Threshold Values for Various Effects

Sensitivity to radiation differs by organ. The testes are most sensitive.

When the testes are exposed to γ-rays or other types of radiation exceeding 0.1 Gy (100 mGy) at one time, this may cause temporary sterility with a temporary decrease in the number of sperm, which is due to radiation damage to cells in the testes that create sperm.

When bone marrow is exposed to radiation exceeding 0.5 Gy (500 mGy), the number of blood cells decreases due to deterioration of hemopoietic capacity.

Some deterministic effects such as cataract take several years to appear.

The threshold dose for cataract had been set at 1.5 Gy, but the ICRP revised this value downward to approx. 0.5 Gy and set a new equivalent dose limit for the eye lens for occupational exposures.

• Included in this reference material on March 31, 2013
• Updated on March 31, 2015