India's Rs.3 billion ($70 million) mango trade is fraught with health hazards due to the get-rich-quick schemes of vendors who artificially ripen the fruit using a harmful chemical.

Calcium carbide, used to ripen mangoes, is extremely hazardous and can have short-term as well as long-term health effects, said S. Krishna, the Chennai Corporation's additional health officer.

"Calcium carbide contains traces of arsenic and phosphorus. Once dissolved in water, it produces acetylene gas that affects the neurological system resulting in headache, dizziness, mood disturbances, sleepiness, mental confusion and seizures on a short-term basis, while it can in the long term cause memory loss and cerebral oedema," Krishna told IANS.

The Tamil Nadu police raided warehouses in six districts during the last fortnight and destroyed four tonnes of mangoes that were treated with calcium carbide.

Police sources said that in raids conducted in neighbouring Karnataka, over 300 kg of mangoes similarly ripened were destroyed in Bangalore city.

Using artificial methods of ripening fruit is punishable under law, as it falls under the Prevention of Food Adulteration Act.

"Propelled by the quick-buck syndrome, vendors who wish to avoid the 3-4 days' wait for the normal method of mango-ripening with hay, use the harmful chemical instead. The chemical gives the fruit a misleading ripe, healthy look," said A. Karmegam, a Chennai trader who buys fruit from all over India.

The practice is prevalent in other parts of the country as well.

N.K. Aher, a wholesaler of mangoes in the Mahatma Phule Market in south Mumbai, told IANS over phone that mangoes were being widely treated with chemicals in Maharashtra. However, since no complaints have been made to the authorities, the practice was going on unchecked.

"This method of ripening is a south Indian import into the rest of India that can affect the Rs.3 billion-rupee nationwide annual turnover in mango trade. In Maharashtra, this has been going on for almost a year now. Even the world famous Alphonso mangoes sold in India have some chemical residues. As complaints are nonexistent, no remedial measures have been initiated," said Aher, who also exports fruit.

Though it is not easy to distinguish between the normal and the artificially ripened fruit, this can be done, Krishna said.

"The chemically altered mangoes have a subtle but bad smell and dark patches on their skin because of the calcium carbide heat. The organically produced and ripened mangoes look very ordinary, while the artificially ripened ones look more inviting," Krishna added.

There is of course, a bigger danger.

"Calcium carbide reacts exothermically with water forming calcium hydroxide and acetylene, an extremely inflammable gas. The heat of the reaction can be sufficient to raise the temperature above the ignition point for acetylene (305 degrees C) and upon mixture with air is likely to explode," according to a study conducted by the University of Wisconsin-Madison published in 2003.

Acetylene - a gas used in metal cutting with a concentrated flame - can burn underwater at over 1,000 degrees C and result in an explosion when in contact with a naked flame, enough to bring down a whole market. People in the vicinity can suffer up to 80 percent burns. This can even be mistaken for terrorist violence resulting in time-consuming investigations and fear, police sources said.