Most bananas we find in grocery stores or markets are not naturally ripen, otherwise they wouldn’t look so nice and wouldn’t all ripe at the same time. Most of the time carbide is used to ripen the banana faster and more evenly. There are traces of toxic arsenic and phosphorous left behind from this process. I didn’t see any talks about this here before.
Should we be concern about this? How much of an impact does it have on health?
Ripening is a biological process. It’s something that cells do. Notably: ripening could not happen if the cells of the banana were biologically dead.
Instead of being biologically dead, the cells inside of fruits are still biologically alive during ripening. If you had plant tissue culture experience, you could actually clone a new banana plant from the living cells in a storebought banana.
Here’s the thing about the things we use to ripen plants: they’re compounds that plants already make themselves. Ethylene, for example: plants use ethylene as a common signalling compound. The information networks that plants use to control their behavior: we’re simply participating in them. That’s all we’re doing.
The living cells of the fresh fruit then respond to that by going through the ripening process. That’s how we ripen them after harvest.
For calcium carbide specifically, the reason why we use it is because it emits acetylene when it comes into contact with water vapor in the air. Acetylene and ethylene are different, but, basically, from the plant’s perspective, acetylene triggers the same signalling pathways as ethylene, so that’s why it works to do ripening.
So when we use calcium carbide, from the fruits’ perspective, still all that’s happening is, the cells are being given a chemical signal to do the process of ripening as it is naturally (and necessarily) encoded in their genes. If the cells weren’t alive and fresh, they wouldn’t even be *able* to do this.
I can’t think of any reason to be worried about any of this.
Now, about those “traces of arsenic and phosphorus”.
Phosphorus is one of the atoms in DNA, so, it’s been present in every food you’ve ever eaten. And it’s supposed to be there, it’s something we actually need to eat in order to keep ourselves healthy, because we need it to make our DNA just like how plants need it to make theirs.
Since it’s in everything, there’s no real danger of us being deficient in it. Phosphorus toxicity is also not a thing unless you’re already living with chronic kidney disease; then your kidneys might throw your phosphorus cycle out of whack.
As for arsenic… that would be unusual, and it should definitely be avoided. It’s toxic because of how important phosphorus is: it disrupts the phosphorus metabolism that our DNA needs.
But I don’t know what arsenic would have to do with calcium carbide. Arsenic isn’t one of the atoms contained in calcium carbide. Calcium carbide is made from lime (aka ground-up limestone) and coke (not the drink, but the fossil fuel, a form of coal). And when you use calcium carbide for ripening, all you do is put some of it in an enclosed space with the things to be ripened. The acetylene gasses off from the carbide, and that’s what signals the fruits to ripen themselves (if they can); any impurities in the original powder get left behind with the powder residue (calcium hydroxide). Since the powder wouldn’t have to come into any contact with the fruit, there wouldn’t have to be any opportunity for arsenic to get on the bananas.
So there’s nothing about the process that makes arsenic like you’re talking about some kind of common or expected side effect. So if you’re a shipping manager or something, and actually know that you found some product with arsenic residue on it, then you should really be talking to someone further up the supply chain for how that happened.
Otherwise, if this stuff about the arsenic is all just talk, then I would say: “Let it be talk.”