,  and  -rays as well as neutrons X-rays.

doubly charged helium nuclei (42He2+) emitted by radioactive elements with a very high atomic number not external radiation hazard but if ingested. The tissue immediately becomes intensely ionized and this leads to cellular injury and cancer

high-speed electrons (  ) a range of kinetic energies. The outer layers of the skin absorb low energy particles those with a high kinetic energy can penetrate up to 3 mm and cause unpleasant skin burns. Many of the isotopes commonly used in biochemistry are  -emitters ( 3 H, 14 C, 32 P).

electromagnetic radiation of short wavelength and has no mass or charge. It is therefore extremely penetrating and creates areas of ionization following collision with atoms. Some of the isotopes used in biochemical work are  - emitters( 131 I, 54 Fe).

carry no charge and so are highly penetrating and thereby dangerous. However, they are rarely met in the biochemical laboratory.

All radiation must be treated as dangerous and exposure kept to an absolute minimum. It is as well to remember that there is no such thing as a 'safe' dose of radiation.