Are you buying artificially ripened Mangoes and Bananas ? If so, you are running into a major health risk.
Industrial-grade calcium carbide may contain traces of arsenic and phosphorus which makes it a human health concern. The use of this chemical for this purpose is illegal in most countries including India.
Clause 2.3.5 of the Food Safety and Standards (Prohibition and Restrictions on Sales) Regulations, 2011, prohibits sale of fruits which have been artificially ripened by use  Calcium Carbide.
Calcium carbide reacts with water to produce acetylene,  which acts as an artificial ripening agent. However this exposes the fruits to deadly Arsenic and Phosphorous which can lead to various disorders including Cancer. Symptoms of such disorders include  include vomiting, diarrhea, burning or tingling sensation, numbness, headache and dizziness. It is,  however,  controversial if the amount used for ripening fruit is enough to cause harm to humans.
The Ministry of Agriculture in India has recommended the use of ethylene (not Acetylene) gas in low concentration exogenously to trigger ripening of fruits. However, Ethylene, which fruits also produce naturally in the ripening process, has proved to be very expensive when used to accelerate fruit ripening.
In a written reply in Parliament, Minister of State for Health Abu Hasem Khan Choudhury  said that,  the Commissioners Food Safety in States are responsible for implementation of Food Safety and Standards Act and to keep a strict vigil on use of carbide gas and other hazardous chemicals for ripening of fruits and to take legal action for violation.
The State Governments have also been advised to educate the public through print and electronic media against consumption of such artificially ripened fruits and vegetables. State Governments have taken measures in this regard, such as ordering the Food Safety Officer (FSOs)/ Designated Officers (DOs) to keep watch on fruit markets, inspection of fruit market, fruit stalls/Â godowns, taking samples of fruits, vegetables & milk, educating fruit vendors to refrain from using these chemicals, etc.