It has a strong ionization effect. Eating or breathing materials emitting alpha ray is said to be harmful to the body, because the body gets
Two protons and two neutrons fly out of a nucleus in groups that form alpha rays.

Its penetration force is so weak that a plastic plate of 1cm thickness can block it.
Internal exposure may be hazardous.
Beta rays are generated when negatively charged electrons are released at high speed. (Electrons are generally thought to be released when neutrons switch places with protons.)

Gamma rays are a kind of electromagnetic wave or, in other words, a kind of light. The same goes for X-rays.
A highly charged nucleus discharges a light-like “wave”. This wave is called an electromagnetic wave. After losing stability due to alpha and beta ray emission, the nucleus emits this wave to regain stability.
What is an X-ray?
As X-rays penetrate powerfully, they enable us to see into human bodies. Roentgen photographs make use of this power. By irradiating particular parts of human bodies with X-rays, which has a weak ionization effect, we can check bones or find abnormalities within our bodies.
Radiation generated by the atomic bombing of Hiroshima
Lead or thick iron plate is necessary to block gamma rays. Gamma rays penetrate human bodies and affect internal organs. More than 90% of the radiation emitted by the atomic explosion in Hiroshima was gamma.

Because of its electrically neutral status, its penetration force is tremendous. When neutrons collide with, and absorbed by, nuclei within elements of materials, the materials become radioactive. When a great amount of neutrons are taken in a human body, they alter various elements within the body, including hydrogen (70% of a human body consists of hydrogen, or body water), and cause severe physical disorders.
Neutron rays are particle beams consisting of neutrons. When a neutron collides with uranium nuclei, nuclear fission takes place and neutrons are emitted. These neutrons then bump into other uranium nuclei to trigger a chain reaction.
Although neutrons are not electrically charged, they can cause protons in hydrogen to be flicked out by colliding with positively charged protons in hydrogen nuclei.