from an article published on the European Chemicals Agency site:
In December 2016, the European Commission decided to restrict BPA in thermal paper in the EU. This ban will take effect in 2020, giving manufacturers, importers and users of thermal paper the time to phase it out and find an alternative.
As a result of the restriction, paper manufacturers will need to replace BPA with other dye developers. One potential replacement that is being considered by industry is the chemical Bisphenol S (BPS). However, concerns have been expressed that it may cause similar health problems to BPA. To make sure that one hazardous chemical is not being replaced by another, BPS is currently under substance evaluation and the European Commission has also asked ECHA to further investigate the use of BPS as a substitute for BPA in thermal paper.