The use of carbide gas from calcium carbide to ripen fruits is extremely hazardous to the human body as calcium carbide also contains traces of arsenic and phosphorus. The practice of ripening fruits using carbide is banned in many countries but may still be practiced in some.
Do you know if the fruits in your area are free from carbide?
Unfortunately, many if not most farmers locally use Carbide to ripen fruits. Many bananas, Pawpaw especially you see the telltale signs. Many places worldwide this practice has been banned but I don't think the authorities pay any mind to this here.