Thorium Safety

 
  • This item contains a small amount of thorium fluoride, a type of source material (less than 10% by weight).
  • It is exempt from USNRC licensing regulations as an “unimportant quantity of source material” per 10 CFR 40.13(c) (7).
  • Shaping, grinding, polishing, or alteration of the optical component is prohibited.
  • Use of this optical component in contact lenses, spectacles, or in eyepieces in binoculars or other similar optical instruments is prohibited.

For additional information contact:

                II-VI Optical Systems
                36570 Briggs Road, Murrieta, CA 92563, USA
                Tel. 951.926.2994
                Email: OpticalSystems.thoriumsafety@ii-vi.com

The purpose of this website is to provide information on coated optics which contain a very small amount of thorium (a naturally occurring radioactive material) as a part of the coating. Please note that optics are delicate, and should be handled with care using gloves to ensure they work effectively as designed.

The radiation exposure a user gets from the optics is a small fraction of the background dose a member of the general public receives. A Pacific Northwest National Laboratory (PNNL) study (Accession Number ML070750105 which can be found on the US Nuclear Regulatory Commission's (USNRC) Adams search engine) indicated that doses from both normal and accident conditions from lenses coated with thorium (such as the product you are using) were estimated to be well below 10 microsievert (mSv) per year (1 mrem per year). This value is a very small fraction of the 620 mrem per year an individual is expected to get from background sources (natural and man-made).

As per NRC regulation 10 CFR 40.13(c) (7), shaping, grinding, polishing, or alteration of finished optical components containing uranium or thorium in the coating is prohibited. If altered, finished optical components are no longer considered II-VI Optical Systems manufactured optical components and will be subject to USNRC distribution regulations if sold in the U.S.

Please note that optical components distributed by II-VI Optical Systems as authorized by USNRC regulation 10 CFR 40 contain thorium, but not uranium.

Use of this optical component containing thorium in the coating in contact lenses, spectacles, or in eyepieces in binoculars or other similar optical instruments is prohibited.

In order for finished optical components manufactured by II-VI Optical Systems and containing thorium to be distributed in the U.S. as authorized by USNRC regulation 10 CFR 40, they must maintain the same safety label that II-VI Optical Systems placed on the packaging for the optical component, or include the following information either on a safety label or in any manuals or safety instructions for the system that incorporates a II-VI Optical Systems optical component:

  • This- system incorporates a II-VI Optical Systems optical component.
  • This optical component contains a small amount of thorium fluoride, a type of source material (less than 10% by weight).
  • It is exempt from USNRC licensing regulations as an “unimportant quantity of source material” per 10 CFR 40.13(c) (7).
  • Shaping, grinding, polishing, or alteration of the optical component is prohibited.
  • Use of this optical component in contact lenses, spectacles, or in eyepieces in binoculars or other similar optical instruments is prohibited.

Cleaning optical components is permitted so long as care is taken not to damage the coated surface of the component as sold.
This II-VI Optical Systems requirement only applies to lenses and optics manufactured and distributed by II-VI Optical Systems. Distributing components or devices that contain lenses and optics manufactured by other companies as if it were manufactured by II-VI Optical Systems is not in compliance with USNRC distribution requirements.

U.S. distribution of components or devices that contain lenses and optics manufactured by other companies which contain uranium and/or thorium requires a USNRC distribution license. Only II-VI Optical Systems manufactured lenses and optics which contain thorium are covered by the II-VI Optical Systems distribution license.