[z2]

The most mainstream phenol free thermal paper out there is one made from a branded chemical "pergafast" which is supposedly based off of urea. This is increasingly the type used by big brand stores where the paper is advertised as BPA and BPS free. It appears safe in studies so far in terms of not being absorbed through the skin nor endocrine disrupting, but is also known to be highly toxic to aquatic life. There's another chemical related to vitamin c branded "Alpha Free" but it's harder to find.

https://www.sciencedirect.com/science/article/abs/pii/S02732...

[account42]

Always remember that X-free or similar claims of not being toxic only means that the substances used instead of X are not yet known to be as toxic (or at just that the laws haven't caught up yet). It isn't guarantee that the new product is any safer than X and it might even be less safe. After all, the X in question was also seen as perfectly fine at some point.

[ComputerGuru]

It's actually known that many of the alternatives companies have substituted for BPA are equally or more dangerous; they're just not blacklisted by the FDA so companies continue to use them with impunity.

https://www.nationalgeographic.com/premium/article/bpa-subst...

https://archive.is/Bu6TE