Calcium carbide (CaC2) is a chemical compound used in the manufacture of acetylene gas, generation of acetylene in carbide lamps and manufacture of chemicals for fertiliser and in steelmaking. It is also used for making toy cannons and naval flares thanks to its explosive properties and this is why it is not a good idea to take a flame near a box of mangoes.
Popularly called masala in fruit markets, Calcium carbide has been banned under PFA Rules, 1955 and also under Food Safety and Standards (prohibition and Restriction on Sales) Regulations, 2011. When Calcium Carbide reacts with water it emits acetylene gas which is similar to the ethylene gas produced by plants to ripen its fruits.
The trouble with fruit ripened artificially is the arsenic and phosphorous hydride created by Calcium carbide. CaC2 has cancer causing properties and could initially lead to vomiting, diarrhoea with blood and pain in the chest with other symptoms. And this is just the beginning.