Eli5:why our body can’t just flush away all the plastic in our bodies?
In: Biology
It doesn’t know what to do with the plastic….the plastic is not harmful for a while; and even if it was, none of our defenses are capable of dealing with it.
Our body is really great at recognizing living things, like diseases (and nonliving viruses), parasites, etc. and giving us some indication of what’s wrong. Microplastics, however, are (by human standards) very new, and our body basically doesn’t know it exists. Our brain, sure, but not our body.
It’s like asking, why doesn’t your body expel a bullet when you’re shot? It does, sometimes, in the same way some plastic is filtered out through your body processes, but for all intents and purposes your body has no idea the plastic is there. It simply isn’t built to detect it, so it can’t force it out.
And also, some microplastics get into your individual cells, and then it’s the lone cells job to clean itself up.
Plastics are a very new material relative to our evolutionary adaption timeline. Our bodies haven’t evolved to expel them because we haven’t grown with it on our species timescale
One of the things that we like about plastic, which makes it useful, is that it tends not to be very reactive to anything. You can put all sorts of things in plastic without it falling apart. Air doesn’t do anything to it, water doesn’t do anything to it, even sunlight doesn’t do a *lot* very quickly.
The benefit is that plastic lasts forever. The downside is that plastic lasts forever. It also means that your body has few, if any tools that can do much to plastic. Your cells don’t have tiny fingers, they only have molecular tools that “grab” stuff using chemical reactions. Since plastic barely reacts to anything, your body has a lot of trouble grabbing it and manipulating it.
Without being able to use those molecular tools, your body really can’t make the plastic go anywhere or do anything beyond floating around in your blood.
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