PTFE, please. But that is a misreading of what the whole perfluoroalkyl substances kerfuffleage is about. Perfluoro refers to the replacement of all the hydrogens in an alkane with fluorine. There are certain perfluoro materials that are dangerous and toxic but there are other perfluoro materials that aren’t, just as will all chemicals. The ones that are toxic are the ones that have some kind of functional group on the molecule that can react with other materials.

Polytetrafluoroethylene (PTFE) has zero detrimental environmental impact because it is completely inert as I detailed above. It can’t be digested. It can’t be incorporated into a biological system because it can’t be broken down nor will it react with any biological system. It has no functionality on the chain of the molecule that can react with anything. It just exists and will exist for an eternity but it will be benign for that entire eternity.

I question the efficacy of PTFE in lubricants not because of environmental problems but because it is just a particle in a medium. In a wax medium, it might stay in place but in an oil medium it is going to flow around and not really do too much. It likely isn’t doing too much in wax either. It’s mostly there as a marketing tool.

Squirt is using a bit of PFAS washing there. There would be no need for any PFAS in Squirt. However that doesn’t get Squirt off the hook. Because Squirt is using water to apply a hydrophobic wax (water hating) to the chain, it has to use chemicals that have short term bioreactivity to do so. Squirt contains ethylene glycol (antifreeze) and morpholine (gives it that vague fish odor) in addition to other undisclosed surfactants to do the job. Ethylene glycol goes through the Kreb cycle (how mammals use food for energy) and metabolizes to oxalic acid which can precipitate out of the blood in the kidneys, resulting in renal failure. It doesn’t have a lot in it but ethylene glycol is far more reactive than any PFAS.

Morpholine is a flammable liquid and is highly corrosive to skin and eyes. Under certain conditions, it can form N-Nitrosomorpholine which is mutagenic and carcinogenic. Nitrites are needed for that but we humans use a lot of nitrites.

Don’t take this as being alarmist but only as information about how chemicals can have unintended consequences. A lot of the PFAS stories out there are alarmist because they don’t differentiate between problematic PFAS and nonproblematic PFAS. People hear the term and assume that all perfluoronated compounds are bad. Some are, some aren’t.