20th February 2000

Forbidden Fruits

By Ayesha R. Rafiq and Faraza Farook

Deadly carbide tale behind juicy red tomatoes, yellow plantains and papaws

An apple a day may keep the doctor away, but those who consume local fruits on an almost daily basis may have to think twice before they bite into that ripe plantain or mango, as rather than keeping the doctor away it's likely to bring him rushing to your door.

Until now a healthy diet has always been supplemented with the best of local fruits such as mango, plantain, papaw, pineapple, durian, and avocado so tempting when they are ripe. But what many may not know is that they are more likely to fall ill or in the extreme long-run, even die as a result of consuming these ripe fruits.

Unscrupulous local traders are resorting to a quick-fire and profitable but potentially poisonous method to ripen fruits in one to two days. The fast ripening ensures quick sales and also a minimum likelihood of the fruits being plagued by various diseases during the ripening stages, thus reducing post harvest loss.

The agent used in the ripening process is Calcium Carbide, a material more commonly used for welding purposes. The Carbide is imported from countries such as China, Taiwan and South Africa. The low price of the carbide - 250g for Rs. 15 - results in it being used widely and indiscriminately.

Dr. Shanthi Wilson, Manager of the Post Harvest Technology Unit of the Ceylon Institute of Scientific and Industrial Research said this technology was widely used in countries such as Malaysia and India.

The use of Carbide is however banned in Sri Lanka under the Food Act regulation of 1993. The relevant regulation reads, 'No person shall sell, use, offer, expose for sale or have in his possession for the purpose of sale or for use as an ingredient in the preparation of any food intended for sale, any fruit which has been artificially ripened by the use of acetylene gas commonly known as carbide gas'. The penalty imposable for such an offence is a fine not less than Rs. 500 and not exceeding Rs. 5000 and/or a jail term not less than three months and not exceeding one year, imposable by a magistrate.

Public health inspectors of Municipal Councils are responsible for detecting and bringing charges against offenders. A health ministry official in the food department however said for the past ten years there has not been a single prosecution.

Calcium Carbide treatment is banned because it contains traces of arsenic and phosphorous, hazardous to human beings.

When the carbide is dissolved in water, it produces acetylene gas. Acetylene gas is an analog of the natural ripening agents produced by fruits known as ethylene. Acetylene imitates the ethylene and quickens the ripening process.

During our investigation at the Pettah market, several of the traders argued that the carbide treatment is done on the fruits before they are brought to the market place. However many of them seemed to have a thorough knowledge of the process and even had space in their stalls to carry out the operation.

They also told us it is rarely that local fruits escape the carbide treatment.

Our investigations at the Maharagama, Wellawatte, Rajagiriya, Bambalapitiya and Deans Road markets also showed that most of the fruits at these markets were also being treated with carbide.

The Pettah market being the main wholesale market in Colombo, the products are sent to markets all over the city as well as outstation. The markets to which products from the Pettah market are sent to are, Dematagoda, Maharagama, Wellawatte, Rajagiriya, Dehiwela, Galkissa, Kollupitiya, Kotte, Pannipitiya, Ja-Ela, Borella, Thotalanga, Kottawa, Kalutara, Minuwangoda, Beliatta, Tangalle, Galle and Matara.

With traders claiming that the fruits are treated before they arrive in Colombo, it is likely that fruits are being treated with carbide islandwide.

Posing as potential traders, we approached a number of stalls with the intention of asking them to demonstrate the methods used. After much hesitation, they explained the methods, but not before cautioning us. We were told that the use of carbide is illegal, and that it was highly poisonous. We were also warned that if our 'customers' were to ask us if carbide is being used, that we were to flatly deny it.

We were also told the treatment kills the vitamin in the fruit. But Dr. Wilson however said this does not happen. When you sometimes pay twice as much for a golden fruit, and it still tastes watery it could be that it has been treated with carbide. In some cases it is only the skin that changes colour, while the fruit itself remains green and raw.

