traces of arsenic and phosphorus.

“Once dissolved in water, the carbide produces acetylene gas. Acetylene gas may affect the neurological system by inducing prolonged hypoxia and can cause headache, dizziness, mood disturbances, sleepiness, mental confusion, memory loss, cerebral oedema and seizures. When mixed with oxygen, calcium carbide acts as a sedative and has been used in anaesthesia. The use of artificial ripening agent can be fatal. Excessive consumption of calcium carbide-laced fruit can cause intoxication.”

The report cites the case of a five-year-old girl who was transferred to the emergency department of the university’s hospital with an eight-hour history of coma and delirium. A careful history from her father showed the patient ate unripe dates treated with calcium carbide.

The study further states that in some cases, it’s only the skin that changes colour, whereas the fruit itself remains green and raw. When the carbide is used on very raw fruit, more of the chemical is needed to ripen the fruit. This makes the fruit even more tasteless, unhealthy and possibly toxic. The report concludes that fresh vegetables and fruit must not be consumed without being washed properly.

Experts comment

Asked if there were any rules and regulations on the use of calcium carbide as a ripening agent, EDO for Health Dr A.D. Sajnani replied in the negative. “I doubt that any research has ever been conducted on the subject in the country. I am also unaware of any harmful effect of the chemical agent on human health, though I feel it does affect the nutritional value of the fruit since it’s an artificial way of ripening fruit.”

Commenting on the problem, Dr Samrina Hashmi, General-Secretary of the Pakistan Medical Association Karachi, said: “Regular intakes of the chemical may cause irritation of digestive system, diarrhoea, jaundice and liver failure. Free radicals from carbide play a major role in the ageing process as well as in the onset of cancer, heart disease, stroke, arthritis and perhaps allergies.“The departments of health and agriculture should realise the gravity of the problem and ban the practice of ripening fruit with chemicals and also the use of toxic colours in food products.”