What type of radiation is most damaging to biological tissue?

Alpha particles are considered the most damaging type of radiation to biological tissue, particularly when they are ingested or inhaled. This is due to their significant mass and charge, which allow them to cause more extensive damage when they interact with biological materials. Because alpha particles have a high energy and a relatively short range, they cannot penetrate the skin effectively. However, if alpha-emitting materials are inhaled or ingested, they can directly impact internal organs and tissues, leading to potentially severe biological damage at the cellular level.

In contrast, gamma rays and X-rays are forms of electromagnetic radiation that, while capable of penetrating tissues, typically deposit less energy in a single location compared to alpha particles. Beta particles, which are charged electrons or positrons, also pose a risk but generally have a less destructive potential than alpha particles when absorbed by tissues. Hence, the unique properties of alpha particles make them particularly hazardous when they enter the body, resulting in a higher potential for biological damage.