With a perspective of typical levels of radiation exposure from different sources, the next question is what effects do exposure to radiation create and what do these effects depend on?
     Radiation biology is the study of the effects of exposure to radiation and their relationship to dose.  These effects progress according to the following chain of events:
    Radiation interacts producing ions, free radicals and chemically active species.
    Chemical reactions change a biologically significant structure or interfere with a biological process.
    An abnormal cell or species is created that may lead to further such material.  (most of the ions and chemical
 species either do nothing or are so destructive that the result is simply discarded trash and is subsequently repaired by systems in the body)
    Eventually the biological system is sufficiently upset that observable clinical symptoms can be observed and treated.  

    The expression of the effects depends for a large part on the amount of time spent around the radiation source.  An acute exposure refers to an exposure time that is very short or a one time exposure to a specific amount of radiation.  A chronic exposure refers to an exposure over a longer period of time such a one extended over hours or days or a perpetual exposure.  The effects can be divided into three categories:
   Somatic effects are observed in the exposed person.
           Prompt somatic effects are observable soon after a large acute dose (see   previous table).  Delayed somatic effects such as cancer may occur as   late as 30 years following exposure.
   Genetic effects are abnormalities that occur in future children of exposed individuals and in subsequent generations.
   Teratogenic effects may be observed in children who were exposed during the fetal and embryonic stages
        of development. 
     To better put into perspective the types of risk one is taking by being occupationally exposed to radiation, a risk comparison is shown in the table at the right which estimates days of life expectancy lost on average from various risks.  The table shows an estimate of 15 days of life expectancy lost from receiving 300 mrem/yr of occupational radiation dose.  This data is taken from the NRC Draft guide DG-8012 and were adapted from B.L. Cohen and I.S. Lee, "Catalogue of Risks Extended and Updates", Health Physics, Vol. 61, Sept 1991.  Laboratory workers at Emory do not receive exposures near 300 mrem/yr.