How does asbestos cause cancer? Isn’t it just a rock? Why does it cause cancer but not sheetrock or fiberglass?
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**What is it**: Asbestos is a naturally-occurring mineral we mine from the ground. It has a [weird fibrous texture](https://upload.wikimedia.org/wikipedia/commons/c/cd/Asbestos_with_muscovite.jpg). So in a way it’s “just a rock”, but one that’s naturally made of spectacularly fine rock needles. More needly than normal rock dust, and finer than fiberglass needles.
**Why do we use it**: We *did* use it a ton, because it’s cheap and widely available, and extremely fire-resistant. So it got pressed into fireproof panels for walls and vehicles, building insulation, and because it’s fibrous it was even woven into fire-resistant clothes.
**Why it’s bad:** At a microscopic scale, asbestos is a [jumble of spiky needles](https://media.springernature.com/full/springer-static/image/art%3A10.1007%2Fs10853-019-03738-8/MediaObjects/10853_2019_3738_Fig5_HTML.jpg). They’re light enough to fly up in the air and get breathed in as dust, and they’re sharp enough to puncture cells and cause irritation and damage. What’s worse is they’re exactly the worst size for your body to eliminate. Normally, you have 2 systems for removing unwanted stuff from your lungs. For “big” stuff like bits of lint or outdoor debris, the tubes in your lungs are lined with [little arms called “cilia”](https://medlineplus.gov/ency/images/ency/fullsize/19533.jpg) that constantly “beat” to push inhaled stuff up out of your lungs to your throat. And for smaller-sized garbage like foreign chemicals or internal waste, the cells have an excretory system to send out any bad stuff that’s inside them. Turns out asbestos spikes are just the right size to stab through single cells – they’re too small to be swept away by cilia, but too big to be excreted by any cells they stab into. Therefore inhaled asbestos can stay in the lungs for years or decades, slowly puncturing and killing more and more lung cells over time and causing irritation and tiny wounds that build scar tissue.
**Cancer:** That scarring in itself is bad for your lung function and will impair you, but there’s also a significant cancer risk. Every time any cell divides, there’s a chance it will screw up and become cancer. Therefore the more cell division takes place, the more likely cancer will randomly arise. Wound-healing sites have particularly high cell-division rates, because your body is re-growing and replacing damaged tissue. So asbestos constantly re-injuring and scratching up your lungs for decades gives you an increasing chance of your lungs developing cancer.
Here is a website with much more information on what asbestos is, how to identify its many types and products, and how it causes sickness:
[https://www.asbestos.com/asbestos/](https://www.asbestos.com/asbestos/)
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