why is it not recommended to reuse plastic bottles on the grounds of “the plastic will leech into the water” when they are used to store sometimes very acidic drinks for months or even years?
In: Chemistry
while leeching might possibly be an issue, a bigger issue is that it is hard to clean a plastic bottle properly so there will likely be bacteria in a reused bottle
I was always told that the leeching comes from sunlight (UV) breaking down the plastic, not acids on the liquid
It is mostly random panic. It only matters if you fill it with something hot, or which is chemically unsuitable for the respective kind of bottle (think caustic soda). Anything cold you plausibly drink should not be an issue. Even if hot you are probably fine; it depends on the plastic, but even the worst case is far away from serious effects.
Some stuff always slowly leeches out, but within reason it isn’t worse than what happens to the original content over a similar timeframe.
Edit: I should probably add that a different factor, abrasion of microplastics, exists. It is not yet understood how much, if anything, it does. It happens if there is damage to the inside surface of the bottle, for example from crushing or hitting it. However, that again also applies as well with the original content.
UV light has enough energy to break plastic.
Heat also does it to a lesser extent.
Thats why plastuc bottles shouldnt be kept under direct sunlight.
Normal light is fine because it does not contain UV rays
First of all, not all things will dissolve in acid. In fact, plastics are typically very resistant to acids, and it depends heavily on the acid being used. Acid is not a magical solvent that dissolves everything it touches.
The answer to your main question though is that it’s not that bad, but potentially could be. The biggest issues are that repeatedly filling the bottle could peach out some chemicals used in fabrication of the plastic, thus weakening it, and putting those chemicals in the water you drink and also getting micro plastics into your drink. This is speculation at this point because serious studies have afaik not been done on the subject. To craft an analogy imagine making a cup of hard salt. Fill it up and let the water sit. It will dissolve some salt into saturated. But if you keep filling it up and enjoying it, you will dissolve more and more of the salt from the cup. That’s the basic concern.
Additionally normal wear and test weekends the plastic intended for a single use, it isn’t designed to what’s being repeatedly used. This will certainly cause issues with the structural integrity of the bottle leading to failure and probably micro plastics in your drink.
And finally the thing we know happens: UV radiation destroys plastic. The longer you use the bottle, the more time the sun has to work on degrading it. So the act of redoing it isn’t the problem it’s the fact that you’re using it more that matters. This would suggest that riding it a few times is probably fine. But don’t keep using it forever. Honestly you’re probably going to notice issue 2, the crushed bottle, before it’s harmful depending on the bottle type.
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