Radiation is energy in motion, in the form of moving waves or particles.
Radiation with enough energy to knock an electron from an atom is called ionising radiation. This means ionising radiation can break chemical bonds, such as those in DNA.
Quotes from ICRP Publications
Publication 103 paragraph 19
[The recommendations of ICRP] ... are confined to protection against ionising radiation. The Commission recognises the importance of adequate control over sources of non-ionising radiation. The International Commission on Non-Ionizing Radiation Protection, ICNIRP, provides recommendations concerning such sources ...