I used to work as a bench tech at a defense contractor (microwave equipment).
Every tech had a little bottle on their bench, with a special lid, that would have a small amount of liquid always in it (you'd pump it, to bring up more liquid). These bottles are still used, today.
This was for removing solder flux. Worked great.
At the end of each row of tech benches, was a red bucket, full of the same stuff. We'd use that to wash entire boards.
If you got the liquid on your skin, it made the skin turn white, and flake off.
Smelled like acetone had a one-night-stand with gasoline.
The liquid was trichlor[0] (not the pool kind).
Our management swore that it was perfectly safe, and that we could even drink it.
The industry started with carbontet (CTC), they replaced it in the 70s with the perchlor stuff you're describing (PCE) in the 80s, then with Trichlorethylene (TCE) in the early 90s, which in turn was replaced with (TCA) Trichlorethane and now all the chlorinated stuff is gone (along with the PCB industry). There's still isopropyl and GBL butyrolactone (which is regulated as a precursor to GHB) for degreasing.
Back in the 60s carbontet was used everywhere (dry cleaning and industrial) and there are superfund sites in Happy Tx and Alabama.
Everyone has seen the walk through dry cleaning right?
https://youtu.be/WbkfkcSiYcI
We're literally 60 years since the first regulation. And your local dry cleaner was leaking chlorinated solvents into the 80s. Now the cleanup for old gas stations is mostly complete, but the new MTBE stuff is nasty!
1,1,1-trichloroethane doesn't seem particularly toxic - "probable carcinogen", some neurological and liver effects but I'd say it's probably still safer than e.g. isopropyl alcohol which definitely leads to neurological issues long-term. The reason it's banned is because of the ozone layer, not because it's unsafe to individual humans.
Every tech had a little bottle on their bench, with a special lid, that would have a small amount of liquid always in it (you'd pump it, to bring up more liquid). These bottles are still used, today.
This was for removing solder flux. Worked great.
At the end of each row of tech benches, was a red bucket, full of the same stuff. We'd use that to wash entire boards.
If you got the liquid on your skin, it made the skin turn white, and flake off.
Smelled like acetone had a one-night-stand with gasoline.
The liquid was trichlor[0] (not the pool kind).
Our management swore that it was perfectly safe, and that we could even drink it.
This was in the early 1980s.
[0] https://en.wikipedia.org/wiki/1,1,1-Trichloroethane