natural processes. For solid radiation damage Solid countermeasures to radiation damage consist of three approaches. Firstly, saturating the matrix with oversized solutes. This acts to trap the swelling that occurs as a result of the creep and dislocation motion. They also act to help prevent diffusion, which restricts the ability of the material to undergo radiation induced segregation. Secondly, dispersing an oxide inside the matrix of the material. Dispersed oxide helps to prevent creep, and to mitigate swelling and reduce radiation induced segregation as well, by preventing dislocation motion and the formation and motion of interstitials. Finally, by engineering grain boundaries to be as small as possible, dislocation motion can be impeded, which prevents the embrittlement and hardening that result in material failure. Effects on humans Ionizing radiation is generally harmful and potentially lethal to living things but can have health benefits in radiation therapy for the treatment of cancer and thyrotoxicosis. Its most common impact is the induction of cancer with a latent period of years or decades after exposure. High doses can cause visually dramatic radiation burns, and/or rapid fatality through acute radiation syndrome. Controlled doses are used for medical imaging and radiotherapy. Most adverse health effects of radiation exposure may be grouped in two general categories: Deterministic effects (harmful tissue reactions) due in large part to the killing/ malfunction of cells following high doses; and Stochastic effects, i.e., cancer and heritable effects involving either cancer development in exposed individuals owing to mutation of somatic cells or heritable disease in their offspring owing to mutation of reproductive (germ) cells. See also Radiation material science Stopping power (particle radiation) Collision cascade Ion track Radiation hardening Radiation Damage in Metals and Alloys References Radiation effects