Answer to Question #5208 Submitted to "Ask the Experts"

I have developed posterior subcapular cataracts. I have received the following doses of ionizing radiation:

Upper bound gamma dose: 6.6 rem
Upper bound neutron dose: 0.003 rem
Mean eye dose (lens) beta plus gamma: 5.0 rem
Upper bound total eye dose(lens): 15.0 rem

Could this be enough radiation to cause my cataracts?

It is extremely unlikely that your cataracts are related to your radiation dose. Available data indicate clearly that cataracts are a deterministic effect, with a well-defined threshold dose. No progressive cataracts that interfere with vision have been found following radiation doses less than 50 rem, delivered as a single dose at a high dose rate. If the dose is spread over time, much larger doses are required. The confusion about sensitivity of the optic lens to radiation-induced cataracts came from misinterpretation of some early data from mouse studies. In those studies, smaller doses were associated with microscopic cataracts that did not grow or interfere with vision.

The National Council on Radiation Protection and Measurements has established an annual occupational dose limit of 15 rem to the eye for radiation workers. They state that this limit will prevent the occurrence of radiation-induced cataracts.

Conclusion: Your occupational radiation dose was not sufficient to cause your cataracts.

S. Julian Gibbs, DDS, PhD