I would probably resin coat my floor instead of using urethane, but I would agree there. Even concrete floor contains silicates. I also wonder what kind of microparticles scuff off of a tile floor.

Shellac or traditional varnish are probably the only things you could put on your floor that aren't produced with an industrial process. Shellac in particular is the harvested secretions of a beetle that have been cleaned and dissolved in alcohol. But it's water-soluble and so probably not appropriate for use on a wood floor. You could also use tung oil or boiled linseed oil but you'd have to sand down to #0000 steel wool to get it to shine like urethane. Tung oil is a nice coating because it doesn't turn orange like BLO, but either one you will have to keep applying every few years or the floor will stop repelling water.

Obviously we'd end up with huge Tung plantations or Shellac plantations if we tried to replace all of our floor coverings with this stuff.

polyurethane is a resin

tung oil is pretty toxic. boiled linseed oil has heavy metal salts in it to make it polymerize, though typically nowadays these are cobalt, iron, and manganese rather than lead; calcium and zinc are basically nontoxic alternatives

shellac is not water-soluble; it's alcohol-soluble and thermoplastic

the plantation sizes necessary to coat everyone's floor with tung oil or shellac are fairly modest

"Boiled" linseed oil is not actually boiled, to save costs they just add metal salts to catalyze the polymerization. You can get linseed oil without the heavy metals, that is actually boiled: https://www.triedandtruewoodfinish.com/products/danish-oil/

danish oil has heavy metal salts in it, specifically salts of cobalt and zirconium: https://www.coo-var.co.uk/files/ww/safety/308-Q271%20-%20DAN...

ionic cobalt and ionic zirconium are both of fairly moderate toxicity; they aren't in the same ballpark as things like lead and mercury, but they also aren't as relatively harmless as calcium or zinc

i think that normal 'boiled' linseed oil does have stand oil in it, as well as the siccatives we're talking about here and other additives like antiskinning agents

The one by Tried&True appears to be pure linseed oil: https://s3.gomedia.ws/wp-content/uploads/sites/11/2016/03/FB...

I’d worry less about silicates than anything. We evolved along sandy coastlines not polyurethane or pvc.

crystalline silica is an iarc group 1 carcinogen, the highest-concern category, and occupational illnesses due to crystalline silica exposure have been well known for thousands of years

When I built my home I used concrete floors that I then kept waxed. It seemed like the best solution I could find. But then we had to cover the floors with wool rugs because the acoustics were painful.

wool is pretty great; the worst you can say about it is that it's a mild allergen and kind of expensive

just to disambiguate, though, the risk of silica exposure from walking around on a concrete floor, or even sweeping it, is not worth worrying about. i wouldn't clean it with a leaf blower though

I assume you don’t cut tile with a tile saw very often without a respirator so its a non issue.

To my knowledge, olefin synthetic carpet is not known to contain phthalates. I would however avoid the ones that claim to be stain-resistant, as they're more likely to contain iffy coatings.

Carpets often repel water… using PFAS.

Yeah, and I bet even the expensive wool stuff that only rich people buy is treated with scotch guard and flame retardants with questionable health effects.

Bonus - scotch guard == PFAS