Typical beta particles can travel several millimeters through tissue, but they generally do not penetrate far enough to reach the vital inner organs. Exposure to beta particles from outside the body is normally thought of as a slight hazard.

However, if the skin is exposed to large amounts of beta radiation for long periods of time, skin burns similar to heat burns may result. If removed from the skin shortly after exposure, beta-emitting materials will not cause serious burns and will not pose a severe external hazard. Beta particles may be a major hazard when emitted by internally deposited radioactive material or when interacting with the lens of the eye.

Beta particles can be taken into the body by eating food, drinking water, or breathing air containing radioactive material. Beta emitting contamination can also enter the body through unprotected open wounds.