There are two main ways for bisphenol A in thermal paper to act on human body, through nose and mouth intervention and through skin pores.
Once exposed to bisphenol A excessively, it will do harm to health.
However, bisphenol A is not very toxic. It is exaggerated to say that holding a shopping receipt in your hand will lead to bisphenol A poisoning and cancer, so don't worry too much.