Thorium fluoride as a coating is transparent to both UV and IR radiation and vacuum deposited thin films of ThF 4 are quite chemically stable. Thorium compounds all contain naturally occurring radioactive thorium.
Ionizing radiation is emitted, including beta and gamma radiation.
There is low risk of external radiation when handling small quantities of thorium compounds. Common sense would dictate that exposure be limited at all times and inhalation of the powder should definitely be avoided. Proper protection such as the use of the proper OSHA approved masks should be used whenever there is even the slightest possibility of air borne particles could be present. Thorium fluoride contains naturally occurring and therefore radioactive thorium, which emits ionizing radiation, mainly alpha particles. While this radio decay is occurring, beta particles and gamma radiation can be expected .