Popular fruits sold in supermarkets, such as bananas and mangoes, can be artificially ripened by a chemical known as Calcium Carbide. It is a known carcinogen, ie. it has cancer-causing properties.

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 it is freely used in Malaysia as well as in the Philippines under the local name of Kalburo.

However, the main ripening agent legally used by fruit exporters is the chemical known as Ethylene, which is sprayed on the green fruit prior to packing and shipping. This should not be confused with the ripening hormone in the fruit which produces ethylene naturally.

It might be wise to avoid bananas which originate from a particular country in South East Asia and certain countries in South America, so as to avoid exposure to either synthetic ethylene or calcium carbide. Fruits are best consumed in their natural states for maximum safety and nutrition to the human body without interference from any foreign chemicals.

How to check if the bananas you get are healthy and free of calcium carbide:

What looks attractive outside may not be good for health. Fruits that have a uniform colour, for example, a bunch of bananas having a uniform colour, are more likely to have been artificially ripened.

Tip from iHerb Singapore:
Befriend your local wet market fruit vendor. He/She will teach you how to select healthy fruits without all the harmful stuff, other than offering discounts to you! They also may have sources to offer certain fruits if you keep asking them! There are a few super fruits in South East Asia which are still not well-known in Singapore.

Please feel free to share this article if you find it to be beneficial to people.

References for interested viewers:
http://www.consumer.org.my/index.php/food/safety/502-ban-the-use-of-carbide-gas-to-ripen-fruits
http://www.catanduanestribune.com/article/2SVA