http://www.epa.gov/rpdweb00/understand/beta.html#affecthealth
Health Effects of Beta particles
How can beta particles affect people's health?
Beta radiation can cause both acute and chronic health effects. Acute exposures are uncommon. Contact with a strong beta source from an abandoned industrial instrument is the type of circumstance in which acute exposure could occur. Chronic effects are much more common.
Chronic effects result from fairly low-level exposures over a along period of time. They develop relatively slowly (5 to 30 years for example). The main chronic health effect from radiation is cancer. When taken internally beta emitters can cause tissue damage and increase the risk of cancer. The risk of cancer increases with increasing dose.
Some beta-emitters, such as carbon-14, distribute widely throughout the body. Others accumulate in specific organs and cause chronic exposures:
* Iodine-131 concentrates heavily in the thyroid gland. It increases the risk of thyroid cancer and other disorders.
* Strontium-90 accumulates in bone and teeth.
