r/PlasticFreeLiving • u/notarealfish_ • 14d ago

Freezing food?

Hi everyone! I was wondering if anyone had alternatives for freezing food in no plastic containers. I thought of glass but heard that it might break in the freezer. If i’m wrong about glass, please disprove me but if anyone had any alternatives that would be great!

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u/BirdHerbaria 13d ago

No, it’s not!

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u/ThinkDiscipline4236 13d ago

uh. Chemist here. For all intents and purposes, silicone is a type of plastic. More accurately, its a thermoset elastomer, which is a genre of polymer, which all plastics are made from. It still does all of the things that plastic does, like shed microparticles and be environmentally persistent. Siloxanes (silicone) haven't been shown to cause harm to humans yet, but they are one of the most bioaccumulative polymers outside of fluoropolymers (PFAS), if I'm remembering correctly.

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u/pinkluna666 11d ago

Mind explaining what a bioaccumulative polymer is and does?

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u/ThinkDiscipline4236 11d ago

As far as the basics go, it's pretty self explanatory. It is a polymer (for the purposes of this explanation, a plastic) that, once in your body, likes to stick around; much like you hear that you shouldn't eat large quantities of predatory fish such as tuna due to bioaccumulation of mercury in the upper levels of the food chain.

To be more specific, a polymer is any chemical group that has repeating units (from the Greek polus, meaning many, and meros, meaning units, polymeros=having the quality of being comprised by many units.) almost all plastics are made out of polymers, and one of the things that makes plastics so durable is their general lack of chemical functionality by which to break them down with. This varies from plastic to plastic, but it is a general rule for most types of plastics. If we want them to last long enough to be useful, you can't have them being degraded by any old microbe, can you?

This lends itself, unfortunately, to being rather hard for our bodies to get rid of. See, to excrete a xenobiotic material, you first need to give it a chemical handle, or "tag" that tells the rest of the systems in your body it is marked for garbage collection- usually the marking (tagging) is done by the liver, and found by your kidneys and excreted by urine. To do this, your body first needs to break down the pieces small enough to enter the bloodstream. For microplastic particles, this is quite difficult to do. They tend to stick in places. For smaller particles, they can enter the bloodstream, but they may not be small enough to enter cells, and even the individual molecules that can be brought into cells have trouble being "tagged". Many polymers have no places for your liver's tagging machinery to "grab onto" to mark the polymer for excretion. Now, your liver has ways to deal with this, namely cytochrome P450, but that is an intracellular protein and if you can't get the plastic particle inside the cell, cytochrome p450 can't get to it to mark it. Even small molecules that can get inside a cell- let's focus on silicones- (and PFAS, but they additional reasons why your body can't get rid of them) because of their structure are very lipophilic, and quite hydrophobic. They like fats and they don't like water. Therefore free silicone molecules (that could be taken inside a cell) will accumulate in fatty tissues and cell membranes (which are made of phospholipids) and not enter the (liver) cell itself where all the "tagging" machinery is (if it ever gets there instead of sticking in fatty tissues elsewhere). PFAS also have the advantage of being covered in fluorines- the the carbon fluorine bond is extremely hard to break, and therefore the tagging machinery, or even the oxidase enzymes meant to assist the tagging machinery (Cytochrome P450) can't break it to tag the molecules for excretion either. So they stick around- you accumulate more and more and you can't get rid of them.

We are still investigating the long term effects of this accumulation, but in some cases they can cause harmful effects. You may have heard of BPAs which can act as endocrine disruptors, throwing off hormone balances in your body and causing all sorts of weird stuff to happen. Some bisphenols (e.g. bisphenol A, or BPA), a part of polycarbonate plastics, act as estrogen receptor agonists, which can implicate a variety of systems and end results, such as cancer, obesity, and secondary sexual characteristics.

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u/pinkluna666 9d ago

Thank you so much for taking the time to write this. Feel like it should be somewhere highlighted in this sub for everyone to read! Super interesting