The field of radiobiology began with the discovery that high doses of radiation could cause cancer and other health effects. Since then, the understanding and control of radiation exposure has been a concern. Because of this concern, radiobiologists know more about the health effects of high doses of radiation than almost any other environmental insult. The challenge of radiobiological research, however, continues to be to determine if there are health effects from low doses of radiation.

Everyone is exposed to low levels of radiation through natural background radiation, medical procedures and common items such as smoke detectors and televisions. Previously, it was necessary to estimate the biological effects of low doses,. which could not be seen, from visible high-dose effects, such as cancer from the A-Bomb. These estimates were necessary because it was not possible to directly measure the biological effects of low dose exposure. National and international committees used these estimates to determine low dose risk. From these extrapolations, they determined that the most prudent public policy would be to assume that each unit of radiation creates an increased health risk. Recent scientific advances developed by biological research efforts, such as the sequencing of the human genome, have opened new horizons for radiobiology. New techniques have made it possible to directly determine how molecules, cells, tissues, animals and humans respond to low doses of radiation.

Over the past five years, the focus of radiobiology in the low dose region has resulted in many interesting observations. Bystander effects, adaptive response, changes in gene expression, genomic instability, and genetic susceptibility have all been observed in this dose region. These new observations of interaction between radiation and cells have required radiobiologists to rethink the concept that every bit of radiation creates an increased health risk. New information from low dose radiation research may provide a link between cell/molecular studies and radiation-induced cancer. Radiobiology continues to provide valuable information that will help develop better methods for using radiation in the treatment of disease as well as provide a scientific basis for radiation protection standards.