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Comment by sgt101 | Hacker News Reader

The question is does it shed nanographite or other nano-carbon particles and if so, at what level. Of course, open fires and photocopiers produce these particles as well so there is some level of background exposure that appears to be somewhat "safe". I expect the "no such thing as safe" crowd will be out if they sniff the opportunity for a witch hunt or 10 [1]

[1] https://particleandfibretoxicology.biomedcentral.com/article...

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I did some IT work at a business that also was a training company for a long time and during renovations I had a desk between a server closet (like small room packed with servers hosting web sites) with no door on it and a massive "bizhub" style copier that was running constantly making training binders for the training business (yes, this was a while ago). My hearing was just shot at the end of each day and I was inhaling so much gunk from the printer that it was like living in a major city with a smog problem (as in stuff was coating the inside of my nose, my skin, etc). It took me a while to realize what was going on and I moved a few doors down to some older office space we had in the back of another business in the same strip of office spaces (this place had an ant infestation and no AC but at least I could breath again). It was a real eye opener in terms of noise/crud.

Are nanocarbon particles harmful? After all it's just carbon. Oragnisms should have a ton of mechanisms for dealing with it safely.

Even non-reactive particles like asbestos can cause a persistent inflammatory response eventually leading to cancer, chronic fatigue, malaise, etc. The ones that get the most attention these days are PM-2.5: tiny particles or droplets in the air that are two and one half microns or less in width, penetrate alveoli, and go straight into your blood stream.

More info: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4740125/

In about a decade or two brake dust pollution will be more recognized as a severe public health problem. It's not on the hype cycle yet. https://pubmed.ncbi.nlm.nih.gov/32593898/

Not just brake dust (which is probably solvable), but also rubber from tires.

But pure carbon is somewhat reactive, so maybe it could be cleaned by the body. Is it not?

Not sure, but there is definite collateral damage because it is biologically active.

From Fig 2. of https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7789336/

Mechanism of DNA methylation and histone modification alterations induced by nanomaterials and nanoparticles:

Exposure to NMs and NPs alters the functioning of chromatin-modifying proteins, e.g., DNA methylation and demethylation machinery, and histone-modifying enzymes, causing changes in the pattern of DNA methylation and histone modifications.

One of the most common effects of NMs and NPs is the induction of cellular stress, e.g., oxidative and endoplasmic reticulum stress, and metabolic disturbances, e.g., one-carbon metabolism and the citric acid cycle.

These events are causing DNA damage and repair response and metabolic alterations affecting the functioning of chromatin-modifying enzymes.

Any or all of these events may result in hypomethylation of DNA and altered histone modification patterns.

Additionally, exposure to NMs and NPs causes activation of the inflammatory response that, in turn, may cause DNA hypermethylation and histone modification changes

Benzene and similar flat aromatic carbon-based compounds are mutagenetic (cancer- and birth defect- causing) because they can slip between base pairs in DNA and disrupt replication.

I wonder whether graphene, itself a flat carbon compound, has the same affinity for DNA?

Molecular bond in benzene is little special. Maybe that's the source of mutagenic properties?

Carbon nanotubes are known to cause lung tumors.

Pure carbon really isn't something that a lot of organisms ever encounter.

Study on rats confirming this https://particleandfibretoxicology.biomedcentral.com/article...

You'd think, but in fact biochemistry is quite bad at disposing of pure carbon compounds. You can test this: stick a pencil lead into some compost for a week and pull it out.

I still have a piece of pencil lead stuck in my finger from 24 years ago, though it has gotten smaller. And I know someone with a piece more than twice that old.

Doesn't it contain a lot of clay?

Comparing my concrete wall to a photocopier seems a little bit strange.

Why?

Because if I do not use my photocopier it does not emit anything, it just emit things during usage. In contrast I do not "use" my wall. It maybe emits things when it is newly made, but otherwise it does not emit things.

The same arguments was true for asbestos as well. Asbestos building materials are totally harmless if left undisturbed. But eventually that wall will have to be be repainted/sanded/drilled into/knocked down.

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