Dr. Wilson also pointed out that when the carbide is used on very raw fruit, the amount of the chemical needed to ripen the fruit has to be increased. This results in the fruit becoming even more tasteless, heaty and possibly toxic.

Early symptoms of arsenic or phosphorous poisoning include vomiting, diarrhoea with or without blood, burning sensation of the chest and abdomen, thirst, weakness and difficulty in swallowing and speech and garlic like odour of breath, a medical officer from the poisons department said.

The patient, as a result could suffer from nerve damage and resulting fits. Other effects include numbness in the legs and hands, general weakness,cold and damp skin, low blood pressure, shock, and in extreme cases comas, the medical officer said.

While most cases of arsenic and phosphorous poisoning are detected before they become fatal, if it is not treated, it could result in death, the medical officer warned. Sometimes on close scrutiny it is possible to identify which fruits have been affected most by carbide treatment. When tomatoes are uniformly red, or mangoes and papaws are uniformly orange, one could surmise that carbide may have been used. Plantains can also be identified if the stem is dark green while the fruits are all yellow.

Meanwhile some vendors told us that 100g of carbide is used per 50kg of fruit. The chemical is dissolved in a coconut shell or similar basin placed in an airtight container. When the chemicals are dissolved it releases acetylene gas and the fruits are then piled on top of it and kept in the container for a day. The next day the raw fruits have turned ripe.

A subsequent attempt to get a photograph of the process was however thwarted by the market mafia. We had found two vendors willing to show us the actual process and let us take photographs and we were proceeding to their stalls when we were stopped. A small crowd of vendors who had gathered there began to mumble about there being no point in demonstrating the process to us as "everyone knows we do not do it here."

The two vendors however continued, until the camera was pulled out. Then the market godfather appeared on the scene and we were chased out of the premises. The two vendors were surrounded and asked whether they were trying to get them all arrested. We later discovered that they were under the impression that we may be CID officials conducting operations under cover.

The two vendors promised to keep the fruits overnight and give it to us the next day. But when we visited the scene the next day, not only had the fruits been forcefully thrown away, but the entire market seemed to have been alerted to the possibility of our visiting them again. On our hasty retreat we heard a health department officer asking some traders whether they used carbide. When they said no without any hesitation, the officer simply moved on to the next stall.

Meanwhile a CISIR official said that ideally 1 gramme of calcium carbide should be used per kilogram of fruit, half of the quantity that the vendors currently use. He also said that the carbide should be wrapped in newspaper and placed at the bottom of the pile so that it does not come into contact with the fruit. He also said that the Food Committee had held a meeting with the Department of Agriculture to consider removing the ban on the use of the chemical as long as it was done in a safe manner, and that the cancellation was still under consideration.

The Food Committee comprises among others the Director General and Deputy Director General of Health Services, Director General of the Sri Lanka Standards Institute, a food technologist from the CISIR, a nutrionist and micro biologist from the Medical Research Institute, a representative of the Consumer Association and members of the Chamber of Commerce.

However the problem lies in whether the traders have the necessary knowledge or incentive to carry out the process in the correct manner. Another alternative would be to use ethrel. Ethrel has many uses such as hastening the production of flowering in fruit trees and hastening ripening. When applied to plants it is absorbed and broken into ethylene which is a natural non toxic substance, the official said. Ethrel is commonly used in Australia and India. While the dipping of fruits in a diluted solution of ethrel has been recommended, the CISIR recommends a different approach where a minimal amount of ethrel is diluted in water, and containers are placed around the room. The fruits are then stacked in the room, and sodium hydroxide is added to the mixture. All ventilation to the room is then blocked off, and the fruits will ripen in three to five days in the gas that is released.

The gas that is released is ethylene, the natural ripening agent found in fruits. This substance ensures that there is a uniform ripening of the fruits, in addition the fruits retaining their flavour. Dr. Wilson pointed out that in both methods, whether using calcium carbide or ethrel the chemical should not touch the substance.

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